After enabling GENERIC_ENTRY on PowerPC, syscall_enter_from_user_mode()
returns -1 as a sentinel to signal that seccomp or ptrace has intercepted
the syscall and already set a return value via syscall_set_return_value().
system_call_exception() was not handling this sentinel, and since -1UL
is >= NR_syscalls, the code fell into the out-of-range path and returned
-ENOSYS, overwriting the errno already placed in regs->gpr[3].
The naive fix of checking r0 == -1L before the NR_syscalls bounds check
is ambiguous: a user legitimately calling syscall(-1) also produces r0 ==
-1L, and a tracer intercepting such a call would have its injected return
value silently discarded.
Fix this by introducing a thread flag that is set whenever
syscall_set_return_value() explicitly updates the return value. In
system_call_exception(), check and clear this flag before dispatching
the syscall, and return the preset value directly when it is present.
This ensures that an explicitly supplied return value always suppresses
syscall execution, regardless of the syscall number.
This handles all seccomp actions correctly:
- SECCOMP_RET_ERRNO, SECCOMP_RET_TRACE (no tracer), SECCOMP_RET_USER_NOTIF:
all call syscall_set_return_value(), flag is set, injected value returned.
- SECCOMP_RET_TRAP, SECCOMP_RET_KILL: call syscall_rollback() and deliver
a signal; flag is not set, but the process is dying so the return value
is irrelevant.
The fix covers both ppc32 and ppc64 with no #ifdefs.
Fixes: bee25f97ad ("powerpc: Enable GENERIC_ENTRY feature")
Reported-by: Michal Suchánek <msuchanek@suse.de>
Closes: https://lore.kernel.org/all/ajpp-_XnbF3UTM_E@kunlun.suse.cz/
Tested-by: Michal Suchánek <msuchanek@suse.de>
Reviewed-by: Michal Suchánek <msuchanek@suse.de>
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260731081521.1852133-1-mkchauras@gmail.com
On pseries LPAR systems, watchdog timers configured from userspace can
remain active after a kernel panic. When a panic triggers kdump, the
crashing kernel jumps directly to the kdump kernel without stopping
active watchdogs. As a result, the watchdogs remain active after the
kdump kernel starts.
If dump capture takes longer than the watchdog timeout, PHYP resets the
LPAR before the dump is fully captured, causing dump capture to fail.
Fix this by issuing the `H_WATCHDOG` hcall during the crash shutdown
sequence to stop all active watchdogs before booting the kdump kernel.
Cc: stable@vger.kernel.org
Fixes: 69472ffa65 ("watchdog/pseries-wdt: initial support for H_WATCHDOG-based watchdog timers")
Reported-by: Mahesh Kumar G <mahe657@linux.ibm.com>
Suggested-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727053416.276317-4-sourabhjain@linux.ibm.com
The pseries watchdog initialization registers the pseries-wdt platform
device using platform_device_register_simple(), but currently ignores
its return value.
Check the returned pointer for errors, log a descriptive error message
when registration fails, and propagate the failure code to the caller.
This avoids silently ignoring platform device registration failures.
Cc: stable@vger.kernel.org
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727053416.276317-3-sourabhjain@linux.ibm.com
The H_WATCHDOG input and output definitions are currently local to the
pseries watchdog driver. The next patch in this series also needs these
definitions to issue H_WATCHDOG hypercalls outside the watchdog driver.
Move the H_WATCHDOG definitions to a new common header,
asm/papr-watchdog.h, so they can be shared without duplicating the
PAPR watchdog definitions.
No functional changes.
Cc: stable@vger.kernel.org
Suggested-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727053416.276317-2-sourabhjain@linux.ibm.com
On IBM POWER systems, newer processor generations can operate in
compatibility modes corresponding to earlier generations. This becomes
relevant for nested virtualization, where nested KVM guests may need to
run with a specific processor compatibility level.
Currently, when running a nested KVM guest (L2) inside a Power11 pSeries
logical partition (L1) booted in Power10 compatibility mode, the guest
fails to boot while setting 'arch_compat'. This happens because the CPU
class is derived from the hardware PVR (via mfspr()), which reflects the
physical processor generation (Power11), rather than the effective
compatibility mode (Power10).
As a result, userspace may request a Power11 arch_compat for the L2
guest. However, the L1 partition, running in Power10 compatibility, has
only negotiated support up to Power10 with the Power Hypervisor (L0).
When H_GUEST_SET_STATE is invoked with a Power11 Logical PVR, the
hypervisor rejects the request, leading to a late guest boot failure:
KVM-NESTEDv2: couldn't set guest wide elements
[..KVM reg dump..]
This situation should be detected earlier and rejected by KVM. Without
proper validation, if userspace ignores the error, the guest may continue
to boot in Power11 raw mode on a Power10 compatibility host, which should
not be allowed.
Introduce a validation mechanism that detects unsupported arch_compat
values early in the guest initialization path. When an unsupported
arch_compat is requested (e.g., Power11 on a Power10 compatibility mode
host), kvmppc_set_arch_compat() uses cpu_has_feature(CPU_FTR_P11_PVR) to
detect the mismatch and sets arch_compat to PVR_ARCH_INVALID (0xffffffff).
This sentinel value is architecturally safe: PAPR specifies that valid
logical PVR values must have 0x0f as the first byte, ensuring 0xffffffff
lies permanently outside the specification-defined range. Setting this
value triggers kvmppc_sanity_check() to mark the vCPU as invalid by
setting vcpu->arch.sane to false. On the next vCPU run, kvmppc_vcpu_run_hv()
checks this flag and returns -EINVAL, preventing the guest from running
with an invalid processor compatibility configuration.
With this, when a Power11 arch_compat is requested on a Power10
compatibility mode host, the guest fails early during boot with:
error: kvm run failed Invalid argument
This provides a much clearer failure mode compared to the previous
behavior where the guest could boot in Power11 raw mode (if userspace
ignored the error) or fail late during H_GUEST_SET_STATE.
Suggested-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Reviewed-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Tested-by: Anushree Mathur <anushree.mathur@linux.ibm.com>
Acked-by: Gautam Menghani <gautam@linux.ibm.com>
Cc: stable@vger.kernel.org # v6.13+
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260714175432.86388-1-amachhiw@linux.ibm.com
smp_muxed_ipi_message_pass() calls smp_ops->cause_ipi() without
checking whether it has been set.
