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authorFrederic Weisbecker <fweisbec@gmail.com>2008-11-23 06:22:56 +0100
committerIngo Molnar <mingo@elte.hu>2008-11-23 09:17:26 +0100
commitf201ae2356c74bcae130b2177b3dca903ea98071 (patch)
treec4b1b43fbe0a4594cb86749b2e7098fe15eb86ba /arch/x86/kernel/ftrace.c
parentMerge branches 'tracing/profiling', 'tracing/options' and 'tracing/urgent' in... (diff)
downloadlinux-f201ae2356c74bcae130b2177b3dca903ea98071.tar.xz
linux-f201ae2356c74bcae130b2177b3dca903ea98071.zip
tracing/function-return-tracer: store return stack into task_struct and allocate it dynamically
Impact: use deeper function tracing depth safely Some tests showed that function return tracing needed a more deeper depth of function calls. But it could be unsafe to store these return addresses to the stack. So these arrays will now be allocated dynamically into task_struct of current only when the tracer is activated. Typical scheme when tracer is activated: - allocate a return stack for each task in global list. - fork: allocate the return stack for the newly created task - exit: free return stack of current - idle init: same as fork I chose a default depth of 50. I don't have overruns anymore. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/ftrace.c')
-rw-r--r--arch/x86/kernel/ftrace.c29
1 files changed, 15 insertions, 14 deletions
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 356bb1eb6e9a..bb137f7297ed 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -350,19 +350,21 @@ static int push_return_trace(unsigned long ret, unsigned long long time,
unsigned long func)
{
int index;
- struct thread_info *ti = current_thread_info();
+
+ if (!current->ret_stack)
+ return -EBUSY;
/* The return trace stack is full */
- if (ti->curr_ret_stack == FTRACE_RET_STACK_SIZE - 1) {
- atomic_inc(&ti->trace_overrun);
+ if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
+ atomic_inc(&current->trace_overrun);
return -EBUSY;
}
- index = ++ti->curr_ret_stack;
+ index = ++current->curr_ret_stack;
barrier();
- ti->ret_stack[index].ret = ret;
- ti->ret_stack[index].func = func;
- ti->ret_stack[index].calltime = time;
+ current->ret_stack[index].ret = ret;
+ current->ret_stack[index].func = func;
+ current->ret_stack[index].calltime = time;
return 0;
}
@@ -373,13 +375,12 @@ static void pop_return_trace(unsigned long *ret, unsigned long long *time,
{
int index;
- struct thread_info *ti = current_thread_info();
- index = ti->curr_ret_stack;
- *ret = ti->ret_stack[index].ret;
- *func = ti->ret_stack[index].func;
- *time = ti->ret_stack[index].calltime;
- *overrun = atomic_read(&ti->trace_overrun);
- ti->curr_ret_stack--;
+ index = current->curr_ret_stack;
+ *ret = current->ret_stack[index].ret;
+ *func = current->ret_stack[index].func;
+ *time = current->ret_stack[index].calltime;
+ *overrun = atomic_read(&current->trace_overrun);
+ current->curr_ret_stack--;
}
/*