From 6d723736e472f7a0cd5b62c84152fceead241328 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 10 Apr 2009 14:53:50 -0400 Subject: tracing/events: add support for modules to TRACE_EVENT Impact: allow modules to add TRACE_EVENTS on load This patch adds the final hooks to allow modules to use the TRACE_EVENT macro. A notifier and a data structure are used to link the TRACE_EVENTs defined in the module to connect them with the ftrace event tracing system. It also adds the necessary automated clean ups to the trace events when a module is removed. Cc: Rusty Russell Signed-off-by: Steven Rostedt --- kernel/module.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'kernel/module.c') diff --git a/kernel/module.c b/kernel/module.c index e797812a4d95..a0394706f10c 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -18,6 +18,7 @@ */ #include #include +#include #include #include #include @@ -2172,6 +2173,12 @@ static noinline struct module *load_module(void __user *umod, sizeof(*mod->tracepoints), &mod->num_tracepoints); #endif +#ifdef CONFIG_EVENT_TRACING + mod->trace_events = section_objs(hdr, sechdrs, secstrings, + "_ftrace_events", + sizeof(*mod->trace_events), + &mod->num_trace_events); +#endif #ifdef CONFIG_MODVERSIONS if ((mod->num_syms && !mod->crcs) -- cgit v1.2.3 From 93eb677d74a4f7d3edfb678c94f6c0544d9fbad2 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 15 Apr 2009 13:24:06 -0400 Subject: ftrace: use module notifier for function tracer The hooks in the module code for the function tracer must be called before any of that module code runs. The function tracer hooks modify the module (replacing calls to mcount to nops). If the code is executed while the change occurs, then the CPU can take a GPF. To handle the above with a bit of paranoia, I originally implemented the hooks as calls directly from the module code. After examining the notifier calls, it looks as though the start up notify is called before any of the module's code is executed. This makes the use of the notify safe with ftrace. Only the startup notify is required to be "safe". The shutdown simply removes the entries from the ftrace function list, and does not modify any code. This change has another benefit. It removes a issue with a reverse dependency in the mutexes of ftrace_lock and module_mutex. [ Impact: fix lock dependency bug, cleanup ] Cc: Rusty Russell Signed-off-by: Steven Rostedt --- kernel/module.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) (limited to 'kernel/module.c') diff --git a/kernel/module.c b/kernel/module.c index a0394706f10c..2383e60fcf3f 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1490,9 +1490,6 @@ static void free_module(struct module *mod) /* Free any allocated parameters. */ destroy_params(mod->kp, mod->num_kp); - /* release any pointers to mcount in this module */ - ftrace_release(mod->module_core, mod->core_size); - /* This may be NULL, but that's OK */ module_free(mod, mod->module_init); kfree(mod->args); @@ -1893,11 +1890,9 @@ static noinline struct module *load_module(void __user *umod, unsigned int symindex = 0; unsigned int strindex = 0; unsigned int modindex, versindex, infoindex, pcpuindex; - unsigned int num_mcount; struct module *mod; long err = 0; void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */ - unsigned long *mseg; mm_segment_t old_fs; DEBUGP("load_module: umod=%p, len=%lu, uargs=%p\n", @@ -2179,7 +2174,13 @@ static noinline struct module *load_module(void __user *umod, sizeof(*mod->trace_events), &mod->num_trace_events); #endif - +#ifdef CONFIG_FTRACE_MCOUNT_RECORD + /* sechdrs[0].sh_size is always zero */ + mod->ftrace_callsites = section_objs(hdr, sechdrs, secstrings, + "__mcount_loc", + sizeof(*mod->ftrace_callsites), + &mod->num_ftrace_callsites); +#endif #ifdef CONFIG_MODVERSIONS if ((mod->num_syms && !mod->crcs) || (mod->num_gpl_syms && !mod->gpl_crcs) @@ -2244,11 +2245,6 @@ static noinline struct module *load_module(void __user *umod, dynamic_debug_setup(debug, num_debug); } - /* sechdrs[0].sh_size is always zero */ - mseg = section_objs(hdr, sechdrs, secstrings, "__mcount_loc", - sizeof(*mseg), &num_mcount); - ftrace_init_module(mod, mseg, mseg + num_mcount); - err = module_finalize(hdr, sechdrs, mod); if (err < 0) goto cleanup; @@ -2309,7 +2305,6 @@ static noinline struct module *load_module(void __user *umod, cleanup: kobject_del(&mod->mkobj.kobj); kobject_put(&mod->mkobj.kobj); - ftrace_release(mod->module_core, mod->core_size); free_unload: module_unload_free(mod); #if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) -- cgit v1.2.3