1 files changed, 24 insertions, 4 deletions

diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
index 3576b70..e511680 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);