x86, 64-bit: Move K8 B step iret fixup to fault entry asm

Move the handling of truncated %rip from an iret fault to the fault
entry path.

This allows x86-64 to use the standard search_extable() function.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <1255357103-5418-1-git-send-email-brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 3 deletions

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index b5c061f8f358..af0f4b226dbe 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1491,12 +1491,17 @@ error_kernelspace:
         leaq irq_return(%rip),%rcx
         cmpq %rcx,RIP+8(%rsp)
         je error_swapgs
-        movl %ecx,%ecx  /* zero extend */
-        cmpq %rcx,RIP+8(%rsp)
-        je error_swapgs
+        movl %ecx,%eax  /* zero extend */
+        cmpq %rax,RIP+8(%rsp)
+        je bstep_iret
         cmpq $gs_change,RIP+8(%rsp)
         je error_swapgs
         jmp error_sti
+
+bstep_iret:
+        /* Fix truncated RIP */
+        movq %rcx,RIP+8(%rsp)
+        je error_swapgs
 END(error_entry)