[PATCH] i386: reliable stack trace support i386 entry.S

To increase the usefulness of reliable stack unwinding, this adds CFI
unwind annotations to many low-level i386 routines.

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

2 files changed, 277 insertions, 11 deletions

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index e802f3cac7e3..e6e4506e749a 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -48,6 +48,7 @@
 #include <asm/smp.h>
 #include <asm/page.h>
 #include <asm/desc.h>
+#include <asm/dwarf2.h>
 #include "irq_vectors.h"
 
 #define nr_syscalls ((syscall_table_size)/4)
@@ -85,31 +86,67 @@ VM_MASK		= 0x00020000
 #define SAVE_ALL \
         cld; \
         pushl %es; \
+        CFI_ADJUST_CFA_OFFSET 4;\
+        /*CFI_REL_OFFSET es, 0;*/\
         pushl %ds; \
+        CFI_ADJUST_CFA_OFFSET 4;\
+        /*CFI_REL_OFFSET ds, 0;*/\
         pushl %eax; \
+        CFI_ADJUST_CFA_OFFSET 4;\
+        CFI_REL_OFFSET eax, 0;\
         pushl %ebp; \
+        CFI_ADJUST_CFA_OFFSET 4;\
+        CFI_REL_OFFSET ebp, 0;\
         pushl %edi; \
+        CFI_ADJUST_CFA_OFFSET 4;\
+        CFI_REL_OFFSET edi, 0;\
         pushl %esi; \
+        CFI_ADJUST_CFA_OFFSET 4;\
+        CFI_REL_OFFSET esi, 0;\
         pushl %edx; \
+        CFI_ADJUST_CFA_OFFSET 4;\
+        CFI_REL_OFFSET edx, 0;\
         pushl %ecx; \
+        CFI_ADJUST_CFA_OFFSET 4;\
+        CFI_REL_OFFSET ecx, 0;\
         pushl %ebx; \
+        CFI_ADJUST_CFA_OFFSET 4;\
+        CFI_REL_OFFSET ebx, 0;\
         movl $(__USER_DS), %edx; \
         movl %edx, %ds; \
         movl %edx, %es;
 
 #define RESTORE_INT_REGS \
         popl %ebx;      \
+        CFI_ADJUST_CFA_OFFSET -4;\
+        CFI_RESTORE ebx;\
         popl %ecx;      \
+        CFI_ADJUST_CFA_OFFSET -4;\
+        CFI_RESTORE ecx;\
         popl %edx;      \
+        CFI_ADJUST_CFA_OFFSET -4;\
+        CFI_RESTORE edx;\
         popl %esi;      \
+        CFI_ADJUST_CFA_OFFSET -4;\
+        CFI_RESTORE esi;\
         popl %edi;      \
+        CFI_ADJUST_CFA_OFFSET -4;\
+        CFI_RESTORE edi;\
         popl %ebp;      \
-        popl %eax
+        CFI_ADJUST_CFA_OFFSET -4;\
+        CFI_RESTORE ebp;\
+        popl %eax;      \
+        CFI_ADJUST_CFA_OFFSET -4;\
+        CFI_RESTORE eax
 
 #define RESTORE_REGS    \
         RESTORE_INT_REGS; \
 1:      popl %ds;       \
+        CFI_ADJUST_CFA_OFFSET -4;\
+        /*CFI_RESTORE ds;*/\
 2:      popl %es;       \
+        CFI_ADJUST_CFA_OFFSET -4;\
+        /*CFI_RESTORE es;*/\
 .section .fixup,"ax";   \
 3:      movl $0,(%esp); \
         jmp 1b;         \
@@ -122,13 +159,43 @@ VM_MASK		= 0x00020000
         .long 2b,4b;    \
 .previous
 
