On 9/11/2023 2:10 PM, Edgecombe, Rick P wrote: > On Mon, 2023-09-11 at 18:02 +0000, Sohil Mehta wrote: >> diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl >> b/arch/powerpc/kernel/syscalls/syscall.tbl >> index 20e50586e8a2..2767b8a42636 100644 >> --- a/arch/powerpc/kernel/syscalls/syscall.tbl >> +++ b/arch/powerpc/kernel/syscalls/syscall.tbl >> @@ -539,3 +539,4 @@ >> 450 nospu set_mempolicy_home_node sys_set_mempolicy_hom >> e_node >> 451 common cachestat sys_cachestat >> 452 common fchmodat2 sys_fchmodat2 >> +453 common map_shadow_stack sys_map_shadow_stack > > I noticed in powerpc, the not implemented syscalls are manually mapped > to sys_ni_syscall. It also has some special extra sys_ni_syscall() > implementation bits to handle both ARCH_HAS_SYSCALL_WRAPPER and > !ARCH_HAS_SYSCALL_WRAPPER. So wondering if it might need special > treatment. Did you see those parts? > Thanks for pointing this out. Powerpc seems to be unique in their handling of not implemented syscalls. Maybe it's because of their special casing of the ARCH_HAS_SYSCALL_WRAPPER. The code below in arch/powerpc/include/asm/syscalls.h suggests to me that it should be safe to map map_shadow_stack() to sys_ni_syscall() and the special handling will be taken care of. #ifndef CONFIG_ARCH_HAS_SYSCALL_WRAPPER long sys_ni_syscall(void); #else long sys_ni_syscall(const struct pt_regs *regs); #endif I don't quite understand the underlying reasoning for it though. Do you have any additional insight into how we should handle this? I am thinking of doing the following in the next iteration unless someone chimes in and says otherwise. --- a/arch/powerpc/kernel/syscalls/syscall.tbl +++ b/arch/powerpc/kernel/syscalls/syscall.tbl @@ -539,4 +539,4 @@ 450 nospu set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat 452 common fchmodat2 sys_fchmodat2 -453 common map_shadow_stack sys_map_shadow_stack +453 common map_shadow_stack sys_ni_syscall
