diff options
| author | Andy Lutomirski <luto@kernel.org> | 2020-10-11 19:51:21 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-10-14 19:53:40 +0200 |
| commit | c3b484c439b0bab7a698495f33ef16286a1000c4 (patch) | |
| tree | bebb383c2c784e27f24861b1173bc975e5876c90 /arch | |
| parent | f2ac57a4c49d40409c21c82d23b5706df9b438af (diff) | |
x86/syscalls: Document the fact that syscalls 512-547 are a legacy mistake
Since this commit:
6365b842aae4 ("x86/syscalls: Split the x32 syscalls into their own table")
there is no need for special x32-specific syscall numbers. I forgot to
update the comments in syscall_64.tbl. Add comments to make it clear to
future contributors that this range is a legacy wart.
Reported-by: Jessica Clarke <jrtc27@jrtc27.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/6c56fb4ddd18fc60a238eb4d867e4b3d97c6351e.1602471055.git.luto@kernel.org
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/entry/syscalls/syscall_64.tbl | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index f30d6ae9a688..4adb5d2a3319 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -363,10 +363,10 @@ 439 common faccessat2 sys_faccessat2 # -# x32-specific system call numbers start at 512 to avoid cache impact -# for native 64-bit operation. The __x32_compat_sys stubs are created -# on-the-fly for compat_sys_*() compatibility system calls if X86_X32 -# is defined. +# Due to a historical design error, certain syscalls are numbered differently +# in x32 as compared to native x86_64. These syscalls have numbers 512-547. +# Do not add new syscalls to this range. Numbers 548 and above are available +# for non-x32 use. # 512 x32 rt_sigaction compat_sys_rt_sigaction 513 x32 rt_sigreturn compat_sys_x32_rt_sigreturn @@ -404,3 +404,5 @@ 545 x32 execveat compat_sys_execveat 546 x32 preadv2 compat_sys_preadv64v2 547 x32 pwritev2 compat_sys_pwritev64v2 +# This is the end of the legacy x32 range. Numbers 548 and above are +# not special and are not to be used for x32-specific syscalls. |