+#define RING0_INT_FRAME \
+        CFI_STARTPROC simple;\
+        CFI_DEF_CFA esp, 3*4;\
+        /*CFI_OFFSET cs, -2*4;*/\
+        CFI_OFFSET eip, -3*4
+
+#define RING0_EC_FRAME \
+        CFI_STARTPROC simple;\
+        CFI_DEF_CFA esp, 4*4;\
+        /*CFI_OFFSET cs, -2*4;*/\
+        CFI_OFFSET eip, -3*4
+
+#define RING0_PTREGS_FRAME \
+        CFI_STARTPROC simple;\
+        CFI_DEF_CFA esp, OLDESP-EBX;\
+        /*CFI_OFFSET cs, CS-OLDESP;*/\
+        CFI_OFFSET eip, EIP-OLDESP;\
+        /*CFI_OFFSET es, ES-OLDESP;*/\
+        /*CFI_OFFSET ds, DS-OLDESP;*/\
+        CFI_OFFSET eax, EAX-OLDESP;\
+        CFI_OFFSET ebp, EBP-OLDESP;\
+        CFI_OFFSET edi, EDI-OLDESP;\
+        CFI_OFFSET esi, ESI-OLDESP;\
+        CFI_OFFSET edx, EDX-OLDESP;\
+        CFI_OFFSET ecx, ECX-OLDESP;\
+        CFI_OFFSET ebx, EBX-OLDESP
 
 ENTRY(ret_from_fork)
+        CFI_STARTPROC
         pushl %eax
+        CFI_ADJUST_CFA_OFFSET -4
         call schedule_tail
         GET_THREAD_INFO(%ebp)
         popl %eax
+        CFI_ADJUST_CFA_OFFSET -4
         jmp syscall_exit
+        CFI_ENDPROC
 
 /*
  * Return to user mode is not as complex as all this looks,
@@ -139,6 +206,7 @@ ENTRY(ret_from_fork)
 
         # userspace resumption stub bypassing syscall exit tracing
         ALIGN
+        RING0_PTREGS_FRAME
 ret_from_exception:
         preempt_stop
 ret_from_intr:
@@ -171,20 +239,33 @@ need_resched:
         call preempt_schedule_irq
         jmp need_resched
 #endif
+        CFI_ENDPROC
 
 /* SYSENTER_RETURN points to after the "sysenter" instruction in
    the vsyscall page.  See vsyscall-sysentry.S, which defines the symbol.  */
 
         # sysenter call handler stub
 ENTRY(sysenter_entry)
+        CFI_STARTPROC simple
+        CFI_DEF_CFA esp, 0
+        CFI_REGISTER esp, ebp
         movl TSS_sysenter_esp0(%esp),%esp
 sysenter_past_esp:
         sti
         pushl $(__USER_DS)
+        CFI_ADJUST_CFA_OFFSET 4
+        /*CFI_REL_OFFSET ss, 0*/
         pushl %ebp
+        CFI_ADJUST_CFA_OFFSET 4
+        CFI_REL_OFFSET esp, 0
         pushfl
+        CFI_ADJUST_CFA_OFFSET 4
         pushl $(__USER_CS)
+        CFI_ADJUST_CFA_OFFSET 4
+        /*CFI_REL_OFFSET cs, 0*/
         pushl $SYSENTER_RETURN
+        CFI_ADJUST_CFA_OFFSET 4
+        CFI_REL_OFFSET eip, 0
 
 /*
  * Load the potential sixth argument from user stack.
@@ -199,6 +280,7 @@ sysenter_past_esp:
 .previous
 
         pushl %eax
+        CFI_ADJUST_CFA_OFFSET 4
         SAVE_ALL
         GET_THREAD_INFO(%ebp)
 
@@ -219,11 +301,14 @@ sysenter_past_esp:
         xorl %ebp,%ebp
         sti
         sysexit
+        CFI_ENDPROC
 
 
         # system call handler stub
 ENTRY(system_call)
+        RING0_INT_FRAME                 # can't unwind into user space anyway
         pushl %eax                      # save orig_eax
+        CFI_ADJUST_CFA_OFFSET 4
         SAVE_ALL
         GET_THREAD_INFO(%ebp)
         testl $TF_MASK,EFLAGS(%esp)
@@ -256,10 +341,12 @@ restore_all:
         movb CS(%esp), %al
         andl $(VM_MASK | (4 << 8) | 3), %eax
         cmpl $((4 << 8) | 3), %eax
+        CFI_REMEMBER_STATE
         je ldt_ss                       # returning to user-space with LDT SS
 restore_nocheck:
         RESTORE_REGS
         addl $4, %esp
+        CFI_ADJUST_CFA_OFFSET -4
 1:      iret
 .section .fixup,"ax"
 iret_exc:
@@ -273,6 +360,7 @@ iret_exc:
         .long 1b,iret_exc
 .previous
 
