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Diffstat (limited to 'kernel/trace/trace.c')
-rw-r--r--kernel/trace/trace.c73
1 files changed, 37 insertions, 36 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 21153e64bf1c..4fc93004feab 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2749,12 +2749,21 @@ trace_function(struct trace_array *tr,
#ifdef CONFIG_STACKTRACE
-#define FTRACE_STACK_MAX_ENTRIES (PAGE_SIZE / sizeof(unsigned long))
+/* Allow 4 levels of nesting: normal, softirq, irq, NMI */
+#define FTRACE_KSTACK_NESTING 4
+
+#define FTRACE_KSTACK_ENTRIES (PAGE_SIZE / FTRACE_KSTACK_NESTING)
+
struct ftrace_stack {
- unsigned long calls[FTRACE_STACK_MAX_ENTRIES];
+ unsigned long calls[FTRACE_KSTACK_ENTRIES];
+};
+
+
+struct ftrace_stacks {
+ struct ftrace_stack stacks[FTRACE_KSTACK_NESTING];
};
-static DEFINE_PER_CPU(struct ftrace_stack, ftrace_stack);
+static DEFINE_PER_CPU(struct ftrace_stacks, ftrace_stacks);
static DEFINE_PER_CPU(int, ftrace_stack_reserve);
static void __ftrace_trace_stack(struct ring_buffer *buffer,
@@ -2763,10 +2772,11 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
{
struct trace_event_call *call = &event_kernel_stack;
struct ring_buffer_event *event;
+ struct ftrace_stack *fstack;
struct stack_entry *entry;
struct stack_trace trace;
- int use_stack;
- int size = FTRACE_STACK_ENTRIES;
+ int size = FTRACE_KSTACK_ENTRIES;
+ int stackidx;
trace.nr_entries = 0;
trace.skip = skip;
@@ -2788,29 +2798,32 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
*/
preempt_disable_notrace();
- use_stack = __this_cpu_inc_return(ftrace_stack_reserve);
+ stackidx = __this_cpu_inc_return(ftrace_stack_reserve) - 1;
+
+ /* This should never happen. If it does, yell once and skip */
+ if (WARN_ON_ONCE(stackidx > FTRACE_KSTACK_NESTING))
+ goto out;
+
/*
- * We don't need any atomic variables, just a barrier.
- * If an interrupt comes in, we don't care, because it would
- * have exited and put the counter back to what we want.
- * We just need a barrier to keep gcc from moving things
- * around.
+ * The above __this_cpu_inc_return() is 'atomic' cpu local. An
+ * interrupt will either see the value pre increment or post
+ * increment. If the interrupt happens pre increment it will have
+ * restored the counter when it returns. We just need a barrier to
+ * keep gcc from moving things around.
*/
barrier();
- if (use_stack == 1) {
- trace.entries = this_cpu_ptr(ftrace_stack.calls);
- trace.max_entries = FTRACE_STACK_MAX_ENTRIES;
- if (regs)
- save_stack_trace_regs(regs, &trace);
- else
- save_stack_trace(&trace);
+ fstack = this_cpu_ptr(ftrace_stacks.stacks) + stackidx;
+ trace.entries = fstack->calls;
+ trace.max_entries = FTRACE_KSTACK_ENTRIES;
- if (trace.nr_entries > size)
- size = trace.nr_entries;
- } else
- /* From now on, use_stack is a boolean */
- use_stack = 0;
+ if (regs)
+ save_stack_trace_regs(regs, &trace);
+ else
+ save_stack_trace(&trace);
+
+ if (trace.nr_entries > size)
+ size = trace.nr_entries;
size *= sizeof(unsigned long);
@@ -2820,19 +2833,7 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer,
goto out;
entry = ring_buffer_event_data(event);
- memset(&entry->caller, 0, size);
-
- if (use_stack)
- memcpy(&entry->caller, trace.entries,
- trace.nr_entries * sizeof(unsigned long));
- else {
- trace.max_entries = FTRACE_STACK_ENTRIES;
- trace.entries = entry->caller;
- if (regs)
- save_stack_trace_regs(regs, &trace);
- else
- save_stack_trace(&trace);
- }
+ memcpy(&entry->caller, trace.entries, size);
entry->size = trace.nr_entries;