/* * 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(struct ftrace_hash *hash, 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);