1 files changed, 20 insertions, 0 deletions

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: