[Xen-devel] [PATCH] linux-2.6.18/i386: fix unwind annotations in failsafe callback

["Jan Beulich" <JBeulich@xxxxxxxx>]

This amends c/s 14245:b1f33c3a97fa (when the sparse Linux tree was
still part of the main Xen repo) in that it
- adds a missing annotation to the "pushl $-1"
- moves the RING0_INT_FRAME earlier (after adjusting the code to do the
  stack pointer adjustment before the conditional branch), thus
  increasing the covered region

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/arch/i386/kernel/entry-xen.S
+++ b/arch/i386/kernel/entry-xen.S
@@ -872,12 +872,11 @@ ENTRY(failsafe_callback)
 4:     mov 16(%esp),%gs
        testl %eax,%eax
        popl %eax
-       jz 5f
-       addl $16,%esp           # EAX != 0 => Category 2 (Bad IRET)
-       jmp iret_exc
-5:     addl $16,%esp           # EAX == 0 => Category 1 (Bad segment)
+       leal (%esp,16),%esp
        RING0_INT_FRAME
-       pushl $-1
+       jnz iret_exc            # EAX != 0 => Category 2 (Bad IRET)
+       pushl $-1               # EAX == 0 => Category 1 (Bad segment)
+       CFI_ADJUST_CFA_OFFSET 4
        SAVE_ALL
        jmp ret_from_exception
 .section .fixup,"ax";          \

Attachment: xen-i386-failsafe-adjust.patch
Description: Text document

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