From 8f86f83709c585742dea5dd7f0d2b79c43f992ec Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Tue, 13 Jan 2015 11:20:43 -0500 Subject: ftrace: Fix updating of filters for shared global_ops filters As the set_ftrace_filter affects both the function tracer as well as the function graph tracer, the ops that represent each have a shared ftrace_ops_hash structure. This allows both to be updated when the filter files are updated. But if function graph is enabled and the global_ops (function tracing) ops is not, then it is possible that the filter could be changed without the update happening for the function graph ops. This will cause the changes to not take place and may even cause a ftrace_bug to occur as it could mess with the trampoline accounting. The solution is to check if the ops uses the shared global_ops filter and if the ops itself is not enabled, to check if there's another ops that is enabled and also shares the global_ops filter. In that case, the modification still needs to be executed. Link: http://lkml.kernel.org/r/20150114154329.055980438@goodmis.org Cc: stable@vger.kernel.org # 3.17+ Reviewed-by: Masami Hiramatsu Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 929a733d302e..2b35d0ba578d 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -4008,8 +4008,32 @@ ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove) static void ftrace_ops_update_code(struct ftrace_ops *ops, struct ftrace_hash *old_hash) { - if (ops->flags & FTRACE_OPS_FL_ENABLED && ftrace_enabled) + struct ftrace_ops *op; + + if (!ftrace_enabled) + return; + + if (ops->flags & FTRACE_OPS_FL_ENABLED) { ftrace_run_modify_code(ops, FTRACE_UPDATE_CALLS, old_hash); + return; + } + + /* + * If this is the shared global_ops filter, then we need to + * check if there is another ops that shares it, is enabled. + * If so, we still need to run the modify code. + */ + if (ops->func_hash != &global_ops.local_hash) + return; + + do_for_each_ftrace_op(op, ftrace_ops_list) { + if (op->func_hash == &global_ops.local_hash && + op->flags & FTRACE_OPS_FL_ENABLED) { + ftrace_run_modify_code(op, FTRACE_UPDATE_CALLS, old_hash); + /* Only need to do this once */ + return; + } + } while_for_each_ftrace_op(op); } static int -- cgit v1.2.3 From 7485058eea40783ac142a60c3e799fc66ce72583 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Tue, 13 Jan 2015 14:03:38 -0500 Subject: ftrace: Check both notrace and filter for old hash Using just the filter for checking for trampolines or regs is not enough when updating the code against the records that represent all functions. Both the filter hash and the notrace hash need to be checked. To trigger this bug (using trace-cmd and perf): # perf probe -a do_fork # trace-cmd start -B foo -e probe # trace-cmd record -p function_graph -n do_fork sleep 1 The trace-cmd record at the end clears the filter before it disables function_graph tracing and then that causes the accounting of the ftrace function records to become incorrect and causes ftrace to bug. Link: http://lkml.kernel.org/r/20150114154329.358378039@goodmis.org Cc: stable@vger.kernel.org [ still need to switch old_hash_ops to old_ops_hash ] Reviewed-by: Masami Hiramatsu Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 2b35d0ba578d..224e768bdc73 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2497,12 +2497,14 @@ static void ftrace_run_update_code(int command) } static void ftrace_run_modify_code(struct ftrace_ops *ops, int command, - struct ftrace_hash *old_hash) + struct ftrace_ops_hash *old_hash) { ops->flags |= FTRACE_OPS_FL_MODIFYING; - ops->old_hash.filter_hash = old_hash; + ops->old_hash.filter_hash = old_hash->filter_hash; + ops->old_hash.notrace_hash = old_hash->notrace_hash; ftrace_run_update_code(command); ops->old_hash.filter_hash = NULL; + ops->old_hash.notrace_hash = NULL; ops->flags &= ~FTRACE_OPS_FL_MODIFYING; } @@ -3579,7 +3581,7 @@ static struct ftrace_ops trace_probe_ops __read_mostly = static int ftrace_probe_registered; -static void __enable_ftrace_function_probe(struct ftrace_hash *old_hash) +static void __enable_ftrace_function_probe(struct ftrace_ops_hash *old_hash) { int ret; int i; @@ -3637,6 +3639,7 @@ int register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops, void *data) { + struct ftrace_ops_hash old_hash_ops; struct ftrace_func_probe *entry; struct ftrace_hash **orig_hash = &trace_probe_ops.func_hash->filter_hash; struct ftrace_hash *old_hash = *orig_hash; @@ -3658,6 +3661,10 @@ register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops, mutex_lock(&trace_probe_ops.func_hash->regex_lock); + old_hash_ops.filter_hash = old_hash; + /* Probes only have filters */ + old_hash_ops.notrace_hash = NULL; + hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, old_hash); if (!hash) { count = -ENOMEM; @@ -3718,7 +3725,7 @@ register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops, ret = ftrace_hash_move(&trace_probe_ops, 1, orig_hash, hash); - __enable_ftrace_function_probe(old_hash); + __enable_ftrace_function_probe(&old_hash_ops); if (!ret) free_ftrace_hash_rcu(old_hash); @@ -4006,7 +4013,7 @@ ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove) } static void ftrace_ops_update_code(struct ftrace_ops *ops, - struct ftrace_hash *old_hash) + struct ftrace_ops_hash *old_hash) { struct ftrace_ops *op; @@ -4041,6 +4048,7 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len, unsigned long ip, int remove, int reset, int enable) { struct ftrace_hash **orig_hash; + struct ftrace_ops_hash old_hash_ops; struct ftrace_hash *old_hash; struct ftrace_hash *hash; int ret; @@ -4077,9 +4085,11 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len, mutex_lock(&ftrace_lock); old_hash = *orig_hash; + old_hash_ops.filter_hash = ops->func_hash->filter_hash; + old_hash_ops.notrace_hash = ops->func_hash->notrace_hash; ret = ftrace_hash_move(ops, enable, orig_hash, hash); if (!ret) { - ftrace_ops_update_code(ops, old_hash); + ftrace_ops_update_code(ops, &old_hash_ops); free_ftrace_hash_rcu(old_hash); } mutex_unlock(&ftrace_lock); @@ -4291,6 +4301,7 @@ static void __init set_ftrace_early_filters(void) int ftrace_regex_release(struct inode *inode, struct file *file) { struct seq_file *m = (struct seq_file *)file->private_data; + struct ftrace_ops_hash old_hash_ops; struct ftrace_iterator *iter; struct ftrace_hash **orig_hash; struct ftrace_hash *old_hash; @@ -4324,10 +4335,12 @@ int ftrace_regex_release(struct inode *inode, struct file *file) mutex_lock(&ftrace_lock); old_hash = *orig_hash; + old_hash_ops.filter_hash = iter->ops->func_hash->filter_hash; + old_hash_ops.notrace_hash = iter->ops->func_hash->notrace_hash; ret = ftrace_hash_move(iter->ops, filter_hash, orig_hash, iter->hash); if (!ret) { - ftrace_ops_update_code(iter->ops, old_hash); + ftrace_ops_update_code(iter->ops, &old_hash_ops); free_ftrace_hash_rcu(old_hash); } mutex_unlock(&ftrace_lock); -- cgit v1.2.3 From 83829b74f54186a154ae6b586c05cdb838c2ebc6 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Wed, 14 Jan 2015 12:24:37 -0500 Subject: tracing: Remove extra call to init_ftrace_syscalls() trace_init() calls init_ftrace_syscalls() and then calls trace_event_init() which also calls init_ftrace_syscalls(). It makes more sense to only call it from trace_event_init(). Calling it twice wastes memory, as it allocates the syscall events twice, and loses the first copy of it. Link: http://lkml.kernel.org/r/54AF53BD.5070303@huawei.com Link: http://lkml.kernel.org/r/20150115040505.930398632@goodmis.org Reported-by: Wang Nan Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 1 - 1 file changed, 1 deletion(-) (limited to 'kernel') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 2e767972e99c..4a9079b9f082 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6918,7 +6918,6 @@ void __init trace_init(void) tracepoint_printk = 