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
