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linux-next/tools/perf/util/thread-stack.c
Adrian Hunter 92a9e4f7db 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: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Jiri 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: Arnaldo Carvalho de Melo <acme@redhat.com>
2014-11-03 17:43:56 -03:00

748 lines
17 KiB
C

/*
* thread-stack.c: Synthesize a thread's stack using call / return events
* Copyright (c) 2014, Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
*/
#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 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)
{
struct thread_stack_entry *new_stack;
size_t sz, new_sz;
new_sz = ts->sz + STACK_GROWTH;
sz = new_sz * sizeof(struct thread_stack_entry);
new_stack = realloc(ts->stack, sz);
if (!new_stack)
return -ENOMEM;
ts->stack = new_stack;
ts->sz = new_sz;
return 0;
}
static struct thread_stack *thread_stack__new(struct thread *thread,
struct call_return_processor *crp)
{
struct thread_stack *ts;
ts = zalloc(sizeof(struct thread_stack));
if (!ts)
return NULL;
if (thread_stack__grow(ts)) {
free(ts);
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;
}
static int thread_stack__push(struct thread_stack *ts, u64 ret_addr)
{
int err = 0;
if (ts->cnt == ts->sz) {
err = thread_stack__grow(ts);
if (err) {
pr_warning("Out of memory: discarding thread stack\n");
ts->cnt = 0;
}
}
ts->stack[ts->cnt++].ret_addr = ret_addr;
return err;
}
static void thread_stack__pop(struct thread_stack *ts, u64 ret_addr)
{
size_t i;
/*
* In some cases there may be functions which are not seen to return.
* For example when setjmp / longjmp has been used. Or the perf context
* switch in the kernel which doesn't stop and start tracing in exactly
* the same code path. When that happens the return address will be
* further down the stack. If the return address is not found at all,
* we assume the opposite (i.e. this is a return for a call that wasn't
* seen for some reason) and leave the stack alone.
*/
for (i = ts->cnt; i; ) {
if (ts->stack[--i].ret_addr == ret_addr) {
ts->cnt = i;
return;
}
}
}
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)
{
if (!thread)
return -EINVAL;
if (!thread->ts) {
thread->ts = thread_stack__new(thread, NULL);
if (!thread->ts) {
pr_warning("Out of memory: no thread stack\n");
return -ENOMEM;
}
thread->ts->trace_nr = trace_nr;
}
/*
* 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 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;
}
/* Stop here if thread_stack__process() is in use */
if (thread->ts->crp)
return 0;
if (flags & PERF_IP_FLAG_CALL) {
u64 ret_addr;
if (!to_ip)
return 0;
ret_addr = from_ip + insn_len;
if (ret_addr == to_ip)
return 0; /* Zero-length calls are excluded */
return thread_stack__push(thread->ts, ret_addr);
} else if (flags & PERF_IP_FLAG_RETURN) {
if (!from_ip)
return 0;
thread_stack__pop(thread->ts, to_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);
}
}
void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,
size_t sz, u64 ip)
{
size_t i;
if (!thread || !thread->ts)
chain->nr = 1;
else
chain->nr = min(sz, thread->ts->cnt + 1);
chain->ips[0] = ip;
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;
}