On Thu, Sep 14, 2023 at 06:58:03PM +0000, Sohil Mehta wrote:
commit c35559f94ebc ("x86/shstk: Introduce map_shadow_stack syscall")
recently added support for map_shadow_stack() but it is limited to x86
only for now. There is a possibility that other architectures (namely,
arm64 and RISC-V), that are implementing equivalent support for shadow
stacks, might need to add support for it.
Independent of that, reserving arch-specific syscall numbers in the
syscall tables of all architectures is good practice and would help
avoid future conflicts. map_shadow_stack() is marked as a conditional
syscall in sys_ni.c. Adding it to the syscall tables of other
architectures is harmless and would return ENOSYS when exercised.
Note, map_shadow_stack() was assigned #453 during the merge process
since #452 was taken by fchmodat2().
For Powerpc, map it to sys_ni_syscall() as is the norm for Powerpc
syscall tables.
For Alpha, map_shadow_stack() takes up #563 as Alpha still diverges from
the common syscall numbering system in the other architectures.
Link: https://lore.kernel.org/lkml/20230515212255.GA562920@xxxxxxxxxxxxxxxxxxxxx/
Link: https://lore.kernel.org/lkml/b402b80b-a7c6-4ef0-b977-c0f5f582b78a@xxxxxxxxxxxxx/
Signed-off-by: Sohil Mehta <sohil.mehta@xxxxxxxxx>
---
v2:
- Skip syscall table changes to tools/. They will be handled separetely by the
perf folks.
- Map Powerpc to sys_ni_syscall (Rick Edgecombe)
---
arch/alpha/kernel/syscalls/syscall.tbl | 1 +
arch/arm/tools/syscall.tbl | 1 +
arch/arm64/include/asm/unistd.h | 2 +-
arch/arm64/include/asm/unistd32.h | 2 ++
For arm64 (compat):
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>