0; } tracer_alloc_buffers(); - init_ftrace_syscalls(); trace_event_init(); } -- cgit v1.2.3 From ce1039bd3a89e99e4f624e75fb1777fc92d76eb3 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Wed, 14 Jan 2015 12:53:45 -0500 Subject: tracing: Fix enabling of syscall events on the command line Commit 5f893b2639b2 "tracing: Move enabling tracepoints to just after rcu_init()" broke the enabling of system call events from the command line. The reason was that the enabling of command line trace events was moved before PID 1 started, and the syscall tracepoints require that all tasks have the TIF_SYSCALL_TRACEPOINT flag set. But the swapper task (pid 0) is not part of that. Since the swapper task is the only task that is running at this early in boot, no task gets the flag set, and the tracepoint never gets reached. Instead of setting the swapper task flag (there should be no reason to do that), re-enabled trace events again after the init thread (PID 1) has been started. It requires disabling all command line events and re-enabling them, as just enabling them again will not reset the logic to set the TIF_SYSCALL_TRACEPOINT flag, as the syscall tracepoint will be fooled into thinking that it was already set, and wont try setting it again. For this reason, we must first disable it and re-enable it. Link: http://lkml.kernel.org/r/1421188517-18312-1-git-send-email-mpe@ellerman.id.au Link: http://lkml.kernel.org/r/20150115040506.216066449@goodmis.org Reported-by: Michael Ellerman Signed-off-by: Steven Rostedt --- kernel/trace/trace_events.c | 69 ++++++++++++++++++++++++++++++++++++--------- 1 file changed, 55 insertions(+), 14 deletions(-) (limited to 'kernel') diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 366a78a3e61e..b03a0ea77b99 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -2429,12 +2429,39 @@ static __init int event_trace_memsetup(void) return 0; } +static __init void +early_enable_events(struct trace_array *tr, bool disable_first) +{ + char *buf = bootup_event_buf; + char *token; + int ret; + + while (true) { + token = strsep(&buf, ","); + + if (!token) + break; + if (!*token) + continue; + + /* Restarting syscalls requires that we stop them first */ + if (disable_first) + ftrace_set_clr_event(tr, token, 0); + + ret = ftrace_set_clr_event(tr, token, 1); + if (ret) + pr_warn("Failed to enable trace event: %s\n", token); + + /* Put back the comma to allow this to be called again */ + if (buf) + *(buf - 1) = ','; + } +} + static __init int event_trace_enable(void) { struct trace_array *tr = top_trace_array(); struct ftrace_event_call **iter, *call; - char *buf = bootup_event_buf; - char *token; int ret; if (!tr) @@ -2456,18 +2483,7 @@ static __init int event_trace_enable(void) */ __trace_early_add_events(tr); - while (true) { - token = strsep(&buf, ","); - - if (!token) - break; - if (!*token) - continue; - - ret = ftrace_set_clr_event(tr, token, 1); - if (ret) - pr_warn("Failed to enable trace event: %s\n", token); - } + early_enable_events(tr, false); trace_printk_start_comm(); @@ -2478,6 +2494,31 @@ static __init int event_trace_enable(void) return 0; } +/* + * event_trace_enable() is called from trace_event_init() first to + * initialize events and perhaps start any events that are on the + * command line. Unfortunately, there are some events that will not + * start this early, like the system call tracepoints that need + * to set the TIF_SYSCALL_TRACEPOINT flag of pid 1. But event_trace_enable() + * is called before pid 1 starts, and this flag is never set, making + * the syscall tracepoint never get reached, but the event is enabled + * regardless (and not doing anything). + */ +static __init int event_trace_enable_again(void) +{ + struct trace_array *tr; + + tr = top_trace_array(); + if (!tr) + return -ENODEV; + + early_enable_events(tr, true); + + return 0; +} + +early_initcall(event_trace_enable_again); + static __init int event_trace_init(void) { struct trace_array *tr; -- cgit v1.2.3