Commit 7ca0758c authored by H. Peter Anvin's avatar H. Peter Anvin

x86-32, vdso: On system call restart after SYSENTER, use int $0x80

When we enter a 32-bit system call via SYSENTER or SYSCALL, we shuffle
the arguments to match the int $0x80 calling convention.  This was
probably a design mistake, but it's what it is now.  This causes
errors if the system call as to be restarted.

For SYSENTER, we have to invoke the instruction from the vdso as the
return address is hardcoded.  Accordingly, we can simply replace the
jump in the vdso with an int $0x80 instruction and use the slower
entry point for a post-restart.
Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/CA%2B55aFztZ=r5wa0x26KJQxvZOaQq8s2v3u50wCyJcA-Sc4g8gQ@mail.gmail.com
Cc: <stable@kernel.org>
parent 05e33fc2
......@@ -43,7 +43,7 @@ __kernel_vsyscall:
.space 7,0x90
/* 14: System call restart point is here! (SYSENTER_RETURN-2) */
jmp .Lenter_kernel
int $0x80
/* 16: System call normal return point is here! */
VDSO32_SYSENTER_RETURN: /* Symbol used by sysenter.c via vdso32-syms.h */
pop %ebp
......
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