/* * 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 <errno.h>#include "thread.h"#include "event.h"#include "machine.h"#include "util.h"#include "debug.h"#include "symbol.h"#include "comm.h"#include "call-path.h"#include "thread-stack.h" #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;} 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; 

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