+        CFI_RESTORE_STATE
 ldt_ss:
         larl OLDSS(%esp), %eax
         jnz restore_nocheck
@@ -285,11 +373,13 @@ ldt_ss:
          * CPUs, which we can try to work around to make
          * dosemu and wine happy. */
         subl $8, %esp           # reserve space for switch16 pointer
+        CFI_ADJUST_CFA_OFFSET 8
         cli
         movl %esp, %eax
         /* Set up the 16bit stack frame with switch32 pointer on top,
          * and a switch16 pointer on top of the current frame. */
         call setup_x86_bogus_stack
+        CFI_ADJUST_CFA_OFFSET -8        # frame has moved
         RESTORE_REGS
         lss 20+4(%esp), %esp    # switch to 16bit stack
 1:      iret
@@ -297,9 +387,11 @@ ldt_ss:
         .align 4
         .long 1b,iret_exc
 .previous
+        CFI_ENDPROC
 
         # perform work that needs to be done immediately before resumption
         ALIGN
+        RING0_PTREGS_FRAME              # can't unwind into user space anyway
 work_pending:
         testb $_TIF_NEED_RESCHED, %cl
         jz work_notifysig
@@ -329,8 +421,10 @@ work_notifysig:				# deal with pending signals and
 work_notifysig_v86:
 #ifdef CONFIG_VM86
         pushl %ecx                      # save ti_flags for do_notify_resume
+        CFI_ADJUST_CFA_OFFSET 4
         call save_v86_state             # %eax contains pt_regs pointer
         popl %ecx
+        CFI_ADJUST_CFA_OFFSET -4
         movl %eax, %esp
         xorl %edx, %edx
         call do_notify_resume
@@ -363,19 +457,21 @@ syscall_exit_work:
         movl $1, %edx
         call do_syscall_trace
         jmp resume_userspace
+        CFI_ENDPROC
 
-        ALIGN
+        RING0_INT_FRAME                 # can't unwind into user space anyway
 syscall_fault:
         pushl %eax                      # save orig_eax
+        CFI_ADJUST_CFA_OFFSET 4
         SAVE_ALL
         GET_THREAD_INFO(%ebp)
         movl $-EFAULT,EAX(%esp)
         jmp resume_userspace
 
-        ALIGN
 syscall_badsys:
         movl $-ENOSYS,EAX(%esp)
         jmp resume_userspace
+        CFI_ENDPROC
 
 #define FIXUP_ESPFIX_STACK \
         movl %esp, %eax; \
@@ -387,16 +483,21 @@ syscall_badsys:
         movl %eax, %esp;
 #define UNWIND_ESPFIX_STACK \
         pushl %eax; \
+        CFI_ADJUST_CFA_OFFSET 4; \
         movl %ss, %eax; \
         /* see if on 16bit stack */ \
         cmpw $__ESPFIX_SS, %ax; \
-        jne 28f; \
-        movl $__KERNEL_DS, %edx; \
-        movl %edx, %ds; \
-        movl %edx, %es; \
+        je 28f; \
+27:     popl %eax; \
+        CFI_ADJUST_CFA_OFFSET -4; \
+.section .fixup,"ax"; \
+28:     movl $__KERNEL_DS, %eax; \
+        movl %eax, %ds; \
+        movl %eax, %es; \
         /* switch to 32bit stack */ \
-        FIXUP_ESPFIX_STACK \
-28:     popl %eax;
+        FIXUP_ESPFIX_STACK; \
+        jmp 27b; \
+.previous
 
 /*
  * Build the entry stubs and pointer table with
@@ -408,9 +509,14 @@ ENTRY(interrupt)
 
 vector=0
 ENTRY(irq_entries_start)
+        RING0_INT_FRAME
 .rept NR_IRQS
         ALIGN
+ .if vector
+        CFI_ADJUST_CFA_OFFSET -4
+ .endif
 1:      pushl $vector-256
+        CFI_ADJUST_CFA_OFFSET 4
         jmp common_interrupt
 .data
         .long 1b
@@ -424,60 +530,99 @@ common_interrupt:
         movl %esp,%eax
         call do_IRQ
         jmp ret_from_intr
+        CFI_ENDPROC
 
