Commit Graph

1400 Commits

Author SHA1 Message Date
Matthew Schwartz
93f53499d0 x86/fred: Reconstruct the #GP context for rejected INT instructions
FRED event delivery does not use the IDT, so the gate DPL check that
rejects a user INT n falls to software (Intel FRED specification [1],
section 8.3). fred_intx() rejects the same vectors as IDT delivery, but
reports a zero error code and the IP after the INT. This breaks the
signal ABI. Wine uses the error code to recognize INT 0x2d, so the
changed context turns a handled breakpoint into an access violation in
Elden Ring.

Rewind IP using the instruction length in the augmented SS and
synthesize the IDT selector error code, (vector << 3) | 2. Set RF in the
saved flags, as the CPU does for a #GP fault. Section 5.2.1 defines the
saved vector, instruction length and RF state. The supplied length
handles prefixes without reading user memory. Limit the changes to
already-rejected software interrupts, preserving the accepted INT3, INT4
and enabled INT80 paths and hardware exceptions. With IA32 emulation
disabled, INT 0x80 now reports the same #GP as the DPL 0 gate IDT
installs there. The rewound IP also stops fixup_iopl_exception() from
inspecting the byte after the INT.

Also clear the software event flag. Section 6.2.3 specifies that ERETU
with this flag and TF set traps before executing any user instruction. A
tracer that suppresses SIGSEGV and resumes with TF set expects the next
instruction to run first, as after IRET. The sigreturn path clears the
same flag for this reason in prevent_single_step_upon_eretu().

[1] Intel Flexible Return and Event Delivery (FRED) Specification,
revision 9.0 (346446-009US), sections 5.2.1, 6.2.3 and 8.3.

Fixes: 14619d912b ("x86/fred: FRED entry/exit and dispatch code")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/work_items/15745
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/work_items/16132
Reported-by: Paul Gofman <pgofman@codeweavers.com>
Signed-off-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: H. Peter Anvin <hpa@zytor.com>
Link: https://cdrdv2.intel.com/v1/dl/getContent/678938 # [1]
Link: https://patch.msgid.link/20260917230907.2080792-2-matthew.schwartz@linux.dev
2026-09-18 12:33:17 +02:00
Linus Torvalds
23eb790181 Fix frame pointer unwinder when it encounters FRED stack frames
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Merge tag 'x86_entry_for_7.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 entry update from Dave Hansen:
 "Fix frame pointer unwinder when it encounters FRED stack frames"

* tag 'x86_entry_for_7.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/entry/fred: Encode frame pointer on entry
2026-08-18 17:38:30 -07:00
Linus Torvalds
104a813376 VDSO updates:
- Consolidate the VDSO datastore further and provide support for
    mlock_all() and prefaulting.
 
  - Provide 32-bit legacy time related functionality only if
    CONFIG_COMPAT_32BIT_TIME is enabled. The config switch exists, but
    architecture code still exposes the legacy functionality even disabled.
 
    Clean this up by adding the missing guards and validating at build time
    that the VDSO is legacy free if disabled.
 
  - Consolidate the VDSO related config options in core and drivers, which
    removes some non-sensical dependencies and quite an amount of #ifdeffery.
 
  - Clean up the PAGE_SIZE definition maze
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Merge tag 'timers-vdso-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull VDSO updates from Thomas Gleixner:

 - Consolidate the VDSO datastore further and provide support for
   mlock_all() and prefaulting.

 - Provide 32-bit legacy time related functionality only if
   CONFIG_COMPAT_32BIT_TIME is enabled. The config switch exists,
   but architecture code still exposes the legacy functionality even
   disabled.

   Clean this up by adding the missing guards and validating at build
   time that the VDSO is legacy free if disabled.

 - Consolidate the VDSO related config options in core and drivers,
   which removes some non-sensical dependencies and quite an amount of
   #ifdeffery.

 - Clean up the PAGE_SIZE definition maze

* tag 'timers-vdso-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
  random: vDSO: Drop custom PAGE_SIZE definitions
  LoongArch: Remove CONFIG_GENERIC_GETTIMEOFDAY ifdeffery
  clocksource/drivers/timer-riscv: Remove CONFIG_GENERIC_GETTIMEOFDAY ifdeffery
  clocksource/drivers/arm_arch_timer: Remove CONFIG_GENERIC_GETTIMEOFDAY ifdeffery
  clocksource/drivers/mips-gic-timer: Remove CONFIG_GENERIC_GETTIMEOFDAY ifdeffery
  MIPS: csrc-r4k: Remove CONFIG_GENERIC_GETTIMEOFDAY ifdeffery
  vDSO: Make clockmode constants available without CONFIG_GENERIC_GETTIMEOFDAY
  kbuild: Support generated asm-headers in subdirectories
  vdso: Rename HAVE_GENERIC_VDSO to VDSO_DATASTORE
  vdso: Drop HAVE_GENERIC_VDSO from architecture kconfig files
  vdso: Automatically select HAVE_GENERIC_VDSO if necessary
  MIPS: vdso: Stop using CONFIG_HAVE_GENERIC_VDSO
  vdso: Remove the dependency on HAVE_GENERIC_VDSO from ARCH_HAS_VDSO_ARCH_DATA
  futex: Remove dependency on HAVE_GENERIC_VDSO from FUTEX_ROBUST_UNLOCK
  vdso/gettimeofday: Verify COMPAT_32BIT_TIME interactions
  sparc: vdso: Respect COMPAT_32BIT_TIME
  MIPS: VDSO: Respect COMPAT_32BIT_TIME
  powerpc/vdso: Respect COMPAT_32BIT_TIME
  ARM: VDSO: Respect COMPAT_32BIT_TIME
  arm64: vdso32: Respect COMPAT_32BIT_TIME
  ...
2026-08-18 16:56:25 -07:00
Linus Torvalds
3424d8c18a Generic entry code updates:
- Make syscall user dispatching configurable
 
     Not all architectures can makes use of syscall user dispatching. Allow
     them to disable the feature completely.
 
   - Consolidate stack randomization for the generic entry code and the
     architectures using it.
 
     Stack randomization on syscall entry was sprinkled throughout the
     architecture specific low level entry code and in some cases at the
     wrong points, e.g. before establishing state, which violates the
     non-instrumentable constraints of that code.
 
     Clean this up by integrating stack randomization into the generic entry
     code helpers so that it is invoked at the earliest possible point right
     after establishing state and converting all generic entry code using
     architecture over.
 
   - Clean up the syscall number handling in the generic entry code. It
     works correctly for architectures which have a separate return value
     storage in pt_regs, but fails to distinguish the case where user space
     handed in -1 as syscall number from the case where the entry code
     rejects it by returning -1 to the callers. Aside of that the return
     value functionality of those interfaces is not really intuitive.
 
     Fix this by separating the decision to reject a syscall (user dispatch,
     ptrace, seccomp ...) from the potential modification of the syscall
     number through these mechanisms.
 
     This solves most of the problems for architectures which do not have a
     separate return value storage in pt_regs except for the case where a
     tracepoint has a BPF script or a probe attached which overwrite both
     the syscall number and the return value. But that's a problem which
     cannot be solved in the generic code, that only can be addressed by
     separating the storage model in the affected architectures.
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Merge tag 'core-entry-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull generic entry code updates from Thomas Gleixner:

 - Make syscall user dispatching configurable

   Not all architectures can makes use of syscall user dispatching.
   Allow them to disable the feature completely.

 - Consolidate stack randomization for the generic entry code and the
   architectures using it.

   Stack randomization on syscall entry was sprinkled throughout the
   architecture specific low level entry code and in some cases at the
   wrong points, e.g. before establishing state, which violates the
   non-instrumentable constraints of that code.

   Clean this up by integrating stack randomization into the generic
   entry code helpers so that it is invoked at the earliest possible
   point right after establishing state and converting all generic entry
   code using architecture over.

 - Clean up the syscall number handling in the generic entry code. It
   works correctly for architectures which have a separate return value
   storage in pt_regs, but fails to distinguish the case where user
   space handed in -1 as syscall number from the case where the entry
   code rejects it by returning -1 to the callers. Aside of that the
   return value functionality of those interfaces is not really
   intuitive.

   Fix this by separating the decision to reject a syscall (user
   dispatch, ptrace, seccomp ...) from the potential modification of the
   syscall number through these mechanisms.

   This solves most of the problems for architectures which do not have
   a separate return value storage in pt_regs except for the case where
   a tracepoint has a BPF script or a probe attached which overwrite
   both the syscall number and the return value. But that's a problem
   which cannot be solved in the generic code, that only can be
   addressed by separating the storage model in the affected
   architectures.

* tag 'core-entry-2026-08-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  entry, treewide: Make syscall_enter_from_user_mode[_work]() indicate syscall execution
  entry: Make return type of syscall_trace_enter() bool
  entry: Rework trace_syscall_enter()
  entry: Rework syscall_audit_enter()
  syscall_user_dispatch: Introduce ARCH_SUPPORTS_SYSCALL_USER_DISPATCH
  entry: Fix seccomp bypass after ptrace with TSYNC
  x86/entry: Simplify the syscall number logic
  x86/entry: Get rid of the sys_ni_syscall() indirection
  x86/entry: Make syscall functions static
  ptrace, treewide: Rename ptrace_report_syscall_entry() to ptrace_report_syscall_permit_entry()
  seccomp, treewide: Rename and convert __secure_computing() to return boolean
  entry: Use syscall number instead of rereading it
  entry: Remove syscall_enter_from_user_mode()
  x86/syscall: Use [syscall_]enter_from_user_mode_randomize_stack()
  s390/syscall: Use enter_from_user_mode_randomize_stack()
  riscv/syscall: Use syscall_enter_from_user_mode_randomize_stack()
  powerpc/syscall: Use syscall_enter_from_user_mode_randomize_stack()
  loongarch/syscall: Use syscall_enter_from_user_mode_randomize_stack()
  entry: Provide [syscall_]enter_from_user_mode_randomize_stack()
  randomize_kstack: Provide add_random_kstack_offset_irqsoff()
  ...
2026-08-18 15:00:56 -07:00
Linus Torvalds
cd051cfe1e vfs-7.3-rc1.failfs
Please consider pulling these changes from the signed vfs-7.3-rc1.failfs tag.
 
 Thanks!
 Christian
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Merge tag 'vfs-7.3-rc1.failfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull failfs filesystem from Christian Brauner:
 "Add failfs and expose a FD_FAILFS_ROOT sentinel.

  This allows userspace to shed their filesystem state completely. A
  process with its root or working directory in failfs must anchor every
  path lookup at an explicit file descriptor. Absolute paths, absolute
  symlinks and AT_FDCWD-relative lookups simply fail.

  Failfs is the counterpart to nullfs. nullfs says adds a permanently
  empty, immutable directory whose lookups fail with ENOENT but which
  can be opened, read, stat'd and mounted upon. Failfs on the other hand
  fails every operation. The root cannot be opened at all. A single
  instance is mounted during early boot via kern_mount(), which makes it
  logically distinct from every mount namespace.

  This is accompanied by a new fchroot() system call which makes
  chrooting via a file descriptor a first class concept. It's possible
  to chroot into failfs as an unprivileged user provided the task has no
  new privileges set"

* tag 'vfs-7.3-rc1.failfs' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  Documentation: add failfs documentation
  selftests/filesystems: add failfs selftests
  arch: hookup fchroot() system call
  fs: support FD_FAILFS_ROOT in fchroot()
  fs: add fchroot()
  fs: support FD_FAILFS_ROOT in fchdir()
  fs: add failfs
2026-08-17 09:15:52 -07:00
Christian Brauner
79d27fd718
arch: hookup fchroot() system call
Wire up the fchroot() system call as number 472 on (nearly) all
architectures and sync the mirrored copies of the syscall tables and
the asm-generic unistd.h under tools/.

Link: https://patch.msgid.link/20260724-work-failfs-v2-5-485dabbae185@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
2026-07-27 17:18:00 +02:00
Borislav Petkov (AMD)
7e7f81cf6f x86/bugs: Make Safe-RET robust against interrupt injection
An attacker injecting interrupts while the Safe-RET mitigation executes
on machines affected by SRSO can neutralize the safe return sequence,
potentially leading to data leakage through speculative execution.

