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authorFrederic Weisbecker <fweisbec@gmail.com>2008-11-11 07:03:45 +0100
committerIngo Molnar <mingo@elte.hu>2008-11-11 10:29:11 +0100
commitcaf4b323b02a16c92fba449952ac6515ddc76d7a (patch)
tree6fc234d00faca192248344996a168afb253e5f40 /include
parentd844222a54c33a960755b44b934cd1b01b05dceb (diff)
tracing, x86: add low level support for ftrace return tracing
Impact: add infrastructure for function-return tracing Add low level support for ftrace return tracing. This plug-in stores return addresses on the thread_info structure of the current task. The index of the current return address is initialized when the task is the first one (init) and when a process forks (the child). It is not needed when a task does a sys_execve because after this syscall, it still needs to return on the kernel functions it called. Note that the code of return_to_handler has been suggested by Steven Rostedt as almost all of the ideas of improvements in this V3. For purpose of security, arch/x86/kernel/process_32.c is not traced because __switch_to() changes the current task during its execution. That could cause inconsistency in the stored return address of this function even if I didn't have any crash after testing with tracing on this function enabled. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include')
-rw-r--r--include/linux/ftrace.h20
-rw-r--r--include/linux/ftrace_irq.h2
-rw-r--r--include/linux/sched.h11
3 files changed, 32 insertions, 1 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1f5608c1102..dcbbf72a88b 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -268,6 +268,26 @@ ftrace_init_module(unsigned long *start, unsigned long *end) { }
/*
+ * Structure that defines a return function trace.
+ */
+struct ftrace_retfunc {
+ unsigned long ret; /* Return address */
+ unsigned long func; /* Current function */
+ unsigned long long calltime;
+ unsigned long long rettime;
+};
+
+#ifdef CONFIG_FUNCTION_RET_TRACER
+/* Type of a callback handler of tracing return function */
+typedef void (*trace_function_return_t)(struct ftrace_retfunc *);
+
+extern void register_ftrace_return(trace_function_return_t func);
+/* The current handler in use */
+extern trace_function_return_t ftrace_function_return;
+extern void unregister_ftrace_return(void);
+#endif
+
+/*
* Structure which defines the trace of an initcall.
* You don't have to fill the func field since it is
* only used internally by the tracer.
diff --git a/include/linux/ftrace_irq.h b/include/linux/ftrace_irq.h
index b1299d6729f..0b4df55d7a7 100644
--- a/include/linux/ftrace_irq.h
+++ b/include/linux/ftrace_irq.h
@@ -2,7 +2,7 @@
#define _LINUX_FTRACE_IRQ_H
-#ifdef CONFIG_DYNAMIC_FTRACE
+#if defined(CONFIG_DYNAMIC_FTRACE) || defined(CONFIG_FUNCTION_RET_TRACER)
extern void ftrace_nmi_enter(void);
extern void ftrace_nmi_exit(void);
#else
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 295b7c756ca..df77abe860c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2005,6 +2005,17 @@ static inline void setup_thread_stack(struct task_struct *p, struct task_struct
{
*task_thread_info(p) = *task_thread_info(org);
task_thread_info(p)->task = p;
+
+#ifdef CONFIG_FUNCTION_RET_TRACER
+ /*
+ * When fork() creates a child process, this function is called.
+ * But the child task may not inherit the return adresses traced
+ * by the return function tracer because it will directly execute
+ * in userspace and will not return to kernel functions its parent
+ * used.
+ */
+ task_thread_info(p)->curr_ret_stack = -1;
+#endif
}
static inline unsigned long *end_of_stack(struct task_struct *p)