 #define BUILD_INTERRUPT(name, nr)       \
 ENTRY(name)                             \
+        RING0_INT_FRAME;                \
         pushl $nr-256;                  \
-        SAVE_ALL                        \
+        CFI_ADJUST_CFA_OFFSET 4;        \
+        SAVE_ALL;                       \
         movl %esp,%eax;                 \
         call smp_/**/name;              \
-        jmp ret_from_intr;
+        jmp ret_from_intr;      \
+        CFI_ENDPROC
 
 /* The include is where all of the SMP etc. interrupts come from */
 #include "entry_arch.h"
 
 ENTRY(divide_error)
+        RING0_INT_FRAME
         pushl $0                        # no error code
+        CFI_ADJUST_CFA_OFFSET 4
         pushl $do_divide_error
+        CFI_ADJUST_CFA_OFFSET 4
         ALIGN
 error_code:
         pushl %ds
+        CFI_ADJUST_CFA_OFFSET 4
+        /*CFI_REL_OFFSET ds, 0*/
         pushl %eax
+        CFI_ADJUST_CFA_OFFSET 4
+        CFI_REL_OFFSET eax, 0
         xorl %eax, %eax
         pushl %ebp
+        CFI_ADJUST_CFA_OFFSET 4
+        CFI_REL_OFFSET ebp, 0
         pushl %edi
+        CFI_ADJUST_CFA_OFFSET 4
+        CFI_REL_OFFSET edi, 0
         pushl %esi
+        CFI_ADJUST_CFA_OFFSET 4
+        CFI_REL_OFFSET esi, 0
         pushl %edx
+        CFI_ADJUST_CFA_OFFSET 4
+        CFI_REL_OFFSET edx, 0
         decl %eax                       # eax = -1
         pushl %ecx
+        CFI_ADJUST_CFA_OFFSET 4
+        CFI_REL_OFFSET ecx, 0
         pushl %ebx
+        CFI_ADJUST_CFA_OFFSET 4
+        CFI_REL_OFFSET ebx, 0
         cld
         pushl %es
+        CFI_ADJUST_CFA_OFFSET 4
+        /*CFI_REL_OFFSET es, 0*/
         UNWIND_ESPFIX_STACK
         popl %ecx
+        CFI_ADJUST_CFA_OFFSET -4
+        /*CFI_REGISTER es, ecx*/
         movl ES(%esp), %edi             # get the function address
         movl ORIG_EAX(%esp), %edx       # get the error code
         movl %eax, ORIG_EAX(%esp)
         movl %ecx, ES(%esp)
+        /*CFI_REL_OFFSET es, ES*/
         movl $(__USER_DS), %ecx
         movl %ecx, %ds
         movl %ecx, %es
         movl %esp,%eax                  # pt_regs pointer
         call *%edi
         jmp ret_from_exception
+        CFI_ENDPROC
 
 ENTRY(coprocessor_error)
+        RING0_INT_FRAME
         pushl $0
+        CFI_ADJUST_CFA_OFFSET 4
         pushl $do_coprocessor_error
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 ENTRY(simd_coprocessor_error)
+        RING0_INT_FRAME
         pushl $0
+        CFI_ADJUST_CFA_OFFSET 4
         pushl $do_simd_coprocessor_error
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 ENTRY(device_not_available)
+        RING0_INT_FRAME
         pushl $-1                       # mark this as an int
+        CFI_ADJUST_CFA_OFFSET 4
         SAVE_ALL
         movl %cr0, %eax
         testl $0x4, %eax                # EM (math emulation bit)
@@ -487,9 +632,12 @@ ENTRY(device_not_available)
         jmp ret_from_exception
 device_not_available_emulate:
         pushl $0                        # temporary storage for ORIG_EIP
+        CFI_ADJUST_CFA_OFFSET 4
         call math_emulate
         addl $4, %esp
+        CFI_ADJUST_CFA_OFFSET -4
         jmp ret_from_exception
+        CFI_ENDPROC
 
 /*
  * Debug traps and NMI can happen at the one SYSENTER instruction
@@ -514,16 +662,19 @@ label:						\
         pushl $sysenter_past_esp
 
