|  | /* | 
|  | * ring buffer based function tracer | 
|  | * | 
|  | * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> | 
|  | * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com> | 
|  | * | 
|  | * Based on code from the latency_tracer, that is: | 
|  | * | 
|  | *  Copyright (C) 2004-2006 Ingo Molnar | 
|  | *  Copyright (C) 2004 William Lee Irwin III | 
|  | */ | 
|  | #include <linux/ring_buffer.h> | 
|  | #include <linux/debugfs.h> | 
|  | #include <linux/uaccess.h> | 
|  | #include <linux/ftrace.h> | 
|  | #include <linux/fs.h> | 
|  |  | 
|  | #include "trace.h" | 
|  |  | 
|  | /* function tracing enabled */ | 
|  | static int			ftrace_function_enabled; | 
|  |  | 
|  | static struct trace_array	*func_trace; | 
|  |  | 
|  | static void tracing_start_function_trace(void); | 
|  | static void tracing_stop_function_trace(void); | 
|  |  | 
|  | static int function_trace_init(struct trace_array *tr) | 
|  | { | 
|  | func_trace = tr; | 
|  | tr->cpu = get_cpu(); | 
|  | put_cpu(); | 
|  |  | 
|  | tracing_start_cmdline_record(); | 
|  | tracing_start_function_trace(); | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | static void function_trace_reset(struct trace_array *tr) | 
|  | { | 
|  | tracing_stop_function_trace(); | 
|  | tracing_stop_cmdline_record(); | 
|  | } | 
|  |  | 
|  | static void function_trace_start(struct trace_array *tr) | 
|  | { | 
|  | tracing_reset_online_cpus(tr); | 
|  | } | 
|  |  | 
|  | static void | 
|  | function_trace_call_preempt_only(unsigned long ip, unsigned long parent_ip) | 
|  | { | 
|  | struct trace_array *tr = func_trace; | 
|  | struct trace_array_cpu *data; | 
|  | unsigned long flags; | 
|  | long disabled; | 
|  | int cpu; | 
|  | int pc; | 
|  |  | 
|  | if (unlikely(!ftrace_function_enabled)) | 
|  | return; | 
|  |  | 
|  | pc = preempt_count(); | 
|  | preempt_disable_notrace(); | 
|  | local_save_flags(flags); | 
|  | cpu = raw_smp_processor_id(); | 
|  | data = tr->data[cpu]; | 
|  | disabled = atomic_inc_return(&data->disabled); | 
|  |  | 
|  | if (likely(disabled == 1)) | 
|  | trace_function(tr, ip, parent_ip, flags, pc); | 
|  |  | 
|  | atomic_dec(&data->disabled); | 
|  | preempt_enable_notrace(); | 
|  | } | 
|  |  | 
|  | static void | 
|  | function_trace_call(unsigned long ip, unsigned long parent_ip) | 
|  | { | 
|  | struct trace_array *tr = func_trace; | 
|  | struct trace_array_cpu *data; | 
|  | unsigned long flags; | 
|  | long disabled; | 
|  | int cpu; | 
|  | int pc; | 
|  |  | 
|  | if (unlikely(!ftrace_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 = tr->data[cpu]; | 
|  | disabled = atomic_inc_return(&data->disabled); | 
|  |  | 
|  | if (likely(disabled == 1)) { | 
|  | pc = preempt_count(); | 
|  | trace_function(tr, ip, parent_ip, flags, pc); | 
|  | } | 
|  |  | 
|  | atomic_dec(&data->disabled); | 
|  | local_irq_restore(flags); | 
|  | } | 
|  |  | 
|  | static void | 
|  | function_stack_trace_call(unsigned long ip, unsigned long parent_ip) | 
|  | { | 
|  | struct trace_array *tr = func_trace; | 
|  | struct trace_array_cpu *data; | 
|  | unsigned long flags; | 
|  | long disabled; | 
|  | int cpu; | 
|  | int pc; | 
|  |  | 
|  | if (unlikely(!ftrace_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 = tr->data[cpu]; | 
