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Diffstat (limited to '')
| -rw-r--r-- | tools/perf/util/thread-stack.c | 1240 |
1 files changed, 1240 insertions, 0 deletions
diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c new file mode 100644 index 000000000..1b992bbba --- /dev/null +++ b/tools/perf/util/thread-stack.c @@ -0,0 +1,1240 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * thread-stack.c: Synthesize a thread's stack using call / return events + * Copyright (c) 2014, Intel Corporation. + */ + +#include <linux/rbtree.h> +#include <linux/list.h> +#include <linux/log2.h> +#include <linux/zalloc.h> +#include <errno.h> +#include <stdlib.h> +#include <string.h> +#include "thread.h" +#include "event.h" +#include "machine.h" +#include "env.h" +#include "debug.h" +#include "symbol.h" +#include "comm.h" +#include "call-path.h" +#include "thread-stack.h" + +#define STACK_GROWTH 2048 + +/* + * State of retpoline detection. + * + * RETPOLINE_NONE: no retpoline detection + * X86_RETPOLINE_POSSIBLE: x86 retpoline possible + * X86_RETPOLINE_DETECTED: x86 retpoline detected + */ +enum retpoline_state_t { + RETPOLINE_NONE, + X86_RETPOLINE_POSSIBLE, + X86_RETPOLINE_DETECTED, +}; + +/** + * 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 + * @insn_count: the instruction count when the entry was created + * @cyc_count the cycle count when the entry was created + * @db_id: id used for db-export + * @cp: call path + * @no_call: a 'call' was not seen + * @trace_end: a 'call' but trace ended + * @non_call: a branch but not a 'call' to the start of a different symbol + */ +struct thread_stack_entry { + u64 ret_addr; + u64 timestamp; + u64 ref; + u64 branch_count; + u64 insn_count; + u64 cyc_count; + u64 db_id; + struct call_path *cp; + bool no_call; + bool trace_end; + bool non_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 + * @insn_count: running instruction count + * @cyc_count running cycle count + * @kernel_start: kernel start address + * @last_time: last timestamp + * @crp: call/return processor + * @comm: current comm + * @arr_sz: size of array if this is the first element of an array + * @rstate: used to detect retpolines + * @br_stack_rb: branch stack (ring buffer) + * @br_stack_sz: maximum branch stack size + * @br_stack_pos: current position in @br_stack_rb + * @mispred_all: mark all branches as mispredicted + */ +struct thread_stack { + struct thread_stack_entry *stack; + size_t cnt; + size_t sz; + u64 trace_nr; + u64 branch_count; + u64 insn_count; + u64 cyc_count; + u64 kernel_start; + u64 last_time; + struct call_return_processor *crp; + struct comm *comm; + unsigned int arr_sz; + enum retpoline_state_t rstate; + struct branch_stack *br_stack_rb; + unsigned int br_stack_sz; + unsigned int br_stack_pos; + bool mispred_all; +}; + +/* + * Assume pid == tid == 0 identifies the idle task as defined by + * perf_session__register_idle_thread(). The idle task is really 1 task per cpu, + * and therefore requires a stack for each cpu. + */ +static inline bool thread_stack__per_cpu(struct thread *thread) +{ + return !(thread->tid || thread->pid_); +} + +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 int thread_stack__init(struct thread_stack *ts, struct thread *thread, + struct call_return_processor *crp, + bool callstack, unsigned int br_stack_sz) +{ + int err; + + if (callstack) { + err = thread_stack__grow(ts); + if (err) + return err; + } + + if (br_stack_sz) { + size_t sz = sizeof(struct branch_stack); + + sz += br_stack_sz * sizeof(struct branch_entry); + ts->br_stack_rb = zalloc(sz); + if (!ts->br_stack_rb) + return -ENOMEM; + ts->br_stack_sz = br_stack_sz; + } + + if (thread->maps && thread->maps->machine) { + struct machine *machine = thread->maps->machine; + const char *arch = perf_env__arch(machine->env); + + ts->kernel_start = machine__kernel_start(machine); + if (!strcmp(arch, "x86")) + ts->rstate = X86_RETPOLINE_POSSIBLE; + } else { + ts->kernel_start = 1ULL << 