On platforms using muxed IPI (e.g. powernv/pseries), smp_ops->cause_ipi
is initialized to NULL in the static smp_ops and only assigned during
the platform smp_probe() handler. If the IPI subsystem fails to
initialize -- for example when xive_init_ipis() fails and
xive_smp_probe() returns an error -- the probe handler returns early
and cause_ipi is never set. Any subsequent IPI send (e.g.
arch_smp_send_reschedule()) would dereference the NULL pointer.
Add a NULL check to avoid the crash in that situation.
Fixes: 23d72bfd8f ("powerpc: Consolidate ipi message mux and demux")
Signed-off-by: Gou Hao <gouhao@uniontech.com>
Reviewed-by: jiazhenyuan <jiazhenyuan@uniontech.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727104215.184786-6-gouhao@uniontech.com
xive_smp_probe() currently assigns smp_ops->cause_ipi = xive_cause_ipi
before calling xive_init_ipis() and xive_setup_cpu_ipi(). If either
call fails, the platform probe handler returns early but cause_ipi
remains pointing to xive_cause_ipi -- which accesses per-cpu IPI data
(xc->ipi_data) that was never properly initialized, leading to
a WARN and a crash.
Move the cause_ipi assignment to after both calls succeed, so that
smp_ops->cause_ipi is only set when the IPI subsystem is fully
initialized.
Signed-off-by: Gou Hao <gouhao@uniontech.com>
Suggested-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: jiazhenyuan <jiazhenyuan@uniontech.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727104215.184786-5-gouhao@uniontech.com
When xive_init_ipis() fails (e.g. irq_domain_alloc_irqs() fails),
the error path frees the global xive_ipis array. However,
xive_smp_probe() previously ignored this failure and proceeded to
call xive_setup_cpu_ipi(), which dereferences the already-freed
xive_ipis pointer -- a use-after-free.
Now that xive_smp_probe() returns int (previous patch), propagate
the error from xive_init_ipis() and xive_setup_cpu_ipi() through
xive_smp_probe(). Check the return value in both pnv_smp_probe()
and pSeries_smp_probe() so that IPI setup is aborted cleanly on
failure, avoiding the use-after-free.
Fixes: 243e25112d ("powerpc/xive: Native exploitation of the XIVE interrupt controller")
Fixes: cbc06f051c ("powerpc/xive: Do not skip CPU-less nodes when creating the IPIs")
Signed-off-by: Gou Hao <gouhao@uniontech.com>
Reviewed-by: Wentao Guan <guanwentao@uniontech.com>
Reviewed-by: jiazhenyuan <jiazhenyuan@uniontech.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727104215.184786-4-gouhao@uniontech.com
xive_smp_probe() calls xive_init_ipis() which can fail, but its
return value is currently ignored. Change xive_smp_probe() to
return int so that errors can be propagated to callers.
This is a preparatory patch for the next one.
No functional change yet; the return value is always 0 at this point.
Signed-off-by: Gou Hao <gouhao@uniontech.com>
Reviewed-by: Wentao Guan <guanwentao@uniontech.com>
Reviewed-by: jiazhenyuan <jiazhenyuan@uniontech.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727104215.184786-3-gouhao@uniontech.com
__GFP_NOFAIL should not be used in new code [1]. xive_init_ipis()
allocates the xive_ipis array with __GFP_NOFAIL, which makes the
subsequent NULL check unreachable dead code.
Remove __GFP_NOFAIL so the allocation can fail, and make all xive_ipis
access paths NULL-safe:
- Return XIVE_BAD_IRQ from xive_ipi_cpu_to_irq() when xive_ipis is NULL.
- Set xive_ipis to NULL after kfree() in the error path to prevent
use-after-free.
- Guard xive_setup_cpu_ipi() and xive_cleanup_cpu_ipi() against
xive_ipi_irq == XIVE_BAD_IRQ to avoid dereferencing an uninitialized
or already-freed xive_ipis array.
No functional change when allocation succeeds.
Link: https://lore.kernel.org/all/20260725202632.dcb325658896a470df91cf57@linux-foundation.org/ [1]
Fixes: 7dcc37b3ef ("powerpc/xive: Map one IPI interrupt per node")
Signed-off-by: Gou Hao <gouhao@uniontech.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Cédric Le Goater <clg@kaod.org>
Suggested-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Wentao Guan <guanwentao@uniontech.com>
Reviewed-by: jiazhenyuan <jiazhenyuan@uniontech.com>
Reviewed-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260727104215.184786-2-gouhao@uniontech.com
Sashiko AI review pointed out the following issue.
The __merge_memory_ranges() function incorrectly handles overlapping
memory ranges when merging them. Although sort_memory_ranges() sorts all
ranges by their start address in ascending order beforehand, the merge
logic remains defective in two ways:
1. It compares the current range's start against the previous element (i-1)
instead of the running target index (idx)
2. It unconditionally overwrites 'ranges[idx].end' with 'ranges[i].end'.
This logic flaw leads to critical memory truncation when a larger memory
range completely subsumes subsequent smaller ranges.
For example, consider a sorted input array with three ranges:
Range A (idx=0): [0x1000 - 0x9000]
Range B (i=1): [0x2000 - 0x5000] (completely inside Range A)
Range C (i=2): [0x6000 - 0x8000] (completely inside Range A)
1. When i=1 (Range B):
ranges[1].start (0x2000) <= ranges[0].end + 1 (0x9001) is TRUE.
The code executes: ranges[0].end = ranges[1].end, which erroneously
shrinks Range A's end from 0x9000 down to 0x5000.
2. When i=2 (Range C):
ranges[2].start (0x6000) <= ranges[1].end + 1 (0x5001) is FALSE.
The code falls into the else block, creating a broken new range.
As a result, valid memory fragments [0x5001 - 0x5fff] and [0x8001 - 0x9000]
are completely lost from the kexec exclude lists, potentially allowing
the crash kernel to overwrite active memory, causing data corruption
or crashes.
Fix this by ensuring the start of the current range is compared against the
end of the active merged range (idx), and use max() to safely prevent the
outer boundary from being truncated.
Cc: stable@vger.kernel.org
Fixes: 180adfc532 ("powerpc/kexec_file: Add helper functions for getting memory ranges")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260729012948.2797865-4-ruanjinjie@huawei.com
A static Sashiko AI review identified a potential NULL pointer
dereference in kexec_extra_fdt_size_ppc64().