Fixup register state as if the Safe-RET sequence executed successfully
by "emulating" it, in a manner of speaking, and avoid executing a RET
instruction after returning from the interrupt.

Co-developed-by: David Kaplan <David.Kaplan@amd.com>
Signed-off-by: David Kaplan <David.Kaplan@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
2026-07-26 07:21:37 -07:00
Thomas Gleixner
05c033db7e entry, treewide: Make syscall_enter_from_user_mode[_work]() indicate syscall execution
The return values of syscall_enter_from_user_mode[_work]() are
non-intuitive. Both functions return the syscall number which should be
invoked by the architecture specific syscall entry code. The returned
number can be:

  - the unmodified syscall number which was handed in by the caller

  - a modified syscall number (ptrace, seccomp, trace/probe/bpf)

That has an additional twist. If the return value is -1L then the caller is
not allowed to modify the return value as that indicates that the modifying
entity requests to abort the syscall and set the return value already. That
can obviously not be differentiated from a syscall which handed in -1 as
syscall number.

The most trivial way to deal with that is:

    set_return_value(regs, -ENOSYS);
    nr = syscall_enter_from_user_mode(regs, nr);
    if (valid(nr))
    	handle_syscall(regs, nr);

That's what LOONGARCH, RISCV, and X86 do. But PowerPC and S390 do not
preset the return value, so when user space hands in -1 and there is
nothing setting the return value in the entry work code, then the syscall
is skipped but the return value is whatever random data has been in the
return value register.

Change the return values of syscall_enter_from_user_mode[_work]() to
boolean and return false, when either ptrace or seccomp request to skip the
syscall. If they return true, update the syscall number as it might have
been changed.

That results in slightly different behaviour of the architectures versus
tracing.

If the syscall tracepoint has probe/BPF attached, those might set the
syscall number to -1 and also set the return value. PowerPC and S390 will
then overwrite that value with -ENOSYS. The other architectures will just
ignore it like any other invalid syscall and use the modified one.

Originally-by: Michal Suchánek <msuchanek@suse.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Michal Suchánek <msuchanek@suse.de>
Link: https://patch.msgid.link/20260712141346.772209074@kernel.org
2026-07-20 20:38:40 +02:00
David Stevens
dab01c597f x86/entry/fred: Encode frame pointer on entry
Add missing ENCODE_FRAME_POINTER macro invocation into FRED_ENTER macro,
to prevent the unwinder from encountering a NULL stack frame pointer
when CONFIG_UNWINDER_FRAME_POINTER is enabled

Fixes: 14619d912b ("x86/fred: FRED entry/exit and dispatch code")
Signed-off-by: David Stevens <stevensd@google.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Link: https://patch.msgid.link/20260424191456.2679717-12-stevensd@google.com
2026-07-14 11:08:12 -07:00
Thomas Gleixner
fb419d53f2 x86/entry: Simplify the syscall number logic
Converting from int to long, back to int and then to unsigned int is
confusing at best.

None of this voodoo is required. Negative syscall numbers including -1
don't need any of this treatment and the low level ASM code already does
the sign extension to 64-bit on a 64-bit kernel.

The only point where signedness matters is the comparison against the
maximum syscall number, but that can be simplified by just using a unsigned
argument for the various syscall invocation functions.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Link: https://patch.msgid.link/20260707190254.545214398@kernel.org
2026-07-12 12:38:02 +02:00
Thomas Gleixner
1b1f3b3e1b x86/entry: Get rid of the sys_ni_syscall() indirection
Invoking sys_ni_syscall() from a code path, which already knows that the
syscall number is invalid just to assign -ENOSYS to regs->ax is a pointless
exercise. It's even redundant as the low level entry code already has set
regs->ax to -ENOSYS on entry.

Remove the extra conditionals and the function calls.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20260707190254.493733289@kernel.org
2026-07-12 12:38:02 +02:00
Thomas Gleixner
2b341c74db x86/entry: Make syscall functions static
They are only used in the respective source files. No point in exposing
them.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Link: https://patch.msgid.link/20260707190254.438361565@kernel.org
2026-07-12 12:38:02 +02:00
Jinjie Ruan
7ba2ba7471 seccomp, treewide: Rename and convert __secure_computing() to return boolean
The return value of __secure_computing() currently uses 0 to indicate
that a system call should be allowed, and -1 to indicate that it should
be blocked/killed. This 0/-1 pattern is non-intuitive for a security
check function and makes the control flow at the call sites less readable.

Furthermore, any potential future changes to these return values would
require a high-risk, error-prone audit of all its users across different
architectures.

Sanitize this logic by converting the return type of __secure_computing()
to a proper boolean, where 'true' explicitly means 'allow' and 'false'
means 'fail/deny'.

Update all the two dozen or so call sites across the tree to align with
this new boolean semantic. No functional changes are intended, as the
callers still return -1 to the lower-level assembly entry code upon
seccomp denial.

Rename the function to __seccomp_permit_syscall() so that the purpose is
entirely clear.

[ tglx: Rename the function ]

Suggested-by: Thomas Gleixner <tglx@kernel.org>
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Link: https://patch.msgid.link/20260707190254.230735780@kernel.org
2026-07-12 12:38:02 +02:00
Thomas Gleixner
9d311796e2 x86/syscall: Use [syscall_]enter_from_user_mode_randomize_stack()
These functions integrate the stack randomization.

syscall_enter_from_user_mode_randomize_stack() has the advantage that the
randomization happens early right after enter_from_user_mode().

In both cases also the overhead of get/put_cpu_var() in
add_random_kstack_offset() is avoided.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Radu Rendec <radu@rendec.net>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Link: https://patch.msgid.link/20260707190254.079478122@kernel.org
2026-07-12 12:38:01 +02:00
Thomas Weißschuh
1a4660da31 x86/vdso: Respect COMPAT_32BIT_TIME
If CONFIG_COMPAT_32BIT_TIME is disabled then the vDSO should not
provide any 32-bit time related functionality. This is the intended
effect of the kconfig option and also the fallback system calls would
also not be implemented.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260702-vdso-compat_32bit_time-v3-3-db9f36d8d432@linutronix.de
2026-07-07 23:52:53 +02:00
Linus Torvalds
c61f479852 - Remove redundant GHCB initialization guards in the SEV page state and SVSM
call paths now that the GHCB helpers handle early-boot fallback internally
 
 - Skip SNP initialization in the CCP driver immediately when the preparation
   step fails rather than proceeding to an operation that will certainly fail
 
 - Abort SNP preparation and return an error when not all CPUs are online,
   since the firmware enforces that every CPU enables SNP and will fail init if
   not
 
 - Simplify the VMM communication exception entry path by replacing separate
   kernel and user mode macros with a single handler that dispatches based on
   the current privilege level
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Merge tag 'x86_sev_for_v7.2_rc1' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip

Pull x86 SEV updates from Borislav Petkov:

 - Remove redundant GHCB initialization guards in the SEV page state and
   SVSM call paths now that the GHCB helpers handle early-boot fallback
   internally

 - Skip SNP initialization in the CCP driver immediately when the
   preparation step fails rather than proceeding to an operation that
   will certainly fail

 - Abort SNP preparation and return an error when not all CPUs are
   online, since the firmware enforces that every CPU enables SNP and
   will fail init if not

 - Simplify the VMM communication exception entry path by replacing
   separate kernel and user mode macros with a single handler that
   dispatches based on the current privilege level

* tag 'x86_sev_for_v7.2_rc1' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip:
  x86/sev: Remove redundant ghcbs_initialized checks around __sev_{get,put}_ghcb()
  crypto/ccp: Skip SNP_INIT if preparation fails
  x86/sev: Do not initialize SNP if missing CPUs
  x86/entry: Zap the #VC entry user and kernel macros
2026-06-16 05:57:30 +05:30
Linus Torvalds
764e77d868 Locking updates for v7.2:
Futex updates:
 
  - Optimize futex hash bucket access patterns (Peter Zijlstra)
 
  - Large series to address the robust futex unlock race for real,
    by Thomas Gleixner:
 
     "The robust futex unlock mechanism is racy in respect
      to the clearing of the robust_list_head::list_op_pending
      pointer because unlock and clearing the pointer are not
      atomic. The race window is between the unlock and clearing the
      pending op pointer. If the task is forced to exit in this
      window, exit will access a potentially invalid pending op
      pointer when cleaning up the robust list. That happens if
      another task manages to unmap the object containing the lock
      before the cleanup, which results in an UAF. In the worst case
      this UAF can lead to memory corruption when unrelated content
      has been mapped to the same address by the time the access
      happens.
 
      User space can't solve this problem without help from the kernel.
      This series provides the kernel side infrastructure to help it
      along:
 
       1) Combined unlock, pointer clearing, wake-up for the
          contended case
 
       2) VDSO based unlock and pointer clearing helpers with a
          fix-up function in the kernel when user space was interrupted
          within the critical section.
 
     ... with help by André Almeida:
 
      - Add a note about robust list race condition (André Almeida)
      - Add self-tests for robust release operations (André Almeida)
 
 Context analysis updates:
 
  - Implement context analysis for 'struct rt_mutex'.
    (Bart Van Assche)
  - Bump required Clang version to 23 (Marco Elver)
 
 Guard infrastructure updates:
 
  - Series to remove NULL check from unconditional guards
    (Dmitry Ilvokhin)
 
 Lockdep updates:
 
  - Restore self-test migrate_disable() and sched_rt_mutex
    state on PREEMPT_RT (Karl Mehltretter)
 
 Membarriers updates:
 
  - Use per-CPU mutexes for targeted commands (Aniket Gattani)
  - Modernize membarrier_global_expedited with cleanup guards
    (Aniket Gattani)
  - Add rseq stress test for CFS throttle interactions (Aniket Gattani)
 
 percpu-rwsems updates:
 
  - Extract __percpu_up_read() to optimize inlining overhead
    (Dmitry Ilvokhin)
 
 Seqlocks updates:
 
  - Allow UBSAN_ALIGNMENT to fail optimizing (Heiko Carstens)
 
 Lock tracing:
 
  - Add contended_release tracepoint to sleepable locks
    such as mutexes, percpu-rwsems, rtmutexes, rwsems
    and semaphores. (Dmitry Ilvokhin)
 
 MAINTAINERS updates:
 
  - MAINTAINERS: Add RUST [SYNC] entry (Boqun Feng)
 
 Misc updates and fixes by Randy Dunlap, YE WEI-HONG,
 Fabricio Parra, Dmitry Ilvokhin and Peter Zijlstra.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-core-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip

Pull locking updates from Ingo Molnar:
 "Futex updates:

   - Optimize futex hash bucket access patterns (Peter Zijlstra)

   - Large series to address the robust futex unlock race for real, by
     Thomas Gleixner:

      "The robust futex unlock mechanism is racy in respect to the
       clearing of the robust_list_head::list_op_pending pointer because
       unlock and clearing the pointer are not atomic.

       The race window is between the unlock and clearing the pending op
       pointer. If the task is forced to exit in this window, exit will
       access a potentially invalid pending op pointer when cleaning up
       the robust list.

       That happens if another task manages to unmap the object
       containing the lock before the cleanup, which results in an UAF.

       In the worst case this UAF can lead to memory corruption when
       unrelated content has been mapped to the same address by the time
       the access happens.

       User space can't solve this problem without help from the kernel.
       This series provides the kernel side infrastructure to help it
       along:

        1) Combined unlock, pointer clearing, wake-up for the
           contended case

        2) VDSO based unlock and pointer clearing helpers with a
           fix-up function in the kernel when user space was interrupted
           within the critical section.

