// SPDX-License-Identifier: GPL-2.0 /* * ring buffer based function tracer * * Copyright (C) 2007-2008 Steven Rostedt * Copyright (C) 2008 Ingo Molnar * * Based on code from the latency_tracer, that is: * * Copyright (C) 2004-2006 Ingo Molnar * Copyright (C) 2004 Nadia Yvette Chambers */ #include #include #include #include #include #include #include "trace.h" static void tracing_start_function_trace(struct trace_array *tr); static void tracing_stop_function_trace(struct trace_array *tr); static void function_trace_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct ftrace_regs *fregs); static void function_stack_trace_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct ftrace_regs *fregs); static struct tracer_flags func_flags; /* Our option */ enum { TRACE_FUNC_OPT_STACK = 0x1, }; int ftrace_allocate_ftrace_ops(struct trace_array *tr) { struct ftrace_ops *ops; /* The top level array uses the "global_ops" */ if (tr->flags & TRACE_ARRAY_FL_GLOBAL) return 0; ops = kzalloc(sizeof(*ops), GFP_KERNEL); if (!ops) return -ENOMEM; /* Currently only the non stack version is supported */ ops->func = function_trace_call; ops->flags = FTRACE_OPS_FL_PID; tr->ops = ops; ops->private = tr; return 0; } void ftrace_free_ftrace_ops(struct trace_array *tr) { kfree(tr->ops); tr->ops = NULL; } int ftrace_create_function_files(struct trace_array *tr, struct dentry *parent) { /* * The top level array uses the "global_ops", and the files are * created on boot up. */ if (tr->flags & TRACE_ARRAY_FL_GLOBAL) return 0; if (!tr->ops) return -EINVAL; ftrace_create_filter_files(tr->ops, parent); return 0; } void ftrace_destroy_function_files(struct trace_array *tr) { ftrace_destroy_filter_files(tr->ops); ftrace_free_ftrace_ops(tr); } static int function_trace_init(struct trace_array *tr) { ftrace_func_t func; /* * Instance trace_arrays get their ops allocated * at instance creation. Unless it failed * the allocation. */ if (!tr->ops) return -ENOMEM; /* Currently only the global instance can do stack tracing */ if (tr->flags & TRACE_ARRAY_FL_GLOBAL && func_flags.val & TRACE_FUNC_OPT_STACK) func = function_stack_trace_call; else func = function_trace_call; ftrace_init_array_ops(tr, func); tr->array_buffer.cpu = raw_smp_processor_id(); tracing_start_cmdline_record(); tracing_start_function_trace(tr); return 0; } static void function_trace_reset(struct trace_array *tr) { tracing_stop_function_trace(tr); tracing_stop_cmdline_record(); ftrace_reset_array_ops(tr); } static void function_trace_start(struct trace_array *tr) { tracing_reset_online_cpus(&tr->array_buffer); } static void function_trace_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct ftrace_regs *fregs) { struct trace_array *tr = op->private; struct trace_array_cpu *data; unsigned long flags; int bit; int cpu; int pc; if (unlikely(!tr->function_enabled)) return; bit = ftrace_test_recursion_trylock(ip, parent_ip); if (bit < 0) return; pc = preempt_count(); preempt_disable_notrace(); cpu = smp_processor_id(); data = per_cpu_ptr(tr->array_buffer.data, cpu); if (!atomic_read(&data->disabled)) { local_save_flags(flags); trace_function(tr, ip, parent_ip, flags, pc); } ftrace_test_recursion_unlock(bit); preempt_enable_notrace(); } #ifdef CONFIG_UNWINDER_ORC /* * Skip 2: * * function_stack_trace_call() * ftrace_call() */ #define STACK_SKIP 2 #else /* * Skip 3: * __trace_stack() * function_stack_trace_call() * ftrace_call() */ #define STACK_SKIP 3 #endif static void function_stack_trace_call(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *op, struct ftrace_regs *fregs) { struct trace_array *tr = op->private; struct trace_array_cpu *data; unsigned long flags; long disabled; int cpu; int pc; if (unlikely(!tr->function_enabled)) return; /* * Need to use raw, since this must be called before the * recursive protection is performed. */ local_irq_save(flags); cpu = raw_smp_processor_id(); data = per_cpu_ptr(tr->array_buffer.data, cpu); disabled = atomic_inc_return(&data->disabled); if (likely(disabled == 1)) { pc = preempt_count(); trace_function(tr, ip, parent_ip, flags, pc); __trace_stack(tr, flags, STACK_SKIP, pc); } atomic_dec(&data->disabled); local_irq_restore(flags); } static struct tracer_opt func_opts[] = { #ifdef CONFIG_STACKTRACE { TRACER_OPT(func_stack_trace, TRACE_FUNC_OPT_STACK) }, #endif { } /* Always set a last empty entry */ }; static struct tracer_flags func_flags = { .val = 0, /* By default: all flags disabled */ .opts = func_opts }; static void tracing_start_function_trace(struct trace_array *tr) { tr->function_enabled = 0; register_ftrace_function(tr->ops); tr->function_enabled = 1; } static void tracing_stop_function_trace(struct trace_array *tr) { tr->function_enabled = 0; unregister_ftrace_function(tr->ops); } static struct tracer function_trace; static int func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) { switch (bit) { case TRACE_FUNC_OPT_STACK: /* do nothing if already set */ if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK)) break; /* We can change this flag when not running. */ if (tr->current_trace != &function_trace) break; unregister_ftrace_function(tr->ops); if (set) { tr->ops->func = function_stack_trace_call; register_ftrace_function(tr->ops); } else { tr->ops->func = function_trace_call; register_ftrace_function(tr->ops); } break; default: return -EINVAL; } return 0; } static struct tracer function_trace __tracer_data = { .name = "function", .init = function_trace_init, .reset = function_trace_reset, .start = function_trace_start, .flags = &func_flags, .set_flag = func_set_flag, .allow_instances = true, #ifdef CONFIG_FTRACE_SELFTEST .selftest = trace_selftest_startup_function, #endif }; #ifdef CONFIG_DYNAMIC_FTRACE static void update_traceon_count(struct ftrace_probe_ops *ops, unsigned long ip, struct trace_array *tr, bool on, void *data) { struct ftrace_func_mapper *mapper = data; long *count; long old_count; /* * Tracing gets disabled (or enabled) once per count. * This function can be called at the same time on multiple CPUs. * It is fine if both disable (or enable) tracing, as disabling * (or enabling) the second time doesn't do anything as the * state of the tracer is already disabled (or enabled). * What needs to be synchronized in this case is that the count * only gets decremented once, even if the tracer is disabled * (or enabled) twice, as the second one is really a nop. * * The memory barriers guarantee that we only decrement the * counter once. First the count is read to a local variable * and a read barrier is used to make sure that it is loaded * before checking if the tracer is in the state we want. * If the tracer is not in the state we want, then the count * is guaranteed to be the old count. * * Next the tracer is set to the state we want (disabled or enabled) * then a write memory barrier is used to make sure that * the new state is visible before changing the counter by * one minus the old counter. This guarantees that another CPU * executing this code will see the new state before seeing * the new counter value, and would not do anything if the new * counter is seen. * * Note, there is no synchronization between this and a user * setting the tracing_on file. But we currently don't care * about that. */ count = (long *)ftrace_func_mapper_find_ip(mapper, ip); old_count = *count; if (old_count <= 0) return; /* Make sure we see count before checking tracing state */ smp_rmb(); if (on == !!tracer_tracing_is_on(tr)) return; if (on) tracer_tracing_on(tr); else tracer_tracing_off(tr); /* Make sure tracing state is visible before updating count */ smp_wmb(); *count = old_count - 1; } static void ftrace_traceon_count(unsigned long ip, unsigned long parent_ip, struct trace_array *tr, struct ftrace_probe_ops *ops, void *data) { update_traceon_count(ops, ip, tr, 1, data); } static void ftrace_traceoff_count(unsigned long ip, unsigned long parent_ip, struct trace_array *tr, struct ftrace_probe_ops *ops, void *data) { update_traceon_count(ops, ip, tr, 0, data); } static void ftrace_traceon(unsigned long ip, unsigned long parent_ip, struct trace_array *tr, struct ftrace_probe_ops *ops, void *data) { if (tracer_tracing_is_on(tr)) return; tracer_tracing_on(tr); } static void ftrace_traceoff(unsigned long ip, unsigned long parent_ip, struct trace_array *tr, struct ftrace_probe_ops *ops, void *data) { if (!tracer_tracing_is_on(tr)) return; tracer_tracing_off(tr); } #ifdef CONFIG_UNWINDER_ORC /* * Skip 3: * * function_trace_probe_call() * ftrace_ops_assist_func() * ftrace_call() */ #define FTRACE_STACK_SKIP 3 #else /* * Skip 5: * * __trace_stack() * ftrace_stacktrace() * function_trace_probe_call() * ftrace_ops_assist_func() * ftrace_call() */ #define FTRACE_STACK_SKIP 5 #endif static __always_inline void trace_stack(struct trace_array *tr) { unsigned long flags; int pc; local_save_flags(flags); pc = preempt_count(); __trace_stack(tr, flags, FTRACE_STACK_SKIP, pc); } static void ftrace_stacktrace(unsigned long ip, unsigned long parent_ip, struct trace_array *tr, struct ftrace_probe_ops *ops, void *data) { trace_stack(tr); } static void ftrace_stacktrace_count(unsigned long ip, unsigned long parent_ip, struct trace_array *tr, struct ftrace_probe_ops *ops, void *data) { struct ftrace_func_mapper *mapper = data; long *count; long old_count; long new_count; if (!tracing_is_on()) return; /* unlimited? */ if (!mapper) { trace_stack(tr); return; } count = (long *)ftrace_func_mapper_find_ip(mapper, ip); /* * Stack traces should only execute the number of times the * user specified in the counter. */ do { old_count = *count; if (!old_count) return; new_count = old_count - 1; new_count = cmpxchg(count, old_count, new_count); if (new_count == old_count) trace_stack(tr); if (!tracing_is_on()) return; } while (new_count != old_count); } static int update_count(struct ftrace_probe_ops *ops, unsigned long ip, void *data) { struct ftrace_func_mapper *mapper = data; long *count = NULL; if (mapper) count = (long *)ftrace_func_mapper_find_ip(mapper, ip); if (count) { if (*count <= 0) return 0; (*count)--; } return 1; } static void ftrace_dump_probe(unsigned long ip, unsigned long parent_ip, struct trace_array *tr, struct ftrace_probe_ops *ops, void *data) { if (update_count(ops, ip, data)) ftrace_dump(DUMP_ALL); } /* Only dump the current CPU buffer. */ static void ftrace_cpudump_probe(unsigned long ip, unsigned long parent_ip, struct trace_array *tr, struct ftrace_probe_ops *ops, void *data) { if (update_count(ops, ip, data)) ftrace_dump(DUMP_ORIG); } static int ftrace_probe_print(const char *name, struct seq_file *m, unsigned long ip, struct ftrace_probe_ops *ops, void *data) { struct ftrace_func_mapper *mapper = data; long *count = NULL; seq_printf(m, "%ps:%s", (void *)ip, name); if (mapper) count = (long *)ftrace_func_mapper_find_ip(mapper, ip); if (count) seq_printf(m, ":count=%ld\n", *count); else seq_puts(m, ":unlimited\n"); return 0; } static int ftrace_traceon_print(struct seq_file *m, unsigned long ip, struct ftrace_probe_ops *ops, void *data) { return ftrace_probe_print("traceon", m, ip, ops, data); } static int ftrace_traceoff_print(struct seq_file *m, unsigned long ip, struct ftrace_probe_ops *ops, void *data) { return ftrace_probe_print("traceoff", m, ip, ops, data); } static int ftrace_stacktrace_print(struct seq_file *m, unsigned long ip, struct ftrace_probe_ops *ops, void *data) { return ftrace_probe_print("stacktrace", m, ip, ops, data); } static int ftrace_dump_print(struct seq_file *m, unsigned long ip, struct ftrace_probe_ops *ops, void *data) { return ftrace_probe_print("dump", m, ip, ops, data); } static int ftrace_cpudump_print(struct seq_file *m, unsigned long ip, struct ftrace_probe_ops *ops, void *data) { return ftrace_probe_print("cpudump", m, ip, ops, data); } static int ftrace_count_init(struct ftrace_probe_ops *ops, struct trace_array *tr, unsigned long ip, void *init_data, void **data) { struct ftrace_func_mapper *mapper = *data; if (!mapper) { mapper = allocate_ftrace_func_mapper(); if (!mapper) return -ENOMEM; *data = mapper; } return ftrace_func_mapper_add_ip(mapper, ip, init_data); } static void ftrace_count_free(struct ftrace_probe_ops *ops, struct trace_array *tr, unsigned long ip, void *data) { struct ftrace_func_mapper *mapper = data; if (!ip) { free_ftrace_func_mapper(mapper, NULL); return; } ftrace_func_mapper_remove_ip(mapper, ip); } static struct ftrace_probe_ops traceon_count_probe_ops = { .func = ftrace_traceon_count, .print = ftrace_traceon_print, .init = ftrace_count_init, .free = ftrace_count_free, }; static struct ftrace_probe_ops traceoff_count_probe_ops = { .func = ftrace_traceoff_count, .print = ftrace_traceoff_print, .init = ftrace_count_init, .free = ftrace_count_free, }; static struct ftrace_probe_ops stacktrace_count_probe_ops = { .func = ftrace_stacktrace_count, .print = ftrace_stacktrace_print, .init = ftrace_count_init, .free = ftrace_count_free, }; static struct