619 строки
14 KiB
C
619 строки
14 KiB
C
/*
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* thread-stack.c: Synthesize a thread's stack using call / return events
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* Copyright (c) 2014, Intel Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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*/
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#include <linux/rbtree.h>
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#include <linux/list.h>
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#include "thread.h"
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#include "event.h"
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#include "machine.h"
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#include "util.h"
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#include "debug.h"
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#include "symbol.h"
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#include "comm.h"
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#include "call-path.h"
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#include "thread-stack.h"
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#define STACK_GROWTH 2048
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/**
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* struct thread_stack_entry - thread stack entry.
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* @ret_addr: return address
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* @timestamp: timestamp (if known)
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* @ref: external reference (e.g. db_id of sample)
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* @branch_count: the branch count when the entry was created
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* @cp: call path
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* @no_call: a 'call' was not seen
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*/
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struct thread_stack_entry {
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u64 ret_addr;
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u64 timestamp;
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u64 ref;
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u64 branch_count;
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struct call_path *cp;
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bool no_call;
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};
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/**
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* struct thread_stack - thread stack constructed from 'call' and 'return'
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* branch samples.
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* @stack: array that holds the stack
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* @cnt: number of entries in the stack
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* @sz: current maximum stack size
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* @trace_nr: current trace number
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* @branch_count: running branch count
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* @kernel_start: kernel start address
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* @last_time: last timestamp
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* @crp: call/return processor
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* @comm: current comm
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*/
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struct thread_stack {
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struct thread_stack_entry *stack;
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size_t cnt;
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size_t sz;
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u64 trace_nr;
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u64 branch_count;
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u64 kernel_start;
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u64 last_time;
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struct call_return_processor *crp;
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struct comm *comm;
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};
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static int thread_stack__grow(struct thread_stack *ts)
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{
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struct thread_stack_entry *new_stack;
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size_t sz, new_sz;
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new_sz = ts->sz + STACK_GROWTH;
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sz = new_sz * sizeof(struct thread_stack_entry);
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new_stack = realloc(ts->stack, sz);
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if (!new_stack)
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return -ENOMEM;
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ts->stack = new_stack;
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ts->sz = new_sz;
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return 0;
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}
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static struct thread_stack *thread_stack__new(struct thread *thread,
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struct call_return_processor *crp)
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{
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struct thread_stack *ts;
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ts = zalloc(sizeof(struct thread_stack));
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if (!ts)
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return NULL;
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if (thread_stack__grow(ts)) {
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free(ts);
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return NULL;
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}
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if (thread->mg && thread->mg->machine)
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ts->kernel_start = machine__kernel_start(thread->mg->machine);
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else
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ts->kernel_start = 1ULL << 63;
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ts->crp = crp;
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return ts;
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}
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static int thread_stack__push(struct thread_stack *ts, u64 ret_addr)
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{
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int err = 0;
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if (ts->cnt == ts->sz) {
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err = thread_stack__grow(ts);
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if (err) {
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pr_warning("Out of memory: discarding thread stack\n");
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ts->cnt = 0;
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}
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}
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ts->stack[ts->cnt++].ret_addr = ret_addr;
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return err;
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}
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static void thread_stack__pop(struct thread_stack *ts, u64 ret_addr)
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{
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size_t i;
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/*
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* In some cases there may be functions which are not seen to return.
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* For example when setjmp / longjmp has been used. Or the perf context
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* switch in the kernel which doesn't stop and start tracing in exactly
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* the same code path. When that happens the return address will be
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* further down the stack. If the return address is not found at all,
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* we assume the opposite (i.e. this is a return for a call that wasn't
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* seen for some reason) and leave the stack alone.
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*/
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for (i = ts->cnt; i; ) {
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if (ts->stack[--i].ret_addr == ret_addr) {
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ts->cnt = i;
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return;
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}
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}
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}
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static bool thread_stack__in_kernel(struct thread_stack *ts)
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{
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if (!ts->cnt)
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return false;
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return ts->stack[ts->cnt - 1].cp->in_kernel;
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}
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static int thread_stack__call_return(struct thread *thread,
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struct thread_stack *ts, size_t idx,
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u64 timestamp, u64 ref, bool no_return)
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{
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struct call_return_processor *crp = ts->crp;
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struct thread_stack_entry *tse;
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struct call_return cr = {
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.thread = thread,
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.comm = ts->comm,
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.db_id = 0,
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};
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tse = &ts->stack[idx];
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cr.cp = tse->cp;
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cr.call_time = tse->timestamp;
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cr.return_time = timestamp;
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cr.branch_count = ts->branch_count - tse->branch_count;
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cr.call_ref = tse->ref;
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cr.return_ref = ref;
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if (tse->no_call)
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cr.flags |= CALL_RETURN_NO_CALL;
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if (no_return)
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cr.flags |= CALL_RETURN_NO_RETURN;
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return crp->process(&cr, crp->data);
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}
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static int __thread_stack__flush(struct thread *thread, struct thread_stack *ts)
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{
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struct call_return_processor *crp = ts->crp;
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int err;
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if (!crp) {
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ts->cnt = 0;
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return 0;
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}
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while (ts->cnt) {
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err = thread_stack__call_return(thread, ts, --ts->cnt,
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ts->last_time, 0, true);
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if (err) {
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pr_err("Error flushing thread stack!\n");
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ts->cnt = 0;
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return err;
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}
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}
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return 0;
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}
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int thread_stack__flush(struct thread *thread)
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{
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if (thread->ts)
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return __thread_stack__flush(thread, thread->ts);
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return 0;
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}
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int thread_stack__event(struct thread *thread, u32 flags, u64 from_ip,
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u64 to_ip, u16 insn_len, u64 trace_nr)
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{
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if (!thread)
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return -EINVAL;
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if (!thread->ts) {
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thread->ts = thread_stack__new(thread, NULL);
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if (!thread->ts) {
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pr_warning("Out of memory: no thread stack\n");
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return -ENOMEM;
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}
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thread->ts->trace_nr = trace_nr;
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}
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/*
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* When the trace is discontinuous, the trace_nr changes. In that case
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* the stack might be completely invalid. Better to report nothing than
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* to report something misleading, so flush the stack.
