Commit 92a9e4f7 authored by Adrian Hunter's avatar Adrian Hunter Committed by Arnaldo Carvalho de Melo
Browse files

perf tools: Enhance the thread stack to output call/return data 



Enhance the thread stack to output detailed information about paired
calls and returns.

The enhanced processing consumes sample information via
thread_stack__process() and outputs information about paired calls /
returns via a call-back.

While the call-back makes it possible for the facility to be used by
arbitrary tools, a subsequent patch will provide the information to
Python scripting via the db-export interface.

An important part of the call/return information is the
call path which provides a structure that defines a context
sensitive call graph.

Note that there are now two ways to use the thread stack.

For simply providing a call stack (like you would get from the perf
record -g option) the interface consists of thread_stack__event() and
thread_stack__sample().

Whereas the enhanced interface consists of call_return_processor__new()
and thread_stack__process().

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1414678188-14946-5-git-send-email-adrian.hunter@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 00447ccd

tools/perf/util/thread-stack.c

+580 −5
Original line number Diff line number Diff line
@@ -13,23 +13,96 @@ 
 *

 */



#include <linux/rbtree.h>

#include <linux/list.h>

#include "thread.h"

#include "event.h"

#include "machine.h"

#include "util.h"

#include "debug.h"

#include "symbol.h"

#include "comm.h"

#include "thread-stack.h"



#define STACK_GROWTH 4096

#define CALL_PATH_BLOCK_SHIFT 8

#define CALL_PATH_BLOCK_SIZE (1 << CALL_PATH_BLOCK_SHIFT)

#define CALL_PATH_BLOCK_MASK (CALL_PATH_BLOCK_SIZE - 1)



struct call_path_block {

	struct call_path cp[CALL_PATH_BLOCK_SIZE];

	struct list_head node;

};



/**

 * struct call_path_root - root of all call paths.

 * @call_path: root call path

 * @blocks: list of blocks to store call paths

 * @next: next free space

 * @sz: number of spaces

 */

struct call_path_root {

	struct call_path call_path;

	struct list_head blocks;

	size_t next;

	size_t sz;

};



/**

 * struct call_return_processor - provides a call-back to consume call-return

 *                                information.

 * @cpr: call path root

 * @process: call-back that accepts call/return information

 * @data: anonymous data for call-back

 */

struct call_return_processor {

	struct call_path_root *cpr;

	int (*process)(struct call_return *cr, void *data);

	void *data;

};



#define STACK_GROWTH 2048



/**

 * struct thread_stack_entry - thread stack entry.

 * @ret_addr: return address

 * @timestamp: timestamp (if known)

 * @ref: external reference (e.g. db_id of sample)

 * @branch_count: the branch count when the entry was created

 * @cp: call path

 * @no_call: a 'call' was not seen

 */

struct thread_stack_entry {

	u64 ret_addr;

	u64 timestamp;

	u64 ref;

	u64 branch_count;

	struct call_path *cp;

	bool no_call;

};



/**

 * struct thread_stack - thread stack constructed from 'call' and 'return'

 *                       branch samples.

 * @stack: array that holds the stack

 * @cnt: number of entries in the stack

 * @sz: current maximum stack size

 * @trace_nr: current trace number

 * @branch_count: running branch count

 * @kernel_start: kernel start address

 * @last_time: last timestamp

 * @crp: call/return processor

 * @comm: current comm

 */

struct thread_stack {

	struct thread_stack_entry *stack;

	size_t cnt;

	size_t sz;

	u64 trace_nr;

	u64 branch_count;

	u64 kernel_start;

	u64 last_time;

	struct call_return_processor *crp;

	struct comm *comm;

};



static int thread_stack__grow(struct thread_stack *ts)
@@ -50,7 +123,8 @@ static int thread_stack__grow(struct thread_stack *ts) 
	return 0;

}



static struct thread_stack *thread_stack__new(void)

static struct thread_stack *thread_stack__new(struct thread *thread,

					      struct call_return_processor *crp)

{

	struct thread_stack *ts;
@@ -63,6 +137,12 @@ static struct thread_stack *thread_stack__new(void) 
		return NULL;

	}



	if (thread->mg && thread->mg->machine)

		ts->kernel_start = machine__kernel_start(thread->mg->machine);

	else

		ts->kernel_start = 1ULL << 63;

	ts->crp = crp;



	return ts;

}
@@ -104,6 +184,64 @@ static void thread_stack__pop(struct thread_stack *ts, u64 ret_addr) 
	}

}



static bool thread_stack__in_kernel(struct thread_stack *ts)