      ... with help by André Almeida:

        - Add a note about robust list race condition (André Almeida)
        - Add self-tests for robust release operations (André Almeida)

  Context analysis updates:

   - Implement context analysis for 'struct rt_mutex'. (Bart Van Assche)
   - Bump required Clang version to 23 (Marco Elver)

  Guard infrastructure updates:

   - Series to remove NULL check from unconditional guards (Dmitry
     Ilvokhin)

  Lockdep updates:

   - Restore self-test migrate_disable() and sched_rt_mutex state on
     PREEMPT_RT (Karl Mehltretter)

  Membarriers updates:

   - Use per-CPU mutexes for targeted commands (Aniket Gattani)
   - Modernize membarrier_global_expedited with cleanup guards (Aniket
     Gattani)
   - Add rseq stress test for CFS throttle interactions (Aniket Gattani)

  percpu-rwsems updates:

   - Extract __percpu_up_read() to optimize inlining overhead (Dmitry
     Ilvokhin)

  Seqlocks updates:

   - Allow UBSAN_ALIGNMENT to fail optimizing (Heiko Carstens)

  Lock tracing:

   - Add contended_release tracepoint to sleepable locks such as
     mutexes, percpu-rwsems, rtmutexes, rwsems and semaphores (Dmitry
     Ilvokhin)

  MAINTAINERS updates:

   - MAINTAINERS: Add RUST [SYNC] entry (Boqun Feng)

  Misc updates and fixes by Randy Dunlap, YE WEI-HONG, Fabricio Parra,
  Dmitry Ilvokhin and Peter Zijlstra"

* tag 'locking-core-2026-06-14' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: (36 commits)
  locking: Add contended_release tracepoint to sleepable locks
  locking/percpu-rwsem: Extract __percpu_up_read()
  tracing/lock: Remove unnecessary linux/sched.h include
  futex: Optimize futex hash bucket access patterns
  rust: sync: completion: Mark inline complete_all and wait_for_completion
  MAINTAINERS: Add RUST [SYNC] entry
  cleanup: Specify nonnull argument index
  selftests: futex: Add tests for robust release operations
  Documentation: futex: Add a note about robust list race condition
  x86/vdso: Implement __vdso_futex_robust_try_unlock()
  x86/vdso: Prepare for robust futex unlock support
  futex: Provide infrastructure to plug the non contended robust futex unlock race
  futex: Add robust futex unlock IP range
  futex: Add support for unlocking robust futexes
  futex: Cleanup UAPI defines
  x86: Select ARCH_MEMORY_ORDER_TSO
  uaccess: Provide unsafe_atomic_store_release_user()
  futex: Provide UABI defines for robust list entry modifiers
  futex: Move futex related mm_struct data into a struct
  futex: Make futex_mm_init() void
  ...
2026-06-15 14:21:14 +05:30
Linus Torvalds
73f399414a Kbuild / Kconfig changes for 7.2
Kbuild:
 
 - Remove broken module linking exclusion for BTF
 
 - Add documentation around how offset header files work
 
 - Include unstripped vDSO libraries in pacman packages
 
 - Bump minimum version of LLVM for building the kernel to 17.0.1 and
   clean up unnecessary workarounds
 
 - Use a context manager in run-clang-tools
 
 - Add dist macro value if present to release tag for RPM packages
 
 - Detect and report truncated buf_printf() output in modpost
 
 - Add __llvm_covfun and __llvm_covmap to section whitelist in modpost
 
 - Support Clang's distributed ThinLTO mode
 
 - Remove architecture specific configurations for AutoFDO and Propeller
   to ease individual architecture maintenance
 
 Kconfig:
 
 - Add kconfig-sym-check target to look for dangling Kconfig symbol
   references and invalid tristate literal values
 
 - Harden against potential NULL pointer dereference
 
 - Fix typo in Kconfig test comment
 
 Signed-off-by: Nathan Chancellor <nathan@kernel.org>
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Merge tag 'kbuild-7.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux

Pull Kbuild / Kconfig updates from Nathan Chancellor:
 "Kbuild:

   - Remove broken module linking exclusion for BTF

   - Add documentation around how offset header files work

   - Include unstripped vDSO libraries in pacman packages

   - Bump minimum version of LLVM for building the kernel to 17.0.1 and
     clean up unnecessary workarounds

   - Use a context manager in run-clang-tools

   - Add dist macro value if present to release tag for RPM packages

   - Detect and report truncated buf_printf() output in modpost

   - Add __llvm_covfun and __llvm_covmap to section whitelist in modpost

   - Support Clang's distributed ThinLTO mode

   - Remove architecture specific configurations for AutoFDO and
     Propeller to ease individual architecture maintenance

  Kconfig:

   - Add kconfig-sym-check target to look for dangling Kconfig symbol
     references and invalid tristate literal values

   - Harden against potential NULL pointer dereference

   - Fix typo in Kconfig test comment"

* tag 'kbuild-7.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (31 commits)
  kconfig: tests: fix typo in comment
  kconfig: Remove the architecture specific config for Propeller
  kconfig: Remove the architecture specific config for AutoFDO
  modpost: Add __llvm_covfun and __llvm_covmap to section_white_list
  kconfig: add kconfig-sym-check static checker
  kbuild: Remove unnecessary 'T' modifier in cmd_ar_builtin_fixup
  kbuild: distributed build support for Clang ThinLTO
  kbuild: move vmlinux.a build rule to scripts/Makefile.vmlinux_a
  scripts: modpost: detect and report truncated buf_printf() output
  kbuild: rpm-pkg: append %{?dist} macro to Release tag
  run-clang-tools: run multiprocessing.Pool as context manager
  compiler-clang.h: Drop explicit version number from "all" diagnostic macro
  compiler-clang.h: Remove __cleanup -Wunused-variable workaround
  kbuild: Remove check for broken scoping with clang < 17 in CC_HAS_ASM_GOTO_OUTPUT
  x86/entry/vdso32: Remove conditional omission of '.cfi_offset eflags'
  x86/module: Revert "Deal with GOT based stack cookie load on Clang < 17"
  x86/build: Drop unnecessary '-ffreestanding' addition to KBUILD_CFLAGS
  scripts/Makefile.warn: Drop -Wformat handling for clang < 16
  riscv: Drop tautological condition from TOOLCHAIN_NEEDS_OLD_ISA_SPEC
  riscv: Remove tautological condition from selection of ARCH_SUPPORTS_CFI
  ...
2026-06-15 05:01:15 +05:30
Thomas Gleixner
a2274cc009 x86/vdso: Implement __vdso_futex_robust_try_unlock()
When the FUTEX_ROBUST_UNLOCK mechanism is used for unlocking (PI-)futexes,
then the unlock sequence in userspace looks like this:

  1)	robust_list_set_op_pending(mutex);
  2)	robust_list_remove(mutex);

  	lval = gettid();
  3)	if (atomic_try_cmpxchg(&mutex->lock, lval, 0))
  4)		robust_list_clear_op_pending();
  	else
  5)		sys_futex(OP,...FUTEX_ROBUST_UNLOCK);

That still leaves a minimal race window between #3 and #4 where the mutex
could be acquired by some other task which observes that it is the last
user and:

  1) unmaps the mutex memory
  2) maps a different file, which ends up covering the same address

When then the original task exits before reaching #5 then the kernel robust
list handling observes the pending op entry and tries to fix up user space.

In case that the newly mapped data contains the TID of the exiting thread
at the address of the mutex/futex the kernel will set the owner died bit in
that memory and therefore corrupt unrelated data.

Provide a VDSO function which exposes the critical section window in the
VDSO symbol table. The resulting addresses are updated in the task's mm
when the VDSO is (re)map()'ed.

The core code detects when a task was interrupted within the critical
section and is about to deliver a signal. It then invokes an architecture
specific function which determines whether the pending op pointer has to be
cleared or not. The unlock assembly sequence on 64-bit is:

	mov		%esi,%eax	// Load TID into EAX
       	xor		%ecx,%ecx	// Set ECX to 0
	lock cmpxchg	%ecx,(%rdi)	// Try the TID -> 0 transition
  .Lstart:
	jnz    		.Lend
	movq		%rcx,(%rdx)	// Clear list_op_pending
  .Lend:
	ret

So the decision can be simply based on the ZF state in regs->flags. The
pending op pointer is always in DX independent of the build mode
(32/64-bit) to make the pending op pointer retrieval uniform. The size of
the pointer is stored in the matching criticial section range struct and
the core code retrieves it from there. So the pointer retrieval function
does not have to care. It is bit-size independent:

     return regs->flags & X86_EFLAGS_ZF ? regs->dx : NULL;

There are two entry points to handle the different robust list pending op
pointer size:

	__vdso_futex_robust_list64_try_unlock()
	__vdso_futex_robust_list32_try_unlock()

The 32-bit VDSO provides only __vdso_futex_robust_list32_try_unlock().

The 64-bit VDSO provides always __vdso_futex_robust_list64_try_unlock() and
when COMPAT is enabled also the list32 variant, which is required to
support multi-size robust list pointers used by gaming emulators.

The unlock function is inspired by an idea from Mathieu Desnoyers.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Acked-by: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/20260311185409.1988269-1-mathieu.desnoyers@efficios.com
Link: https://patch.msgid.link/20260602090535.883796247@kernel.org
2026-06-03 11:38:52 +02:00
Thomas Gleixner
61cfc8e372 x86/vdso: Prepare for robust futex unlock support
There will be a VDSO function to unlock non-contended robust futexes in
user space. The unlock sequence is racy vs. clearing the list_pending_op
pointer in the task's robust list head. To plug this race the kernel needs
to know the critical section window so it can clear the pointer when the
task is interrupted within that race window. The window is determined by
labels in the inline assembly.

Add these symbols to the vdso2c generator and use them in the VDSO VMA code
to update the critical section addresses in mm_struct::futex on (re)map().

The symbols are not exported to user space, but available in the debug
version of the vDSO.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://patch.msgid.link/20260602090535.828312645@kernel.org
2026-06-03 11:38:52 +02:00
Peter Zijlstra
8aeb879baf x86/kvm/vmx: Fix x86_64 CFI build
It was missed that idt_do_interrupt_irqoff() gets compiled on x84_64;
this is a problem for CFI builds because it includes an unadorned
indirect call. It is however completely dead code.

Rework things to not emit this function at all.

Fixes: 0701c9e17b ("x86/kvm/vmx: Move IRQ/NMI dispatch from KVM into x86 core")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: Calvin Owens <calvin@wbinvd.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260526090631.GA4149641@noisy.programming.kicks-ass.net
2026-05-28 11:31:50 +02:00
Nathan Chancellor
4e7af20d0d
x86/entry/vdso32: Remove conditional omission of '.cfi_offset eflags'
Now that the minimum supported version of LLVM for building the kernel
has been raised to 17.0.1, the inclusion condition added by

  3e30278e0c ("x86/entry/vdso32: Omit '.cfi_offset eflags' for LLVM < 16")

will always be true. Revert the change to clean up the source code.

Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Link: https://patch.msgid.link/20260517-bump-minimum-supported-llvm-version-to-17-v2-13-b3b8cda46bdd@kernel.org
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
2026-05-27 15:20:06 -07:00
Peter Zijlstra
5fcc48d521 x86/kvm/vmx: Fix VMX vs hrtimer_rearm_deferred()
Vishal reported that KVM unit test 'x2apic' started failing after commit
0e98eb1481 ("entry: Prepare for deferred hrtimer rearming").

The reason is that KVM/VMX is injecting interrupts while it has interrupts
disabled, for a context that will enable interrupts, this means that
regs->flags.X86_EFLAGS_IF == 0 and irqentry_exit() will not do the right
thing.

Notably, irqentry_exit() must not call hrtimer_rearm_deferred() when the return
context does not have IF set, because this will cause problems vs NMIs.

Therefore, fix up the state after the injection.

Fixes: 0e98eb1481 ("entry: Prepare for deferred hrtimer rearming")
Reported-by: "Verma, Vishal L" <vishal.l.verma@intel.com>
Suggested-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: "Verma, Vishal L" <vishal.l.verma@intel.com>
Tested-by: David Woodhouse <dwmw@amazon.co.uk>
Tested-by: Zhao Liu <zhao1.liu@intel.com>
Tested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Link: https://patch.msgid.link/20260423155936.957351833@infradead.org
Closes: https://lore.kernel.org/r/70cd3e97fbb796e2eb2ff8cd4b7614ada05a5f24.camel%40intel.com
2026-05-19 20:25:51 +02:00
Peter Zijlstra
0701c9e17b x86/kvm/vmx: Move IRQ/NMI dispatch from KVM into x86 core
Move the VMX interrupt dispatch magic into the x86 core code. This
isolates KVM from the FRED/IDT decisions and reduces the amount of
EXPORT_SYMBOL_FOR_KVM().

