From: Masami Hiramatsu (Google) <mhira...@kernel.org> Support raw tracepoint event on module by fprobe events. Since it only uses for_each_kernel_tracepoint() to find a tracepoint, the tracepoints on modules are not handled. Thus if user specified a tracepoint on a module, it shows an error. This adds new for_each_module_tracepoint() API to tracepoint subsystem, and uses it to find tracepoints on modules.
Reported-by: don <zds...@gmail.com> Closes: https://lore.kernel.org/all/20240530215718.aeec973a1d0bf058d39cb...@kernel.org/ Signed-off-by: Masami Hiramatsu (Google) <mhira...@kernel.org> --- Changes in v2: - Fix build errors with CONFIG_MODULES=y. --- kernel/trace/trace_fprobe.c | 46 ++++++++++++++++++++++++++++++++++++------- 1 file changed, 38 insertions(+), 8 deletions(-) diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c index 62e6a8f4aae9..8b1127e37da5 100644 --- a/kernel/trace/trace_fprobe.c +++ b/kernel/trace/trace_fprobe.c @@ -385,6 +385,7 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group, const char *event, const char *symbol, struct tracepoint *tpoint, + struct module *mod, int maxactive, int nargs, bool is_return) { @@ -405,6 +406,7 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group, tf->fp.entry_handler = fentry_dispatcher; tf->tpoint = tpoint; + tf->mod = mod; tf->fp.nr_maxactive = maxactive; ret = trace_probe_init(&tf->tp, event, group, false, nargs); @@ -895,8 +897,23 @@ static struct notifier_block tracepoint_module_nb = { struct __find_tracepoint_cb_data { const char *tp_name; struct tracepoint *tpoint; + struct module *mod; }; +static void __find_tracepoint_module_cb(struct tracepoint *tp, struct module *mod, void *priv) +{ + struct __find_tracepoint_cb_data *data = priv; + + if (!data->tpoint && !strcmp(data->tp_name, tp->name)) { + data->tpoint = tp; + data->mod = mod; + if (!try_module_get(data->mod)) { + data->tpoint = NULL; + data->mod = NULL; + } + } +} + static void __find_tracepoint_cb(struct tracepoint *tp, void *priv) { struct __find_tracepoint_cb_data *data = priv; @@ -905,14 +922,28 @@ static void __find_tracepoint_cb(struct tracepoint *tp, void *priv) data->tpoint = tp; } -static struct tracepoint *find_tracepoint(const char *tp_name) +/* + * Find a tracepoint from kernel and module. If the tracepoint is in a module, + * this increments the module refcount to prevent unloading until the + * trace_fprobe is registered to the list. After registering the trace_fprobe + * on the trace_fprobe list, the module refcount is decremented because + * tracepoint_probe_module_cb will handle it. + */ +static struct tracepoint *find_tracepoint(const char *tp_name, + struct module **tp_mod) { struct __find_tracepoint_cb_data data = { .tp_name = tp_name, + .mod = NULL, }; for_each_kernel_tracepoint(__find_tracepoint_cb, &data); + if (!data.tpoint && IS_ENABLED(CONFIG_MODULES)) { + for_each_module_tracepoint(__find_tracepoint_module_cb, &data); + *tp_mod = data.mod; + } + return data.tpoint; } @@ -996,6 +1027,7 @@ static int __trace_fprobe_create(int argc, const char *argv[]) char abuf[MAX_BTF_ARGS_LEN]; char *dbuf = NULL; bool is_tracepoint = false; + struct module *tp_mod = NULL; struct tracepoint *tpoint = NULL; struct traceprobe_parse_context ctx = { .flags = TPARG_FL_KERNEL | TPARG_FL_FPROBE, @@ -1080,7 +1112,7 @@ static int __trace_fprobe_create(int argc, const char *argv[]) if (is_tracepoint) { ctx.flags |= TPARG_FL_TPOINT; - tpoint = find_tracepoint(symbol); + tpoint = find_tracepoint(symbol, &tp_mod); if (!tpoint) { trace_probe_log_set_index(1); trace_probe_log_err(0, NO_TRACEPOINT); @@ -1110,8 +1142,8 @@ static int __trace_fprobe_create(int argc, const char *argv[]) goto out; /* setup a probe */ - tf = alloc_trace_fprobe(group, event, symbol, tpoint, maxactive, - argc, is_return); + tf = alloc_trace_fprobe(group, event, symbol, tpoint, tp_mod, + maxactive, argc, is_return); if (IS_ERR(tf)) { ret = PTR_ERR(tf); /* This must return -ENOMEM, else there is a bug */ @@ -1119,10 +1151,6 @@ static int __trace_fprobe_create(int argc, const char *argv[]) goto out; /* We know tf is not allocated */ } - if (is_tracepoint) - tf->mod = __module_text_address( - (unsigned long)tf->tpoint->probestub); - /* parse arguments */ for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) { trace_probe_log_set_index(i + 2); @@ -1155,6 +1183,8 @@ static int __trace_fprobe_create(int argc, const char *argv[]) } out: + if (tp_mod) + module_put(tp_mod); traceprobe_finish_parse(&ctx); trace_probe_log_clear(); kfree(new_argv);