{

	if (!ts->cnt)

		return false;



	return ts->stack[ts->cnt - 1].cp->in_kernel;

}



static int thread_stack__call_return(struct thread *thread,

				     struct thread_stack *ts, size_t idx,

				     u64 timestamp, u64 ref, bool no_return)

{

	struct call_return_processor *crp = ts->crp;

	struct thread_stack_entry *tse;

	struct call_return cr = {

		.thread = thread,

		.comm = ts->comm,

		.db_id = 0,

	};



	tse = &ts->stack[idx];

	cr.cp = tse->cp;

	cr.call_time = tse->timestamp;

	cr.return_time = timestamp;

	cr.branch_count = ts->branch_count - tse->branch_count;

	cr.call_ref = tse->ref;

	cr.return_ref = ref;

	if (tse->no_call)

		cr.flags |= CALL_RETURN_NO_CALL;

	if (no_return)

		cr.flags |= CALL_RETURN_NO_RETURN;



	return crp->process(&cr, crp->data);

}



static int thread_stack__flush(struct thread *thread, struct thread_stack *ts)

{

	struct call_return_processor *crp = ts->crp;

	int err;



	if (!crp) {

		ts->cnt = 0;

		return 0;

	}



	while (ts->cnt) {

		err = thread_stack__call_return(thread, ts, --ts->cnt,

						ts->last_time, 0, true);

		if (err) {

			pr_err("Error flushing thread stack!\n");

			ts->cnt = 0;

			return err;

		}

	}



	return 0;

}



int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip,

			u64 to_ip, u16 insn_len, u64 trace_nr)

{
@@ -111,7 +249,7 @@ int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip, 
		return -EINVAL;



	if (!thread->ts) {

		thread->ts = thread_stack__new();

		thread->ts = thread_stack__new(thread, NULL);

		if (!thread->ts) {

			pr_warning("Out of memory: no thread stack\n");

			return -ENOMEM;
@@ -122,13 +260,18 @@ int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip, 
	/*

	 * When the trace is discontinuous, the trace_nr changes.  In that case

	 * the stack might be completely invalid.  Better to report nothing than

	 * to report something misleading, so reset the stack count to zero.

	 * to report something misleading, so flush the stack.

	 */

	if (trace_nr != thread->ts->trace_nr) {

		if (thread->ts->trace_nr)

			thread_stack__flush(thread, thread->ts);

		thread->ts->trace_nr = trace_nr;

		thread->ts->cnt = 0;

	}



	/* Stop here if thread_stack__process() is in use */

	if (thread->ts->crp)

		return 0;



	if (flags & PERF_IP_FLAG_CALL) {

		u64 ret_addr;
@@ -147,9 +290,22 @@ int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip, 
	return 0;

}



void thread_stack__set_trace_nr(struct thread *thread, u64 trace_nr)

{

	if (!thread || !thread->ts)

		return;



	if (trace_nr != thread->ts->trace_nr) {

		if (thread->ts->trace_nr)

			thread_stack__flush(thread, thread->ts);

		thread->ts->trace_nr = trace_nr;

	}

}



void thread_stack__free(struct thread *thread)

{

	if (thread->ts) {

		thread_stack__flush(thread, thread->ts);

		zfree(&thread->ts->stack);

		zfree(&thread->ts);

	}
@@ -170,3 +326,422 @@ void thread_stack__sample(struct thread *thread, struct ip_callchain *chain, 
	for (i = 1; i < chain->nr; i++)

		chain->ips[i] = thread->ts->stack[thread->ts->cnt - i].ret_addr;

}



static void call_path__init(struct call_path *cp, struct call_path *parent,

			    struct symbol *sym, u64 ip, bool in_kernel)

{

	cp->parent = parent;

	cp->sym = sym;

	cp->ip = sym ? 0 : ip;

	cp->db_id = 0;

	cp->in_kernel = in_kernel;

	RB_CLEAR_NODE(&cp->rb_node);

	cp->children = RB_ROOT;

}



static struct call_path_root *call_path_root__new(void)

{

	struct call_path_root *cpr;



	cpr = zalloc(sizeof(struct call_path_root));

	if (!cpr)

		return NULL;

	call_path__init(&cpr->call_path, NULL, NULL, 0, false);

	INIT_LIST_HEAD(&cpr->blocks);

	return cpr;

}



static void call_path_root__free(struct call_path_root *cpr)

{

	struct call_path_block *pos, *n;



	list_for_each_entry_safe(pos, n, &cpr->blocks, node) {

		list_del(&pos->node);

		free(pos);

	}

	free(cpr);

