From 3bd29515d1cad26fa85a1a9b442de8816c1f5c54 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Fri, 16 Oct 2015 15:42:55 -0700 Subject: [PATCH] x86/entry/32: Fix FS and GS restore in opportunistic SYSEXIT We either need to restore them before popping and thus changing ESP, or we need to adjust the offsets. The former is simpler. Reported-and-tested-by: Borislav Petkov Signed-off-by: Andy Lutomirski Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 5f310f739b4c x86/entry/32: ("Re-implement SYSENTER using the new C path") Link: http://lkml.kernel.org/r/461e5c7d8fa3821529893a4893ac9c4bc37f9e17.1445035014.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/entry/entry_32.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 4f97f49261d3..3eb572ed3d7a 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -315,14 +315,14 @@ sysenter_past_esp: TRACE_IRQS_ON /* User mode traces as IRQs on. */ movl PT_EIP(%esp), %edx /* pt_regs->ip */ movl PT_OLDESP(%esp), %ecx /* pt_regs->sp */ +1: mov PT_FS(%esp), %fs + PTGS_TO_GS popl %ebx /* pt_regs->bx */ addl $2*4, %esp /* skip pt_regs->cx and pt_regs->dx */ popl %esi /* pt_regs->si */ popl %edi /* pt_regs->di */ popl %ebp /* pt_regs->bp */ popl %eax /* pt_regs->ax */ -1: mov PT_FS(%esp), %fs - PTGS_TO_GS /* * Return back to the vDSO, which will pop ecx and edx. -- 2.20.1