3 files changed, 29 insertions, 2 deletions

diff --git a/arch/sh/kernel/cpu/sh3/entry.S b/arch/sh/kernel/cpu/sh3/entry.S
index 3f7e2a22c7c2..f6a389c996cb 100644
--- a/arch/sh/kernel/cpu/sh3/entry.S
+++ b/arch/sh/kernel/cpu/sh3/entry.S
@@ -132,7 +132,6 @@ ENTRY(tlb_protection_violation_store)
          mov    #1, r5
 
 call_handle_tlbmiss:
-        setup_frame_reg
         mov.l   1f, r0
         mov     r5, r8
         mov.l   @r0, r6
@@ -365,6 +364,8 @@ handle_exception:
          mov.l  @k2, k2         ! read out vector and keep in k2
 
 handle_exception_special:
+        setup_frame_reg
+
         ! Setup return address and jump to exception handler
         mov.l   7f, r9          ! fetch return address
         stc     r2_bank, r0     ! k2 (vector)
diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
index 88d28ec3780a..e51168064e56 100644
--- a/arch/sh/kernel/dwarf.c
+++ b/arch/sh/kernel/dwarf.c
@@ -540,6 +540,8 @@ void dwarf_free_frame(struct dwarf_frame *frame)
         mempool_free(frame, dwarf_frame_pool);
 }
 
+extern void ret_from_irq(void);
+
 /**
  *      dwarf_unwind_stack - unwind the stack
  *
@@ -678,6 +680,24 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
         addr = frame->cfa + reg->addr;
         frame->return_addr = __raw_readl(addr);
 
+        /*
+         * Ah, the joys of unwinding through interrupts.
+         *
+         * Interrupts are tricky - the DWARF info needs to be _really_
+         * accurate and unfortunately I'm seeing a lot of bogus DWARF
+         * info. For example, I've seen interrupts occur in epilogues
+         * just after the frame pointer (r14) had been restored. The
+         * problem was that the DWARF info claimed that the CFA could be
+         * reached by using the value of the frame pointer before it was
+         * restored.
+         *
+         * So until the compiler can be trusted to produce reliable
+         * DWARF info when it really matters, let's stop unwinding once
+         * we've calculated the function that was interrupted.
+         */
+        if (prev && prev->pc == (unsigned long)ret_from_irq)
+                frame->return_addr = 0;
+
         return frame;
 
 bail:
diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S
index f0abd58c3a69..2b15ae60c3a0 100644
--- a/arch/sh/kernel/entry-common.S
+++ b/arch/sh/kernel/entry-common.S
@@ -70,8 +70,14 @@ ret_from_exception:
         CFI_STARTPROC simple
         CFI_DEF_CFA r14, 0
         CFI_REL_OFFSET 17, 64
-        CFI_REL_OFFSET 15, 0
+        CFI_REL_OFFSET 15, 60
         CFI_REL_OFFSET 14, 56
+        CFI_REL_OFFSET 13, 52
+        CFI_REL_OFFSET 12, 48
+        CFI_REL_OFFSET 11, 44
+        CFI_REL_OFFSET 10, 40
+        CFI_REL_OFFSET 9, 36
+        CFI_REL_OFFSET 8, 32
         preempt_stop()
 ENTRY(ret_from_irq)
         !