1 files changed, 24 insertions, 4 deletions

diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
index 3576b709f052..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:
@@ -892,18 +912,18 @@ static struct unwinder dwarf_unwinder = {
 
 static void dwarf_unwinder_cleanup(void)
 {
-        struct dwarf_cie *cie;
-        struct dwarf_fde *fde;
+        struct dwarf_cie *cie, *cie_tmp;
+        struct dwarf_fde *fde, *fde_tmp;
 
         /*
          * Deallocate all the memory allocated for the DWARF unwinder.
          * Traverse all the FDE/CIE lists and remove and free all the
          * memory associated with those data structures.
          */
-        list_for_each_entry(cie, &dwarf_cie_list, link)
+        list_for_each_entry_safe(cie, cie_tmp, &dwarf_cie_list, link)
                 kfree(cie);
 
-        list_for_each_entry(fde, &dwarf_fde_list, link)
+        list_for_each_entry_safe(fde, fde_tmp, &dwarf_fde_list, link)
                 kfree(fde);
 
         kmem_cache_destroy(dwarf_reg_cachep);