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Commit 86387f7e authored by Ingo Molnar's avatar Ingo Molnar Committed by Thomas Gleixner
Browse files

ftrace: add stack tracing 



Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 57422797

include/linux/ftrace.h

+2 −0
Original line number Diff line number Diff line
@@ -93,6 +93,7 @@ static inline void tracer_disable(void) 
# define CALLER_ADDR3 ((unsigned long)__builtin_return_address(3))

# define CALLER_ADDR4 ((unsigned long)__builtin_return_address(4))

# define CALLER_ADDR5 ((unsigned long)__builtin_return_address(5))

# define CALLER_ADDR6 ((unsigned long)__builtin_return_address(6))

#else

# define CALLER_ADDR0 ((unsigned long)__builtin_return_address(0))

# define CALLER_ADDR1 0UL
@@ -100,6 +101,7 @@ static inline void tracer_disable(void) 
# define CALLER_ADDR3 0UL

# define CALLER_ADDR4 0UL

# define CALLER_ADDR5 0UL

# define CALLER_ADDR6 0UL

#endif



#ifdef CONFIG_IRQSOFF_TRACER

kernel/trace/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ config TRACER_MAX_TRACE 
config TRACING

	bool

	select DEBUG_FS

	select STACKTRACE



config FTRACE

	bool "Kernel Function Tracer"

kernel/trace/trace.c

+85 −18
Original line number Diff line number Diff line
@@ -28,6 +28,8 @@ 
#include <linux/gfp.h>

#include <linux/fs.h>



#include <linux/stacktrace.h>



#include "trace.h"



unsigned long __read_mostly	tracing_max_latency = (cycle_t)ULONG_MAX;
@@ -88,6 +90,7 @@ enum trace_type { 
	TRACE_FN,

	TRACE_CTX,

	TRACE_WAKE,

	TRACE_STACK,

	TRACE_SPECIAL,



	__TRACE_LAST_TYPE
@@ -109,6 +112,7 @@ enum trace_iterator_flags { 
	TRACE_ITER_HEX			= 0x20,

	TRACE_ITER_BIN			= 0x40,

	TRACE_ITER_BLOCK		= 0x80,

	TRACE_ITER_STACKTRACE		= 0x100,

};



#define TRACE_ITER_SYM_MASK \
@@ -124,10 +128,11 @@ static const char *trace_options[] = { 
	"hex",

	"bin",

	"block",

	"stacktrace",

	NULL

};



static unsigned trace_flags;

static unsigned trace_flags = TRACE_ITER_PRINT_PARENT | TRACE_ITER_STACKTRACE;



static DEFINE_SPINLOCK(ftrace_max_lock);
@@ -688,10 +693,36 @@ trace_special(struct trace_array *tr, struct trace_array_cpu *data, 
		wake_up(&trace_wait);

}



void __trace_stack(struct trace_array *tr,

		   struct trace_array_cpu *data,

		   unsigned long flags,

		   int skip)

{

	struct trace_entry *entry;

	struct stack_trace trace;



	if (!(trace_flags & TRACE_ITER_STACKTRACE))

		return;



	entry			= tracing_get_trace_entry(tr, data);

	tracing_generic_entry_update(entry, flags);

	entry->type		= TRACE_STACK;



	memset(&entry->stack, 0, sizeof(entry->stack));



	trace.nr_entries	= 0;

	trace.max_entries	= FTRACE_STACK_ENTRIES;

	trace.skip		= skip;

	trace.entries		= entry->stack.caller;



	save_stack_trace(&trace);

}



void

tracing_sched_switch_trace(struct trace_array *tr,

			   struct trace_array_cpu *data,

			   struct task_struct *prev, struct task_struct *next,

			   struct task_struct *prev,

			   struct task_struct *next,

			   unsigned long flags)

{

	struct trace_entry *entry;
@@ -706,6 +737,7 @@ tracing_sched_switch_trace(struct trace_array *tr, 
	entry->ctx.prev_state	= prev->state;

	entry->ctx.next_pid	= next->pid;

	entry->ctx.next_prio	= next->prio;

	__trace_stack(tr, data, flags, 4);

	spin_unlock_irqrestore(&data->lock, irq_flags);



	if (!(trace_flags & TRACE_ITER_BLOCK))
@@ -715,7 +747,8 @@ tracing_sched_switch_trace(struct trace_array *tr, 
void

tracing_sched_wakeup_trace(struct trace_array *tr,

			   struct trace_array_cpu *data,

			   struct task_struct *wakee, struct task_struct *curr,

			   struct task_struct *wakee,

			   struct task_struct *curr,

			   unsigned long flags)

{

	struct trace_entry *entry;
@@ -730,6 +763,7 @@ tracing_sched_wakeup_trace(struct trace_array *tr, 
	entry->ctx.prev_state	= curr->state;

	entry->ctx.next_pid	= wakee->pid;

	entry->ctx.next_prio	= wakee->prio;