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: "Verma, Vishal L" <vishal.l.verma@intel.com>
Tested-by: Zhao Liu <zhao1.liu@intel.com>
Tested-by: Zhao Liu <zhao1.liu@intel.com>
Tested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Binbin Wu <binbin.wu@linxu.intel.com>
Acked-by: Sean Christopherson <seanjc@google.com>
Link: https://patch.msgid.link/20260508091829.GO3126523@noisy.programming.kicks-ass.net
2026-05-19 20:25:51 +02:00
Guilherme Giacomo Simoes
b088fe3501 x86/vdso: Fix incorrect size in munmap() on map_vdso() failure
In map_vdso(), if a failure occurs during the installation of the VVAR
mappings, the error path attempts to clean up previously allocated mappings
using do_munmap(). However, the cleanup for the VVAR mapping is incorrectly
using image->size (the size of the vDSO text) instead of the actual size
allocated for the VVAR area.

Replace the incorrect do_munmap() image->size parameter with the constant
VDSO_NR_PAGES * PAGE_SIZE. Ensure the unmap size exactly matches the size
used during the vdso_install_vvar_mapping() phase to provide a symmetrical
and complete teardown of the memory region.

Fixes: e93d2521b2 ("x86/vdso: Split virtual clock pages into dedicated mapping")
Signed-off-by: Guilherme Giacomo Simoes <trintaeoitogc@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Link: https://patch.msgid.link/20260503191609.551817-1-trintaeoitogc@gmail.com
2026-05-19 16:36:34 +02:00
Borislav Petkov (AMD)
52705e72e2 x86/entry: Zap the #VC entry user and kernel macros
Drop the separate kernel and user macros in favor of calling a single #VC
C handler which multiplexes between the kernel and user #VC entry points
by looking at CS's RPL.

Zap unused DEFINE_IDTENTRY_VC while at it.

There should be no functionality change resulting from this - just code
simplification.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikunj A. Dadhania <nikunj@amd.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Acked-by: Joerg Roedel <joerg.roedel@amd.com>
Tested-by: Nikunj A. Dadhania <nikunj@amd.com>
Link: https://patch.msgid.link/20260420164352.32129-1-bp@kernel.org
2026-05-04 11:18:41 +02:00
Linus Torvalds
334fbe734e mm.git review status for linus..mm-stable
Everything:
 
 Total patches:       368
 Reviews/patch:       1.56
 Reviewed rate:       74%
 
 Excluding DAMON:
 
 Total patches:       316
 Reviews/patch:       1.77
 Reviewed rate:       81%
 
 Excluding DAMON and zram:
 
 Total patches:       306
 Reviews/patch:       1.81
 Reviewed rate:       82%
 
 Excluding DAMON, zram and maple_tree:
 
 Total patches:       276
 Reviews/patch:       2.01
 Reviewed rate:       91%
 
 Significant patch series in this merge:
 
 - The 30 patch series "maple_tree: Replace big node with maple copy"
   from Liam Howlett is mainly prepararatory work for ongoing development
   but it does reduce stack usage and is an improvement.
 
 - The 12 patch series "mm, swap: swap table phase III: remove swap_map"
   from Kairui Song offers memory savings by removing the static swap_map.
   It also yields some CPU savings and implements several cleanups.
 
 - The 2 patch series "mm: memfd_luo: preserve file seals" from Pratyush
   Yadav adds file seal preservation to LUO's memfd code.
 
 - The 2 patch series "mm: zswap: add per-memcg stat for incompressible
   pages" from Jiayuan Chen adds additional userspace stats reportng to
   zswap.
 
 - The 4 patch series "arch, mm: consolidate empty_zero_page" from Mike
   Rapoport implements some cleanups for our handling of ZERO_PAGE() and
   zero_pfn.
 
 - The 2 patch series "mm/kmemleak: Improve scan_should_stop()
   implementation" from Zhongqiu Han provides an robustness improvement and
   some cleanups in the kmemleak code.
 
 - The 4 patch series "Improve khugepaged scan logic" from Vernon Yang
   "improves the khugepaged scan logic and reduces CPU consumption by
   prioritizing scanning tasks that access memory frequently".
 
 - The 2 patch series "Make KHO Stateless" from Jason Miu simplifies
   Kexec Handover by "transitioning KHO from an xarray-based metadata
   tracking system with serialization to a radix tree data structure that
   can be passed directly to the next kernel"
 
 - The 3 patch series "mm: vmscan: add PID and cgroup ID to vmscan
   tracepoints" from Thomas Ballasi and Steven Rostedt enhances vmscan's
   tracepointing.
 
 - The 5 patch series "mm: arch/shstk: Common shadow stack mapping helper
   and VM_NOHUGEPAGE" from Catalin Marinas is a cleanup for the shadow
   stack code: remove per-arch code in favour of a generic implementation.
 
 - The 2 patch series "Fix KASAN support for KHO restored vmalloc
   regions" from Pasha Tatashin fixes a WARN() which can be emitted the KHO
   restores a vmalloc area.
 
 - The 4 patch series "mm: Remove stray references to pagevec" from Tal
   Zussman provides several cleanups, mainly udpating references to "struct
   pagevec", which became folio_batch three years ago.
 
 - The 17 patch series "mm: Eliminate fake head pages from vmemmap
   optimization" from Kiryl Shutsemau simplifies the HugeTLB vmemmap
   optimization (HVO) by changing how tail pages encode their relationship
   to the head page.
 
 - The 2 patch series "mm/damon/core: improve DAMOS quota efficiency for
   core layer filters" from SeongJae Park improves two problematic
   behaviors of DAMOS that makes it less efficient when core layer filters
   are used.
 
 - The 3 patch series "mm/damon: strictly respect min_nr_regions" from
   SeongJae Park improves DAMON usability by extending the treatment of the
   min_nr_regions user-settable parameter.
 
 - The 3 patch series "mm/page_alloc: pcp locking cleanup" from Vlastimil
   Babka is a proper fix for a previously hotfixed SMP=n issue.  Code
   simplifications and cleanups ennsed.
 
 - The 16 patch series "mm: cleanups around unmapping / zapping" from
   David Hildenbrand implements "a bunch of cleanups around unmapping and
   zapping.  Mostly simplifications, code movements, documentation and
   renaming of zapping functions".
 
 - The 6 patch series "support batched checking of the young flag for
   MGLRU" from Baolin Wang supports batched checking of the young flag for
   MGLRU.  It's part cleanups; one benchmark shows large performance
   benefits for arm64.
 
 - The 5 patch series "memcg: obj stock and slab stat caching cleanups"
   from Johannes Weiner provides memcg cleanup and robustness improvements.
 
 - The 5 patch series "Allow order zero pages in page reporting" from
   Yuvraj Sakshith enhances page_reporting's free page reporting - it is
   presently and undesirably order-0 pages when reporting free memory.
 
 - The 6 patch series "mm: vma flag tweaks" from Lorenzo Stoakes is
   cleanup work following from the recent conversion of the VMA flags to a
   bitmap.
 
 - The 10 patch series "mm/damon: add optional debugging-purpose sanity
   checks" from SeongJae Park adds some more developer-facing debug checks
   into DAMON core.
 
 - The 2 patch series "mm/damon: test and document power-of-2
   min_region_sz requirement" from SeongJae Park adds an additional DAMON
   kunit test and makes some adjustments to the addr_unit parameter
   handling.
 
 - The 3 patch series "mm/damon/core: make passed_sample_intervals
   comparisons overflow-safe" from SeongJae Park fixes a hard-to-hit time
   overflow issue in DAMON core.
 
 - The 7 patch series "mm/damon: improve/fixup/update ratio calculation,
   test and documentation" from SeongJae Park is a "batch of misc/minor
   improvements and fixups" for DAMON.
 
 - The 4 patch series "mm: move vma_(kernel|mmu)_pagesize() out of
   hugetlb.c" from David Hildenbrand fixes a possible issue with dax-device
   when CONFIG_HUGETLB=n.  Some code movement was required.
 
 - The 6 patch series "zram: recompression cleanups and tweaks" from
   Sergey Senozhatsky provides "a somewhat random mix of fixups,
   recompression cleanups and improvements" in the zram code.
 
 - The 11 patch series "mm/damon: support multiple goal-based quota
   tuning algorithms" from SeongJae Park extend DAMOS quotas goal
   auto-tuning to support multiple tuning algorithms that users can select.
 
 - The 4 patch series "mm: thp: reduce unnecessary
   start_stop_khugepaged()" from Breno Leitao fixes the khugpaged sysfs
   handling so we no longer spam the logs with reams of junk when
   starting/stopping khugepaged.
 
 - The 3 patch series "mm: improve map count checks" from Lorenzo Stoakes
   provides some cleanups and slight fixes in the mremap, mmap and vma
   code.
 
 - The 5 patch series "mm/damon: support addr_unit on default monitoring
   targets for modules" from SeongJae Park extends the use of DAMON core's
   addr_unit tunable.
 
 - The 5 patch series "mm: khugepaged cleanups and mTHP prerequisites"
   from Nico Pache provides cleanups in the khugepaged and is a base for
   Nico's planned khugepaged mTHP support.
 
 - The 15 patch series "mm: memory hot(un)plug and SPARSEMEM cleanups"
   from David Hildenbrand implements code movement and cleanups in the
   memhotplug and sparsemem code.
 
 - The 2 patch series "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and
   cleanup CONFIG_MIGRATION" from David Hildenbrand rationalizes some
   memhotplug Kconfig support.
 
 - The 6 patch series "change young flag check functions to return bool"
   from Baolin Wang is "a cleanup patchset to change all young flag check
   functions to return bool".
 
 - The 3 patch series "mm/damon/sysfs: fix memory leak and NULL
   dereference issues" from Josh Law and SeongJae Park fixes a few
   potential DAMON bugs.
 
 - The 25 patch series "mm/vma: convert vm_flags_t to vma_flags_t in vma
   code" from "converts a lot of the existing use of the legacy vm_flags_t
   data type to the new vma_flags_t type which replaces it".  Mainly in the
   vma code.
 
 - The 21 patch series "mm: expand mmap_prepare functionality and usage"
   from Lorenzo Stoakes "expands the mmap_prepare functionality, which is
   intended to replace the deprecated f_op->mmap hook which has been the
   source of bugs and security issues for some time".  Cleanups,
   documentation, extension of mmap_prepare into filesystem drivers.
 
 - The 13 patch series "mm/huge_memory: refactor zap_huge_pmd()" from
   Lorenzo Stoakes simplifies and cleans up zap_huge_pmd().  Additional
   cleanups around vm_normal_folio_pmd() and the softleaf functionality are
   performed.
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Merge tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - "maple_tree: Replace big node with maple copy" (Liam Howlett)

   Mainly prepararatory work for ongoing development but it does reduce
   stack usage and is an improvement.

 - "mm, swap: swap table phase III: remove swap_map" (Kairui Song)

   Offers memory savings by removing the static swap_map. It also yields
   some CPU savings and implements several cleanups.

