Add a helper to check if the calling syscall needs a fixup for non-natural 64-bit type alignment in the compat ABI. This will only return true for i386 syscalls on x86_64. Signed-off-by: Christoph Hellwig <hch@xxxxxx> --- arch/x86/include/asm/compat.h | 1 + include/linux/compat.h | 9 +++++++++ 2 files changed, 10 insertions(+) diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h index bf547701f41f87..0e327a01f50fbb 100644 --- a/arch/x86/include/asm/compat.h +++ b/arch/x86/include/asm/compat.h @@ -209,6 +209,7 @@ static inline bool in_compat_syscall(void) return in_32bit_syscall(); } #define in_compat_syscall in_compat_syscall /* override the generic impl */ +#define compat_need_64bit_alignment_fixup in_ia32_syscall #endif struct compat_siginfo; diff --git a/include/linux/compat.h b/include/linux/compat.h index e90100c0de72e4..a195f90f156cf6 100644 --- a/include/linux/compat.h +++ b/include/linux/compat.h @@ -937,6 +937,15 @@ static inline bool in_compat_syscall(void) { return false; } #endif /* CONFIG_COMPAT */ +/* + * Some legacy ABIs like the i386 one use less than natural alignment for 64-bit + * types, and will need special compat treatment for that. Most architectures + * don't need that special handling even for compat syscalls. + */ +#ifndef compat_need_64bit_alignment_fixup +#define compat_need_64bit_alignment_fixup() false +#endif + /* * A pointer passed in from user mode. This should not * be used for syscall parameters, just declare them -- 2.27.0