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*/
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if (trace_nr != thread->ts->trace_nr) {
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if (thread->ts->trace_nr)
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__thread_stack__flush(thread, thread->ts);
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thread->ts->trace_nr = trace_nr;
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}
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/* Stop here if thread_stack__process() is in use */
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if (thread->ts->crp)
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return 0;
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if (flags & PERF_IP_FLAG_CALL) {
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u64 ret_addr;
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if (!to_ip)
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return 0;
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ret_addr = from_ip + insn_len;
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if (ret_addr == to_ip)
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return 0; /* Zero-length calls are excluded */
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return thread_stack__push(thread->ts, ret_addr);
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} else if (flags & PERF_IP_FLAG_RETURN) {
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if (!from_ip)
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return 0;
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thread_stack__pop(thread->ts, to_ip);
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}
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return 0;
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}
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void thread_stack__set_trace_nr(struct thread *thread, u64 trace_nr)
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{
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if (!thread || !thread->ts)
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return;
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if (trace_nr != thread->ts->trace_nr) {
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if (thread->ts->trace_nr)
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__thread_stack__flush(thread, thread->ts);
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thread->ts->trace_nr = trace_nr;
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}
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}
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void thread_stack__free(struct thread *thread)
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{
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if (thread->ts) {
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__thread_stack__flush(thread, thread->ts);
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zfree(&thread->ts->stack);
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zfree(&thread->ts);
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}
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}
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void thread_stack__sample(struct thread *thread, struct ip_callchain *chain,
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size_t sz, u64 ip)
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{
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size_t i;
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if (!thread || !thread->ts)
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chain->nr = 1;
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else
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chain->nr = min(sz, thread->ts->cnt + 1);
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chain->ips[0] = ip;
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for (i = 1; i < chain->nr; i++)
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chain->ips[i] = thread->ts->stack[thread->ts->cnt - i].ret_addr;
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}
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struct call_return_processor *
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call_return_processor__new(int (*process)(struct call_return *cr, void *data),
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void *data)
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{
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struct call_return_processor *crp;
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crp = zalloc(sizeof(struct call_return_processor));
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if (!crp)
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return NULL;
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crp->cpr = call_path_root__new();
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if (!crp->cpr)
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goto out_free;
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crp->process = process;
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crp->data = data;
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return crp;
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out_free:
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free(crp);
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return NULL;
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}
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void call_return_processor__free(struct call_return_processor *crp)
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{
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if (crp) {
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call_path_root__free(crp->cpr);
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free(crp);
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}
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}
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static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr,
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u64 timestamp, u64 ref, struct call_path *cp,
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bool no_call)
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{
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struct thread_stack_entry *tse;
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int err;
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if (ts->cnt == ts->sz) {
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err = thread_stack__grow(ts);
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if (err)
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return err;
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}
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tse = &ts->stack[ts->cnt++];
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tse->ret_addr = ret_addr;
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tse->timestamp = timestamp;
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tse->ref = ref;
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tse->branch_count = ts->branch_count;
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tse->cp = cp;
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tse->no_call = no_call;
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return 0;
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}
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static int thread_stack__pop_cp(struct thread *thread, struct thread_stack *ts,
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u64 ret_addr, u64 timestamp, u64 ref,
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struct symbol *sym)
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{
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int err;
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if (!ts->cnt)
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return 1;
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if (ts->cnt == 1) {
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struct thread_stack_entry *tse = &ts->stack[0];
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if (tse->cp->sym == sym)
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return thread_stack__call_return(thread, ts, --ts->cnt,
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timestamp, ref, false);
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}
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if (ts->stack[ts->cnt - 1].ret_addr == ret_addr) {
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return thread_stack__call_return(thread, ts, --ts->cnt,
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timestamp, ref, false);
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} else {
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size_t i = ts->cnt - 1;
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while (i--) {
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if (ts->stack[i].ret_addr != ret_addr)
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continue;
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i += 1;
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while (ts->cnt > i) {
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err = thread_stack__call_return(thread, ts,
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--ts->cnt,
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timestamp, ref,
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true);
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if (err)
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return err;
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}
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return thread_stack__call_return(thread, ts, --ts->cnt,
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timestamp, ref, false);
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}
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}
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return 1;
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}
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static int thread_stack__bottom(struct thread *thread, struct thread_stack *ts,
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struct perf_sample *sample,
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struct addr_location *from_al,
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struct addr_location *to_al, u64 ref)
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{