}



static struct call_path *call_path__new(struct call_path_root *cpr,

					struct call_path *parent,

					struct symbol *sym, u64 ip,

					bool in_kernel)

{

	struct call_path_block *cpb;

	struct call_path *cp;

	size_t n;



	if (cpr->next < cpr->sz) {

		cpb = list_last_entry(&cpr->blocks, struct call_path_block,

				      node);

	} else {

		cpb = zalloc(sizeof(struct call_path_block));

		if (!cpb)

			return NULL;

		list_add_tail(&cpb->node, &cpr->blocks);

		cpr->sz += CALL_PATH_BLOCK_SIZE;

	}



	n = cpr->next++ & CALL_PATH_BLOCK_MASK;

	cp = &cpb->cp[n];



	call_path__init(cp, parent, sym, ip, in_kernel);



	return cp;

}



static struct call_path *call_path__findnew(struct call_path_root *cpr,

					    struct call_path *parent,

					    struct symbol *sym, u64 ip, u64 ks)

{

	struct rb_node **p;

	struct rb_node *node_parent = NULL;

	struct call_path *cp;

	bool in_kernel = ip >= ks;



	if (sym)

		ip = 0;



	if (!parent)

		return call_path__new(cpr, parent, sym, ip, in_kernel);



	p = &parent->children.rb_node;

	while (*p != NULL) {

		node_parent = *p;

		cp = rb_entry(node_parent, struct call_path, rb_node);



		if (cp->sym == sym && cp->ip == ip)

			return cp;



		if (sym < cp->sym || (sym == cp->sym && ip < cp->ip))

			p = &(*p)->rb_left;

		else

			p = &(*p)->rb_right;

	}



	cp = call_path__new(cpr, parent, sym, ip, in_kernel);

	if (!cp)

		return NULL;



	rb_link_node(&cp->rb_node, node_parent, p);

	rb_insert_color(&cp->rb_node, &parent->children);



	return cp;

}



struct call_return_processor *

call_return_processor__new(int (*process)(struct call_return *cr, void *data),

			   void *data)

{

	struct call_return_processor *crp;



	crp = zalloc(sizeof(struct call_return_processor));

	if (!crp)

		return NULL;

	crp->cpr = call_path_root__new();

	if (!crp->cpr)

		goto out_free;

	crp->process = process;

	crp->data = data;

	return crp;



out_free:

	free(crp);

	return NULL;

}



void call_return_processor__free(struct call_return_processor *crp)

{

	if (crp) {

		call_path_root__free(crp->cpr);

		free(crp);

	}

}



static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr,

				 u64 timestamp, u64 ref, struct call_path *cp,

				 bool no_call)

{

	struct thread_stack_entry *tse;

	int err;



	if (ts->cnt == ts->sz) {

		err = thread_stack__grow(ts);

		if (err)

			return err;

	}



	tse = &ts->stack[ts->cnt++];

	tse->ret_addr = ret_addr;

	tse->timestamp = timestamp;

	tse->ref = ref;

	tse->branch_count = ts->branch_count;

	tse->cp = cp;

	tse->no_call = no_call;



	return 0;

}



static int thread_stack__pop_cp(struct thread *thread, struct thread_stack *ts,

				u64 ret_addr, u64 timestamp, u64 ref,

				struct symbol *sym)

{

	int err;



	if (!ts->cnt)

		return 1;



	if (ts->cnt == 1) {

		struct thread_stack_entry *tse = &ts->stack[0];



		if (tse->cp->sym == sym)

			return thread_stack__call_return(thread, ts, --ts->cnt,

							 timestamp, ref, false);

	}



	if (ts->stack[ts->cnt - 1].ret_addr == ret_addr) {

		return thread_stack__call_return(thread, ts, --ts->cnt,

						 timestamp, ref, false);

	} else {

		size_t i = ts->cnt - 1;



		while (i--) {

			if (ts->stack[i].ret_addr != ret_addr)

				continue;

			i += 1;

			while (ts->cnt > i) {

				err = thread_stack__call_return(thread, ts,

								--ts->cnt,

								timestamp, ref,

								true);

				if (err)

					return err;

			}

			return thread_stack__call_return(thread, ts, --ts->cnt,

							 timestamp, ref, false);

		}

	}



	return 1;

}



static int thread_stack__bottom(struct thread *thread, struct thread_stack *ts,

				struct perf_sample *sample,

				struct addr_location *from_al,

				struct addr_location *to_al, u64 ref)

{

	struct call_path_root *cpr = ts->crp->cpr;

	struct call_path *cp;

	struct symbol *sym;

	u64 ip;



	if (sample->ip) {

		ip = sample->ip;

		sym = from_al->sym;

