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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
parenta0a70c735ef714fe1b6777b571630c3d50c7b008 (diff)
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')
-rw-r--r--arch/x86/include/asm/ftrace.h1
-rw-r--r--arch/x86/include/asm/thread_info.h29
-rw-r--r--arch/x86/kernel/ftrace.c29
3 files changed, 15 insertions, 44 deletions
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 2bb43b433e0..754a3e082f9 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -29,7 +29,6 @@ struct dyn_arch_ftrace {
#endif /* CONFIG_FUNCTION_TRACER */
#ifdef CONFIG_FUNCTION_RET_TRACER
-#define FTRACE_RET_STACK_SIZE 20
#ifndef __ASSEMBLY__
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index e90e81ef6ab..0921b4018c1 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -40,36 +40,8 @@ struct thread_info {
*/
__u8 supervisor_stack[0];
#endif
-
-#ifdef CONFIG_FUNCTION_RET_TRACER
- /* Index of current stored adress in ret_stack */
- int curr_ret_stack;
- /* Stack of return addresses for return function tracing */
- struct ftrace_ret_stack ret_stack[FTRACE_RET_STACK_SIZE];
- /*
- * Number of functions that haven't been traced
- * because of depth overrun.
- */
- atomic_t trace_overrun;
-#endif
};
-#ifdef CONFIG_FUNCTION_RET_TRACER
-#define INIT_THREAD_INFO(tsk) \
-{ \
- .task = &tsk, \
- .exec_domain = &default_exec_domain, \
- .flags = 0, \
- .cpu = 0, \
- .preempt_count = 1, \
- .addr_limit = KERNEL_DS, \
- .restart_block = { \
- .fn = do_no_restart_syscall, \
- }, \
- .curr_ret_stack = -1,\
- .trace_overrun = ATOMIC_INIT(0) \
-}
-#else
#define INIT_THREAD_INFO(tsk) \
{ \
.task = &tsk, \
@@ -82,7 +54,6 @@ struct thread_info {
.fn = do_no_restart_syscall, \
}, \
}
-#endif
#define init_thread_info (init_thread_union.thread_info)
#define init_stack (init_thread_union.stack)
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 356bb1eb6e9..bb137f7297e 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--;
}
/*