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-rw-r--r--kernel/trace/Kconfig14
-rw-r--r--kernel/trace/Makefile1
-rw-r--r--kernel/trace/ftrace.c16
-rw-r--r--kernel/trace/trace.c65
-rw-r--r--kernel/trace/trace.h35
-rw-r--r--kernel/trace/trace_functions_return.c82
6 files changed, 205 insertions, 8 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index fc4febc3334a..d986216c8327 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -9,6 +9,9 @@ config NOP_TRACER
config HAVE_FUNCTION_TRACER
bool
+config HAVE_FUNCTION_RET_TRACER
+ bool
+
config HAVE_FUNCTION_TRACE_MCOUNT_TEST
bool
help
@@ -54,6 +57,17 @@ config FUNCTION_TRACER
(the bootup default), then the overhead of the instructions is very
small and not measurable even in micro-benchmarks.
+config FUNCTION_RET_TRACER
+ bool "Kernel Function return Tracer"
+ depends on !DYNAMIC_FTRACE
+ depends on HAVE_FUNCTION_RET_TRACER
+ depends on FUNCTION_TRACER
+ help
+ Enable the kernel to trace a function at its return.
+ It's first purpose is to trace the duration of functions.
+ This is done by setting the current return address on the thread
+ info structure of the current task.
+
config IRQSOFF_TRACER
bool "Interrupts-off Latency Tracer"
default n
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index c8228b1a49e9..3e1f361bbc17 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -24,5 +24,6 @@ obj-$(CONFIG_NOP_TRACER) += trace_nop.o
obj-$(CONFIG_STACK_TRACER) += trace_stack.o
obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o
obj-$(CONFIG_BOOT_TRACER) += trace_boot.o
+obj-$(CONFIG_FUNCTION_RET_TRACER) += trace_functions_return.o
libftrace-y := ftrace.o
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 4d2e751bfb11..f03fe74ecd67 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1484,3 +1484,19 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
return ret;
}
+#ifdef CONFIG_FUNCTION_RET_TRACER
+trace_function_return_t ftrace_function_return =
+ (trace_function_return_t)ftrace_stub;
+void register_ftrace_return(trace_function_return_t func)
+{
+ ftrace_function_return = func;
+}
+
+void unregister_ftrace_return(void)
+{
+ ftrace_function_return = (trace_function_return_t)ftrace_stub;
+}
+#endif
+
+
+
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 216bbe7547a4..a3f7ae9cd8e1 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -244,13 +244,6 @@ unsigned long nsecs_to_usecs(unsigned long nsecs)
return nsecs / 1000;
}
-/*
- * TRACE_ITER_SYM_MASK masks the options in trace_flags that
- * control the output of kernel symbols.
- */
-#define TRACE_ITER_SYM_MASK \
- (TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)
-
/* These must match the bit postions in trace_iterator_flags */
static const char *trace_options[] = {
"print-parent",
@@ -810,6 +803,35 @@ trace_function(struct trace_array *tr, struct trace_array_cpu *data,
ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
}
+#ifdef CONFIG_FUNCTION_RET_TRACER
+static void __trace_function_return(struct trace_array *tr,
+ struct trace_array_cpu *data,
+ struct ftrace_retfunc *trace,
+ unsigned long flags,
+ int pc)
+{
+ struct ring_buffer_event *event;
+ struct ftrace_ret_entry *entry;
+ unsigned long irq_flags;
+
+ if (unlikely(local_read(&__get_cpu_var(ftrace_cpu_disabled))))
+ return;
+
+ event = ring_buffer_lock_reserve(global_trace.buffer, sizeof(*entry),
+ &irq_flags);
+ if (!event)
+ return;
+ entry = ring_buffer_event_data(event);
+ tracing_generic_entry_update(&entry->ent, flags, pc);
+ entry->ent.type = TRACE_FN_RET;
+ entry->ip = trace->func;
+ entry->parent_ip = trace->ret;
+ entry->rettime = trace->rettime;
+ entry->calltime = trace->calltime;
+ ring_buffer_unlock_commit(global_trace.buffer, event, irq_flags);
+}
+#endif
+
void
ftrace(struct trace_array *tr, struct trace_array_cpu *data,
unsigned long ip, unsigned long parent_ip, unsigned long flags,
@@ -1038,6 +1060,29 @@ function_trace_call(unsigned long ip, unsigned long parent_ip)
raw_local_irq_restore(flags);
}
+#ifdef CONFIG_FUNCTION_RET_TRACER
+void trace_function_return(struct ftrace_retfunc *trace)
+{
+ struct trace_array *tr = &global_trace;
+ struct trace_array_cpu *data;
+ unsigned long flags;
+ long disabled;
+ int cpu;
+ int pc;
+
+ raw_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_return(tr, data, trace, flags, pc);
+ }
+ atomic_dec(&data->disabled);
+ raw_local_irq_restore(flags);
+}
+#endif /* CONFIG_FUNCTION_RET_TRACER */
+
static struct ftrace_ops trace_ops __read_mostly =
{
.func = function_trace_call,
@@ -1285,7 +1330,7 @@ seq_print_sym_offset(struct trace_seq *s, const char *fmt,
# define IP_FMT "%016lx"
#endif
-static int
+int
seq_print_ip_sym(struct trace_seq *s, unsigned long ip, unsigned long sym_flags)
{
int ret;
