Commit 527c4125 authored Sep 17, 2020 by Christoph Hellwig Committed by Al Viro Sep 17, 2020

compat: add a compat_need_64bit_alignment_fixup() helper



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@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent cc7886d2

arch/x86/include/asm/compat.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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;

include/linux/compat.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -932,6 +932,15 @@ 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