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struct call_path_root *cpr = ts->crp->cpr;
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struct call_path *cp;
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struct symbol *sym;
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u64 ip;
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if (sample->ip) {
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ip = sample->ip;
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sym = from_al->sym;
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} else if (sample->addr) {
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ip = sample->addr;
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sym = to_al->sym;
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} else {
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return 0;
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}
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cp = call_path__findnew(cpr, &cpr->call_path, sym, ip,
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ts->kernel_start);
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if (!cp)
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return -ENOMEM;
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return thread_stack__push_cp(thread->ts, ip, sample->time, ref, cp,
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true);
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}
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static int thread_stack__no_call_return(struct thread *thread,
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struct thread_stack *ts,
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struct perf_sample *sample,
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struct addr_location *from_al,
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struct addr_location *to_al, u64 ref)
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{
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struct call_path_root *cpr = ts->crp->cpr;
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struct call_path *cp, *parent;
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u64 ks = ts->kernel_start;
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int err;
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if (sample->ip >= ks && sample->addr < ks) {
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/* Return to userspace, so pop all kernel addresses */
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while (thread_stack__in_kernel(ts)) {
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err = thread_stack__call_return(thread, ts, --ts->cnt,
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sample->time, ref,
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true);
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if (err)
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return err;
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}
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/* If the stack is empty, push the userspace address */
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if (!ts->cnt) {
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cp = call_path__findnew(cpr, &cpr->call_path,
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to_al->sym, sample->addr,
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ts->kernel_start);
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if (!cp)
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return -ENOMEM;
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return thread_stack__push_cp(ts, 0, sample->time, ref,
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cp, true);
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}
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} else if (thread_stack__in_kernel(ts) && sample->ip < ks) {
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/* Return to userspace, so pop all kernel addresses */
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while (thread_stack__in_kernel(ts)) {
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err = thread_stack__call_return(thread, ts, --ts->cnt,
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sample->time, ref,
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true);
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if (err)
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return err;
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}
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}
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if (ts->cnt)
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parent = ts->stack[ts->cnt - 1].cp;
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else
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parent = &cpr->call_path;
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/* This 'return' had no 'call', so push and pop top of stack */
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cp = call_path__findnew(cpr, parent, from_al->sym, sample->ip,
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ts->kernel_start);
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if (!cp)
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return -ENOMEM;
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err = thread_stack__push_cp(ts, sample->addr, sample->time, ref, cp,
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true);
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if (err)
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return err;
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return thread_stack__pop_cp(thread, ts, sample->addr, sample->time, ref,
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to_al->sym);
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}
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static int thread_stack__trace_begin(struct thread *thread,
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struct thread_stack *ts, u64 timestamp,
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u64 ref)
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{
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struct thread_stack_entry *tse;
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int err;
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if (!ts->cnt)
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return 0;
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/* Pop trace end */
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tse = &ts->stack[ts->cnt - 1];
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if (tse->cp->sym == NULL && tse->cp->ip == 0) {
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err = thread_stack__call_return(thread, ts, --ts->cnt,
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timestamp, ref, false);
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if (err)
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return err;
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}
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return 0;
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}
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static int thread_stack__trace_end(struct thread_stack *ts,
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struct perf_sample *sample, u64 ref)
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{
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struct call_path_root *cpr = ts->crp->cpr;
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struct call_path *cp;
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u64 ret_addr;
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/* No point having 'trace end' on the bottom of the stack */
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if (!ts->cnt || (ts->cnt == 1 && ts->stack[0].ref == ref))
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return 0;
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cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp, NULL, 0,
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ts->kernel_start);
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if (!cp)
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return -ENOMEM;
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ret_addr = sample->ip + sample->insn_len;
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return thread_stack__push_cp(ts, ret_addr, sample->time, ref, cp,
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false);
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}
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int thread_stack__process(struct thread *thread, struct comm *comm,
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struct perf_sample *sample,
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struct addr_location *from_al,
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struct addr_location *to_al, u64 ref,
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struct call_return_processor *crp)
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{
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struct thread_stack *ts = thread->ts;
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int err = 0;
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if (ts) {
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if (!ts->crp) {
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/* Supersede thread_stack__event() */
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thread_stack__free(thread);
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thread->ts = thread_stack__new(thread, crp);
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if (!thread->ts)
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return -ENOMEM;
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ts = thread->ts;
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ts->comm = comm;
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}
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} else {
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thread->ts = thread_stack__new(thread, crp);
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if (!thread->ts)
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return -ENOMEM;
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ts = thread->ts;
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ts->comm = comm;
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|
}
|
|
|
|
/* 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;
|
|
}
|