From 000ab691172db3921efa3cb7f17fc79235a1de7f Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 17 Feb 2009 13:35:06 -0500 Subject: ftrace: allow archs to preform pre and post process for code modification This patch creates the weak functions: ftrace_arch_code_modify_prepare and ftrace_arch_code_modify_post_process that are called before and after the stop machine is called to modify the kernel text. If the arch needs to do pre or post processing, it only needs to define these functions. [ Update: Ingo Molnar suggested using the name ftrace_arch_code_modify_* over using ftrace_arch_modify_* ] Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'kernel/trace/ftrace.c') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index fdf913dfc7e..72316d9647b 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -585,6 +585,24 @@ ftrace_code_disable(struct module *mod, struct dyn_ftrace *rec) return 1; } +/* + * archs can override this function if they must do something + * before the modifying code is performed. + */ +int __weak ftrace_arch_code_modify_prepare(void) +{ + return 0; +} + +/* + * archs can override this function if they must do something + * after the modifying code is performed. + */ +int __weak ftrace_arch_code_modify_post_process(void) +{ + return 0; +} + static int __ftrace_modify_code(void *data) { int *command = data; @@ -607,7 +625,17 @@ static int __ftrace_modify_code(void *data) static void ftrace_run_update_code(int command) { + int ret; + + ret = ftrace_arch_code_modify_prepare(); + FTRACE_WARN_ON(ret); + if (ret) + return; + stop_machine(__ftrace_modify_code, &command, NULL); + + ret = ftrace_arch_code_modify_post_process(); + FTRACE_WARN_ON(ret); } static ftrace_func_t saved_ftrace_func; -- cgit v1.2.3 From 4377245aa93b65b6597e4b7bb460fb9abc48b56b Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 19 Feb 2009 13:41:27 -0500 Subject: ftrace: break out modify loop immediately on detection of error Impact: added precaution on failure detection Break out of the modifying loop as soon as a failure is detected. This is just an added precaution found by code review and was not found by any bug chasing. Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'kernel/trace/ftrace.c') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 72316d9647b..11ad796ca04 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -561,8 +561,11 @@ static void ftrace_replace_code(int enable) if ((system_state == SYSTEM_BOOTING) || !core_kernel_text(rec->ip)) { ftrace_free_rec(rec); - } else + } else { ftrace_bug(failed, rec->ip); + /* Stop processing */ + return; + } } } } -- cgit v1.2.3