On platforms without any reserved memory regions,
get_reserved_memory_ranges() can return 0 while leaving 'rmem'
unallocated as NULL. Passing it directly leads to a kernel panic when
evaluating 'rmem->nr_ranges'.
Add a NULL check for 'rmem' to prevent this crash.
Cc: stable@vger.kernel.org
Fixes: 0d3ff06733 ("powerpc/kexec_file: fix extra size calculation for kexec FDT")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260729012948.2797865-3-ruanjinjie@huawei.com
In get_crash_memory_ranges(), if crash_exclude_mem_range() failed
after realloc_mem_ranges() has successfully allocated the cmem
memory, it just returns an error but leaves cmem pointing to
the allocated memory, nor is it freed in the caller
update_crash_elfcorehdr(), which cause a memory leak, goto out
to free the cmem.
Fixes: 849599b702 ("powerpc/crash: add crash memory hotplug support")
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260729012948.2797865-2-ruanjinjie@huawei.com
The PPC4xx GPIO driver stopped assigning an explicit parent
to the gpio_chip when it moved away from of_mm_gpiochip_add_data().
Restore that association from the platform device so OF GPIO lookup
can match phandles to the registered gpiochip.
Tested on: Cisco MX60W. No more probe deferral.
Assisted-by: Codex:GPT-5.5
Fixes: 1044dbaf2a ("powerpc/44x: Change GPIO driver to a proper platform driver")
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260517063754.21819-1-rosenp@gmail.com
The lack of get_direction() callback in this driver causes GPIOLIB to
emit a warning. Implement it.
Fixes: e623c4303e ("gpiolib: sanitize the return value of gpio_chip::get_direction()")
Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/c6eb70aa0e1ba6e15f947c827006aa79edace05c.1785318836.git.chleroy@kernel.org
Include asm-generic/serial.h and use the generic BASE_BAUD definition
instead of redefining it.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Amit Machhiwal <amachhiw@linux.ibm.com>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260729223807.570178-3-thorsten.blum@linux.dev
There have been no sprintf() callers in the boot wrapper since commit
e275e023aa ("powerpc/44x: Warp patches for the new NDFC driver").
Remove the function definition and declaration.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260724172200.208722-2-thorsten.blum@linux.dev
Check only the first byte instead of scanning the entire string with
strlen().
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260721155346.121975-4-thorsten.blum@linux.dev
Check only the first byte instead of scanning the entire string with
strlen().
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260721155346.121975-3-thorsten.blum@linux.dev
Use cpu_relax() to wait for the execution status SPE_EX_STATE_EXECUTED.
Drop the comments while at it.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260720231153.116827-2-thorsten.blum@linux.dev
Check only the first byte instead of scanning the entire string with
strlen(). While at it, keep dt_cpu_name static, but move it into
dt_cpu_ftrs_scan_callback(), where it is assigned.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260701114428.818748-3-thorsten.blum@linux.dev
Now that struct rtas_error_log uses a flexible array member for the
extended log buffer, use struct_size() to calculate the total RTAS error
log size and avoid using the hard-coded header size of 8 bytes.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260627104730.276858-4-thorsten.blum@linux.dev
Now that struct rtas_error_log uses a flexible array member for the
extended log buffer, use struct_size() to calculate the total RTAS error
log size and avoid using the hard-coded header size of 8 bytes.
Use min() to replace the open-coded implementation while at it.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260627104730.276858-3-thorsten.blum@linux.dev
Drop the local 10-byte buffer. The old code copied at most 9 bytes from
the user buffer, but only the first byte was used to select the RTAS
operation.
Use get_user() to read the command byte instead and compare it directly
with '0' and '1'. Drop the explicit user buffer check, since get_user()
will fail on a NULL pointer and correctly return -EFAULT instead of
-EINVAL. Remove the now-obsolete string constants as well as any
strncmp() and strlen() calls.
Return the original count instead of a potentially capped value, since
the full user write has been consumed once the command is accepted.
Use unsigned int op to better match the manage_flash() interface.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260528201226.1599977-3-thorsten.blum@linux.dev
Drop the redundant buffer assignment in serial_edit_cmdline() since the
cp pointer is immediately overwritten.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260528082357.1397611-3-thorsten.blum@linux.dev
Replace the manual string length accounting, memcpy(), and NUL
termination with a single snprintf() call to prepend the elfcorehdr=
address and to detect string truncation at the same time.
Use kmalloc() to avoid unnecessarily zeroing the memory. While at it,
also use "prepending" instead of "appending" in the error message.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260527000105.1081651-3-thorsten.blum@linux.dev
Now that all kvm entry to guest paths handle the task work
using the generic framework, enable HAVE_POSIX_CPU_TIMERS_TASK_WORK
which allows running posix cpu timers in task context instead of running
them in hardirq. This would is a necessary step towards enabling
PREEMPT_RT on powerNV systems.
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Vishal Chourasia <vishalc@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260709092140.1753715-5-vishalc@linux.ibm.com
Since commit 2cd571245b ("sched/fair: Add related data structure for
task based throttle") in v6.18, CFS bandwidth throttling no longer
dequeues a task directly; it queues task_work via TWA_RESUME and sets
TIF_NOTIFY_RESUME, relying on that work running before the task returns
to guest/user mode. The powerpc KVM run loops only checked for reschedule
and signals, never TIF_NOTIFY_RESUME, so the deferred throttle never ran
while a vCPU stayed in the run loop: a CPU-bound guest that rarely exits
to userspace ran far past its cpu.max quota and then appeared frozen for
minutes while the accrued throttle debt was repaid.
Use the generic infrastructure to check for and handle pending work
before transitioning into guest mode, replacing the open-coded
need_resched() and cond_resched() checks in the Book3S HV run loops and
in the common kvmppc_prepare_to_enter() used by the Book3S PR and BookE
run loops. The redundant signal_pending() recheck (and its sigpend label)
in kvmhv_run_single_vcpu() is also dropped, as
xfer_to_guest_mode_work_pending() is a superset of it.
This picks up handling for TIF_NOTIFY_RESUME, which was previously
ignored, meaning task work will now be correctly handled on every
guest re-entry.
Selecting VIRT_XFER_TO_GUEST_WORK disables RCU's last-resort self-IPI
fallback for vCPU tasks (see rcu_irq_work_resched()), which on
nohz_full CPUs was what forced a reschedule for deferred rcuog wakeups
queued right before guest entry. Take over that obligation the same way
x86 and s390 do: call xfer_to_guest_mode_prepare() with IRQs disabled
immediately before the final xfer_to_guest_mode_work_pending() check at
each guest-entry gate (kvmhv_run_single_vcpu(), kvmppc_run_core() and
kvmppc_prepare_to_enter()).