 - "mm: memfd_luo: preserve file seals" (Pratyush Yadav)

   File seal preservation to LUO's memfd code

 - "mm: zswap: add per-memcg stat for incompressible pages" (Jiayuan
   Chen)

   Additional userspace stats reportng to zswap

 - "arch, mm: consolidate empty_zero_page" (Mike Rapoport)

   Some cleanups for our handling of ZERO_PAGE() and zero_pfn

 - "mm/kmemleak: Improve scan_should_stop() implementation" (Zhongqiu
   Han)

   A robustness improvement and some cleanups in the kmemleak code

 - "Improve khugepaged scan logic" (Vernon Yang)

   Improve khugepaged scan logic and reduce CPU consumption by
   prioritizing scanning tasks that access memory frequently

 - "Make KHO Stateless" (Jason Miu)

   Simplify Kexec Handover by transitioning KHO from an xarray-based
   metadata tracking system with serialization to a radix tree data
   structure that can be passed directly to the next kernel

 - "mm: vmscan: add PID and cgroup ID to vmscan tracepoints" (Thomas
   Ballasi and Steven Rostedt)

   Enhance vmscan's tracepointing

 - "mm: arch/shstk: Common shadow stack mapping helper and
   VM_NOHUGEPAGE" (Catalin Marinas)

   Cleanup for the shadow stack code: remove per-arch code in favour of
   a generic implementation

 - "Fix KASAN support for KHO restored vmalloc regions" (Pasha Tatashin)

   Fix a WARN() which can be emitted the KHO restores a vmalloc area

 - "mm: Remove stray references to pagevec" (Tal Zussman)

   Several cleanups, mainly udpating references to "struct pagevec",
   which became folio_batch three years ago

 - "mm: Eliminate fake head pages from vmemmap optimization" (Kiryl
   Shutsemau)

   Simplify the HugeTLB vmemmap optimization (HVO) by changing how tail
   pages encode their relationship to the head page

 - "mm/damon/core: improve DAMOS quota efficiency for core layer
   filters" (SeongJae Park)

   Improve two problematic behaviors of DAMOS that makes it less
   efficient when core layer filters are used

 - "mm/damon: strictly respect min_nr_regions" (SeongJae Park)

   Improve DAMON usability by extending the treatment of the
   min_nr_regions user-settable parameter

 - "mm/page_alloc: pcp locking cleanup" (Vlastimil Babka)

   The proper fix for a previously hotfixed SMP=n issue. Code
   simplifications and cleanups ensued

 - "mm: cleanups around unmapping / zapping" (David Hildenbrand)

   A bunch of cleanups around unmapping and zapping. Mostly
   simplifications, code movements, documentation and renaming of
   zapping functions

 - "support batched checking of the young flag for MGLRU" (Baolin Wang)

   Batched checking of the young flag for MGLRU. It's part cleanups; one
   benchmark shows large performance benefits for arm64

 - "memcg: obj stock and slab stat caching cleanups" (Johannes Weiner)

   memcg cleanup and robustness improvements

 - "Allow order zero pages in page reporting" (Yuvraj Sakshith)

   Enhance free page reporting - it is presently and undesirably order-0
   pages when reporting free memory.

 - "mm: vma flag tweaks" (Lorenzo Stoakes)

   Cleanup work following from the recent conversion of the VMA flags to
   a bitmap

 - "mm/damon: add optional debugging-purpose sanity checks" (SeongJae
   Park)

   Add some more developer-facing debug checks into DAMON core

 - "mm/damon: test and document power-of-2 min_region_sz requirement"
   (SeongJae Park)

   An additional DAMON kunit test and makes some adjustments to the
   addr_unit parameter handling

 - "mm/damon/core: make passed_sample_intervals comparisons
   overflow-safe" (SeongJae Park)

   Fix a hard-to-hit time overflow issue in DAMON core

 - "mm/damon: improve/fixup/update ratio calculation, test and
   documentation" (SeongJae Park)

   A batch of misc/minor improvements and fixups for DAMON

 - "mm: move vma_(kernel|mmu)_pagesize() out of hugetlb.c" (David
   Hildenbrand)

   Fix a possible issue with dax-device when CONFIG_HUGETLB=n. Some code
   movement was required.

 - "zram: recompression cleanups and tweaks" (Sergey Senozhatsky)

   A somewhat random mix of fixups, recompression cleanups and
   improvements in the zram code

 - "mm/damon: support multiple goal-based quota tuning algorithms"
   (SeongJae Park)

   Extend DAMOS quotas goal auto-tuning to support multiple tuning
   algorithms that users can select

 - "mm: thp: reduce unnecessary start_stop_khugepaged()" (Breno Leitao)

   Fix the khugpaged sysfs handling so we no longer spam the logs with
   reams of junk when starting/stopping khugepaged

 - "mm: improve map count checks" (Lorenzo Stoakes)

   Provide some cleanups and slight fixes in the mremap, mmap and vma
   code

 - "mm/damon: support addr_unit on default monitoring targets for
   modules" (SeongJae Park)

   Extend the use of DAMON core's addr_unit tunable

 - "mm: khugepaged cleanups and mTHP prerequisites" (Nico Pache)

   Cleanups to khugepaged and is a base for Nico's planned khugepaged
   mTHP support

 - "mm: memory hot(un)plug and SPARSEMEM cleanups" (David Hildenbrand)

   Code movement and cleanups in the memhotplug and sparsemem code

 - "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and cleanup
   CONFIG_MIGRATION" (David Hildenbrand)

   Rationalize some memhotplug Kconfig support

 - "change young flag check functions to return bool" (Baolin Wang)

   Cleanups to change all young flag check functions to return bool

 - "mm/damon/sysfs: fix memory leak and NULL dereference issues" (Josh
   Law and SeongJae Park)

   Fix a few potential DAMON bugs

 - "mm/vma: convert vm_flags_t to vma_flags_t in vma code" (Lorenzo
   Stoakes)

   Convert a lot of the existing use of the legacy vm_flags_t data type
   to the new vma_flags_t type which replaces it. Mainly in the vma
   code.

 - "mm: expand mmap_prepare functionality and usage" (Lorenzo Stoakes)

   Expand the mmap_prepare functionality, which is intended to replace
   the deprecated f_op->mmap hook which has been the source of bugs and
   security issues for some time. Cleanups, documentation, extension of
   mmap_prepare into filesystem drivers

 - "mm/huge_memory: refactor zap_huge_pmd()" (Lorenzo Stoakes)

   Simplify and clean up zap_huge_pmd(). Additional cleanups around
   vm_normal_folio_pmd() and the softleaf functionality are performed.

* tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits)
  mm: fix deferred split queue races during migration
  mm/khugepaged: fix issue with tracking lock
  mm/huge_memory: add and use has_deposited_pgtable()
  mm/huge_memory: add and use normal_or_softleaf_folio_pmd()
  mm: add softleaf_is_valid_pmd_entry(), pmd_to_softleaf_folio()
  mm/huge_memory: separate out the folio part of zap_huge_pmd()
  mm/huge_memory: use mm instead of tlb->mm
  mm/huge_memory: remove unnecessary sanity checks
  mm/huge_memory: deduplicate zap deposited table call
  mm/huge_memory: remove unnecessary VM_BUG_ON_PAGE()
  mm/huge_memory: add a common exit path to zap_huge_pmd()
  mm/huge_memory: handle buggy PMD entry in zap_huge_pmd()
  mm/huge_memory: have zap_huge_pmd return a boolean, add kdoc
  mm/huge: avoid big else branch in zap_huge_pmd()
  mm/huge_memory: simplify vma_is_specal_huge()
  mm: on remap assert that input range within the proposed VMA
  mm: add mmap_action_map_kernel_pages[_full]()
  uio: replace deprecated mmap hook with mmap_prepare in uio_info
  drivers: hv: vmbus: replace deprecated mmap hook with mmap_prepare
  mm: allow handling of stacked mmap_prepare hooks in more drivers
  ...
2026-04-15 12:59:16 -07:00
Linus Torvalds
9f2bb6c7b3 - Complete LASS enabling: deal with vsyscall and EFI
- Clean up CPUID usage in newer Intel audio driver
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Merge tag 'x86_cpu_for_7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 cpu updates from Dave Hansen:

 - Complete LASS enabling: deal with vsyscall and EFI

   The existing Linear Address Space Separation (LASS) support punted
   on support for common EFI and vsyscall configs. Complete the
   implementation by supporting EFI and vsyscall=xonly.

 - Clean up CPUID usage in newer Intel "avs" audio driver and update the
   x86-cpuid-db file

* tag 'x86_cpu_for_7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tools/x86/kcpuid: Update bitfields to x86-cpuid-db v3.0
  ASoC: Intel: avs: Include CPUID header at file scope
  ASoC: Intel: avs: Check maximum valid CPUID leaf
  x86/cpu: Remove LASS restriction on vsyscall emulation
  x86/vsyscall: Disable LASS if vsyscall mode is set to EMULATE
  x86/vsyscall: Restore vsyscall=xonly mode under LASS
  x86/traps: Consolidate user fixups in the #GP handler
  x86/vsyscall: Reorganize the page fault emulation code
  x86/cpu: Remove LASS restriction on EFI
  x86/efi: Disable LASS while executing runtime services
  x86/cpu: Defer LASS enabling until userspace comes up
2026-04-14 14:24:45 -07:00
Linus Torvalds
49b30f3e9c x86/vdso changes for v7.1, by Thomas Weißschuh:
- Clean up remnants of VDSO32_NOTE_MASK
  - Drop pointless #ifdeffery in vvar_vclock_fault()
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-vdso-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 vdso updates from Ingo Molnar:
 "vdso cleanups by Thomas Weißschuh:

   - Clean up remnants of VDSO32_NOTE_MASK

   - Drop pointless #ifdeffery in vvar_vclock_fault()"

* tag 'x86-vdso-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vdso: Drop pointless #ifdeffery in vvar_vclock_fault()
  x86/vdso: Clean up remnants of VDSO32_NOTE_MASK
2026-04-14 14:16:27 -07:00
Linus Torvalds
f21f7b5162 Update to the VDSO subsystem:
- Make the handling of compat functions consistent and more robust
 
      - Rework the underlying data store so that it is dynamically
        allocated, which allows the conversion of the last holdout SPARC64
        to the generic VDSO implementation
 
      - Rework the SPARC64 VDSO to utilize the generic implementation
 
      - Mop up the left overs of the non-generic VDSO support in the core
        code.
 
      - Expand the VDSO selftest and make them more robust
 
      - Allow time namespaces to be enabled independently of the generic
        VDSO support, which was not possible before due to SPARC64 not
        using it.
 
      - Various cleanups and improvements in the related code.
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Merge tag 'timers-vdso-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull vdso updates from Thomas Gleixner:

 - Make the handling of compat functions consistent and more robust

 - Rework the underlying data store so that it is dynamically allocated,
   which allows the conversion of the last holdout SPARC64 to the
   generic VDSO implementation

 - Rework the SPARC64 VDSO to utilize the generic implementation

 - Mop up the left overs of the non-generic VDSO support in the core
   code

 - Expand the VDSO selftest and make them more robust

 - Allow time namespaces to be enabled independently of the generic VDSO
   support, which was not possible before due to SPARC64 not using it

 - Various cleanups and improvements in the related code

* tag 'timers-vdso-2026-04-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (51 commits)
  timens: Use task_lock guard in timens_get*()
  timens: Use mutex guard in proc_timens_set_offset()
  timens: Simplify some calls to put_time_ns()
  timens: Add a __free() wrapper for put_time_ns()
  timens: Remove dependency on the vDSO
  vdso/timens: Move functions to new file
  selftests: vDSO: vdso_test_correctness: Add a test for time()
  selftests: vDSO: vdso_test_correctness: Use facilities from parse_vdso.c
  selftests: vDSO: vdso_test_correctness: Handle different tv_usec types
  selftests: vDSO: vdso_test_correctness: Drop SYS_getcpu fallbacks
  selftests: vDSO: vdso_test_gettimeofday: Remove nolibc checks
  Revert "selftests: vDSO: parse_vdso: Use UAPI headers instead of libc headers"
  random: vDSO: Remove ifdeffery
  random: vDSO: Trim vDSO includes
  vdso/datapage: Trim down unnecessary includes
  vdso/datapage: Remove inclusion of gettimeofday.h
  vdso/helpers: Explicitly include vdso/processor.h
  vdso/gettimeofday: Add explicit includes
  random: vDSO: Add explicit includes
  MIPS: vdso: Explicitly include asm/vdso/vdso.h
  ...
2026-04-14 10:53:44 -07:00
Linus Torvalds
d568788baa hardening updates for v7.1-rc1
- randomize_kstack: Improve implementation across arches (Ryan Roberts)
 
 - lkdtm/fortify: Drop unneeded FORTIFY_STR_OBJECT test
 
 - refcount: Remove unused __signed_wrap function annotations
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Merge tag 'hardening-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull hardening updates from Kees Cook:

 - randomize_kstack: Improve implementation across arches (Ryan Roberts)

 - lkdtm/fortify: Drop unneeded FORTIFY_STR_OBJECT test

 - refcount: Remove unused __signed_wrap function annotations

* tag 'hardening-v7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  lkdtm/fortify: Drop unneeded FORTIFY_STR_OBJECT test
  refcount: Remove unused __signed_wrap function annotations
  randomize_kstack: Unify random source across arches
  randomize_kstack: Maintain kstack_offset per task
2026-04-13 17:52:29 -07:00
Kiryl Shutsemau (Meta)
76351f2f0c x86/vdso: undefine CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP for vdso32
The 32-bit VDSO build on x86_64 uses fake_32bit_build.h to undefine
various kernel configuration options that are not suitable for the VDSO
context or may cause build issues when including kernel headers.

