[PATCH 2/2] x86: Fix dumpstack_64 irq stack handling

From: Steven Rostedt
Date: Wed Apr 02 2014 - 13:31:14 EST


From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>

Commit 2223f6f6eeaa "x86: Clean up dumpstack_64.c code" changed
the irq_stack processing a little from what it was before.
The irq_stack_end variable needed to be cleared after its first
use. By setting irq_stack to the per cpu irq_stack and passing
that to analyze_stack(), and then clearing it after it is processed,
we can get back the original behavior.

Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
arch/x86/kernel/dumpstack_64.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 74c262a..1abcb50 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -116,9 +116,9 @@ enum stack_type {

static enum stack_type
analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,
- unsigned long **stack_end, unsigned *used, char **id)
+ unsigned long **stack_end, unsigned long *irq_stack,
+ unsigned *used, char **id)
{
- unsigned long *irq_stack;
unsigned long addr;

addr = ((unsigned long)stack & (~(THREAD_SIZE - 1)));
@@ -130,11 +130,11 @@ analyze_stack(int cpu, struct task_struct *task, unsigned long *stack,
if (*stack_end)
return STACK_IS_EXCEPTION;

- *stack_end = (unsigned long *)per_cpu(irq_stack_ptr, cpu);
- if (!*stack_end)
- return STACK_IS_UNKNOWN;
+ if (!irq_stack)
+ return STACK_IS_NORMAL;

- irq_stack = *stack_end - irq_stack_size;
+ *stack_end = irq_stack;
+ irq_stack = irq_stack - irq_stack_size;

if (in_irq_stack(stack, irq_stack, *stack_end))
return STACK_IS_IRQ;
@@ -155,7 +155,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
{
const unsigned cpu = get_cpu();
struct thread_info *tinfo;
- unsigned long *irq_stack;
+ unsigned long *irq_stack = (unsigned long *)per_cpu(irq_stack_ptr, cpu);
unsigned long dummy;
unsigned used = 0;
int graph = 0;
@@ -186,7 +186,8 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
enum stack_type stype;
char *id;

- stype = analyze_stack(cpu, task, stack, &stack_end, &used, &id);
+ stype = analyze_stack(cpu, task, stack, &stack_end,
+ irq_stack, &used, &id);

/* Default finish unless specified to continue */
done = 1;
@@ -226,7 +227,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
* pointer (index -1 to end) in the IRQ stack:
*/
stack = (unsigned long *) (stack_end[-1]);
- irq_stack = stack_end - irq_stack_size;
+ irq_stack = NULL;
ops->stack(data, "EOI");
done = 0;
break;
--
1.8.5.3


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