|  | disabled = atomic_inc_return(&data->disabled); | 
|  |  | 
|  | if (likely(disabled == 1)) { | 
|  | pc = preempt_count(); | 
|  | trace_function(tr, ip, parent_ip, flags, pc); | 
|  | /* | 
|  | * skip over 5 funcs: | 
|  | *    __ftrace_trace_stack, | 
|  | *    __trace_stack, | 
|  | *    function_stack_trace_call | 
|  | *    ftrace_list_func | 
|  | *    ftrace_call | 
|  | */ | 
|  | __trace_stack(tr, flags, 5, pc); | 
|  | } | 
|  |  | 
|  | atomic_dec(&data->disabled); | 
|  | local_irq_restore(flags); | 
|  | } | 
|  |  | 
|  |  | 
|  | static struct ftrace_ops trace_ops __read_mostly = | 
|  | { | 
|  | .func = function_trace_call, | 
|  | .flags = FTRACE_OPS_FL_GLOBAL, | 
|  | }; | 
|  |  | 
|  | static struct ftrace_ops trace_stack_ops __read_mostly = | 
|  | { | 
|  | .func = function_stack_trace_call, | 
|  | .flags = FTRACE_OPS_FL_GLOBAL, | 
|  | }; | 
|  |  | 
|  | /* Our two options */ | 
|  | enum { | 
|  | TRACE_FUNC_OPT_STACK = 0x1, | 
|  | }; | 
|  |  | 
|  | 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(void) | 
|  | { | 
|  | ftrace_function_enabled = 0; | 
|  |  | 
|  | if (trace_flags & TRACE_ITER_PREEMPTONLY) | 
|  | trace_ops.func = function_trace_call_preempt_only; | 
|  | else | 
|  | trace_ops.func = function_trace_call; | 
|  |  | 
|  | if (func_flags.val & TRACE_FUNC_OPT_STACK) | 
|  | register_ftrace_function(&trace_stack_ops); | 
|  | else | 
|  | register_ftrace_function(&trace_ops); | 
|  |  | 
|  | ftrace_function_enabled = 1; | 
|  | } | 
|  |  | 
|  | static void tracing_stop_function_trace(void) | 
|  | { | 
|  | ftrace_function_enabled = 0; | 
|  |  | 
|  | if (func_flags.val & TRACE_FUNC_OPT_STACK) | 
|  | unregister_ftrace_function(&trace_stack_ops); | 
|  | else | 
|  | unregister_ftrace_function(&trace_ops); | 
|  | } | 
|  |  | 
|  | static int func_set_flag(u32 old_flags, u32 bit, int set) | 
|  | { | 
|  | if (bit == TRACE_FUNC_OPT_STACK) { | 
|  | /* do nothing if already set */ | 
|  | if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK)) | 
|  | return 0; | 
|  |  | 
|  | if (set) { | 
|  | unregister_ftrace_function(&trace_ops); | 
|  | register_ftrace_function(&trace_stack_ops); | 
|  | } else { | 
|  | unregister_ftrace_function(&trace_stack_ops); | 
|  | register_ftrace_function(&trace_ops); | 
|  | } | 
|  |  | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | return -EINVAL; | 
|  | } | 
|  |  | 
|  | static struct tracer function_trace __read_mostly = | 
|  | { | 
|  | .name		= "function", | 
|  | .init		= function_trace_init, | 
|  | .reset		= function_trace_reset, | 
|  | .start		= function_trace_start, | 
|  | .wait_pipe	= poll_wait_pipe, | 
|  | .flags		= &func_flags, | 
|  | .set_flag	= func_set_flag, | 
|  | #ifdef CONFIG_FTRACE_SELFTEST | 
|  | .selftest	= trace_selftest_startup_function, | 
|  | #endif | 
|  | }; | 
|  |  | 
|  | #ifdef CONFIG_DYNAMIC_FTRACE | 
|  | static void | 
|  | ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data) | 
|  | { | 
|  | long *count = (long *)data; | 
|  |  | 
|  | if (tracing_is_on()) | 
|  | return; | 
|  |  | 
|  | if (!*count) | 
|  | return; | 
|  |  | 
|  | if (*count != -1) | 
|  | (*count)--; | 
|  |  | 
|  | tracing_on(); | 
|  | } | 
|  |  | 
|  | static void | 