Undefine CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP in fake_32bit_build.h to
prepare for change in HugeTLB Vmemmap Optimization.

Link: https://lkml.kernel.org/r/20260227194302.274384-12-kas@kernel.org
Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Baoquan He <bhe@redhat.com>
Cc: Christoph Lameter <cl@gentwo.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Frank van der Linden <fvdl@google.com>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-04-05 13:53:09 -07:00
Thomas Weißschuh
6ccd0843b9 x86/vdso: Drop pointless #ifdeffery in vvar_vclock_fault()
Sparse complains rightfully when CONFIG_PARAVIRT_CLOCK and
CONFIG_HYPERV_TIMER are both not set:

  arch/x86/entry/vdso/vma.c:94:9: warning: switch with no cases

The #ifdeffery is not actually necessary as the compiler can optimize away
the branches already if these config options are not set.

Remove the #ifdeffery to make the code simpler and Sparse happy.

Closes: https://lore.kernel.org/lkml/20260117215542.405790227@kernel.org/

Reported-by: Thomas Gleixner <tglx@kernel.org>
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Link: https://patch.msgid.link/20260331-vdso-x86-ifdef-v1-1-6be9a58b1e7e@linutronix.de
2026-03-31 10:06:39 +02:00
Ryan Roberts
a96ef5848c randomize_kstack: Unify random source across arches
Previously different architectures were using random sources of
differing strength and cost to decide the random kstack offset. A number
of architectures (loongarch, powerpc, s390, x86) were using their
timestamp counter, at whatever the frequency happened to be. Other
arches (arm64, riscv) were using entropy from the crng via
get_random_u16().

There have been concerns that in some cases the timestamp counters may
be too weak, because they can be easily guessed or influenced by user
space. And get_random_u16() has been shown to be too costly for the
level of protection kstack offset randomization provides.

So let's use a common, architecture-agnostic source of entropy; a
per-cpu prng, seeded at boot-time from the crng. This has a few
benefits:

  - We can remove choose_random_kstack_offset(); That was only there to
    try to make the timestamp counter value a bit harder to influence
    from user space [*].

  - The architecture code is simplified. All it has to do now is call
    add_random_kstack_offset() in the syscall path.

  - The strength of the randomness can be reasoned about independently
    of the architecture.

  - Arches previously using get_random_u16() now have much faster
    syscall paths, see below results.

[*] Additionally, this gets rid of some redundant work on s390 and x86.
Before this patch, those architectures called
choose_random_kstack_offset() under arch_exit_to_user_mode_prepare(),
which is also called for exception returns to userspace which were *not*
syscalls (e.g. regular interrupts). Getting rid of
choose_random_kstack_offset() avoids a small amount of redundant work
for the non-syscall cases.

In some configurations, add_random_kstack_offset() will now call
instrumentable code, so for a couple of arches, I have moved the call a
bit later to the first point where instrumentation is allowed. This
doesn't impact the efficacy of the mechanism.

There have been some claims that a prng may be less strong than the
timestamp counter if not regularly reseeded. But the prng has a period
of about 2^113. So as long as the prng state remains secret, it should
not be possible to guess. If the prng state can be accessed, we have
bigger problems.

Additionally, we are only consuming 6 bits to randomize the stack, so
there are only 64 possible random offsets. I assert that it would be
trivial for an attacker to brute force by repeating their attack and
waiting for the random stack offset to be the desired one. The prng
approach seems entirely proportional to this level of protection.

Performance data are provided below. The baseline is v6.18 with rndstack
on for each respective arch. (I)/(R) indicate statistically significant
improvement/regression. arm64 platform is AWS Graviton3 (m7g.metal).
x86_64 platform is AWS Sapphire Rapids (m7i.24xlarge):

+-----------------+--------------+---------------+---------------+
| Benchmark       | Result Class |  per-cpu-prng |  per-cpu-prng |
|                 |              | arm64 (metal) |   x86_64 (VM) |
+=================+==============+===============+===============+
| syscall/getpid  | mean (ns)    |    (I) -9.50% |   (I) -17.65% |
|                 | p99 (ns)     |   (I) -59.24% |   (I) -24.41% |
|                 | p99.9 (ns)   |   (I) -59.52% |   (I) -28.52% |
+-----------------+--------------+---------------+---------------+
| syscall/getppid | mean (ns)    |    (I) -9.52% |   (I) -19.24% |
|                 | p99 (ns)     |   (I) -59.25% |   (I) -25.03% |
|                 | p99.9 (ns)   |   (I) -59.50% |   (I) -28.17% |
+-----------------+--------------+---------------+---------------+
| syscall/invalid | mean (ns)    |   (I) -10.31% |   (I) -18.56% |
|                 | p99 (ns)     |   (I) -60.79% |   (I) -20.06% |
|                 | p99.9 (ns)   |   (I) -61.04% |   (I) -25.04% |
+-----------------+--------------+---------------+---------------+

I tested an earlier version of this change on x86 bare metal and it
showed a smaller but still significant improvement. The bare metal
system wasn't available this time around so testing was done in a VM
instance. I'm guessing the cost of rdtsc is higher for VMs.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Link: https://patch.msgid.link/20260303150840.3789438-3-ryan.roberts@arm.com
Signed-off-by: Kees Cook <kees@kernel.org>
2026-03-24 21:12:03 -07:00
Nikunj A Dadhania
3645eb7e39 x86/fred: Fix early boot failures on SEV-ES/SNP guests
FRED-enabled SEV-(ES,SNP) guests fail to boot due to the following issues
in the early boot sequence:

* FRED does not have a #VC exception handler in the dispatch logic

* Early FRED #VC exceptions attempt to use uninitialized per-CPU GHCBs
  instead of boot_ghcb

Add X86_TRAP_VC case to fred_hwexc() with a new exc_vmm_communication()
function that provides the unified entry point FRED requires, dispatching
to existing user/kernel handlers based on privilege level. The function is
already declared via DECLARE_IDTENTRY_VC().

Fix early GHCB access by falling back to boot_ghcb in
__sev_{get,put}_ghcb() when per-CPU GHCBs are not yet initialized.

Fixes: 14619d912b ("x86/fred: FRED entry/exit and dispatch code")
Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: <stable@kernel.org>  # 6.12+
Link: https://patch.msgid.link/20260318075654.1792916-4-nikunj@amd.com
2026-03-23 14:18:18 +01:00
Vladimir Oltean
63f8b60151 x86/entry/vdso: Fix path of included gettimeofday.c
Commit in Fixes forgot to convert one include path to be relative to the
kernel source directory after adding latter to flags-y.

Fix it.

  [ bp: Rewrite commit message. ]

Fixes: 693c819fed ("x86/entry/vdso: Refactor the vdso build")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20260307174406.1808981-1-vladimir.oltean@nxp.com
2026-03-20 17:56:52 +01:00
Sohil Mehta
b36d1f53d9 x86/vsyscall: Disable LASS if vsyscall mode is set to EMULATE
The EMULATE mode of vsyscall maps the vsyscall page with a high kernel
address directly into user address space. Reading the vsyscall page in
EMULATE mode would cause LASS to trigger a #GP.

Fixing the LASS violation in EMULATE mode would require complex
instruction decoding because the resulting #GP does include the
necessary error information, and the vsyscall address is not
readily available in the RIP.

The EMULATE mode has been deprecated since 2022 and can only be enabled
using the command line parameter vsyscall=emulate. See commit
bf00745e77 ("x86/vsyscall: Remove CONFIG_LEGACY_VSYSCALL_EMULATE") for
details. At this point, no one is expected to be using this insecure
mode. The rare usages that need it obviously do not care about security.

Disable LASS when EMULATE mode is requested to avoid breaking legacy
user software. Also, update the vsyscall documentation to reflect this.
LASS will only be supported if vsyscall mode is set to XONLY (default)
or NONE.

Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Tested-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Link: https://patch.msgid.link/20260309181029.398498-5-sohil.mehta@intel.com
2026-03-19 15:11:13 -07:00
Sohil Mehta
8376b503b0 x86/vsyscall: Restore vsyscall=xonly mode under LASS
Background
==========
The vsyscall page is located in the high/kernel part of the address
space. Prior to LASS, a vsyscall page access from userspace would always
generate a #PF. The kernel emulates the accesses in the #PF handler and
returns the appropriate values to userspace.

Vsyscall emulation has two modes of operation, specified by the
vsyscall={xonly, emulate} kernel command line option. The vsyscall page
behaves as execute-only in XONLY mode or read-execute in EMULATE mode.
XONLY mode is the default and the only one expected to be commonly used.
The EMULATE mode has been deprecated since 2022 and is considered
insecure.

With LASS, a vsyscall page access triggers a #GP instead of a #PF.
Currently, LASS is only enabled when all vsyscall modes are disabled.

LASS with XONLY mode
====================
Now add support for LASS specifically with XONLY vsyscall emulation. For
XONLY mode, all that is needed is the faulting RIP, which is trivially
available regardless of the type of fault. Reuse the #PF emulation code
during the #GP when the fault address points to the vsyscall page.

As multiple fault handlers will now be using the emulation code, add a
sanity check to ensure that the fault truly happened in 64-bit user
mode.

LASS with EMULATE mode
======================
Supporting vsyscall=emulate with LASS is much harder because the #GP
doesn't provide enough error information (such as PFEC and CR2 as in
case of a #PF). So, complex instruction decoding would be required to
emulate this mode in the #GP handler.

This isn't worth the effort as remaining users of EMULATE mode can be
reasonably assumed to be niche users, who are already trading off
security for compatibility. LASS and vsyscall=emulate will be kept
mutually exclusive for simplicity.

Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Tested-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Link: https://patch.msgid.link/20260309181029.398498-4-sohil.mehta@intel.com
2026-03-19 15:11:13 -07:00
Sohil Mehta
3ddd2e12c7 x86/vsyscall: Reorganize the page fault emulation code
With LASS, vsyscall page accesses will cause a #GP instead of a #PF.
Separate out the core vsyscall emulation code from the #PF specific
handling in preparation for the upcoming #GP emulation.

No functional change intended.

Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Link: https://patch.msgid.link/20260309181029.398498-2-sohil.mehta@intel.com
2026-03-19 15:11:12 -07:00
Thomas Weißschuh
56f85f67b3 x86/vdso: Use 32-bit CHECKFLAGS for compat vDSO
When building the compat vDSO the CHECKFLAGS from the 64-bit kernel
are used. These are combined with the 32-bit CFLAGS. This confuses
sparse, producing false-positive warnings or potentially missing
real issues.

Manually override the CHECKFLAGS for the compat vDSO with the correct
32-bit configuration.

Reported-by: Sun Jian <sun.jian.kdev@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20260302-vdso-compat-checkflags-v2-1-78e55baa58ba@linutronix.de
Closes: https://lore.kernel.org/lkml/20260114084529.1676356-1-sun.jian.kdev@gmail.com/
Closes: https://lore.kernel.org/lkml/20260117215542.342638347@kernel.org/
Closes: https://lore.kernel.org/r/202602111941.PIhubgrb-lkp@intel.com/
2026-03-11 10:15:42 +01:00
H. Peter Anvin
b5ef09a77d x86/entry/vdso32: Work around libgcc unwinder bug
The unwinder code in libgcc has a long standing bug which causes it to
fail to pick up the signal frame CFI flag. This is a generic bug
across all platforms.

It affects the __kernel_sigreturn and __kernel_rt_sigreturn vdso entry
points on i386. The x86-64 kernel doesn't provide a sigreturn stub,
and so there is no kernel-provided code that is affected on x86-64.

libgcc does have a legacy fallback path which happens to work as long
as the bytes immediately before each of the sigreturn functions fall
outside any function. This patch adds a nop before the ALIGN to each
of the sigreturn stubs to ensure that this is, indeed, the case.

The rest of the patch is just a comment which documents the invariants
that need to be maintained for this legacy path to work correctly.

