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| author | H. Peter Anvin <hpa@zytor.com> | 2025-12-16 13:26:03 -0800 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2026-01-13 16:37:58 -0800 |
| commit | f49ecf5e110ab0ed255ddea5e321689faf4e50e6 (patch) | |
| tree | 74b9f5720872d9e256f22e037f628cdef1e35fae /arch/x86/entry | |
| parent | a0636d4c3ad0da0cd6069eb6fef5d2b7d3449378 (diff) | |
| download | lwn-f49ecf5e110ab0ed255ddea5e321689faf4e50e6.tar.gz lwn-f49ecf5e110ab0ed255ddea5e321689faf4e50e6.zip | |
x86/cpufeature: Replace X86_FEATURE_SYSENTER32 with X86_FEATURE_SYSFAST32
In most cases, the use of "fast 32-bit system call" depends either on
X86_FEATURE_SEP or X86_FEATURE_SYSENTER32 || X86_FEATURE_SYSCALL32.
However, nearly all the logic for both is identical.
Define X86_FEATURE_SYSFAST32 which indicates that *either* SYSENTER32 or
SYSCALL32 should be used, for either 32- or 64-bit kernels. This
defaults to SYSENTER; use SYSCALL if the SYSCALL32 bit is also set.
As this removes ALL existing uses of X86_FEATURE_SYSENTER32, which is
a kernel-only synthetic feature bit, simply remove it and replace it
with X86_FEATURE_SYSFAST32.
This leaves an unused alternative for a true 32-bit kernel, but that
should really not matter in any way.
The clearing of X86_FEATURE_SYSCALL32 can be removed once the patches
for automatically clearing disabled features has been merged.
Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://patch.msgid.link/20251216212606.1325678-10-hpa@zytor.com
Diffstat (limited to 'arch/x86/entry')
| -rw-r--r-- | arch/x86/entry/vdso/vdso32/system_call.S | 8 |
1 files changed, 2 insertions, 6 deletions
diff --git a/arch/x86/entry/vdso/vdso32/system_call.S b/arch/x86/entry/vdso/vdso32/system_call.S index 2a15634bbe75..7b1c0f16e511 100644 --- a/arch/x86/entry/vdso/vdso32/system_call.S +++ b/arch/x86/entry/vdso/vdso32/system_call.S @@ -52,13 +52,9 @@ __kernel_vsyscall: #define SYSENTER_SEQUENCE "movl %esp, %ebp; sysenter" #define SYSCALL_SEQUENCE "movl %ecx, %ebp; syscall" -#ifdef BUILD_VDSO32_64 /* If SYSENTER (Intel) or SYSCALL32 (AMD) is available, use it. */ - ALTERNATIVE_2 "", SYSENTER_SEQUENCE, X86_FEATURE_SYSENTER32, \ - SYSCALL_SEQUENCE, X86_FEATURE_SYSCALL32 -#else - ALTERNATIVE "", SYSENTER_SEQUENCE, X86_FEATURE_SEP -#endif + ALTERNATIVE_2 "", SYSENTER_SEQUENCE, X86_FEATURE_SYSFAST32, \ + SYSCALL_SEQUENCE, X86_FEATURE_SYSCALL32 /* Enter using int $0x80 */ int $0x80 |