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| author | Ben Kallus <benjamin.p.kallus.gr@dartmouth.edu> | 2025-05-18 19:45:07 -0400 |
|---|---|---|
| committer | Alejandro Colomar <alx@kernel.org> | 2025-05-22 14:32:31 +0200 |
| commit | 125f3b3c3ee3b99f94e08214f610bde06a9bb754 (patch) | |
| tree | ad376d2ec0b2930bb9d3e4384709b03d0be69979 | |
| parent | ff69c843992d53a5a094b90cb6990069dec06cc0 (diff) | |
| download | man-pages-125f3b3c3ee3b99f94e08214f610bde06a9bb754.tar.gz | |
man/man2/syscall.2: x86-64 + x32 syscall numbers go in eax
The kernel sign-extends eax before dispatching syscalls.
From arch/x86/entry/entry_64.S:
> movslq %eax, %rsi
> IBRS_ENTER
> UNTRAIN_RET
> CLEAR_BRANCH_HISTORY
>
> call do_syscall_64 /* returns with IRQs disabled */
This patch updates syscall.2 to document this. ARM64 exhibits a
similar behavior (w8 is extended), which is already documented.
Signed-off-by: Ben Kallus <benjamin.p.kallus.gr@dartmouth.edu>
Message-ID: <20250518234507.404608-1-benjamin.p.kallus.gr@dartmouth.edu>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
| -rw-r--r-- | man/man2/syscall.2 | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/man/man2/syscall.2 b/man/man2/syscall.2 index f50d7cfc7b..be645c0f4a 100644 --- a/man/man2/syscall.2 +++ b/man/man2/syscall.2 @@ -190,8 +190,8 @@ superh trapa #31 r3 r0 r1 - 4, 6 sparc/32 t 0x10 g1 o0 o1 psr/csr 1, 6 sparc/64 t 0x6d g1 o0 o1 psr/csr 1, 6 tile swint1 R10 R00 - R01 1 -x86-64 syscall rax rax rdx - 5 -x32 syscall rax rax rdx - 5 +x86-64 syscall eax rax rdx - 5 +x32 syscall eax rax rdx - 5 xtensa syscall a2 a2 - - .TE .P |