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author | Frederic Weisbecker <fweisbec@gmail.com> | 2008-11-11 07:03:45 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-11-11 10:29:11 +0100 |
commit | caf4b323b02a16c92fba449952ac6515ddc76d7a (patch) | |
tree | 6fc234d00faca192248344996a168afb253e5f40 /include/linux/sched.h | |
parent | d844222a54c33a960755b44b934cd1b01b05dceb (diff) | |
download | linux-caf4b323b02a16c92fba449952ac6515ddc76d7a.tar.gz linux-caf4b323b02a16c92fba449952ac6515ddc76d7a.tar.bz2 linux-caf4b323b02a16c92fba449952ac6515ddc76d7a.zip |
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/linux/sched.h')
-rw-r--r-- | include/linux/sched.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 295b7c756ca6..df77abe860c9 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) |