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linux-next/tools/perf/util/thread-stack.c
Adrian Hunter a5499b3719 perf tools: Ensure thread-stack is flushed
The thread-stack represents a thread's current stack.  When a thread
exits there can still be many functions on the stack e.g. exit() can be
called many levels deep, so all the callers will never return.  To get
that information output, the thread-stack must be flushed.

Previously it was assumed the thread-stack would be flushed when the
struct thread was deleted.  With thread ref-counting it is no longer
clear when that will be, if ever. So instead explicitly flush all the
thread-stacks at the end of a session.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1432906425-9911-3-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2015-06-19 16:03:33 -03:00

756 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__flush(struct thread *thread)
{
if (thread->ts)
return __thread_stack__flush(thread, thread->ts);
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;
}