	} else if (sample->addr) {

		ip = sample->addr;

		sym = to_al->sym;

	} else {

		return 0;

	}



	cp = call_path__findnew(cpr, &cpr->call_path, sym, ip,

				ts->kernel_start);

	if (!cp)

		return -ENOMEM;



	return thread_stack__push_cp(thread->ts, ip, sample->time, ref, cp,

				     true);

}



static int thread_stack__no_call_return(struct thread *thread,

					struct thread_stack *ts,

					struct perf_sample *sample,

					struct addr_location *from_al,

					struct addr_location *to_al, u64 ref)

{

	struct call_path_root *cpr = ts->crp->cpr;

	struct call_path *cp, *parent;

	u64 ks = ts->kernel_start;

	int err;



	if (sample->ip >= ks && sample->addr < ks) {

		/* Return to userspace, so pop all kernel addresses */

		while (thread_stack__in_kernel(ts)) {

			err = thread_stack__call_return(thread, ts, --ts->cnt,

							sample->time, ref,

							true);

			if (err)

				return err;

		}



		/* If the stack is empty, push the userspace address */

		if (!ts->cnt) {

			cp = call_path__findnew(cpr, &cpr->call_path,

						to_al->sym, sample->addr,

						ts->kernel_start);

			if (!cp)

				return -ENOMEM;

			return thread_stack__push_cp(ts, 0, sample->time, ref,

						     cp, true);

		}

	} else if (thread_stack__in_kernel(ts) && sample->ip < ks) {

		/* Return to userspace, so pop all kernel addresses */

		while (thread_stack__in_kernel(ts)) {

			err = thread_stack__call_return(thread, ts, --ts->cnt,

							sample->time, ref,

							true);

			if (err)

				return err;

		}

	}



	if (ts->cnt)

		parent = ts->stack[ts->cnt - 1].cp;

	else

		parent = &cpr->call_path;



	/* This 'return' had no 'call', so push and pop top of stack */

	cp = call_path__findnew(cpr, parent, from_al->sym, sample->ip,

				ts->kernel_start);

	if (!cp)

		return -ENOMEM;



	err = thread_stack__push_cp(ts, sample->addr, sample->time, ref, cp,

				    true);

	if (err)

		return err;



	return thread_stack__pop_cp(thread, ts, sample->addr, sample->time, ref,

				    to_al->sym);

}



static int thread_stack__trace_begin(struct thread *thread,

				     struct thread_stack *ts, u64 timestamp,

				     u64 ref)

{

	struct thread_stack_entry *tse;

	int err;



	if (!ts->cnt)

		return 0;



	/* Pop trace end */

	tse = &ts->stack[ts->cnt - 1];

	if (tse->cp->sym == NULL && tse->cp->ip == 0) {

		err = thread_stack__call_return(thread, ts, --ts->cnt,

						timestamp, ref, false);

		if (err)

			return err;

	}



	return 0;

}



static int thread_stack__trace_end(struct thread_stack *ts,

				   struct perf_sample *sample, u64 ref)

{

	struct call_path_root *cpr = ts->crp->cpr;

	struct call_path *cp;

	u64 ret_addr;



	/* No point having 'trace end' on the bottom of the stack */

	if (!ts->cnt || (ts->cnt == 1 && ts->stack[0].ref == ref))

		return 0;



	cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp, NULL, 0,

				ts->kernel_start);

	if (!cp)

		return -ENOMEM;



	ret_addr = sample->ip + sample->insn_len;



	return thread_stack__push_cp(ts, ret_addr, sample->time, ref, cp,

				     false);

}



int thread_stack__process(struct thread *thread, struct comm *comm,

			  struct perf_sample *sample,

			  struct addr_location *from_al,

			  struct addr_location *to_al, u64 ref,

			  struct call_return_processor *crp)

{

	struct thread_stack *ts = thread->ts;

	int err = 0;



	if (ts) {

		if (!ts->crp) {

			/* Supersede thread_stack__event() */

			thread_stack__free(thread);

			thread->ts = thread_stack__new(thread, crp);

			if (!thread->ts)

				return -ENOMEM;

			ts = thread->ts;

			ts->comm = comm;

		}

	} else {

		thread->ts = thread_stack__new(thread, crp);

		if (!thread->ts)

			return -ENOMEM;

		ts = thread->ts;

		ts->comm = comm;

	}



	/* Flush stack on exec */

	if (ts->comm != comm && thread->pid_ == thread->tid) {

		err = thread_stack__flush(thread, ts);

		if (err)

			return err;

		ts->comm = comm;

