x86-32, espfix: Remove filter for espfix32 due to race

It is not safe to use LAR to filter when to go down the espfix path,
because the LDT is per-process (rather than per-thread) and another
thread might change the descriptors behind our back.  Fortunately it
is always *safe* (if a bit slow) to go down the espfix path, and a
32-bit LDT stack segment is extremely rare.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/1398816946-3351-1-git-send-email-hpa@linux.intel.com
Cc: <stable@vger.kernel.org> # consider after upstream merge

1 files changed, 0 insertions, 5 deletions

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index a2a4f4697889..2780b8f3b96c 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -551,11 +551,6 @@ ENTRY(iret_exc)
 
         CFI_RESTORE_STATE
 ldt_ss:
-        larl PT_OLDSS(%esp), %eax
-        jnz restore_nocheck
-        testl $0x00400000, %eax         # returning to 32bit stack?
-        jnz restore_nocheck             # allright, normal return
-
 #ifdef CONFIG_PARAVIRT
         /*
          * The kernel can't run on a non-flat stack if paravirt mode