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>

3 files changed, 8 insertions, 35 deletions

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index d2c6c930b491..abd3e0ea762a 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -570,7 +570,6 @@ extern struct movsl_mask {
 #ifdef CONFIG_X86_32
 # include "uaccess_32.h"
 #else
-# define ARCH_HAS_SEARCH_EXTABLE
 # include "uaccess_64.h"
 #endif
 
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)
 
 
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c
index 61b41ca3b5a2..d0474ad2a6e5 100644
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -35,34 +35,3 @@ int fixup_exception(struct pt_regs *regs)
 
         return 0;
 }
-
-#ifdef CONFIG_X86_64
-/*
- * Need to defined our own search_extable on X86_64 to work around
- * a B stepping K8 bug.
- */
-const struct exception_table_entry *
-search_extable(const struct exception_table_entry *first,
-               const struct exception_table_entry *last,
-               unsigned long value)
-{
-        /* B stepping K8 bug */
-        if ((value >> 32) == 0)
-                value |= 0xffffffffUL << 32;
-
-        while (first <= last) {
-                const struct exception_table_entry *mid;
-                long diff;
-
-                mid = (last - first) / 2 + first;
-                diff = mid->insn - value;
-                if (diff == 0)
-                        return mid;
-                else if (diff < 0)
-                        first = mid+1;
-                else
-                        last = mid-1;
-        }
-        return NULL;
-}
-#endif