[PATCH] x86_64: reliable stack trace support (x86-64 IRQ stack

Change the switching to/from the IRQ stack so that unwind annotations can
be added for it without requiring CFA expressions.

AK: I cleaned it up a bit, making it unconditional and removing the
obsolete DEBUG_INFO full frame code.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 8 insertions, 25 deletions

diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 6c68beec51b3..4f407ef6b865 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -473,29 +473,18 @@ END(stub_rt_sigreturn)
 /* 0(%rsp): interrupt number */ 
         .macro interrupt func
         cld
-#ifdef CONFIG_DEBUG_INFO
-        SAVE_ALL        
-        movq %rsp,%rdi
-        /*
-         * Setup a stack frame pointer.  This allows gdb to trace
-         * back to the original stack.
-         */
-        movq %rsp,%rbp
-        CFI_DEF_CFA_REGISTER    rbp
-#else           
         SAVE_ARGS
         leaq -ARGOFFSET(%rsp),%rdi      # arg1 for handler
-#endif  
+        pushq %rbp
+        CFI_ADJUST_CFA_OFFSET   8
+        CFI_REL_OFFSET          rbp, 0
+        movq %rsp,%rbp
+        CFI_DEF_CFA_REGISTER    rbp
         testl $3,CS(%rdi)
         je 1f
         swapgs  
 1:      incl    %gs:pda_irqcount        # RED-PEN should check preempt count
-        movq %gs:pda_irqstackptr,%rax
-        cmoveq %rax,%rsp /*todo This needs CFI annotation! */
-        pushq %rdi                      # save old stack        
-#ifndef CONFIG_DEBUG_INFO
-        CFI_ADJUST_CFA_OFFSET   8
-#endif
+        cmoveq %gs:pda_irqstackptr,%rsp
         call \func
         .endm
 
@@ -504,17 +493,11 @@ ENTRY(common_interrupt)
         interrupt do_IRQ
         /* 0(%rsp): oldrsp-ARGOFFSET */
 ret_from_intr:
-        popq  %rdi
-#ifndef CONFIG_DEBUG_INFO
-        CFI_ADJUST_CFA_OFFSET   -8
-#endif
         cli     
         decl %gs:pda_irqcount
-#ifdef CONFIG_DEBUG_INFO
-        movq RBP(%rdi),%rbp
+        leaveq
         CFI_DEF_CFA_REGISTER    rsp
-#endif
-        leaq ARGOFFSET(%rdi),%rsp /*todo This needs CFI annotation! */
+        CFI_ADJUST_CFA_OFFSET   -8
 exit_intr:
         GET_THREAD_INFO(%rcx)
         testl $3,CS-ARGOFFSET(%rsp)