In kvmppc_prepare_to_enter(), IRQs are now disabled with
local_irq_disable() before hard_irq_disable(): on 32-bit,
hard_irq_disable() is a raw MSR[EE] clear that bypasses the
lockdep/irq-tracing state, and the strict xfer_to_guest_mode helpers
assert that IRQs are seen as disabled. This also allows upgrading the
racy __xfer_to_guest_mode_work_pending() check to the asserting
variant, as this loop is the terminal gate for the PR and BookE paths.
In kvmhv_run_single_vcpu(), the -EINTR exit and the pre-existing
kvmhv_setup_mmu() failure exit now leave via the done label instead of
returning directly, keeping the run_vcpu enter/exit tracepoints
balanced and vcpu->arch.ret consistent with the returned value.
In kvmppc_prepare_to_enter() the generic helper accounts the signal exit
(vcpu->stat.signal_exits and KVM_EXIT_INTR) but does not set the exit
type, so kvmppc_set_exit_type(SIGNAL_EXITS) is retained on the signal
path to preserve the E500 CONFIG_KVM_EXIT_TIMING histogram; it is a no-op
otherwise.
Signed-off-by: Vishal Chourasia <vishalc@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260709092140.1753715-4-vishalc@linux.ibm.com
For now only Big Endian 32-bit PowerPC is supported, as that is the only
hardware I have. This has been tested on the Nintendo Wii so far, but I
plan on also using it on the GameCube, Wii U and Apple G4.
These changes aren’t the only ones required to get the kernel to compile
and link on PowerPC, libcore will also have to be changed to not use
integer division to format u64, u128 and core::time::Duration, otherwise
__udivdi3() and __umoddi3() will have to be added. I have tested this
change by replacing the three implementations with unimplemented!() and
it linked just fine.
Signed-off-by: Link Mauve <linkmauve@linkmauve.fr>
Link: https://github.com/Rust-for-Linux/linux/issues/105
Link: https://github.com/linuxppc/issues/issues/451
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://github.com/rust-lang/compiler-team/issues/986
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260708082454.1254320-7-mkchauras@gmail.com
The core crate currently depends on these two functions for i64/u64/
i128/u128/core::time::Duration formatting, but we shouldn’t use that in
the kernel so let’s panic if they are ever called.
This doesn’t yet fix drm_panic_qr.rs, which also uses __udivdi3 when
CONFIG_CC_OPTIMIZE_FOR_SIZE=y, but at least makes the rest of the kernel
build on PPC32.
Signed-off-by: Link Mauve <linkmauve@linkmauve.fr>
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260708082454.1254320-6-mkchauras@gmail.com
Added support for a new macro ARCH_STATIC_BRANCH_ASM in powerpc
to avoid duplication of inline asm between C and Rust. This is
inline with 'commit aecaf18165 ("jump_label: adjust inline asm to be consistent")'
Co-developed-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://github.com/Rust-for-Linux/linux/issues/105
Link: https://github.com/linuxppc/issues/issues/451
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260708082454.1254320-4-mkchauras@gmail.com
When building with LLVM=1 for architectures like powerpc where
CONFIG_DMA_SHARED_BUFFER is not enabled, the build fails with:
ld.lld: error: undefined symbol: dma_resv_reset_max_fences
>>> referenced by helpers.c
>>> rust/helpers/helpers.o:(rust_helper_dma_resv_unlock)
The issue occurs because:
1. CONFIG_DEBUG_MUTEXES=y is enabled
2. CONFIG_DMA_SHARED_BUFFER is not enabled
3. dma_resv_reset_max_fences() is declared in the header when
CONFIG_DEBUG_MUTEXES is set
4. But the function is only compiled in drivers/dma-buf/dma-resv.c,
which is only built when CONFIG_DMA_SHARED_BUFFER is enabled
5. Rust helpers call dma_resv_unlock() which calls
dma_resv_reset_max_fences(), causing an undefined symbol
Fix this by compiling `dma-resv.c` file only when CONFIG_DMA_SHARED_BUFFER
is enabled.
Fixes: 9b836641d3 ("rust: helpers: Add bindings/wrappers for dma_resv_lock")
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260708082454.1254320-3-mkchauras@gmail.com
When building Rust code for powerpc64le with LLVM=1 and -j1, rustc
encounters an error: "multiple candidates for `rmeta` dependency `core`
found", with two candidates:
1. The host's standard library from the rustup toolchain
2. The kernel's custom libcore.rmeta in the rust/ directory
This occurs because the build system uses `-L$(objtree)/rust` for host
library builds (proc_macro2, quote, syn), which causes rustc to search
the rust/ directory. During this search, rustc finds both the kernel's
custom libcore.rmeta and gains access to the host's standard library,
creating a conflict.
The solution is to separate host libraries into a dedicated rust/host/
subdirectory and use `-L$(objtree)/rust/host` for host builds instead
of `-L$(objtree)/rust`. This ensures that:
1. Host library builds (proc_macro2, quote, syn) only search rust/host/
and never encounter the kernel's libcore.rmeta
2. Proc macro builds use `-L$(objtree)/rust/host` to find their
dependencies
Special handling is added for rustdoc-pin_init, which is a host build
(to access the alloc crate) but depends on proc macros from the main
rust/ directory. It uses explicit `--extern` paths to reference the
proc macros without adding `-L$(objtree)/rust`, which would reintroduce
the conflict.
The rust/host/ directory is added to clean-files to ensure it's removed
during `make clean`.
Link: https://github.com/Rust-for-Linux/linux/issues/105
Link: https://github.com/linuxppc/issues/issues/451
Signed-off-by: Mukesh Kumar Chaurasiya (IBM) <mkchauras@gmail.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260708082454.1254320-2-mkchauras@gmail.com
Please consider pulling these changes from the signed vfs-7.2-rc5.fixes tag.
Thanks!
Christian
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Merge tag 'vfs-7.2-rc5.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs fixes from Christian Brauner:
- vfs: Preserve the ACL_DONT_CACHE state in forget_cached_acl().
ACL_DONT_CACHE is meant to be a permanent opt-out from ACL caching
which FUSE relies on for servers that don't negotiate FUSE_POSIX_ACL.
