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path: root/arch/x86/include/asm/vdso/sys_call.h
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2026-01-13x86/entry/vdso32: When using int $0x80, use it directlyH. Peter Anvin
When neither sysenter32 nor syscall32 is available (on either FRED-capable 64-bit hardware or old 32-bit hardware), there is no reason to do a bunch of stack shuffling in __kernel_vsyscall. Unfortunately, just overwriting the initial "push" instructions will mess up the CFI annotations, so suffer the 3-byte NOP if not applicable. Similarly, inline the int $0x80 when doing inline system calls in the vdso instead of calling __kernel_vsyscall. 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/20251216212606.1325678-11-hpa@zytor.com
2026-01-13x86/vdso: Abstract out vdso system call internalsH. Peter Anvin
Abstract out the calling of true system calls from the vdso into macros. It has been a very long time since gcc did not allow %ebx or %ebp in inline asm in 32-bit PIC mode; remove the corresponding hacks. Remove the use of memory output constraints in gettimeofday.h in favor of "memory" clobbers. The resulting code is identical for the current use cases, as the system call is usually a terminal fallback anyway, and it merely complicates the macroization. This patch adds only a handful of more lines of code than it removes, and in fact could be made substantially smaller by removing the macros for the argument counts that aren't currently used, however, it seems better to be general from the start. [ v3: remove stray comment from prototyping; remove VDSO_SYSCALL6() since it would require special handling on 32 bits and is currently unused. (Uros Biszjak) Indent nested preprocessor directives. ] Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Uros Bizjak <ubizjak@gmail.com> Link: https://patch.msgid.link/20251216212606.1325678-9-hpa@zytor.com