Commit-ID: 3bd29515d1cad26fa85a1a9b442de8816c1f5c54
Gitweb: http://git.kernel.org/tip/3bd29515d1cad26fa85a1a9b442de8816c1f5c54
Author: Andy Lutomirski <luto@xxxxxxxxxx>
AuthorDate: Fri, 16 Oct 2015 15:42:55 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sun, 18 Oct 2015 12:11:16 +0200
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 <bp@xxxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Fixes: 5f310f739b4c x86/entry/32: ("Re-implement SYSENTER using the new C path")
Link: http://lkml.kernel.org/r/461e5c7d8fa3821529893a4893ac9c4bc37f9e17.1445035014.git.luto@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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 4f97f49..3eb572e 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.
--
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