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authorSteven Rostedt <srostedt@redhat.com>2014-02-06 09:41:31 -0500
committerH. Peter Anvin <hpa@linux.intel.com>2014-03-06 16:56:55 -0800
commit198d208df4371734ac4728f69cb585c284d20a15 (patch)
treef5a3f120d02678987f35d272653bef6a6d02efe5 /arch/x86/kernel/dumpstack_32.c
parent0788aa6a23cb9d693fc5040ec774b979f1e906cd (diff)
x86: Keep thread_info on thread stack in x86_32
x86_64 uses a per_cpu variable kernel_stack to always point to the thread stack of current. This is where the thread_info is stored and is accessed from this location even when the irq or exception stack is in use. This removes the complexity of having to maintain the thread info on the stack when interrupts are running and having to copy the preempt_count and other fields to the interrupt stack. x86_32 uses the old method of copying the thread_info from the thread stack to the exception stack just before executing the exception. Having the two different requires #ifdefs and also the x86_32 way is a bit of a pain to maintain. By converting x86_32 to the same method of x86_64, we can remove #ifdefs, clean up the x86_32 code a little, and remove the overhead of the copy. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Brian Gerst <brgerst@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20110806012354.263834829@goodmis.org Link: http://lkml.kernel.org/r/20140206144321.852942014@goodmis.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/dumpstack_32.c')
-rw-r--r--arch/x86/kernel/dumpstack_32.c41
1 files changed, 34 insertions, 7 deletions
diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index 187d6a749c19..dca820b627d6 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -16,11 +16,33 @@
#include <asm/stacktrace.h>
+static void *is_irq_stack(void *p, void *irq)
+{
+ if (p < irq || p >= (irq + THREAD_SIZE))
+ return NULL;
+ return irq + THREAD_SIZE;
+}
+
+
+static void *is_hardirq_stack(unsigned long *stack, int cpu)
+{
+ void *irq = per_cpu(hardirq_stack, cpu);
+
+ return is_irq_stack(stack, irq);
+}
+
+static void *is_softirq_stack(unsigned long *stack, int cpu)
+{
+ void *irq = per_cpu(softirq_stack, cpu);
+
+ return is_irq_stack(stack, irq);
+}
void dump_trace(struct task_struct *task, struct pt_regs *regs,
unsigned long *stack, unsigned long bp,
const struct stacktrace_ops *ops, void *data)
{
+ const unsigned cpu = get_cpu();
int graph = 0;
u32 *prev_esp;
@@ -40,18 +62,22 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
for (;;) {
struct thread_info *context;
+ void *end_stack;
+
+ end_stack = is_hardirq_stack(stack, cpu);
+ if (!end_stack)
+ end_stack = is_softirq_stack(stack, cpu);
- context = (struct thread_info *)
- ((unsigned long)stack & (~(THREAD_SIZE - 1)));
- bp = ops->walk_stack(context, stack, bp, ops, data, NULL, &graph);
+ context = task_thread_info(task);
+ bp = ops->walk_stack(context, stack, bp, ops, data,
+ end_stack, &graph);
/* Stop if not on irq stack */
- if (task_stack_page(task) == context)
+ if (!end_stack)
break;
- /* The previous esp is just above the context */
- prev_esp = (u32 *) ((char *)context + sizeof(struct thread_info) -
- sizeof(long));
+ /* The previous esp is saved on the bottom of the stack */
+ prev_esp = (u32 *)(end_stack - THREAD_SIZE);
stack = (unsigned long *)*prev_esp;
if (!stack)
break;
@@ -60,6 +86,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
break;
touch_nmi_watchdog();
}
+ put_cpu();
}
EXPORT_SYMBOL(dump_trace);