|  | ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data) | 
|  | { | 
|  | long *count = (long *)data; | 
|  |  | 
|  | if (!tracing_is_on()) | 
|  | return; | 
|  |  | 
|  | if (!*count) | 
|  | return; | 
|  |  | 
|  | if (*count != -1) | 
|  | (*count)--; | 
|  |  | 
|  | tracing_off(); | 
|  | } | 
|  |  | 
|  | static int | 
|  | ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip, | 
|  | struct ftrace_probe_ops *ops, void *data); | 
|  |  | 
|  | static struct ftrace_probe_ops traceon_probe_ops = { | 
|  | .func			= ftrace_traceon, | 
|  | .print			= ftrace_trace_onoff_print, | 
|  | }; | 
|  |  | 
|  | static struct ftrace_probe_ops traceoff_probe_ops = { | 
|  | .func			= ftrace_traceoff, | 
|  | .print			= ftrace_trace_onoff_print, | 
|  | }; | 
|  |  | 
|  | static int | 
|  | ftrace_trace_onoff_print(struct seq_file *m, unsigned long ip, | 
|  | struct ftrace_probe_ops *ops, void *data) | 
|  | { | 
|  | long count = (long)data; | 
|  |  | 
|  | seq_printf(m, "%ps:", (void *)ip); | 
|  |  | 
|  | if (ops == &traceon_probe_ops) | 
|  | seq_printf(m, "traceon"); | 
|  | else | 
|  | seq_printf(m, "traceoff"); | 
|  |  | 
|  | if (count == -1) | 
|  | seq_printf(m, ":unlimited\n"); | 
|  | else | 
|  | seq_printf(m, ":count=%ld\n", count); | 
|  |  | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | static int | 
|  | ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param) | 
|  | { | 
|  | struct ftrace_probe_ops *ops; | 
|  |  | 
|  | /* we register both traceon and traceoff to this callback */ | 
|  | if (strcmp(cmd, "traceon") == 0) | 
|  | ops = &traceon_probe_ops; | 
|  | else | 
|  | ops = &traceoff_probe_ops; | 
|  |  | 
|  | unregister_ftrace_function_probe_func(glob, ops); | 
|  |  | 
|  | return 0; | 
|  | } | 
|  |  | 
|  | static int | 
|  | ftrace_trace_onoff_callback(char *glob, char *cmd, char *param, int enable) | 
|  | { | 
|  | struct ftrace_probe_ops *ops; | 
|  | void *count = (void *)-1; | 
|  | char *number; | 
|  | int ret; | 
|  |  | 
|  | /* hash funcs only work with set_ftrace_filter */ | 
|  | if (!enable) | 
|  | return -EINVAL; | 
|  |  | 
|  | if (glob[0] == '!') | 
|  | return ftrace_trace_onoff_unreg(glob+1, cmd, param); | 
|  |  | 
|  | /* we register both traceon and traceoff to this callback */ | 
|  | if (strcmp(cmd, "traceon") == 0) | 
|  | ops = &traceon_probe_ops; | 
|  | else | 
|  | ops = &traceoff_probe_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 = strict_strtoul(number, 0, (unsigned long *)&count); | 
|  | if (ret) | 
|  | return ret; | 
|  |  | 
|  | out_reg: | 
|  | ret = register_ftrace_function_probe(glob, ops, count); | 
|  |  | 
|  | return ret < 0 ? ret : 0; | 
|  | } | 
|  |  | 
|  | 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 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) | 
|  | unregister_ftrace_command(&ftrace_traceoff_cmd); | 
|  | return ret; | 
|  | } | 
|  | #else | 
|  | static inline int init_func_cmd_traceon(void) | 
|  | { | 
|  | return 0; | 
|  | } | 
|  | #endif /* CONFIG_DYNAMIC_FTRACE */ | 
|  |  | 
|  | static __init int init_function_trace(void) | 
|  | { | 
|  | init_func_cmd_traceon(); | 
|  | return register_tracer(&function_trace); | 
|  | } | 
|  | device_initcall(init_function_trace); | 
|  |  |