	}



	/* If the stack is empty, put the current symbol on the stack */

	if (!ts->cnt) {

		err = thread_stack__bottom(thread, ts, sample, from_al, to_al,

					   ref);

		if (err)

			return err;

	}



	ts->branch_count += 1;

	ts->last_time = sample->time;



	if (sample->flags & PERF_IP_FLAG_CALL) {

		struct call_path_root *cpr = ts->crp->cpr;

		struct call_path *cp;

		u64 ret_addr;



		if (!sample->ip || !sample->addr)

			return 0;



		ret_addr = sample->ip + sample->insn_len;

		if (ret_addr == sample->addr)

			return 0; /* Zero-length calls are excluded */



		cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp,

					to_al->sym, sample->addr,

					ts->kernel_start);

		if (!cp)

			return -ENOMEM;

		err = thread_stack__push_cp(ts, ret_addr, sample->time, ref,

					    cp, false);

	} else if (sample->flags & PERF_IP_FLAG_RETURN) {

		if (!sample->ip || !sample->addr)

			return 0;



		err = thread_stack__pop_cp(thread, ts, sample->addr,

					   sample->time, ref, from_al->sym);

		if (err) {

			if (err < 0)

				return err;

			err = thread_stack__no_call_return(thread, ts, sample,

							   from_al, to_al, ref);

		}

	} else if (sample->flags & PERF_IP_FLAG_TRACE_BEGIN) {

		err = thread_stack__trace_begin(thread, ts, sample->time, ref);

	} else if (sample->flags & PERF_IP_FLAG_TRACE_END) {

		err = thread_stack__trace_end(ts, sample, ref);

	}



	return err;

}

tools/perf/util/thread-stack.h

+79 −0
Original line number Diff line number Diff line
@@ -19,14 +19,93 @@ 
#include <sys/types.h>



#include <linux/types.h>

#include <linux/rbtree.h>



struct thread;

struct comm;

struct ip_callchain;

struct symbol;

struct dso;

struct call_return_processor;

struct comm;

struct perf_sample;

struct addr_location;



/*

 * Call/Return flags.

 *

 * CALL_RETURN_NO_CALL: 'return' but no matching 'call'

 * CALL_RETURN_NO_RETURN: 'call' but no matching 'return'

 */

enum {

	CALL_RETURN_NO_CALL	= 1 << 0,

	CALL_RETURN_NO_RETURN	= 1 << 1,

};



/**

 * struct call_return - paired call/return information.

 * @thread: thread in which call/return occurred

 * @comm: comm in which call/return occurred

 * @cp: call path

 * @call_time: timestamp of call (if known)

 * @return_time: timestamp of return (if known)

 * @branch_count: number of branches seen between call and return

 * @call_ref: external reference to 'call' sample (e.g. db_id)

 * @return_ref:  external reference to 'return' sample (e.g. db_id)

 * @db_id: id used for db-export

 * @flags: Call/Return flags

 */

struct call_return {

	struct thread *thread;

	struct comm *comm;

	struct call_path *cp;

	u64 call_time;

	u64 return_time;

	u64 branch_count;

	u64 call_ref;

	u64 return_ref;

	u64 db_id;

	u32 flags;

};



/**

 * struct call_path - node in list of calls leading to a function call.

 * @parent: call path to the parent function call

 * @sym: symbol of function called

 * @ip: only if sym is null, the ip of the function

 * @db_id: id used for db-export

 * @in_kernel: whether function is a in the kernel

 * @rb_node: node in parent's tree of called functions

 * @children: tree of call paths of functions called

 *

 * In combination with the call_return structure, the call_path structure

 * defines a context-sensitve call-graph.

 */

struct call_path {

	struct call_path *parent;

	struct symbol *sym;

	u64 ip;

	u64 db_id;

	bool in_kernel;

	struct rb_node rb_node;

	struct rb_root children;

};



int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip,

			u64 to_ip, u16 insn_len, u64 trace_nr);

void thread_stack__set_trace_nr(struct thread *thread, u64 trace_nr);

void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,

			  size_t sz, u64 ip);

void thread_stack__free(struct thread *thread);



struct call_return_processor *

call_return_processor__new(int (*process)(struct call_return *cr, void *data),

			   void *data);

void call_return_processor__free(struct call_return_processor *crp);

int thread_stack__process(struct thread *thread, struct comm *comm,

			  struct perf_sample *sample,

			  struct addr_location *from_al,

			  struct addr_location *to_al, u64 ref,

			  struct call_return_processor *crp);



#endif

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