Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1249202

[PATCH v2 2/2] x86/entry/32: Fix FS and GS restore in opportunistic SYSEXIT

Show all headers | View raw

We either need to restore them before popping and thus changing ESP,
or we need to adjust the offsets.  The former is simpler.

Fixes: 5f310f739b4c x86/entry/32: ("Re-implement SYSENTER using the new C path")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 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 ba0dad937be9..e3ede42d30e2 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -315,6 +315,8 @@ 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 */
 	popl	%eax			/* skip pt_regs->cx */
 	popl	%eax			/* skip pt_regs->dx */
@@ -322,8 +324,6 @@ sysenter_past_esp:
 	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.
-- 
2.4.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v2 0/2] x86/entry: 32-bit facepalm fixes Andy Lutomirski <luto@kernel.org> - 2015-10-17 00:50 +0200
  [PATCH v2 2/2] x86/entry/32: Fix FS and GS restore in opportunistic SYSEXIT Andy Lutomirski <luto@kernel.org> - 2015-10-17 00:50 +0200
  Re: [PATCH v2 0/2] x86/entry: 32-bit facepalm fixes Borislav Petkov <bp@alien8.de> - 2015-10-17 13:50 +0200

csiph-web