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3424d8c18a
- 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()
...
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| .. | ||
| cpu | ||
| syscalls | ||
| .gitignore | ||
| asm-offsets.c | ||
| dma.c | ||
| entry.S | ||
| exceptions.c | ||
| ftrace.c | ||
| head.S | ||
| hw_exception_handler.S | ||
| irq.c | ||
| kgdb.c | ||
| Makefile | ||
| mcount.S | ||
| microblaze_ksyms.c | ||
| misc.S | ||
| module.c | ||
| process.c | ||
| prom.c | ||
| ptrace.c | ||
| reset.c | ||
| setup.c | ||
| signal.c | ||
| stacktrace.c | ||
| sys_microblaze.c | ||
| syscall_table.S | ||
| timer.c | ||
| traps.c | ||
| unwind.c | ||
| vmlinux.lds.S | ||