diff options
| -rw-r--r-- | kernel/trace/Kconfig | 13 | ||||
| -rw-r--r-- | kernel/trace/Makefile | 1 | ||||
| -rw-r--r-- | kernel/trace/trace_functions.c | 73 |
3 files changed, 87 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index ce70677afbf9..1399f372b5dc 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -8,3 +8,16 @@ config TRACING bool select DEBUG_FS +config FTRACE + bool "Kernel Function Tracer" + depends on DEBUG_KERNEL && HAVE_FTRACE + select FRAME_POINTER + select TRACING + help + Enable the kernel to trace every kernel function. This is done + by using a compiler feature to insert a small, 5-byte No-Operation + instruction to the beginning of every kernel function, which NOP + sequence is then dynamically patched into a tracer call when + tracing is enabled by the administrator. If it's runtime disabled + (the bootup default), then the overhead of the instructions is very + small and not measurable even in micro-benchmarks. diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 7af403175255..6bb5e50b4a40 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -1,5 +1,6 @@ obj-$(CONFIG_FTRACE) += libftrace.o obj-$(CONFIG_TRACING) += trace.o +obj-$(CONFIG_FTRACE) += trace_functions.o libftrace-y := ftrace.o diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c new file mode 100644 index 000000000000..82988c5336e0 --- /dev/null +++ b/kernel/trace/trace_functions.c @@ -0,0 +1,73 @@ +/* + * 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/fs.h> +#include <linux/debugfs.h> +#include <linux/uaccess.h> +#include <linux/ftrace.h> + +#include "trace.h" + +static notrace void function_reset(struct trace_array *tr) +{ + int cpu; + + tr->time_start = now(tr->cpu); + + for_each_online_cpu(cpu) + tracing_reset(tr->data[cpu]); +} + +static notrace void start_function_trace(struct trace_array *tr) +{ + function_reset(tr); + tracing_start_function_trace(); +} + +static notrace void stop_function_trace(struct trace_array *tr) +{ + tracing_stop_function_trace(); +} + +static notrace void function_trace_init(struct trace_array *tr) +{ + if (tr->ctrl) + start_function_trace(tr); +} + +static notrace void function_trace_reset(struct trace_array *tr) +{ + if (tr->ctrl) + stop_function_trace(tr); +} + +static notrace void function_trace_ctrl_update(struct trace_array *tr) +{ + if (tr->ctrl) + start_function_trace(tr); + else + stop_function_trace(tr); +} + +static struct tracer function_trace __read_mostly = +{ + .name = "ftrace", + .init = function_trace_init, + .reset = function_trace_reset, + .ctrl_update = function_trace_ctrl_update, +}; + +static __init int init_function_trace(void) +{ + return register_tracer(&function_trace); +} + +device_initcall(init_function_trace); |