 KPROBE_ENTRY(debug)
+        RING0_INT_FRAME
         cmpl $sysenter_entry,(%esp)
         jne debug_stack_correct
         FIX_STACK(12, debug_stack_correct, debug_esp_fix_insn)
 debug_stack_correct:
         pushl $-1                       # mark this as an int
+        CFI_ADJUST_CFA_OFFSET 4
         SAVE_ALL
         xorl %edx,%edx                  # error code 0
         movl %esp,%eax                  # pt_regs pointer
         call do_debug
         jmp ret_from_exception
+        CFI_ENDPROC
         .previous .text
 /*
  * NMI is doubly nasty. It can happen _while_ we're handling
@@ -534,14 +685,18 @@ debug_stack_correct:
  * fault happened on the sysenter path.
  */
 ENTRY(nmi)
+        RING0_INT_FRAME
         pushl %eax
+        CFI_ADJUST_CFA_OFFSET 4
         movl %ss, %eax
         cmpw $__ESPFIX_SS, %ax
         popl %eax
+        CFI_ADJUST_CFA_OFFSET -4
         je nmi_16bit_stack
         cmpl $sysenter_entry,(%esp)
         je nmi_stack_fixup
         pushl %eax
+        CFI_ADJUST_CFA_OFFSET 4
         movl %esp,%eax
         /* Do not access memory above the end of our stack page,
          * it might not exist.
@@ -549,16 +704,19 @@ ENTRY(nmi)
         andl $(THREAD_SIZE-1),%eax
         cmpl $(THREAD_SIZE-20),%eax
         popl %eax
+        CFI_ADJUST_CFA_OFFSET -4
         jae nmi_stack_correct
         cmpl $sysenter_entry,12(%esp)
         je nmi_debug_stack_check
 nmi_stack_correct:
         pushl %eax
+        CFI_ADJUST_CFA_OFFSET 4
         SAVE_ALL
         xorl %edx,%edx          # zero error code
         movl %esp,%eax          # pt_regs pointer
         call do_nmi
         jmp restore_all
+        CFI_ENDPROC
 
 nmi_stack_fixup:
         FIX_STACK(12,nmi_stack_correct, 1)
@@ -574,97 +732,150 @@ nmi_debug_stack_check:
         jmp nmi_stack_correct
 
 nmi_16bit_stack:
+        RING0_INT_FRAME
         /* create the pointer to lss back */
         pushl %ss
+        CFI_ADJUST_CFA_OFFSET 4
         pushl %esp
+        CFI_ADJUST_CFA_OFFSET 4
         movzwl %sp, %esp
         addw $4, (%esp)
         /* copy the iret frame of 12 bytes */
         .rept 3
         pushl 16(%esp)
+        CFI_ADJUST_CFA_OFFSET 4
         .endr
         pushl %eax
+        CFI_ADJUST_CFA_OFFSET 4
         SAVE_ALL
         FIXUP_ESPFIX_STACK              # %eax == %esp
+        CFI_ADJUST_CFA_OFFSET -20       # the frame has now moved
         xorl %edx,%edx                  # zero error code
         call do_nmi
         RESTORE_REGS
         lss 12+4(%esp), %esp            # back to 16bit stack
 1:      iret
+        CFI_ENDPROC
 .section __ex_table,"a"
         .align 4
         .long 1b,iret_exc
 .previous
 
 KPROBE_ENTRY(int3)
+        RING0_INT_FRAME
         pushl $-1                       # mark this as an int
+        CFI_ADJUST_CFA_OFFSET 4
         SAVE_ALL
         xorl %edx,%edx          # zero error code
         movl %esp,%eax          # pt_regs pointer
         call do_int3
         jmp ret_from_exception
+        CFI_ENDPROC
         .previous .text
 
 ENTRY(overflow)
+        RING0_INT_FRAME
         pushl $0
+        CFI_ADJUST_CFA_OFFSET 4
         pushl $do_overflow
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 ENTRY(bounds)
+        RING0_INT_FRAME
         pushl $0
+        CFI_ADJUST_CFA_OFFSET 4
         pushl $do_bounds
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 ENTRY(invalid_op)
+        RING0_INT_FRAME
         pushl $0
+        CFI_ADJUST_CFA_OFFSET 4
         pushl $do_invalid_op
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 ENTRY(coprocessor_segment_overrun)
+        RING0_INT_FRAME
         pushl $0
+        CFI_ADJUST_CFA_OFFSET 4
         pushl $do_coprocessor_segment_overrun
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 ENTRY(invalid_TSS)
+        RING0_EC_FRAME
         pushl $do_invalid_TSS
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 ENTRY(segment_not_present)
+        RING0_EC_FRAME
         pushl $do_segment_not_present
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 ENTRY(stack_segment)
+        RING0_EC_FRAME
         pushl $do_stack_segment
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 KPROBE_ENTRY(general_protection)
+        RING0_EC_FRAME
         pushl $do_general_protection
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
         .previous .text
 
