From 7132e2d669bd42c3783327f301aaac5f4463299b Mon Sep 17 00:00:00 2001 From: Thiago Jung Bauermann Date: Mon, 25 Apr 2016 18:56:14 -0300 Subject: ftrace: Match dot symbols when searching functions on ppc64 In the ppc64 big endian ABI, function symbols point to function descriptors. The symbols which point to the function entry points have a dot in front of the function name. Consequently, when the ftrace filter mechanism searches for the symbol corresponding to an entry point address, it gets the dot symbol. As a result, ftrace filter users have to be aware of this ABI detail on ppc64 and prepend a dot to the function name when setting the filter. The perf probe command insulates the user from this by ignoring the dot in front of the symbol name when matching function names to symbols, but the sysfs interface does not. This patch makes the ftrace filter mechanism do the same when searching symbols. Fixes the following failure in ftracetest's kprobe_ftrace.tc: .../kprobe_ftrace.tc: line 9: echo: write error: Invalid argument That failure is on this line of kprobe_ftrace.tc: echo _do_fork > set_ftrace_filter This is because there's no _do_fork entry in the functions list: # cat available_filter_functions | grep _do_fork ._do_fork This change introduces no regressions on the perf and ftracetest testsuite results. Cc: Steven Rostedt Cc: Ingo Molnar Cc: Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Thiago Jung Bauermann Acked-by: Steven Rostedt Signed-off-by: Michael Ellerman --- kernel/trace/ftrace.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'kernel/trace/ftrace.c') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 7e8d792da963..a6c8252d7776 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -3456,11 +3456,23 @@ struct ftrace_glob { int type; }; +/* + * If symbols in an architecture don't correspond exactly to the user-visible + * name of what they represent, it is possible to define this function to + * perform the necessary adjustments. +*/ +char * __weak arch_ftrace_match_adjust(char *str, const char *search) +{ + return str; +} + static int ftrace_match(char *str, struct ftrace_glob *g) { int matched = 0; int slen; + str = arch_ftrace_match_adjust(str, g->search); + switch (g->type) { case MATCH_FULL: if (strcmp(str, g->search) == 0) -- cgit v1.2.3 From 6112a300c9e41993cc0dc56ac393743d28381284 Mon Sep 17 00:00:00 2001 From: Soumya PN Date: Tue, 17 May 2016 21:31:14 +0530 Subject: ftrace: Don't disable irqs when taking the tasklist_lock read_lock In ftrace.c inside the function alloc_retstack_tasklist() (which will be invoked when function_graph tracing is on) the tasklist_lock is being held as reader while iterating through a list of threads. Here the lock is being held as reader with irqs disabled. The tasklist_lock is never write_locked in interrupt context so it is safe to not disable interrupts for the duration of read_lock in this block which, can be significant, given the block of code iterates through all threads. Hence changing the code to call read_lock() and read_unlock() instead of read_lock_irqsave() and read_unlock_irqrestore(). A similar change was made in commits: 8063e41d2ffc ("tracing: Change syscall_*regfunc() to check PF_KTHREAD and use for_each_process_thread()")' and 3472eaa1f12e ("sched: normalize_rt_tasks(): Don't use _irqsave for tasklist_lock, use task_rq_lock()")' Link: http://lkml.kernel.org/r/1463500874-77480-1-git-send-email-soumya.p.n@hpe.com Signed-off-by: Soumya PN Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'kernel/trace/ftrace.c') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index b1870fbd2b67..a6804823a058 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -5713,7 +5713,6 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) { int i; int ret = 0; - unsigned long flags; int start = 0, end = FTRACE_RETSTACK_ALLOC_SIZE; struct task_struct *g, *t; @@ -5729,7 +5728,7 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) } } - read_lock_irqsave(&tasklist_lock, flags); + read_lock(&tasklist_lock); do_each_thread(g, t) { if (start == end) { ret = -EAGAIN; @@ -5747,7 +5746,7 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list) } while_each_thread(g, t); unlock: - read_unlock_irqrestore(&tasklist_lock, flags); + read_unlock(&tasklist_lock); free: for (i = start; i < end; i++) kfree(ret_stack_list[i]); -- cgit v1.2.3