The helper replaced it with ACL_NOT_CACHED, silently re-enabling the
cache, and as fuse doesn't invalidate the cache for such servers a
properly timed get_acl() returned stale ACLs. Comes with a fuse
selftest reproducing this.
- pidfs:
- Preserve PIDFD_THREAD when a thread pidfd is reopened via
open_by_handle_at(). PIDFD_THREAD shares the O_EXCL bit which
do_dentry_open() strips after the flags have been validated, so
the reopened pidfd silently became a process pidfd. Comes with a
selftest.
- Add a pidfs_dentry_open() helper so the regular pidfd allocation
path and the file handle path share the code that forces O_RDWR
and reapplies the pidfd flags that do_dentry_open() strips.
- Handle FS_IOC32_GETVERSION in the compat ioctl path.
- Make pidfs_ino_lock static.
- iomap:
- Fix the block range calculation in ifs_clear_range_dirty() so a
partial clear doesn't drop the dirty state of blocks the range
only partially covers.
- Support invalidating partial folios so a partial truncate or hole
punch with blocksize < foliosize doesn't leave stale dirty bits
behind.
- Only set did_zero when iomap_zero_iter() actually zeroed
something.
- Guard ifs_set_range_dirty() and ifs_set_range_uptodate() against
zero-length ranges where the unsigned last-block calculation
underflows and bitmap_set() writes far beyond the ifs->state
allocation.
- Don't merge ioends with different io_private values as the merge
could leak or corrupt the private data of the individual ioends.
- exec:
- Raise bprm->have_execfd only once the binfmt_misc interpreter has
actually been opened. The flag was set as soon as a matching 'O'
or 'C' entry was found. If the interpreter open failed with
ENOEXEC the exec fell through to the next binary format with
have_execfd raised but no executable staged and begin_new_exec()
NULL derefed past the point of no return.
- Fix an unsigned loop counter wrap in transfer_args_to_stack() on
nommu. An overlong argument or environment string pushes bprm->p
below PAGE_SIZE, the stop index becomes zero, and the loop never
terminates, wrapping its counter and copying garbage from in
front of the page array into the new process stack.
- Make binfmt_elf_fdpic only honour the first PT_INTERP like
binfmt_elf does. Each additional PT_INTERP overwrote the previous
interpreter, leaking the name allocation and the interpreter file
reference together with the write denial open_exec() took,
leaving the file unwritable for as long as the system runs.
- overlayfs:
- Compare the full escaped xattr prefix including the trailing dot.
An xattr like "trusted.overlay.overlayfoo" was misclassified as
an escaped overlay xattr.
- Check read access to the copy_file_range() source with the
source's mounter credentials.
- super: Thawing a filesystem whose block device was frozen with
bdev_freeze() deadlocked. Dropping the last block layer freeze
reference from under s_umount ends up in fs_bdev_thaw() which
reacquires s_umount on the same task. Pin the superblock with an
active reference instead and call bdev_thaw() without holding
s_umount.
- procfs: Return EACCES instead of success when the ptrace access check
for namespace links fails.
- afs: Use afs_dir_get_block() rather than afs_dir_find_block() for
block 0 in afs_edit_dir_remove(), matching afs_edit_dir_add().
- Push the memcg gating of ->nr_cached_objects() down into the btrfs
and shmem callbacks instead of skipping every callback during
non-root memcg reclaim. The blanket check short-circuited XFS whose
inode reclaim hook is intentionally driven from per-memcg contexts to
free memcg-charged slab.
- eventpoll: Pin files while checking reverse paths.
Since struct file became SLAB_TYPESAFE_BY_RCU a concurrent close
could free and recycle the file under the check which then took and
dropped the f_lock of whatever live file now occupies that slot.
* tag 'vfs-7.2-rc5.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (24 commits)
super: fix emergency thaw deadlock on frozen block devices
pidfs: make pidfs_ino_lock static
eventpoll: pin files while checking reverse paths
fs: push nr_cached_objects memcg gating into individual filesystems
afs: Fix afs_edit_dir_remove() to get, not find, block 0
iomap: prevent ioend merge when io_private differs
iomap: add comments for ifs_clear/set_range_dirty()
iomap: fix out-of-bounds bitmap_set() with zero-length range
iomap: fix incorrect did_zero setting in iomap_zero_iter()
iomap: support invalidating partial folios
iomap: correct the range of a partial dirty clear
fs/super: fix emergency thaw double-unlock of s_umount
pidfs: handle FS_IOC32_GETVERSION in compat ioctl
ovl: check access to copy_file_range source with src mounter creds
proc: Fix broken error paths for namespace links
pidfs: add pidfs_dentry_open() helper
selftests/pidfd: check PIDFD_THREAD survives open_by_handle_at()
pidfs: preserve thread pidfds reopened by file handle
ovl: fix trusted xattr escape prefix matching
selftests/fuse: add ACL_DONT_CACHE regression test
...
Just a couple of small bits for the SpacemiT driver - one small fix, and
a new compatible in the DT binding.
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Merge tag 'spi-fix-v7.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi
Pull spi fixes from Mark Brown:
"Just a couple of small bits for the SpacemiT driver - one small fix,
and a new compatible in the DT binding"
* tag 'spi-fix-v7.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
spi: dt-bindings: spacemit: add K3 SPI compatible
spi: spacemit: Correct TX FIFO slot calculation
One driver specific fix where one of the MediaTek drivers duplicated
some core code buggily, and a core fix for an ordering issue on startup
where we could end up configuring a voltage outside of constraints due
to the order in which we applied constraints.
