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Subject[ 02/25] x86, 64-bit: Move K8 B step iret fixup to fault entry asm
2.6.32-longterm review patch.  If anyone has any objections, please let me know.

------------------

From: Brian Gerst <brgerst@gmail.com>

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>
(cherry picked from commit ae24ffe5ecec17c956ac25371d7c2e12b4b36e53)
[wt: only merged to fix patch context and ease merging of next patches]
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
arch/x86/include/asm/uaccess.h | 1 -
arch/x86/kernel/entry_64.S | 11 ++++++++---
arch/x86/mm/extable.c | 31 -------------------------------
3 files changed, 8 insertions(+), 35 deletions(-)

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 61c5874..99f0ad7 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 34a56a9..4f577eb 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 61b41ca..d0474ad 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
--
1.7.12.2.21.g234cd45.dirty




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