/* * 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;

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