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Merge tag 'regulator-fix-v7.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator
Pull regulator fixes from Mark Brown:
"One driver specific fix where one of the MediaTek drivers duplicated
some core code buggily, and a core fix for an ordering issue on
startup where we could end up configuring a voltage outside of
constraints due to the order in which we applied constraints"
* tag 'regulator-fix-v7.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
regulator: core: clamp voltage constraints before applying apply_uV
regulator: mt6358: use regmap helper to read fixed LDO calibration
Here are a number of small char/misc/etc. driver fixes for 7.2-rc5 that
resolve a bunch of different reported issues. Included in here are:
- rust_binder error message reporting fix
- stratix10-svc firmware driver fixes
- mei driver fix
- intel_th hardware tracing driver fix
- comedi driver fix
- uio_hv_generic driver fix
- ntsync selftest fix
- nsm misc driver fix
- some MAINTAINER file updates
All of these have been in linux-next for over a week with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver fixes from Greg KH:
"Here are a number of small char/misc/etc driver fixes for 7.2-rc5 that
resolve a bunch of different reported issues. Included in here are:
- rust_binder error message reporting fix
- stratix10-svc firmware driver fixes
- mei driver fix
- intel_th hardware tracing driver fix
- comedi driver fix
- uio_hv_generic driver fix
- ntsync selftest fix
- nsm misc driver fix
- some MAINTAINER file updates
All of these have been in linux-next for over a week with no reported
issues"
* tag 'char-misc-7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
MAINTAINERS: Update wine-devel list address
rust_binder: only print failure if error has source
intel_th: fix MSC output device reference leak
misc: nsm: pin the module while the device is open
mei: bus: access mei_device under device_lock on cleanup
misc: nsm: only unlock nsm_dev on post-lock error paths
selftests: ntsync: correct CONFIG_NTSYNC name
comedi: comedi_parport: deal with premature interrupt
uio_hv_generic: Bind to FCopy device by default
MAINTAINERS: Add Greg Kroah-Hartman to GPIB
firmware: stratix10-svc: fix teardown order in remove to prevent race
firmware: stratix10-svc: handle NO_RESPONSE in async poll
firmware: stratix10-svc: fix FCS SMC call kernel-doc
firmware: stratix10-svc: fix memory leaks and list corruption bugs
Here are two small staging driver fixes for 7.2-rc5. They both resolve
some reported bugs in the rtl8723bs staging driver and have been in
linux-next for over a week with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'staging-7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
Pull staging driver fixes from Greg KH:
"Here are two small staging driver fixes for 7.2-rc5. They both resolve
some reported bugs in the rtl8723bs staging driver and have been in
linux-next for over a week with no reported issues"
* tag 'staging-7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
staging: rtl8723bs: fix OOB reads in rtw_get_wps_ie()
staging: rtl8723bs: fix inverted HT40 secondary channel offset
Here are two small serial driver fixes for 7.2-rc5. They are:
- sc16is7xx get_direction() callback fix, which resolves a
user-triggerable warning in the driver
- NULL pointer dereference on some platforms using the 8250_mid serial
driver
Both have been in linux-next for over a week with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull serial driver fixes from Greg KH:
"Here are two small serial driver fixes for 7.2-rc5. They are:
- sc16is7xx get_direction() callback fix, which resolves a
user-triggerable warning in the driver
- NULL pointer dereference on some platforms using the 8250_mid
serial driver
Both have been in linux-next for over a week with no reported issues"
* tag 'tty-7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
serial: sc16is7xx: implement gpio get_direction() callback
serial: 8250_mid: Fix NULL function pointer dereference on DNV/ICX-D/SNR platforms
Here are some small USB fixes and new device quirks and ids for 7.2-rc5.
Included in here are:
- usb storage quirk added
- new usb serial device ids added
- usb-serial device name leak and other bug fixes
- small xhci driver fixes
- normal batch of typec driver fixes for reported issues
- usb-atm much-reported-by-syzbot fix for firmware download races
- sysfs BOS device removal race fix
- lots of usb gadget driver fixes for reported issues
- other small USB driver fixes for other reported problems.
All of these have been in linux-next this past week, many of them much
longer.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'usb-7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
Pull USB fixes from Greg KH:
"Here are some small USB fixes and new device quirks and ids:
- usb storage quirk added
- new usb serial device ids added
- usb-serial device name leak and other bug fixes
- small xhci driver fixes
- normal batch of typec driver fixes for reported issues
- usb-atm much-reported-by-syzbot fix for firmware download races
- sysfs BOS device removal race fix
- lots of usb gadget driver fixes for reported issues
- other small USB driver fixes for other reported problems
All of these have been in linux-next this past week, many of them much
longer"
* tag 'usb-7.2-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (30 commits)
usb: typec: ucsi: Correct teardown ordering in ucsi_init() error path
USB: serial: io_edgeport: cap received transmit credits
USB: serial: option: add TDTECH MT5710-CN
USB: serial: io_ti: reject oversized boot-mode firmware
USB: serial: mxuport: validate firmware header size
usb: atm: ueagle-atm: reject descriptors that confuse probe and disconnect
usb: typec: ucsi: yoga_c630: Remove redundant duplicate altmode handling
usb: typec: ucsi: Add duplicate detection to nvidia registration path
usb: typec: ucsi: Detect and skip duplicate altmodes from buggy firmware
usb: gadget: dummy_hcd: prevent fifo_req reuse during giveback
usb: chipidea: fix usage_count leak when autosuspend_delay is negative
usb: core: sysfs: add lock to bos_descriptors_read()
usb: musb: omap2430: Do not put borrowed of_node in probe
usb: core: port: Deattach Type-C connector on component unbind
USB: storage: add NO_ATA_1X quirk for Longmai USB Key
USB: serial: ftdi_sio: add support for E+H FXA291
USB: serial: keyspan_pda: fix data loss on receive throttling
usb: gadget: printer: fix infinite loop in printer_read()
usb: gadget: f_midi: cancel pending IN work before freeing the midi object
usb: gadget: udc: bdc: free IRQ and drain func_wake_notify before teardown
...
- Move rb_desc->nr_page_va before updating dynamic array
The rb_descr->page_va is a dynamic array counted by nr_page_va. But the
updating of the page_va[] is done before the nr_page_va is incremented
causing a build with CONFIG_UBSAN_BOUNDS to flag it as an overflow.
Move the increment of the counted by value before the array element is
updated.
- Propagate errors from remote event bulk updates
The return value of trace_remote_enable_event() was not being checked by
remote_events_dir_enable_write() where it would silently fail. Have it
check the return value and propagate that back up to user space.
- Fix resource leak on mmiotrace trace_pipe close
The mmiotrace tracer was created in 2008 before the trace_pipe had a close
callback to allow tracers to do clean up from trace_pipe open. The
trace_pipe close cleanup callback was added in 2009 but the mmiotrace
tracer was not updated. It had a hack to do the cleanup in the read call,
where it may leak if user space did not read the entire buffer.
Add a callback to mmiotrace trace_pipe close do to the cleanup properly.
- Fix a possible NULL pointer dereference in the mmiotrace tracer
If the mmio_pipe_open() fails to find a PCI device, it will set the
hiter->dev pointer to NULL. The read function will blindly dereference
that pointer. Fix the read call to check to see if that pointer is
populated before dereferencing it.