@@ -1738,6 +1783,10 @@ static enum print_line_t print_trace_fmt(struct trace_iterator *iter)
trace_seq_print_cont(s, iter);
break;
}
+ case TRACE_FN_RET: {
+ return print_return_function(iter);
+ break;
+ }
}
return TRACE_TYPE_HANDLED;
}
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 978145088fb8..e40ce0c14690 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -22,6 +22,7 @@ enum trace_type {
TRACE_MMIO_RW,
TRACE_MMIO_MAP,
TRACE_BOOT,
+ TRACE_FN_RET,
__TRACE_LAST_TYPE
};
@@ -48,6 +49,15 @@ struct ftrace_entry {
unsigned long ip;
unsigned long parent_ip;
};
+
+/* Function return entry */
+struct ftrace_ret_entry {
+ struct trace_entry ent;
+ unsigned long ip;
+ unsigned long parent_ip;
+ unsigned long long calltime;
+ unsigned long long rettime;
+};
extern struct tracer boot_tracer;
/*
@@ -218,6 +228,7 @@ extern void __ftrace_bad_type(void);
IF_ASSIGN(var, ent, struct trace_mmiotrace_map, \
TRACE_MMIO_MAP); \
IF_ASSIGN(var, ent, struct trace_boot, TRACE_BOOT); \
+ IF_ASSIGN(var, ent, struct ftrace_ret_entry, TRACE_FN_RET); \
__ftrace_bad_type(); \
} while (0)
@@ -321,6 +332,8 @@ void trace_function(struct trace_array *tr,
unsigned long ip,
unsigned long parent_ip,
unsigned long flags, int pc);
+void
+trace_function_return(struct ftrace_retfunc *trace);
void tracing_start_cmdline_record(void);
void tracing_stop_cmdline_record(void);
@@ -393,6 +406,10 @@ extern void *head_page(struct trace_array_cpu *data);
extern int trace_seq_printf(struct trace_seq *s, const char *fmt, ...);
extern void trace_seq_print_cont(struct trace_seq *s,
struct trace_iterator *iter);
+
+extern int
+seq_print_ip_sym(struct trace_seq *s, unsigned long ip,
+ unsigned long sym_flags);
extern ssize_t trace_seq_to_user(struct trace_seq *s, char __user *ubuf,
size_t cnt);
extern long ns2usecs(cycle_t nsec);
@@ -400,6 +417,17 @@ extern int trace_vprintk(unsigned long ip, const char *fmt, va_list args);
extern unsigned long trace_flags;
+/* Standard output formatting function used for function return traces */
+#ifdef CONFIG_FUNCTION_RET_TRACER
+extern enum print_line_t print_return_function(struct trace_iterator *iter);
+#else
+static inline enum print_line_t
+print_return_function(struct trace_iterator *iter)
+{
+ return TRACE_TYPE_UNHANDLED;
+}
+#endif
+
/*
* trace_iterator_flags is an enumeration that defines bit
* positions into trace_flags that controls the output.
@@ -422,6 +450,13 @@ enum trace_iterator_flags {
TRACE_ITER_PREEMPTONLY = 0x800,
};
+/*
+ * TRACE_ITER_SYM_MASK masks the options in trace_flags that
+ * control the output of kernel symbols.
+ */
+#define TRACE_ITER_SYM_MASK \
+ (TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)
+
extern struct tracer nop_trace;
/**
diff --git a/kernel/trace/trace_functions_return.c b/kernel/trace/trace_functions_return.c
new file mode 100644
index 000000000000..7680b21537dd
--- /dev/null
+++ b/kernel/trace/trace_functions_return.c
@@ -0,0 +1,82 @@
+/*
+ *
+ * Function return tracer.
+ * Copyright (c) 2008 Frederic Weisbecker <fweisbec@gmail.com>
+ * Mostly borrowed from function tracer which
+ * is Copyright (c) Steven Rostedt <srostedt@redhat.com>
+ *
+ */
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/ftrace.h>
+#include <linux/fs.h>
+
+#include "trace.h"
+
+
+static void start_return_trace(struct trace_array *tr)
+{
+ register_ftrace_return(&trace_function_return);
+}
+
+static void stop_return_trace(struct trace_array *tr)
+{
+ unregister_ftrace_return();
+}
+
+static void return_trace_init(struct trace_array *tr)
+{
+ int cpu;
+ for_each_online_cpu(cpu)
+ tracing_reset(tr, cpu);
+
+ start_return_trace(tr);
+}
+
+static void return_trace_reset(struct trace_array *tr)
+{
+ stop_return_trace(tr);
+}
+
+
+enum print_line_t
+print_return_function(struct trace_iterator *iter)
+{
+ struct trace_seq *s = &iter->seq;
+ struct trace_entry *entry = iter->ent;
+ struct ftrace_ret_entry *field;
+ int ret;
+
+ if (entry->type == TRACE_FN_RET) {
+ trace_assign_type(field, entry);
+ ret = trace_seq_printf(s, "%pF -> ", (void *)field->parent_ip);
+ if (!ret)
+ return TRACE_TYPE_PARTIAL_LINE;
+ ret = seq_print_ip_sym(s, field->ip,
+ trace_flags & TRACE_ITER_SYM_MASK);
+ if (!ret)
+ return TRACE_TYPE_PARTIAL_LINE;
+ ret = trace_seq_printf(s, " (%llu ns)\n",
+ field->rettime - field->calltime);
+ if (!ret)
+ return TRACE_TYPE_PARTIAL_LINE;
+ else
+ return TRACE_TYPE_HANDLED;
+ }
+ return TRACE_TYPE_UNHANDLED;
+}
+
+static struct tracer return_trace __read_mostly =
+{
+ .name = "return",
+ .init = return_trace_init,
+ .reset = return_trace_reset,
+ .print_line = print_return_function
+};
+
+static __init int init_return_trace(void)
+{
+ return register_tracer(&return_trace);
+}
+
+device_initcall(init_return_trace);