63; + } + ts->crp = crp; + + return 0; +} + +static struct thread_stack *thread_stack__new(struct thread *thread, int cpu, + struct call_return_processor *crp, + bool callstack, + unsigned int br_stack_sz) +{ + struct thread_stack *ts = thread->ts, *new_ts; + unsigned int old_sz = ts ? ts->arr_sz : 0; + unsigned int new_sz = 1; + + if (thread_stack__per_cpu(thread) && cpu > 0) + new_sz = roundup_pow_of_two(cpu + 1); + + if (!ts || new_sz > old_sz) { + new_ts = calloc(new_sz, sizeof(*ts)); + if (!new_ts) + return NULL; + if (ts) + memcpy(new_ts, ts, old_sz * sizeof(*ts)); + new_ts->arr_sz = new_sz; + zfree(&thread->ts); + thread->ts = new_ts; + ts = new_ts; + } + + if (thread_stack__per_cpu(thread) && cpu > 0 && + (unsigned int)cpu < ts->arr_sz) + ts += cpu; + + if (!ts->stack && + thread_stack__init(ts, thread, crp, callstack, br_stack_sz)) + return NULL; + + return ts; +} + +static struct thread_stack *thread__cpu_stack(struct thread *thread, int cpu) +{ + struct thread_stack *ts = thread->ts; + + if (cpu < 0) + cpu = 0; + + if (!ts || (unsigned int)cpu >= ts->arr_sz) + return NULL; + + ts += cpu; + + if (!ts->stack) + return NULL; + + return ts; +} + +static inline struct thread_stack *thread__stack(struct thread *thread, + int cpu) +{ + if (!thread) + return NULL; + + if (thread_stack__per_cpu(thread)) + return thread__cpu_stack(thread, cpu); + + return thread->ts; +} + +static int thread_stack__push(struct thread_stack *ts, u64 ret_addr, + bool trace_end) +{ + 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].trace_end = trace_end; + 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 void thread_stack__pop_trace_end(struct thread_stack *ts) +{ + size_t i; + + for (i = ts->cnt; i; ) { + if (ts->stack[--i].trace_end) + ts->cnt = i; + else + 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, + }; + u64 *parent_db_id; + + 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.insn_count = ts->insn_count - tse->insn_count; + cr.cyc_count = ts->cyc_count - tse->cyc_count; + cr.db_id = tse->db_id; + 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; + if (tse->non_call) + cr.flags |= CALL_RETURN_NON_CALL; + + /* + * The parent db_id must be assigned before exporting the child. Note + * it is not possible to export the parent first because its information + * is not yet complete because its 'return' has not yet been processed. + */ + parent_db_id = idx ? &(tse - 1)->db_id : NULL; + + return crp->process(&cr, parent_db_id, 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; + ts->br_stack_pos = 0; + if (ts->br_stack_rb) + ts->br_stack_rb->nr = 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) +{ + struct thread_stack *ts = thread->ts; + unsigned int pos; + int err = 0; + + if (ts) { + for (pos = 0; pos < ts->arr_sz; pos++) { + int ret = __thread_stack__flush(thread, ts + pos); + + if (ret) + err = ret; + } + } + + return err; +} + +static void thread_stack__update_br_stack(struct thread_stack *ts, u32 flags, + u64 from_ip, u64 to_ip) +{ + struct branch_stack *bs = ts->br_stack_rb; + struct branch_entry *be; + + if (!ts->br_stack_pos) + ts->br_stack_pos = ts->br_stack_sz; + + ts->br_stack_pos -= 1; + + be = &bs->entries[ts->br_stack_pos]; + be->from = from_ip; + be->to = to_ip; + be->flags.value = 0; + be->flags.abort = !!(flags & PERF_IP_FLAG_TX_ABORT); + be->flags.in_tx = !!(flags & PERF_IP_FLAG_IN_TX); + /* No support for mispredict */ + be->flags.mispred = ts->mispred_all; + + if (bs->nr < ts->br_stack_sz) + bs->nr += 1; +} + +int thread_stack__event(struct thread *thread, int cpu, u32 flags, u64 from_ip, + u64 to_ip, u16 insn_len, u64 trace_nr, bool callstack, + unsigned int br_stack_sz, bool mispred_all) +{ + struct thread_stack *ts = thread__stack(thread, cpu); + + if (!thread) + return -EINVAL; + + if (!ts) { + ts = thread_stack__new(thread, cpu, NULL, callstack, br_stack_sz); + if (!ts) { + pr_warning("Out of memory: no thread stack\n"); + return -ENOMEM; + } + ts->trace_nr = trace_nr; + ts->mispred_all = mispred_all; + } + + /* + * 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 != ts->trace_nr) { + if (ts->trace_nr) + __thread_stack__flush(thread, ts); + ts->trace_nr = trace_nr; + } + + if (br_stack_sz) + thread_stack__update_br_stack(ts, flags, from_ip, to_ip); + + /* + * Stop here if thread_stack__process() is in use, or not recording call + * stack. + */ + if (ts->crp || !callstack) + 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(ts, ret_addr, + flags & PERF_IP_FLAG_TRACE_END); + } else if (flags & PERF_IP_FLAG_TRACE_BEGIN) { + /* + * If the caller did not change the trace number (which would + * have flushed the stack) then try to make sense of the stack. + * Possibly, tracing began after returning to the current + * address, so try to pop that. Also, do not expect a call made + * when the trace ended, to return, so pop that. + */ + thread_stack__pop(ts, to_ip); + thread_stack__pop_trace_end(ts); + } else if ((flags & PERF_IP_FLAG_RETURN) && from_ip) { + thread_stack__pop(ts, to_ip); + } + + return 0; +} + +void thread_stack__set_trace_nr(struct thread *thread, int cpu, u64 trace_nr) +{ + struct thread_stack *ts = thread__stack(thread, cpu); + + if (!ts) + return; + + if (trace_nr != ts->trace_nr) { + if (ts->trace_nr) + __thread_stack__flush(thread, ts); + ts->trace_nr = trace_nr; + } +} + +static void __thread_stack__free(struct thread *thread, struct thread_stack *ts) +{ + __thread_stack__flush(thread, ts); + zfree(&ts->stack); + zfree(&ts->br_stack_rb); +} + +static void thread_stack__reset(struct thread *thread, struct thread_stack *ts) +{ + unsigned int arr_sz = ts->arr_sz; + + __thread_stack__free(thread, ts); + memset(ts, 0, sizeof(*ts)); + ts->arr_sz = arr_sz; +} + +void thread_stack__free(struct thread *thread) +{ + struct thread_stack *ts = thread->ts; + unsigned int pos; + + if (ts) { + for (pos = 0; pos < ts->arr_sz; pos++) + __thread_stack__free(thread, ts + pos); + zfree(&thread->ts); + } +} + +static inline u64 callchain_context(u64 ip, u64 kernel_start) +{ + return ip < kernel_start ? PERF_CONTEXT_USER : PERF_CONTEXT_KERNEL; +} + +void thread_stack__sample(struct thread *thread, int cpu, + struct ip_callchain *chain, + size_t sz, u64 ip, u64 kernel_start) +{ + struct thread_stack *ts = thread__stack(thread, cpu); + u64 context = callchain_context(ip, kernel_start); + u64 last_context; + size_t i, j; + + if (sz < 2) { + chain->nr = 0; + return; + } + + chain->ips[0] = context; + chain->ips[1] = ip; + + if (!ts) { + chain->nr = 2; + return; + } + + last_context = context; + + for (i = 2, j = 1; i < sz && j <= ts->cnt; i++, j++) { + ip = ts->stack[ts->cnt - j].ret_addr; + context = callchain_context(ip, kernel_start); + if (context != last_context) { + if (i >= sz - 1) + break; + chain->ips[i++] = context; + last_context = context; + } + chain->ips[i] = ip; + } + + chain->nr = i; +} + +/* + * Hardware sample records, created some time after the event occurred, need to + * have subsequent addresses removed from the call chain. + */ +void thread_stack__sample_late(struct thread *thread, int cpu, + struct ip_callchain *chain, size_t sz, + u64 sample_ip, u64 kernel_start) +{ + struct thread_stack *ts = thread__stack(thread, cpu); + u64 sample_context = callchain_context(sample_ip, kernel_start); + u64 last_context, context, ip; + size_t nr = 0, j; + + if (sz < 2) { + chain->nr = 0; + return; + } + + if (!ts) + goto out; + + /* + * When tracing kernel space, kernel addresses occur at the top of the + * call chain after the event occurred but before tracing stopped. + * Skip them. + */ + for (j = 1; j <= ts->cnt; j++) { + ip = ts->stack[ts->cnt - j].ret_addr; + context = callchain_context(ip, kernel_start); + if (context == PERF_CONTEXT_USER || + (context == sample_context && ip == sample_ip)) + break; + } + + last_context = sample_ip; /* Use sample_ip as an invalid context */ + + for (; nr < sz && j <= ts->cnt; nr++, j++) { + ip = ts->stack[ts->cnt - j].ret_addr; + context = callchain_context(ip, kernel_start); + if (context != last_context) { + if (nr >= sz - 1) + break; + chain->ips[nr++] = context; + last_context = context; + } + chain->ips[nr] = ip; + } +out: + if (nr) { + chain->nr = nr; + } else { + chain->ips[0] = sample_context; + chain->ips[1] = sample_ip; + chain->nr = 2; + } +} + +void thread_stack__br_sample(struct thread *thread, int cpu, + struct branch_stack *dst, unsigned int sz) +{ + struct thread_stack *ts = thread__stack(thread, cpu); + const size_t bsz = sizeof(struct branch_entry); + struct branch_stack *src; + struct branch_entry *be; + unsigned int nr; + + dst->nr = 0; + + if (!ts) + return; + + src = ts->br_stack_rb; + if (!src->nr) + return; + + dst->nr = min((unsigned int)src->nr, sz); + + be = &dst->entries[0]; + nr = min(ts->br_stack_sz - ts->br_stack_pos, (unsigned int)dst->nr); + memcpy(be, &src->entries[ts->br_stack_pos], bsz * nr); + + if (src->nr >= ts->br_stack_sz) { + sz -= nr; + be = &dst->entries[nr]; + nr = min(ts->br_stack_pos, sz); + memcpy(be, &src->entries[0], bsz * ts->br_stack_pos); + } +} + +/* Start of user space branch entries */ +static bool us_start(struct branch_entry *be, u64 kernel_start, bool *start) +{ + if (!*start) + *start = be->to && be->to < kernel_start; + + return *start; +} + +/* + * Start of branch entries after the ip fell in between 2 branches, or user + * space branch entries. + */ +static bool ks_start(struct branch_entry *be, u64 sample_ip, u64 kernel_start, + bool *start, struct branch_entry *nb) +{ + if (!*start) { + *start = (nb && sample_ip >= be->to && sample_ip <= nb->from) || + be->from < kernel_start || + (be->to && be->to < kernel_start); + } + + return *start; +} + +/* + * Hardware sample records, created some time after the event occurred, need to + * have subsequent addresses removed from the branch stack. + */ +void thread_stack__br_sample_late(struct thread *thread, int cpu, + struct branch_stack *dst, unsigned int sz, + u64 ip, u64 kernel_start) +{ + struct thread_stack *ts = thread__stack(thread, cpu); + struct branch_entry *d, *s, *spos, *ssz; + struct branch_stack *src; + unsigned int nr = 0; + bool start = false; + + dst->nr = 0; + + if (!ts) + return; + + src = ts->br_stack_rb; + if (!src->nr) + return; + + spos = &src->entries[ts->br_stack_pos]; + ssz = &src->entries[ts->br_stack_sz]; + + d = &dst->entries[0]; + s = spos; + + if (ip < kernel_start) { + /* + * User space sample: start copying branch entries when the + * branch is in user space. + */ + for (s = spos; s < ssz && nr < sz; s++) { + if (us_start(s, kernel_start, &start)) { + *d++ = *s; + nr += 1; + } + } + + if (src->nr >= ts->br_stack_sz) { + for (s = &src->entries[0]; s < spos && nr < sz; s++) { + if (us_start(s, kernel_start, &start)) { + *d++ = *s; + nr += 1; + } + } + } + } else { + struct branch_entry *nb = NULL; + + /* + * Kernel space sample: start copying branch entries when the ip + * falls in between 2 branches (or the branch is in user space + * because then the start must have been missed). + */ + for (s = spos; s < ssz && nr < sz; s++) { + if (ks_start(s, ip, kernel_start, &start, nb)) { + *d++ = *s; + nr += 1; + } + nb = s; + } + + if (src->nr >= ts->br_stack_sz) { + for (s = &src->entries[0]; s < spos && nr < sz; s++) { + if (ks_start(s, ip, kernel_start, &start, nb)) { + *d++ = *s; + nr += 1; + } + nb = s; + } + } + } + + dst->nr = nr; +} + +struct call_return_processor * +call_return_processor__new(int (*process)(struct call_return *cr, u64 *parent_db_id, 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, bool trace_end) +{ + struct thread_stack_entry *tse; + int err; + + if (!cp) + return -ENOMEM; + + 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->insn_count = ts->insn_count; + tse->cyc_count = ts->cyc_count; + tse->cp = cp; + tse->no_call = no_call; + tse->trace_end = trace_end; + tse->non_call = false; + tse->db_id = 0; + + 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 && + !ts->stack[ts->cnt - 1].non_call) { + 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 || + ts->stack[i].non_call) + 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_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); + + return thread_stack__push_cp(ts, ip, sample->time, ref, cp, + true, false); +} + +static int thread_stack__pop_ks(struct thread *thread, struct thread_stack *ts, + struct perf_sample *sample, u64 ref) +{ + u64 tm = sample->time; + int err; + + /* Return to userspace, so pop all kernel addresses */ + while (thread_stack__in_kernel(ts)) { + err = thread_stack__call_return(thread, ts, --ts->cnt, + tm, ref, true); + if (err) + return err; + } + + return 0; +} + +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 *root = &cpr->call_path; + struct symbol *fsym = from_al->sym; + struct symbol *tsym = to_al->sym; + struct call_path *cp, *parent; + u64 ks = ts->kernel_start; + u64 addr = sample->addr; + u64 tm = sample->time; + u64 ip = sample->ip; + int err; + + if (ip >= ks && addr < ks) { + /* Return to userspace, so pop all kernel addresses */ + err = thread_stack__pop_ks(thread, ts, sample, ref); + if (err) + return err; + + /* If the stack is empty, push the userspace address */ + if (!ts->cnt) { + cp = call_path__findnew(cpr, root, tsym, addr, ks); + return thread_stack__push_cp(ts, 0, tm, ref, cp, true, + false); + } + } else if (thread_stack__in_kernel(ts) && ip < ks) { + /* Return to userspace, so pop all kernel addresses */ + err = thread_stack__pop_ks(thread, ts, sample, ref); + if (err) + return err; + } + + if (ts->cnt) + parent = ts->stack[ts->cnt - 1].cp; + else + parent = root; + + if (parent->sym == from_al->sym) { + /* + * At the bottom of the stack, assume the missing 'call' was + * before the trace started. So, pop the current symbol and push + * the 'to' symbol. + */ + if (ts->cnt == 1) { + err = thread_stack__call_return(thread, ts, --ts->cnt, + tm, ref, false); + if (err) + return err; + } + + if (!ts->cnt) { + cp = call_path__findnew(cpr, root, tsym, addr, ks); + + return thread_stack__push_cp(ts, addr, tm, ref, cp, + true, false); + } + + /* + * Otherwise assume the 'return' is being used as a jump (e.g. + * retpoline) and just push the 'to' symbol. + */ + cp = call_path__findnew(cpr, parent, tsym, addr, ks); + + err = thread_stack__push_cp(ts, 0, tm, ref, cp, true, false); + if (!err) + ts->stack[ts->cnt - 1].non_call = true; + + return err; + } + + /* + * Assume 'parent' has not yet returned, so push 'to', and then push and + * pop 'from'. + */ + + cp = call_path__findnew(cpr, parent, tsym, addr, ks); + + err = thread_stack__push_cp(ts, addr, tm, ref, cp, true, false); + if (err) + return err; + + cp = call_path__findnew(cpr, cp, fsym, ip, ks); + + err = thread_stack__push_cp(ts, ip, tm, ref, cp, true, false); + if (err) + return err; + + return thread_stack__call_return(thread, ts, --ts->cnt, tm, ref, false); +} + +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->trace_end) { + 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); + + ret_addr = sample->ip + sample->insn_len; + + return thread_stack__push_cp(ts, ret_addr, sample->time, ref, cp, + false, true); +} + +static bool is_x86_retpoline(const char *name) +{ + const char *p = strstr(name, "__x86_indirect_thunk_"); + + return p == name || !strcmp(name, "__indirect_thunk_start"); +} + +/* + * x86 retpoline functions pollute the call graph. This function removes them. + * This does not handle function return thunks, nor is there any improvement + * for the handling of inline thunks or extern thunks. + */ +static int thread_stack__x86_retpoline(struct thread_stack *ts, + struct perf_sample *sample, + struct addr_location *to_al) +{ + struct thread_stack_entry *tse = &ts->stack[ts->cnt - 1]; + struct call_path_root *cpr = ts->crp->cpr; + struct symbol *sym = tse->cp->sym; + struct symbol *tsym = to_al->sym; + struct call_path *cp; + + if (sym && is_x86_retpoline(sym->name)) { + /* + * This is a x86 retpoline