- Fix union collision of module and refcnt for dynamic events
In 'struct trace_event_call', the 'module' pointer and the 'refcnt' atomic
variable share the same memory space in a union. The filter on module
logic only checked if the 'module' was set to determine if the event
belonged to the module. As dynamic events are always builtin, it doesn't
need the 'module' field of the structure and used a refcount. But the
module filtering logic would then mistaken these dynamic events as a
module and call module_name(event->module) on it.
Add a check to see if the event is a dynamic event and if so, do not check
it for being part of the given module.
- Reset the top level buffer in selftests before running instances
The ftracetest selftest initializes each instance before executing the
tests. But it does not reset the top level buffer. Dynamic events are only
added and removed by the top level so any left over dynamic events will
not be removed by the reset in the instances.
Left over dynamic events can cause the tests to incorrectly fail. Reset
the top level buffer before running the instances.
- Make the context_switch counter 64 bit
The code to read user space for a system call trace event or for a
trace_marker will disable migration, enable preemption, read user space
into a per CPU buffer, disable preemption and enable migration again.
It checks if the per CPU context switch counter to see if it changed, and
if it did not, it would know that the per CPU buffer was not touched by
another task.
But the save counter was 32 bit and it would compare it to the 64 bit
context_switch variable. A long running system could have the
context_switch variable greater that 1<<32 in which case the compare will
always fail. The compare will promote the 32 bit int saved value to 64 bit
and compare it to the full 64 bit counter. Since the top 32 bits of the
saved value was zero, it would never match.
- Fix a use-after-free of the event_enable trigger
The event_enable trigger allows for enabling one event when another event
is triggered. When the trigger is removed, it must go through a
synchronization phase to make sure it is not triggered again. The trigger
itself is delayed by the "bulk delay" logic that was recently added.
But the code that frees the event_enable data used to rely on the trigger
code to do the synchronization. Now that the code uses the call RCU
functions (and a workqueue), that delay no longer is there.
Add a callback private_data_free() function that allows triggers to clean
up data after the synchronization phase has completed.
- Move the module_ref counter into the delay callback
Since an event of the event_enable trigger can enable an event for a
module, it ups the module ref count for that event's module. This prevents
the event from trying to enable an event that no longer exists and cause a
use-after-free bug.
The ref counter was set back down when the trigger was removed but not
after thy synchronization phase. This could lead to the module data being
accessed after module was unloaded.
Move the module ref decrement into the private_data_free() callback of the
event_enable trigger.
- Add mutex to protect parser in ftrace filtering
The set_ftrace_filter file uses a parsing descriptor that is allocated at
open and modified by writes. If multiple threads were to write to the
descriptor at the same time, it can corrupt the parser.
Add a mutex around the modifications of the parser descriptor.
- Fix possible corruption in perf syscall tracing
The perf system call trace events can now read user space. To do so, the
reads of user space enable preemption and disables it again. During this
time that preemption is enabled, the task can migrate. The perf event list
head is assigned via a per CPU pointer. It is done before the user space
part is called. If the user space reading migrates the task to another
CPU, then the head pointer is no longer valid.
Re-assign the head pointer after the reading of user space to keep it
using the correct data.
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Merge tag 'trace-v7.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull tracing fixes from Steven Rostedt:
- Move rb_desc->nr_page_va before updating dynamic array
The rb_descr->page_va is a dynamic array counted by nr_page_va. But
the updating of the page_va[] is done before the nr_page_va is
incremented causing a build with CONFIG_UBSAN_BOUNDS to flag it as an
overflow.
Move the increment of the counted by value before the array element
is updated.
- Propagate errors from remote event bulk updates
The return value of trace_remote_enable_event() was not being checked
by remote_events_dir_enable_write() where it would silently fail.
Have it check the return value and propagate that back up to user
space.
- Fix resource leak on mmiotrace trace_pipe close
The mmiotrace tracer was created in 2008 before the trace_pipe had a
close callback to allow tracers to do clean up from trace_pipe open.
The trace_pipe close cleanup callback was added in 2009 but the
mmiotrace tracer was not updated. It had a hack to do the cleanup in
the read call, where it may leak if user space did not read the
entire buffer.
Add a callback to mmiotrace trace_pipe close do to the cleanup
properly.
- Fix a possible NULL pointer dereference in the mmiotrace tracer
If the mmio_pipe_open() fails to find a PCI device, it will set the
hiter->dev pointer to NULL. The read function will blindly
dereference that pointer. Fix the read call to check to see if that
pointer is populated before dereferencing it.
- Fix union collision of module and refcnt for dynamic events
In 'struct trace_event_call', the 'module' pointer and the 'refcnt'
atomic variable share the same memory space in a union. The filter on
module logic only checked if the 'module' was set to determine if the
event belonged to the module. As dynamic events are always builtin,
it doesn't need the 'module' field of the structure and used a
refcount. But the module filtering logic would then mistaken these
dynamic events as a module and call module_name(event->module) on it.
Add a check to see if the event is a dynamic event and if so, do not
check it for being part of the given module.
- Reset the top level buffer in selftests before running instances
The ftracetest selftest initializes each instance before executing
the tests. But it does not reset the top level buffer. Dynamic events
are only added and removed by the top level so any left over dynamic
events will not be removed by the reset in the instances.
Left over dynamic events can cause the tests to incorrectly fail.
Reset the top level buffer before running the instances.
- Make the context_switch counter 64 bit
The code to read user space for a system call trace event or for a
trace_marker will disable migration, enable preemption, read user
space into a per CPU buffer, disable preemption and enable migration
again. It checks if the per CPU context switch counter to see if it
changed, and if it did not, it would know that the per CPU buffer was
not touched by another task.
But the save counter was 32 bit and it would compare it to the 64 bit
context_switch variable. A long running system could have the
context_switch variable greater that 1<<32 in which case the compare
will always fail. The compare will promote the 32 bit int saved value
to 64 bit and compare it to the full 64 bit counter. Since the top 32
bits of the saved value was zero, it would never match.
- Fix a use-after-free of the event_enable trigger
The event_enable trigger allows for enabling one event when another
event is triggered. When the trigger is removed, it must go through a
synchronization phase to make sure it is not triggered again. The
trigger itself is delayed by the "bulk delay" logic that was recently
added. But the code that frees the event_enable data used to rely on
the trigger code to do the synchronization. Now that the code uses
the call RCU functions (and a workqueue), that delay no longer is
there.
Add a callback private_data_free() function that allows triggers to
clean up data after the synchronization phase has completed.
