1 files changed, 84 insertions, 34 deletions

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index addb207dab92..1abcb50b48ae 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -104,6 +104,44 @@ in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
         return (stack >= irq_stack && stack < irq_stack_end);
 }
 
+static const unsigned long irq_stack_size =
+        (IRQ_STACK_SIZE - 64) / sizeof(unsigned long);
+
+enum stack_type {
+        STACK_IS_UNKNOWN,
+        STACK_IS_NORMAL,
+        STACK_IS_EXCEPTION,
+        STACK_IS_IRQ,
+};
+
+static enum stack_type
+analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,
+              unsigned long **stack_end, unsigned long *irq_stack,
+              unsigned *used, char **id)
+{
+        unsigned long addr;
+
+        addr = ((unsigned long)stack & (~(THREAD_SIZE - 1)));
+        if ((unsigned long)task_stack_page(task) == addr)
+                return STACK_IS_NORMAL;
+
+        *stack_end = in_exception_stack(cpu, (unsigned long)stack,
+                                        used, id);
+        if (*stack_end)
+                return STACK_IS_EXCEPTION;
+
+        if (!irq_stack)
+                return STACK_IS_NORMAL;
+
+        *stack_end = irq_stack;
+        irq_stack = irq_stack - irq_stack_size;
+
+        if (in_irq_stack(stack, irq_stack, *stack_end))
+                return STACK_IS_IRQ;
+
+        return STACK_IS_UNKNOWN;
+}
+
 /*
  * x86-64 can have up to three kernel stacks:
  * process stack
@@ -116,12 +154,12 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
                 const struct stacktrace_ops *ops, void *data)
 {
         const unsigned cpu = get_cpu();
-        unsigned long *irq_stack_end =
-                (unsigned long *)per_cpu(irq_stack_ptr, cpu);
-        unsigned used = 0;
         struct thread_info *tinfo;
-        int graph = 0;
+        unsigned long *irq_stack = (unsigned long *)per_cpu(irq_stack_ptr, cpu);
         unsigned long dummy;
+        unsigned used = 0;
+        int graph = 0;
+        int done = 0;
 
         if (!task)
                 task = current;
@@ -143,49 +181,61 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
          * exceptions
          */
         tinfo = task_thread_info(task);
-        for (;;) {
+        while (!done) {
+                unsigned long *stack_end;
+                enum stack_type stype;
                 char *id;
-                unsigned long *estack_end;
-                estack_end = in_exception_stack(cpu, (unsigned long)stack,
-                                                &used, &id);
 
-                if (estack_end) {
+                stype = analyze_stack(cpu, task, stack, &stack_end,
+                                      irq_stack, &used, &id);
+
+                /* Default finish unless specified to continue */
+                done = 1;
+
+                switch (stype) {
+
+                /* Break out early if we are on the thread stack */
+                case STACK_IS_NORMAL:
+                        break;
+
+                case STACK_IS_EXCEPTION:
+
                         if (ops->stack(data, id) < 0)
                                 break;
 
                         bp = ops->walk_stack(tinfo, stack, bp, ops,
-                                             data, estack_end, &graph);
+                                             data, stack_end, &graph);
                         ops->stack(data, "<EOE>");
                         /*
                          * We link to the next stack via the
                          * second-to-last pointer (index -2 to end) in the
                          * exception stack:
                          */
-                        stack = (unsigned long *) estack_end[-2];
-                        continue;
-                }
-                if (irq_stack_end) {
-                        unsigned long *irq_stack;
-                        irq_stack = irq_stack_end -
-                                (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);
-
-                        if (in_irq_stack(stack, irq_stack, irq_stack_end)) {
-                                if (ops->stack(data, "IRQ") < 0)
-                                        break;
-                                bp = ops->walk_stack(tinfo, stack, bp,
-                                        ops, data, irq_stack_end, &graph);
-                                /*
-                                 * We link to the next stack (which would be
-                                 * the process stack normally) the last
-                                 * pointer (index -1 to end) in the IRQ stack:
-                                 */
-                                stack = (unsigned long *) (irq_stack_end[-1]);
-                                irq_stack_end = NULL;
-                                ops->stack(data, "EOI");
-                                continue;
-                        }
+                        stack = (unsigned long *) stack_end[-2];
+                        done = 0;
+                        break;
+
+                case STACK_IS_IRQ:
+
+                        if (ops->stack(data, "IRQ") < 0)
+                                break;
+                        bp = ops->walk_stack(tinfo, stack, bp,
+                                     ops, data, stack_end, &graph);
+                        /*
+                         * We link to the next stack (which would be
+                         * the process stack normally) the last
+                         * pointer (index -1 to end) in the IRQ stack:
+                         */
+                        stack = (unsigned long *) (stack_end[-1]);
+                        irq_stack = NULL;
+                        ops->stack(data, "EOI");
+                        done = 0;
+                        break;
+
+                case STACK_IS_UNKNOWN:
+                        ops->stack(data, "UNK");
+                        break;
                 }
-                break;
         }
 
         /*