Commit 1427cdf0 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Ingo Molnar
Browse files

tracing: infrastructure for supporting binary record 



Impact: save on memory for tracing

Current tracers are typically using a struct(like struct ftrace_entry,
struct ctx_switch_entry, struct special_entr etc...)to record a binary
event. These structs can only record a their own kind of events.
A new kind of tracer need a new struct and a lot of code too handle it.

So we need a generic binary record for events. This infrastructure
is for this purpose.

[fweisbec@gmail.com: rebase against latest -tip, make it safe while sched
tracing as reported by Steven Rostedt]

Signed-off-by: default avatarLai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 546e5354

include/linux/ftrace.h

+3 −0
Original line number Diff line number Diff line
@@ -223,6 +223,9 @@ extern int ftrace_make_nop(struct module *mod, 
 */

extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);



#ifdef CONFIG_TRACE_BPRINTK

extern int trace_vbprintk(unsigned long ip, const char *fmt, va_list args);

#endif



/* May be defined in arch */

extern int ftrace_arch_read_dyn_info(char *buf, int size);

kernel/trace/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -97,6 +97,12 @@ config FUNCTION_GRAPH_TRACER 
	  This is done by setting the current return address on the current

	  task structure into a stack of calls.



config TRACE_BPRINTK

	bool "Binary printk for tracing"

	default y

	depends on TRACING

	select BINARY_PRINTF



config IRQSOFF_TRACER

	bool "Interrupts-off Latency Tracer"

	default n

kernel/trace/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ obj-$(CONFIG_TRACING) += trace.o 
obj-$(CONFIG_TRACING) += trace_clock.o

obj-$(CONFIG_TRACING) += trace_output.o

obj-$(CONFIG_TRACING) += trace_stat.o

obj-$(CONFIG_TRACE_BPRINTK) += trace_bprintk.o

obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o

obj-$(CONFIG_SYSPROF_TRACER) += trace_sysprof.o

obj-$(CONFIG_FUNCTION_TRACER) += trace_functions.o

kernel/trace/trace.c

+56 −0
Original line number Diff line number Diff line
@@ -3792,6 +3792,62 @@ int __ftrace_vprintk(unsigned long ip, const char *fmt, va_list ap) 
}

EXPORT_SYMBOL_GPL(__ftrace_vprintk);



/**

 * trace_vbprintk - write binary msg to tracing buffer

 *

 * Caller must insure @fmt are valid when msg is in tracing buffer.

 */

int trace_vbprintk(unsigned long ip, const char *fmt, va_list args)

{

	static DEFINE_SPINLOCK(trace_buf_lock);

	static u32 trace_buf[TRACE_BUF_SIZE];



	struct ring_buffer_event *event;

	struct trace_array *tr = &global_trace;

	struct trace_array_cpu *data;

	struct bprintk_entry *entry;

	unsigned long flags;

	int resched;

	int cpu, len = 0, size, pc;



	if (tracing_disabled || !trace_bprintk_enable)

		return 0;



	pc = preempt_count();

	resched = ftrace_preempt_disable();

	cpu = raw_smp_processor_id();

	data = tr->data[cpu];



	if (unlikely(atomic_read(&data->disabled)))

		goto out;



	spin_lock_irqsave(&trace_buf_lock, flags);

	len = vbin_printf(trace_buf, TRACE_BUF_SIZE, fmt, args);



	if (len > TRACE_BUF_SIZE || len < 0)

		goto out_unlock;



	size = sizeof(*entry) + sizeof(u32) * len;

	event = trace_buffer_lock_reserve(tr, TRACE_BPRINTK, size, flags, pc);

	if (!event)

		goto out_unlock;

	entry = ring_buffer_event_data(event);

	entry->ip			= ip;

	entry->fmt			= fmt;



	memcpy(entry->buf, trace_buf, sizeof(u32) * len);

	ring_buffer_unlock_commit(tr->buffer, event);



out_unlock:

	spin_unlock_irqrestore(&trace_buf_lock, flags);



out:

	ftrace_preempt_enable(resched);



	return len;

}

EXPORT_SYMBOL_GPL(trace_vbprintk);



static int trace_panic_handler(struct notifier_block *this,

			       unsigned long event, void *unused)

{

kernel/trace/trace.h

+12 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ enum trace_type { 
	TRACE_WAKE,

	TRACE_STACK,

	TRACE_PRINT,

	TRACE_BPRINTK,

	TRACE_SPECIAL,

	TRACE_MMIO_RW,

	TRACE_MMIO_MAP,
@@ -124,6 +125,16 @@ struct print_entry { 
	char			buf[];

};



struct bprintk_entry {

	struct trace_entry ent;

	unsigned long ip;

	const char *fmt;

	u32 buf[];

};

#ifdef CONFIG_TRACE_BPRINTK

extern int trace_bprintk_enable;

#endif



#define TRACE_OLD_SIZE		88



struct trace_field_cont {
@@ -285,6 +296,7 @@ extern void __ftrace_bad_type(void); 
		IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK);	\

		IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\

		IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT);	\

		IF_ASSIGN(var, ent, struct bprintk_entry, TRACE_BPRINTK);\

		IF_ASSIGN(var, ent, struct special_entry, 0);		\

		IF_ASSIGN(var, ent, struct trace_mmiotrace_rw,		\

			  TRACE_MMIO_RW);				\

CRA Git | Maintained and supported by SUSTech CRA and CCSE