- Move the module_ref counter into the delay callback
Since an event of the event_enable trigger can enable an event for a
module, it ups the module ref count for that event's module. This
prevents the event from trying to enable an event that no longer
exists and cause a use-after-free bug.
The ref counter was set back down when the trigger was removed but
not after thy synchronization phase. This could lead to the module
data being accessed after module was unloaded.
Move the module ref decrement into the private_data_free() callback
of the event_enable trigger.
- Add mutex to protect parser in ftrace filtering
The set_ftrace_filter file uses a parsing descriptor that is
allocated at open and modified by writes. If multiple threads were to
write to the descriptor at the same time, it can corrupt the parser.
Add a mutex around the modifications of the parser descriptor.
- Fix possible corruption in perf syscall tracing
The perf system call trace events can now read user space. To do so,
the reads of user space enable preemption and disables it again.
During this time that preemption is enabled, the task can migrate.
The perf event list head is assigned via a per CPU pointer. It is
done before the user space part is called. If the user space reading
migrates the task to another CPU, then the head pointer is no longer
valid.
Re-assign the head pointer after the reading of user space to keep it
using the correct data.
* tag 'trace-v7.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing: perf: Fix stale head for perf syscall tracing
ftrace: Add global mutex to serialize trace_parser access
tracing: Delay module ref count for "enable_event" trigger
tracing: Fix use-after-free freeing trigger private data
tracing: Fix context switch counter truncation
selftests/ftrace: Reset triggers at top level before instance loop
tracing: Fix union collision of module and refcnt for dynamic events
tracing: Fix mmiotrace possible NULL dereferencing of hiter->dev
tracing: Fix resource leak on mmiotrace trace_pipe close
tracing: Propagate errors from remote event bulk updates
tracing/remotes: Fix page_va[] access before counter update in trace_remote_alloc_buffer()
a bit more widely, because newer versions of LLVM started
optimizing it a bit better and introduced run-time relocations
in PIE code. (Nathan Chancellor)
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-urgent-2026-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fix from Ingo Molnar:
- Disable jump/lookup tables in the x86 boot decompressor code
a bit more widely, because newer versions of LLVM started
optimizing it a bit better and introduced run-time relocations
in PIE code (Nathan Chancellor)
* tag 'x86-urgent-2026-07-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot/compressed: Disable jump tables
do_thaw_all_callback() calls bdev_thaw() while holding sb->s_umount
exclusively. If the block device was frozen via bdev_freeze() dropping
the last block layer freeze reference calls fs_bdev_thaw() which
reacquires s_umount:
do_thaw_all_callback(sb)
super_lock_excl(sb) # holds sb->s_umount
bdev_thaw(sb->s_bdev)
mutex_lock(&bdev->bd_fsfreeze_mutex)
# bd_fsfreeze_count drops 1 -> 0
bd_holder_ops->thaw == fs_bdev_thaw
get_bdev_super(bdev)
bdev_super_lock(bdev, true)
super_lock(sb, true)
down_write(&sb->s_umount) # same task: deadlock
The emergency thaw worker deadlocks against itself holding both
s_umount and bd_fsfreeze_mutex. That fscks any subsequent unmount,
freeze, or thaw of that filesystem and block device.
[ 81.878470] sysrq: Show Blocked State
[ 81.880140] task:kworker/0:1 state:D stack:0 pid:11 tgid:11 ppid:2 task_flags:0x4208060 flags:0x00080000
[ 81.884876] Workqueue: events do_thaw_all
[ 81.886656] Call Trace:
[ 81.887759] <TASK>
[ 81.888763] __schedule+0x579/0x1420
[ 81.890372] schedule+0x3a/0x100
[ 81.891794] schedule_preempt_disabled+0x15/0x30
[ 81.893848] rwsem_down_write_slowpath+0x1ea/0x900
[ 81.895191] ? __pfx_do_thaw_all_callback+0x10/0x10
[ 81.896528] down_write+0xbd/0xc0
[ 81.897505] super_lock+0x91/0x180
[ 81.898457] ? __mutex_lock+0xa99/0x1140
[ 81.900748] ? __mutex_unlock_slowpath+0x1f/0x400
[ 81.902069] bdev_super_lock+0x5b/0x150
[ 81.903132] get_bdev_super+0x10/0x60
[ 81.904042] fs_bdev_thaw+0x23/0xf0
[ 81.904755] bdev_thaw+0x82/0x100
[ 81.905484] do_thaw_all_callback+0x2c/0x50
[ 81.906298] __iterate_supers+0x5d/0x130
[ 81.907067] do_thaw_all+0x20/0x40
[ 81.907739] process_one_work+0x206/0x5e0
[ 81.908545] worker_thread+0x1e2/0x3c0
[ 81.909339] ? __pfx_worker_thread+0x10/0x10
[ 81.910171] kthread+0xf4/0x130
[ 81.910799] ? __pfx_kthread+0x10/0x10
[ 81.911528] ret_from_fork+0x2e2/0x3b0
[ 81.912259] ? __pfx_kthread+0x10/0x10
[ 81.913010] ret_from_fork_asm+0x1a/0x30
[ 81.913806] </TASK>
bdev_super_lock() even documents the violated requirement with
lockdep_assert_not_held(&sb->s_umount).
Acquiring bd_fsfreeze_mutex under s_umount also inverts the
bd_fsfreeze_mutex vs. s_umount ordering established by
bdev_{freeze,thaw}() and can thus ABBA against a concurrent block-layer
freeze even when the recursive path isn't hit.
Fix this by not holding s_umount around the bdev_thaw() loop at all. Pin
the superblock with an active reference instead as
filesystems_freeze_callback() does. The active reference keeps the
superblock from being shut down and so ->s_bdev stays valid without
holding s_umount. The block-layer-held freeze is dropped by
fs_bdev_thaw() with FREEZE_MAY_NEST | FREEZE_HOLDER_USERSPACE exactly as
a regular unfreeze would and thaw_super_locked() handles
filesystem-level freezes as before.
The emergency thaw path has deadlocked like this in one form or
another for a long long time but the current exclusively-held
shape dates back to commit [1] where thaw_bdev() already ended in
thaw_super() with s_umount held by do_thaw_all_callback().
Fixes: 08fdc8a013 ("buffer.c: call thaw_super during emergency thaw") [1]
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260723-work-super-emergency_thaw-v1-1-7c315c600245@kernel.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