fn. It pollutes the call graph by + * showing up everywhere there is an indirect branch, but does + * not itself mean anything. Here the top-of-stack is removed, + * by decrementing the stack count, and then further down, the + * resulting top-of-stack is replaced with the actual target. + * The result is that the retpoline functions will no longer + * appear in the call graph. Note this only affects the call + * graph, since all the original branches are left unchanged. + */ + ts->cnt -= 1; + sym = ts->stack[ts->cnt - 2].cp->sym; + if (sym && sym == tsym && to_al->addr != tsym->start) { + /* + * Target is back to the middle of the symbol we came + * from so assume it is an indirect jmp and forget it + * altogether. + */ + ts->cnt -= 1; + return 0; + } + } else if (sym && sym == tsym) { + /* + * Target is back to the symbol we came from so assume it is an + * indirect jmp and forget it altogether. + */ + ts->cnt -= 1; + return 0; + } + + cp = call_path__findnew(cpr, ts->stack[ts->cnt - 2].cp, tsym, + sample->addr, ts->kernel_start); + if (!cp) + return -ENOMEM; + + /* Replace the top-of-stack with the actual target */ + ts->stack[ts->cnt - 1].cp = cp; + + return 0; +} + +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__stack(thread, sample->cpu); + enum retpoline_state_t rstate; + int err = 0; + + if (ts && !ts->crp) { + /* Supersede thread_stack__event() */ + thread_stack__reset(thread, ts); + ts = NULL; + } + + if (!ts) { + ts = thread_stack__new(thread, sample->cpu, crp, true, 0); + if (!ts) + return -ENOMEM; + ts->comm = comm; + } + + rstate = ts->rstate; + if (rstate == X86_RETPOLINE_DETECTED) + ts->rstate = X86_RETPOLINE_POSSIBLE; + + /* 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(ts, sample, from_al, to_al, ref); + if (err) + return err; + } + + ts->branch_count += 1; + ts->insn_count += sample->insn_cnt; + ts->cyc_count += sample->cyc_cnt; + ts->last_time = sample->time; + + if (sample->flags & PERF_IP_FLAG_CALL) { + bool trace_end = sample->flags & PERF_IP_FLAG_TRACE_END; + 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); + err = thread_stack__push_cp(ts, ret_addr, sample->time, ref, + cp, false, trace_end); + + /* + * A call to the same symbol but not the start of the symbol, + * may be the start of a x86 retpoline. + */ + if (!err && rstate == X86_RETPOLINE_POSSIBLE && to_al->sym && + from_al->sym == to_al->sym && + to_al->addr != to_al->sym->start) + ts->rstate = X86_RETPOLINE_DETECTED; + + } else if (sample->flags & PERF_IP_FLAG_RETURN) { + if (!sample->addr) { + u32 return_from_kernel = PERF_IP_FLAG_SYSCALLRET | + PERF_IP_FLAG_INTERRUPT; + + if (!(sample->flags & return_from_kernel)) + return 0; + + /* Pop kernel stack */ + return thread_stack__pop_ks(thread, ts, sample, ref); + } + + if (!sample->ip) + return 0; + + /* x86 retpoline 'return' doesn't match the stack */ + if (rstate == X86_RETPOLINE_DETECTED && ts->cnt > 2 && + ts->stack[ts->cnt - 1].ret_addr != sample->addr) + return thread_stack__x86_retpoline(ts, sample, to_al); + + 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); + } else if (sample->flags & PERF_IP_FLAG_BRANCH && + from_al->sym != to_al->sym && to_al->sym && + to_al->addr == to_al->sym->start) { + struct call_path_root *cpr = ts->crp->cpr; + struct call_path *cp; + + /* + * The compiler might optimize a call/ret combination by making + * it a jmp. Make that visible by recording on the stack a + * branch to the start of a different symbol. Note, that means + * when a ret pops the stack, all jmps must be popped off first. + */ + cp = call_path__findnew(cpr, ts->stack[ts->cnt - 1].cp, + to_al->sym, sample->addr, + ts->kernel_start); + err = thread_stack__push_cp(ts, 0, sample->time, ref, cp, false, + false); + if (!err) + ts->stack[ts->cnt - 1].non_call = true; + } + + return err; +} + +size_t thread_stack__depth(struct thread *thread, int cpu) +{ + struct thread_stack *ts = thread__stack(thread, cpu); + + if (!ts) + return 0; + return ts->cnt; +} |