This is a manifest bug: in the current vdso, __kernel_vsyscall is a
multiple of 16 bytes long and thus __kernel_sigreturn does not have
any padding in front of it.

Closes: https://lore.kernel.org/lkml/f3412cc3e8f66d1853cc9d572c0f2fab076872b1.camel@xry111.site
Fixes: 884961618e ("x86/entry/vdso32: Remove open-coded DWARF in sigreturn.S")
Reported-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124050
Link: https://patch.msgid.link/20260227010308.310342-1-hpa@zytor.com
2026-03-04 17:06:08 +01:00
Andrew Cooper
aa280a08e7 x86/fred: Correct speculative safety in fred_extint()
array_index_nospec() is no use if the result gets spilled to the stack, as
it makes the believed safe-under-speculation value subject to memory
predictions.

For all practical purposes, this means array_index_nospec() must be used in
the expression that accesses the array.

As the code currently stands, it's the wrong side of irqentry_enter(), and
'index' is put into %ebp across the function call.

Remove the index variable and reposition array_index_nospec(), so it's
calculated immediately before the array access.

Fixes: 14619d912b ("x86/fred: FRED entry/exit and dispatch code")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260106131504.679932-1-andrew.cooper3@citrix.com
2026-02-23 11:19:11 +01:00
Linus Torvalds
1ca28333e4 x86: keep legacy generated vdso files around in .gitignore file
Commit 93d73005bf ("x86/entry/vdso: Rename vdso_image_* to
vdso*_image") updated the vdso .gitignore file with the new filenames,
which is certainly not incorrect.

However, while adding new generated names is obviously the right thing
to do, you should *not* immediately remove the old filenames from the
.gitignore file when things move around or get renamed, because people
still have those old generated files in their build trees - and they
haven't suddenly become valid files to commit to the repository just
because they were moved or renamed.

While it's mostly just a slight visual nuisance for 'git status' that
can be fixed up with a clean build tree, it can become more serious than
that: see for example commit 04a3389b35 ("Remove stale generated
'genheaders' file").

That commit removed up a stale generated file that had been carelessly
committed by a kernel developer because it wasn't properly ignored any
more and thus showed up as a new file in their tree.

Fixes: 93d73005bf ("x86/entry/vdso: Rename vdso_image_* to vdso*_image")
Cc: Peter Anvin <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-02-10 20:03:30 -08:00
Linus Torvalds
6f7e6393d1 * VDSO rework and cleanups
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Merge tag 'x86_entry_for_7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 entry code updates from Dave Hansen:
 "This is entirely composed of a set of long overdue VDSO cleanups. They
  makes the VDSO build much more logical and zap quite a bit of old
  cruft.

  It also results in a coveted net-code-removal diffstat"

* tag 'x86_entry_for_7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/entry/vdso: Add vdso2c to .gitignore
  x86/entry/vdso32: Omit '.cfi_offset eflags' for LLVM < 16
  MAINTAINERS: Adjust vdso file entry in INTEL SGX
  x86/entry/vdso/selftest: Update location of vgetrandom-chacha.S
  x86/entry/vdso: Fix filtering of vdso compiler flags
  x86/entry/vdso: Update the object paths for "make vdso_install"
  x86/entry/vdso32: When using int $0x80, use it directly
  x86/cpufeature: Replace X86_FEATURE_SYSENTER32 with X86_FEATURE_SYSFAST32
  x86/vdso: Abstract out vdso system call internals
  x86/entry/vdso: Include GNU_PROPERTY and GNU_STACK PHDRs
  x86/entry/vdso32: Remove open-coded DWARF in sigreturn.S
  x86/entry/vdso32: Remove SYSCALL_ENTER_KERNEL macro in sigreturn.S
  x86/entry/vdso32: Don't rely on int80_landing_pad for adjusting ip
  x86/entry/vdso: Refactor the vdso build
  x86/entry/vdso: Move vdso2c to arch/x86/tools
  x86/entry/vdso: Rename vdso_image_* to vdso*_image
2026-02-10 19:34:26 -08:00
Linus Torvalds
57cb845067 - A nice cleanup to the paravirt code containing a unification of the paravirt
clock interface, taming the include hell by splitting the pv_ops structure
   and removing of a bunch of obsolete code. Work by Juergen Gross.
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Merge tag 'x86_paravirt_for_v7.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 paravirt updates from Borislav Petkov:

 - A nice cleanup to the paravirt code containing a unification of the
   paravirt clock interface, taming the include hell by splitting the
   pv_ops structure and removing of a bunch of obsolete code (Juergen
   Gross)

* tag 'x86_paravirt_for_v7.0_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  x86/paravirt: Use XOR r32,r32 to clear register in pv_vcpu_is_preempted()
  x86/paravirt: Remove trailing semicolons from alternative asm templates
  x86/pvlocks: Move paravirt spinlock functions into own header
  x86/paravirt: Specify pv_ops array in paravirt macros
  x86/paravirt: Allow pv-calls outside paravirt.h
  objtool: Allow multiple pv_ops arrays
  x86/xen: Drop xen_mmu_ops
  x86/xen: Drop xen_cpu_ops
  x86/xen: Drop xen_irq_ops
  x86/paravirt: Move pv_native_*() prototypes to paravirt.c
  x86/paravirt: Introduce new paravirt-base.h header
  x86/paravirt: Move paravirt_sched_clock() related code into tsc.c
  x86/paravirt: Use common code for paravirt_steal_clock()
  riscv/paravirt: Use common code for paravirt_steal_clock()
  loongarch/paravirt: Use common code for paravirt_steal_clock()
  arm64/paravirt: Use common code for paravirt_steal_clock()
  arm/paravirt: Use common code for paravirt_steal_clock()
  sched: Move clock related paravirt code to kernel/sched
  paravirt: Remove asm/paravirt_api_clock.h
  x86/paravirt: Move thunk macros to paravirt_types.h
  ...
2026-02-10 19:01:45 -08:00
Linus Torvalds
f1c538ca81 Updates for the VDSO subsystem:
- Provide the missing 64-bit variant of clock_getres()
 
     This allows the extension of CONFIG_COMPAT_32BIT_TIME to the vDSO and
     finally the removal of 32-bit time types from the kernel and UAPI.
 
   - Remove the useless and broken getcpu_cache from the VDSO
 
     The intention was to provide a trivial way to retrieve the CPU number from
     the VDSO, but as the VDSO data is per process there is no way to make it
     work.
 
   - Switch get/put_unaligned() from packed struct to memcpy()
 
     The packed struct violates strict aliasing rules which requires to pass
     -fno-strict-aliasing to the compiler. As this are scalar values
     __builtin_memcpy() turns them into simple loads and stores
 
   - Use __typeof_unqual__() for __unqual_scalar_typeof()
 
     The get/put_unaligned() changes triggered a new sparse warning when __beNN
     types are used with get/put_unaligned() as sparse builds add a special
     'bitwise' attribute to them which prevents sparse to evaluate the Generic
     in __unqual_scalar_typeof().
 
     Newer sparse versions support __typeof_unqual__() which avoids the problem,
     but requires a recent sparse install. So this adds a sanity check to sparse
     builds, which validates that sparse is available and capable of handling it.
 
   - Force inline __cvdso_clock_getres_common()
 
     Compilers sometimes un-inline agressively, which results in function call
     overhead and problems with automatic stack variable initialization.
 
     Interestingly enough the force inlining results in smaller code than the
     un-inlined variant produced by GCC when optimizing for size.
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Merge tag 'timers-vdso-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull VDSO updates from Thomas Gleixner:

 - Provide the missing 64-bit variant of clock_getres()

   This allows the extension of CONFIG_COMPAT_32BIT_TIME to the vDSO and
   finally the removal of 32-bit time types from the kernel and UAPI.

 - Remove the useless and broken getcpu_cache from the VDSO

   The intention was to provide a trivial way to retrieve the CPU number
   from the VDSO, but as the VDSO data is per process there is no way to
   make it work.

 - Switch get/put_unaligned() from packed struct to memcpy()

   The packed struct violates strict aliasing rules which requires to
   pass -fno-strict-aliasing to the compiler. As this are scalar values
   __builtin_memcpy() turns them into simple loads and stores

 - Use __typeof_unqual__() for __unqual_scalar_typeof()

   The get/put_unaligned() changes triggered a new sparse warning when
   __beNN types are used with get/put_unaligned() as sparse builds add a
   special 'bitwise' attribute to them which prevents sparse to evaluate
   the Generic in __unqual_scalar_typeof().

   Newer sparse versions support __typeof_unqual__() which avoids the
   problem, but requires a recent sparse install. So this adds a sanity
   check to sparse builds, which validates that sparse is available and
   capable of handling it.

 - Force inline __cvdso_clock_getres_common()

   Compilers sometimes un-inline agressively, which results in function
   call overhead and problems with automatic stack variable
   initialization.

   Interestingly enough the force inlining results in smaller code than
   the un-inlined variant produced by GCC when optimizing for size.

* tag 'timers-vdso-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  vdso/gettimeofday: Force inlining of __cvdso_clock_getres_common()
  x86/percpu: Make CONFIG_USE_X86_SEG_SUPPORT work with sparse
  compiler: Use __typeof_unqual__() for __unqual_scalar_typeof()
  powerpc/vdso: Provide clock_getres_time64()
  tools headers: Remove unneeded ignoring of warnings in unaligned.h
  tools headers: Update the linux/unaligned.h copy with the kernel sources
  vdso: Switch get/put_unaligned() from packed struct to memcpy()
  parisc: Inline a type punning version of get_unaligned_le32()
  vdso: Remove struct getcpu_cache
  MIPS: vdso: Provide getres_time64() for 32-bit ABIs
  arm64: vdso32: Provide clock_getres_time64()
  ARM: VDSO: Provide clock_getres_time64()
  ARM: VDSO: Patch out __vdso_clock_getres() if unavailable
  x86/vdso: Provide clock_getres_time64() for x86-32
  selftests: vDSO: vdso_test_abi: Add test for clock_getres_time64()
  selftests: vDSO: vdso_test_abi: Use UAPI system call numbers
  selftests: vDSO: vdso_config: Add configurations for clock_getres_time64()
  vdso: Add prototype for __vdso_clock_getres_time64()
2026-02-10 17:02:23 -08:00
Linus Torvalds
36ae1c45b2 Scheduler changes for v7.0:
Scheduler Kconfig space updates:
 
  - Further consolidate configurable preemption modes: reduce
    the number of architectures that are allowed to offer
    PREEMPT_NONE and PREEMPT_VOLUNTARY, reducing the number
    of preemption models from four to just two: 'full' and 'lazy'
    on up-to-date architectures (arm64, loongarch, powerpc,
    riscv, s390, x86).
 
    None and voluntary are only available as legacy features
    on platforms that don't implement lazy preemption yet,
    or which don't even support preemption.
 
    The goal is to eventually remove cond_resched() and
    voluntary preemption altogether.
 
    (Peter Zijlstra)
 
 RSEQ based 'scheduler time slice extension' support:
 
 This allows a thread to request a time slice extension when it
 enters a critical section to avoid contention on a resource when
 the thread is scheduled out inside of the critical section.
 
