From 2fd0ebad27bcd4c8fc61c61a98d4283c47054bcf Mon Sep 17 00:00:00 2001 From: Sohil Mehta Date: Thu, 14 Sep 2023 18:58:03 +0000 Subject: arch: Reserve map_shadow_stack() syscall number for all architectures 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@debug.ba.rivosinc.com/ Link: https://lore.kernel.org/lkml/b402b80b-a7c6-4ef0-b977-c0f5f582b78a@sirena.org.uk/ Signed-off-by: Sohil Mehta Reviewed-by: Rick Edgecombe Reviewed-by: Arnd Bergmann Acked-by: Michael Ellerman (powerpc) Acked-by: Catalin Marinas Acked-by: Geert Uytterhoeven Signed-off-by: Arnd Bergmann --- include/uapi/asm-generic/unistd.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/uapi/asm-generic') diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index 76d946445391..00df5af71ca1 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -823,8 +823,11 @@ __SYSCALL(__NR_cachestat, sys_cachestat) #define __NR_fchmodat2 452 __SYSCALL(__NR_fchmodat2, sys_fchmodat2) +#define __NR_map_shadow_stack 453 +__SYSCALL(__NR_map_shadow_stack, sys_map_shadow_stack) + #undef __NR_syscalls -#define __NR_syscalls 453 +#define __NR_syscalls 454 /* * 32 bit systems traditionally used different -- cgit v1.2.3