	__trace_stack(tr, data, flags, 5);

	spin_unlock_irqrestore(&data->lock, irq_flags);



	if (!(trace_flags & TRACE_ITER_BLOCK))
@@ -1179,6 +1213,7 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu) 
	unsigned long rel_usecs;

	char *comm;

	int S;

	int i;



	if (!next_entry)

		next_entry = entry;
@@ -1197,9 +1232,11 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu) 
				 abs_usecs % 1000, rel_usecs/1000,

				 rel_usecs % 1000);

	} else {

		if (entry->type != TRACE_STACK) {

			lat_print_generic(s, entry, cpu);

			lat_print_timestamp(s, abs_usecs, rel_usecs);

		}

	}

	switch (entry->type) {

	case TRACE_FN:

		seq_print_ip_sym(s, entry->fn.ip, sym_flags);
@@ -1226,6 +1263,14 @@ print_lat_fmt(struct trace_iterator *iter, unsigned int trace_idx, int cpu) 
				 entry->special.arg2,

				 entry->special.arg3);

		break;

	case TRACE_STACK:

		for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {

			if (i)

				trace_seq_puts(s, " <= ");

			seq_print_ip_sym(s, entry->stack.caller[i], sym_flags);

		}

		trace_seq_puts(s, "\n");

		break;

	default:

		trace_seq_printf(s, "Unknown type %d\n", entry->type);

	}
@@ -1241,8 +1286,9 @@ static int print_trace_fmt(struct trace_iterator *iter) 
	unsigned long long t;

	unsigned long secs;

	char *comm;

	int S;

	int ret;

	int S;

	int i;



	entry = iter->ent;
@@ -1252,6 +1298,7 @@ static int print_trace_fmt(struct trace_iterator *iter) 
	usec_rem = do_div(t, 1000000ULL);

	secs = (unsigned long)t;



	if (entry->type != TRACE_STACK) {

		ret = trace_seq_printf(s, "%16s-%-5d ", comm, entry->pid);

		if (!ret)

			return 0;
@@ -1261,6 +1308,7 @@ static int print_trace_fmt(struct trace_iterator *iter) 
		ret = trace_seq_printf(s, "%5lu.%06lu: ", secs, usec_rem);

		if (!ret)

			return 0;

	}



	switch (entry->type) {

	case TRACE_FN:
@@ -1303,6 +1351,22 @@ static int print_trace_fmt(struct trace_iterator *iter) 
		if (!ret)

			return 0;

		break;

	case TRACE_STACK:

		for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {

			if (i) {

				ret = trace_seq_puts(s, " <= ");

				if (!ret)

					return 0;

			}

			ret = seq_print_ip_sym(s, entry->stack.caller[i],

					       sym_flags);

			if (!ret)

				return 0;

		}

		ret = trace_seq_puts(s, "\n");

		if (!ret)

			return 0;

		break;

	}

	return 1;

}
@@ -1344,6 +1408,7 @@ static int print_raw_fmt(struct trace_iterator *iter) 
			return 0;

		break;

	case TRACE_SPECIAL:

	case TRACE_STACK:

		ret = trace_seq_printf(s, " %lx %lx %lx\n",

				 entry->special.arg1,

				 entry->special.arg2,
@@ -1399,6 +1464,7 @@ static int print_hex_fmt(struct trace_iterator *iter) 
		SEQ_PUT_HEX_FIELD_RET(s, entry->fn.parent_ip);

		break;

	case TRACE_SPECIAL:

	case TRACE_STACK:

		SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg1);

		SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg2);

		SEQ_PUT_HEX_FIELD_RET(s, entry->special.arg3);
@@ -1433,6 +1499,7 @@ static int print_bin_fmt(struct trace_iterator *iter) 
		SEQ_PUT_FIELD_RET(s, entry->ctx.next_prio);

		break;

	case TRACE_SPECIAL:

	case TRACE_STACK:

		SEQ_PUT_FIELD_RET(s, entry->special.arg1);

		SEQ_PUT_FIELD_RET(s, entry->special.arg2);

		SEQ_PUT_FIELD_RET(s, entry->special.arg3);

kernel/trace/trace.h

+11 −0
Original line number Diff line number Diff line
@@ -34,6 +34,16 @@ struct special_entry { 
	unsigned long		arg3;

};



/*

 * Stack-trace entry:

 */



#define FTRACE_STACK_ENTRIES	5



struct stack_entry {

	unsigned long		caller[FTRACE_STACK_ENTRIES];

};



/*

 * The trace entry - the most basic unit of tracing. This is what

 * is printed in the end as a single line in the trace output, such as:
@@ -51,6 +61,7 @@ struct trace_entry { 
		struct ftrace_entry		fn;

		struct ctx_switch_entry		ctx;

		struct special_entry		special;

		struct stack_entry		stack;

	};

};