ftrace_probe_ops dump_probe_ops = { .func = ftrace_dump_probe, .print = ftrace_dump_print, .init = ftrace_count_init, .free = ftrace_count_free, }; static struct ftrace_probe_ops cpudump_probe_ops = { .func = ftrace_cpudump_probe, .print = ftrace_cpudump_print, }; static struct ftrace_probe_ops traceon_probe_ops = { .func = ftrace_traceon, .print = ftrace_traceon_print, }; static struct ftrace_probe_ops traceoff_probe_ops = { .func = ftrace_traceoff, .print = ftrace_traceoff_print, }; static struct ftrace_probe_ops stacktrace_probe_ops = { .func = ftrace_stacktrace, .print = ftrace_stacktrace_print, }; static int ftrace_trace_probe_callback(struct trace_array *tr, struct ftrace_probe_ops *ops, struct ftrace_hash *hash, char *glob, char *cmd, char *param, int enable) { void *count = (void *)-1; char *number; int ret; /* hash funcs only work with set_ftrace_filter */ if (!enable) return -EINVAL; if (glob[0] == '!') return unregister_ftrace_function_probe_func(glob+1, tr, ops); if (!param) goto out_reg; number = strsep(¶m, ":"); if (!strlen(number)) goto out_reg; /* * We use the callback data field (which is a pointer) * as our counter. */ ret = kstrtoul(number, 0, (unsigned long *)&count); if (ret) return ret; out_reg: ret = register_ftrace_function_probe(glob, tr, ops, count); return ret < 0 ? ret : 0; } static int ftrace_trace_onoff_callback(struct trace_array *tr, struct ftrace_hash *hash, char *glob, char *cmd, char *param, int enable) { struct ftrace_probe_ops *ops; if (!tr) return -ENODEV; /* we register both traceon and traceoff to this callback */ if (strcmp(cmd, "traceon") == 0) ops = param ? &traceon_count_probe_ops : &traceon_probe_ops; else ops = param ? &traceoff_count_probe_ops : &traceoff_probe_ops; return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd, param, enable); } static int ftrace_stacktrace_callback(struct trace_array *tr, struct ftrace_hash *hash, char *glob, char *cmd, char *param, int enable) { struct ftrace_probe_ops *ops; if (!tr) return -ENODEV; ops = param ? &stacktrace_count_probe_ops : &stacktrace_probe_ops; return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd, param, enable); } static int ftrace_dump_callback(struct trace_array *tr, struct ftrace_hash *hash, char *glob, char *cmd, char *param, int enable) { struct ftrace_probe_ops *ops; if (!tr) return -ENODEV; ops = &dump_probe_ops; /* Only dump once. */ return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd, "1", enable); } static int ftrace_cpudump_callback(struct trace_array *tr, struct ftrace_hash *hash, char *glob, char *cmd, char *param, int enable) { struct ftrace_probe_ops *ops; if (!tr) return -ENODEV; ops = &cpudump_probe_ops; /* Only dump once. */ return ftrace_trace_probe_callback(tr, ops, hash, glob, cmd, "1", enable); } static struct ftrace_func_command ftrace_traceon_cmd = { .name = "traceon", .func = ftrace_trace_onoff_callback, }; static struct ftrace_func_command ftrace_traceoff_cmd = { .name = "traceoff", .func = ftrace_trace_onoff_callback, }; static struct ftrace_func_command ftrace_stacktrace_cmd = { .name = "stacktrace", .func = ftrace_stacktrace_callback, }; static struct ftrace_func_command ftrace_dump_cmd = { .name = "dump", .func = ftrace_dump_callback, }; static struct ftrace_func_command ftrace_cpudump_cmd = { .name = "cpudump", .func = ftrace_cpudump_callback, }; static int __init init_func_cmd_traceon(void) { int ret; ret = register_ftrace_command(&ftrace_traceoff_cmd); if (ret) return ret; ret = register_ftrace_command(&ftrace_traceon_cmd); if (ret) goto out_free_traceoff; ret = register_ftrace_command(&ftrace_stacktrace_cmd); if (ret) goto out_free_traceon; ret = register_ftrace_command(&ftrace_dump_cmd); if (ret) goto out_free_stacktrace; ret = register_ftrace_command(&ftrace_cpudump_cmd); if (ret) goto out_free_dump; return 0; out_free_dump: unregister_ftrace_command(&ftrace_dump_cmd); out_free_stacktrace: unregister_ftrace_command(&ftrace_stacktrace_cmd); out_free_traceon: unregister_ftrace_command(&ftrace_traceon_cmd); out_free_traceoff: unregister_ftrace_command(&ftrace_traceoff_cmd); return ret; } #else static inline int init_func_cmd_traceon(void) { return 0; } #endif /* CONFIG_DYNAMIC_FTRACE */ __init int init_function_trace(void) { init_func_cmd_traceon(); return register_tracer(&function_trace); }