  - Add fields and constants for time slice extension
  - Provide static branch for time slice extensions
  - Add statistics for time slice extensions
  - Add prctl() to enable time slice extensions
  - Implement sys_rseq_slice_yield()
  - Implement syscall entry work for time slice extensions
  - Implement time slice extension enforcement timer
  - Reset slice extension when scheduled
  - Implement rseq_grant_slice_extension()
  - entry: Hook up rseq time slice extension
  - selftests: Implement time slice extension test
 
    (Thomas Gleixner)
 
  - Allow registering RSEQ with slice extension
  - Move slice_ext_nsec to debugfs
  - Lower default slice extension
  - selftests/rseq: Add rseq slice histogram script
 
    (Peter Zijlstra)
 
 Scheduler performance/scalability improvements:
 
  - Update rq->avg_idle when a task is moved to an idle CPU,
    which improves the scalability of various workloads.
    (Shubhang Kaushik)
 
  - Reorder fields in 'struct rq' for better caching
    (Blake Jones)
 
  - Fair scheduler SMP NOHZ balancing code speedups:
 
    - Move checking for nohz cpus after time check
    - Change likelyhood of nohz.nr_cpus
    - Remove nohz.nr_cpus and use weight of cpumask instead
 
      (Shrikanth Hegde)
 
  - Avoid false sharing for sched_clock_irqtime (Wangyang Guo)
 
  - Drop useless cpumask_empty() in find_energy_efficient_cpu()
  - Simplify task_numa_find_cpu()
  - Use cpumask_weight_and() in sched_balance_find_dst_group()
 
    (Yury Norov)
 
 DL scheduler updates:
 
  - Add a deadline server for sched_ext tasks (by Andrea Righi and
    Joel Fernandes, with fixes by Peter Zijlstra)
 
 RT scheduler updates:
 
  - Skip currently executing CPU in rto_next_cpu() (Chen Jinghuang)
 
 Entry code updates and performance improvements, which is part of the
 scheduler tree in this cycle due to interdependencies with the RSEQ
 based time slice extension work:
 
   - Remove unused syscall argument from syscall_trace_enter()
   - Rework syscall_exit_to_user_mode_work() for architecture reuse
   - Add arch_ptrace_report_syscall_entry/exit()
   - Inline syscall_exit_work() and syscall_trace_enter()
 
     (Jinjie Ruan)
 
 Scheduler core updates:
 
  - Rework sched_class::wakeup_preempt() and rq_modified_*()
  - Avoid rq->lock bouncing in sched_balance_newidle()
  - Rename rcu_dereference_check_sched_domain() =>
           rcu_dereference_sched_domain()
  - <linux/compiler_types.h>: Add the __signed_scalar_typeof() helper
 
    (Peter Zijlstra)
 
 Fair scheduler updates/refactoring:
 
  - Fold the sched_avg update
  - Change rcu_dereference_check_sched_domain() to rcu-sched
  - Switch to rcu_dereference_all()
  - Remove superfluous rcu_read_lock()
  - Limit hrtick work
 
    (Peter Zijlstra)
 
  - Join two #ifdef CONFIG_FAIR_GROUP_SCHED blocks
  - Clean up comments in 'struct cfs_rq'
  - Separate se->vlag from se->vprot
  - Rename cfs_rq::avg_load to cfs_rq::sum_weight
  - Rename cfs_rq::avg_vruntime to ::sum_w_vruntime & helper functions
  - Introduce and use the vruntime_cmp() and vruntime_op() wrappers
    for wrapped-signed aritmetics
  - Sort out 'blocked_load*' namespace noise
 
    (Ingo Molnar)
 
 Scheduler debugging code updates:
 
  - Export hidden tracepoints to modules (Gabriele Monaco)
 
  - Convert copy_from_user() + kstrtouint() to kstrtouint_from_user()
    (Fushuai Wang)
 
  - Add assertions to QUEUE_CLASS (Peter Zijlstra)
 
  - hrtimer: Fix tracing oddity (Thomas Gleixner)
 
 Misc fixes and cleanups:
 
  - Re-evaluate scheduling when migrating queued tasks out of
    throttled cgroups (Zicheng Qu)
 
  - Remove task_struct->faults_disabled_mapping (Christoph Hellwig)
 
  - Fix math notation errors in avg_vruntime comment (Zhan Xusheng)
 
  - sched/cpufreq: Use %pe format for PTR_ERR() printing (zenghongling)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:
 "Scheduler Kconfig space updates:

   - Further consolidate configurable preemption modes (Peter Zijlstra)

     Reduce the number of architectures that are allowed to offer
     PREEMPT_NONE and PREEMPT_VOLUNTARY, reducing the number of
     preemption models from four to just two: 'full' and 'lazy' on
     up-to-date architectures (arm64, loongarch, powerpc, riscv, s390,
     x86).

     None and voluntary are only available as legacy features on
     platforms that don't implement lazy preemption yet, or which don't
     even support preemption.

     The goal is to eventually remove cond_resched() and voluntary
     preemption altogether.

  RSEQ based 'scheduler time slice extension' support (Thomas Gleixner
  and Peter Zijlstra):

  This allows a thread to request a time slice extension when it enters
  a critical section to avoid contention on a resource when the thread
  is scheduled out inside of the critical section.

   - Add fields and constants for time slice extension
   - Provide static branch for time slice extensions
   - Add statistics for time slice extensions
   - Add prctl() to enable time slice extensions
   - Implement sys_rseq_slice_yield()
   - Implement syscall entry work for time slice extensions
   - Implement time slice extension enforcement timer
   - Reset slice extension when scheduled
   - Implement rseq_grant_slice_extension()
   - entry: Hook up rseq time slice extension
   - selftests: Implement time slice extension test
   - Allow registering RSEQ with slice extension
   - Move slice_ext_nsec to debugfs
   - Lower default slice extension
   - selftests/rseq: Add rseq slice histogram script

  Scheduler performance/scalability improvements:

   - Update rq->avg_idle when a task is moved to an idle CPU, which
     improves the scalability of various workloads (Shubhang Kaushik)

   - Reorder fields in 'struct rq' for better caching (Blake Jones)

   - Fair scheduler SMP NOHZ balancing code speedups (Shrikanth Hegde):
      - Move checking for nohz cpus after time check
      - Change likelyhood of nohz.nr_cpus
      - Remove nohz.nr_cpus and use weight of cpumask instead

   - Avoid false sharing for sched_clock_irqtime (Wangyang Guo)

   - Cleanups (Yury Norov):
      - Drop useless cpumask_empty() in find_energy_efficient_cpu()
      - Simplify task_numa_find_cpu()
      - Use cpumask_weight_and() in sched_balance_find_dst_group()

  DL scheduler updates:

   - Add a deadline server for sched_ext tasks (by Andrea Righi and Joel
     Fernandes, with fixes by Peter Zijlstra)

  RT scheduler updates:

   - Skip currently executing CPU in rto_next_cpu() (Chen Jinghuang)

  Entry code updates and performance improvements (Jinjie Ruan)

  This is part of the scheduler tree in this cycle due to inter-
  dependencies with the RSEQ based time slice extension work:

    - Remove unused syscall argument from syscall_trace_enter()
    - Rework syscall_exit_to_user_mode_work() for architecture reuse
    - Add arch_ptrace_report_syscall_entry/exit()
    - Inline syscall_exit_work() and syscall_trace_enter()

  Scheduler core updates (Peter Zijlstra):

   - Rework sched_class::wakeup_preempt() and rq_modified_*()
   - Avoid rq->lock bouncing in sched_balance_newidle()
   - Rename rcu_dereference_check_sched_domain() =>
            rcu_dereference_sched_domain()
   - <linux/compiler_types.h>: Add the __signed_scalar_typeof() helper

  Fair scheduler updates/refactoring (Peter Zijlstra and Ingo Molnar):

   - Fold the sched_avg update
   - Change rcu_dereference_check_sched_domain() to rcu-sched
   - Switch to rcu_dereference_all()
   - Remove superfluous rcu_read_lock()
   - Limit hrtick work
   - Join two #ifdef CONFIG_FAIR_GROUP_SCHED blocks
   - Clean up comments in 'struct cfs_rq'
   - Separate se->vlag from se->vprot
   - Rename cfs_rq::avg_load to cfs_rq::sum_weight
   - Rename cfs_rq::avg_vruntime to ::sum_w_vruntime & helper functions
   - Introduce and use the vruntime_cmp() and vruntime_op() wrappers for
     wrapped-signed aritmetics
   - Sort out 'blocked_load*' namespace noise

  Scheduler debugging code updates:

   - Export hidden tracepoints to modules (Gabriele Monaco)

   - Convert copy_from_user() + kstrtouint() to kstrtouint_from_user()
     (Fushuai Wang)

   - Add assertions to QUEUE_CLASS (Peter Zijlstra)

   - hrtimer: Fix tracing oddity (Thomas Gleixner)

  Misc fixes and cleanups:

   - Re-evaluate scheduling when migrating queued tasks out of throttled
     cgroups (Zicheng Qu)

   - Remove task_struct->faults_disabled_mapping (Christoph Hellwig)

   - Fix math notation errors in avg_vruntime comment (Zhan Xusheng)

   - sched/cpufreq: Use %pe format for PTR_ERR() printing
     (zenghongling)"

* tag 'sched-core-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits)
  sched: Re-evaluate scheduling when migrating queued tasks out of throttled cgroups
  sched/cpufreq: Use %pe format for PTR_ERR() printing
  sched/rt: Skip currently executing CPU in rto_next_cpu()
  sched/clock: Avoid false sharing for sched_clock_irqtime
  selftests/sched_ext: Add test for DL server total_bw consistency
  selftests/sched_ext: Add test for sched_ext dl_server
  sched/debug: Fix dl_server (re)start conditions
  sched/debug: Add support to change sched_ext server params
  sched_ext: Add a DL server for sched_ext tasks
  sched/debug: Stop and start server based on if it was active
  sched/debug: Fix updating of ppos on server write ops
  sched/deadline: Clear the defer params
  entry: Inline syscall_exit_work() and syscall_trace_enter()
  entry: Add arch_ptrace_report_syscall_entry/exit()
  entry: Rework syscall_exit_to_user_mode_work() for architecture reuse
  entry: Remove unused syscall argument from syscall_trace_enter()
  sched: remove task_struct->faults_disabled_mapping
  sched: Update rq->avg_idle when a task is moved to an idle CPU
  selftests/rseq: Add rseq slice histogram script
  hrtimer: Fix trace oddity
  ...
2026-02-10 12:50:10 -08:00
Nathan Chancellor
3e30278e0c x86/entry/vdso32: Omit '.cfi_offset eflags' for LLVM < 16
After commit:

  884961618e ("x86/entry/vdso32: Remove open-coded DWARF in sigreturn.S")

building arch/x86/entry/vdso/vdso32/sigreturn.S with LLVM 15 fails with:

  <instantiation>:18:20: error: invalid register name
   .cfi_offset eflags, 64
                     ^
  arch/x86/entry/vdso/vdso32/sigreturn.S:33:2: note: while in macro instantiation
   STARTPROC_SIGNAL_FRAME 8
   ^

Support for eflags as an argument to .cfi_offset was added in the LLVM
16 development cycle:

    67bd3c58c0 [1]

Only add this .cfi_offset directive if it is supported by the assembler
to clear up the error.

[ mingo: Tidied up the changelog and the comment a bit ]

Fixes: 884961618e ("x86/entry/vdso32: Remove open-coded DWARF in sigreturn.S")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Link: https://patch.msgid.link/20260123-x86-vdso32-wa-llvm-15-cfi-offset-eflags-v1-1-0f412e3516a4@kernel.org
2026-01-24 10:18:28 +01:00
Thomas Gleixner
99d2592023 rseq: Implement sys_rseq_slice_yield()
Provide a new syscall which has the only purpose to yield the CPU after the
kernel granted a time slice extension.

sched_yield() is not suitable for that because it unconditionally
schedules, but the end of the time slice extension is not required to
schedule when the task was already preempted. This also allows to have a
strict check for termination to catch user space invoking random syscalls
including sched_yield() from a time slice extension region.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20251215155708.929634896@linutronix.de
2026-01-22 11:11:17 +01:00
H. Peter Anvin
a48acbaf99 x86/entry/vdso: Fix filtering of vdso compiler flags
This fixes several typos in the filtering of compiler flags for vdso,
discovered by Chris Mason using an AI script:

1. "-fno-PIE" was written as "fno-PIE".
2. "CC_PLUGINS_FLAGS" was written as "CC_PLUGIN_FLAGS"

To the best of my knowledge, none of these actually had any real
impact on the build at this time but they are genuine bugs which could
break things at any point in the future.

Chris's script also found that "CONFIG_X86_USER_SHADOW_STACK" was
missing "CONFIG_", but it needs a different fix.

[ dhansen: remove CONFIG_X86_USER_SHADOW_STACK munging,
	   add mention in changelog. ]

Closes: https://lore.kernel.org/20260116035807.2307742-1-clm@meta.com
Fixes: 693c819fed ("x86/entry/vdso: Refactor the vdso build")
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://patch.msgid.link/20260116204057.386268-3-hpa@zytor.com
2026-01-16 13:25:33 -08:00