 ENTRY(alignment_check)
+        RING0_EC_FRAME
         pushl $do_alignment_check
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 KPROBE_ENTRY(page_fault)
+        RING0_EC_FRAME
         pushl $do_page_fault
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
         .previous .text
 
 #ifdef CONFIG_X86_MCE
 ENTRY(machine_check)
+        RING0_INT_FRAME
         pushl $0
+        CFI_ADJUST_CFA_OFFSET 4
         pushl machine_check_vector
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 #endif
 
 ENTRY(spurious_interrupt_bug)
+        RING0_INT_FRAME
         pushl $0
+        CFI_ADJUST_CFA_OFFSET 4
         pushl $do_spurious_interrupt_bug
+        CFI_ADJUST_CFA_OFFSET 4
         jmp error_code
+        CFI_ENDPROC
 
 #ifdef CONFIG_STACK_UNWIND
 ENTRY(arch_unwind_init_running)
+        CFI_STARTPROC
         movl    4(%esp), %edx
         movl    (%esp), %ecx
         leal    4(%esp), %eax
@@ -689,6 +900,7 @@ ENTRY(arch_unwind_init_running)
         movl    EBX(%edx), %ebx
         movl    $__KERNEL_DS, OLDSS(%edx)
         jmpl    *%eax
+        CFI_ENDPROC
 ENDPROC(arch_unwind_init_running)
 #endif
 
diff --git a/include/asm-i386/dwarf2.h b/include/asm-i386/dwarf2.h
new file mode 100644
index 000000000000..2280f6272f80
--- /dev/null
+++ b/include/asm-i386/dwarf2.h
@@ -0,0 +1,54 @@
+#ifndef _DWARF2_H
+#define _DWARF2_H
+
+#include <linux/config.h>
+
+#ifndef __ASSEMBLY__
+#warning "asm/dwarf2.h should be only included in pure assembly files"
+#endif
+
+/*
+   Macros for dwarf2 CFI unwind table entries.
+   See "as.info" for details on these pseudo ops. Unfortunately
+   they are only supported in very new binutils, so define them
+   away for older version.
+ */
+
+#ifdef CONFIG_UNWIND_INFO
+
+#define CFI_STARTPROC .cfi_startproc
+#define CFI_ENDPROC .cfi_endproc
+#define CFI_DEF_CFA .cfi_def_cfa
+#define CFI_DEF_CFA_REGISTER .cfi_def_cfa_register
+#define CFI_DEF_CFA_OFFSET .cfi_def_cfa_offset
+#define CFI_ADJUST_CFA_OFFSET .cfi_adjust_cfa_offset
+#define CFI_OFFSET .cfi_offset
+#define CFI_REL_OFFSET .cfi_rel_offset
+#define CFI_REGISTER .cfi_register
+#define CFI_RESTORE .cfi_restore
+#define CFI_REMEMBER_STATE .cfi_remember_state
+#define CFI_RESTORE_STATE .cfi_restore_state
+
+#else
+
+/* Due to the structure of pre-exisiting code, don't use assembler line
+   comment character # to ignore the arguments. Instead, use a dummy macro. */
+.macro ignore a=0, b=0, c=0, d=0
+.endm
+
+#define CFI_STARTPROC   ignore
+#define CFI_ENDPROC     ignore
+#define CFI_DEF_CFA     ignore
+#define CFI_DEF_CFA_REGISTER    ignore
+#define CFI_DEF_CFA_OFFSET      ignore
+#define CFI_ADJUST_CFA_OFFSET   ignore
+#define CFI_OFFSET      ignore
+#define CFI_REL_OFFSET  ignore
+#define CFI_REGISTER    ignore
+#define CFI_RESTORE     ignore
+#define CFI_REMEMBER_STATE ignore
+#define CFI_RESTORE_STATE ignore
+
+#endif
+
+#endif