From: "H. Peter Anvin" Date: Mon, 22 Aug 2011 13:27:06 -0700 Subject: x86-32, vdso: On system call restart after SYSENTER, use int $0x80 From: "H. Peter Anvin" commit 7ca0758cdb7c241cb4e0490a8d95f0eb5b861daf upstream. 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: Linus Torvalds Signed-off-by: H. Peter Anvin Link: http://lkml.kernel.org/r/CA%2B55aFztZ=r5wa0x26KJQxvZOaQq8s2v3u50wCyJcA-Sc4g8gQ@mail.gmail.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/vdso/vdso32/sysenter.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/vdso/vdso32/sysenter.S +++ b/arch/x86/vdso/vdso32/sysenter.S @@ -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