diff options
Diffstat (limited to 'tools/perf/util/thread-stack.c')
-rw-r--r-- | tools/perf/util/thread-stack.c | 251 |
1 files changed, 215 insertions, 36 deletions
diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c index d52f27f373ce..41942c2aaa18 100644 --- a/tools/perf/util/thread-stack.c +++ b/tools/perf/util/thread-stack.c @@ -20,6 +20,7 @@ #include "thread.h" #include "event.h" #include "machine.h" +#include "env.h" #include "util.h" #include "debug.h" #include "symbol.h" @@ -29,24 +30,41 @@ #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 + * @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 db_id; struct call_path *cp; bool no_call; bool trace_end; + bool non_call; }; /** @@ -62,6 +80,7 @@ struct thread_stack_entry { * @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 */ struct thread_stack { struct thread_stack_entry *stack; @@ -74,6 +93,7 @@ struct thread_stack { struct call_return_processor *crp; struct comm *comm; unsigned int arr_sz; + enum retpoline_state_t rstate; }; /* @@ -113,10 +133,16 @@ static int thread_stack__init(struct thread_stack *ts, struct thread *thread, if (err) return err; - if (thread->mg && thread->mg->machine) - ts->kernel_start = machine__kernel_start(thread->mg->machine); - else + if (thread->mg && thread->mg->machine) { + struct machine *machine = thread->mg->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; @@ -256,20 +282,31 @@ static int thread_stack__call_return(struct 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.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, crp->data); + return crp->process(&cr, parent_db_id, crp->data); } static int __thread_stack__flush(struct thread *thread, struct thread_stack *ts) @@ -458,7 +495,7 @@ void thread_stack__sample(struct thread *thread, int cpu, } struct call_return_processor * -call_return_processor__new(int (*process)(struct call_return *cr, void *data), +call_return_processor__new(int (*process)(struct call_return *cr, u64 *parent_db_id, void *data), void *data) { struct call_return_processor *crp; @@ -493,6 +530,9 @@ static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr, struct thread_stack_entry *tse; int err; + if (!cp) + return -ENOMEM; + if (ts->cnt == ts->sz) { err = thread_stack__grow(ts); if (err) @@ -507,6 +547,8 @@ static int thread_stack__push_cp(struct thread_stack *ts, u64 ret_addr, tse->cp = cp; tse->no_call = no_call; tse->trace_end = trace_end; + tse->non_call = false; + tse->db_id = 0; return 0; } @@ -528,14 +570,16 @@ static int thread_stack__pop_cp(struct thread *thread, struct thread_stack *ts, timestamp, ref, false); } - if (ts->stack[ts->cnt - 1].ret_addr == ret_addr) { + 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) + if (ts->stack[i].ret_addr != ret_addr || + ts->stack[i].non_call) continue; i += 1; while (ts->cnt > i) { @@ -576,8 +620,6 @@ static int thread_stack__bottom(struct thread_stack *ts, cp = call_path__findnew(cpr, &cpr->call_path, sym, ip, ts->kernel_start); - if (!cp) - return -ENOMEM; return thread_stack__push_cp(ts, ip, sample->time, ref, cp, true, false); @@ -590,36 +632,36 @@ static int thread_stack__no_call_return(struct thread *thread, 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 (sample->ip >= ks && sample->addr < ks) { + if (ip >= ks && 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); + tm, 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, false); + 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) && sample->ip < ks) { + } else if (thread_stack__in_kernel(ts) && 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); + tm, ref, true); if (err) return err; } @@ -628,21 +670,59 @@ static int thread_stack__no_call_return(struct thread *thread, if (ts->cnt) parent = ts->stack[ts->cnt - 1].cp; else - parent = &cpr->call_path; + parent = root; - /* 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; + 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; - err = thread_stack__push_cp(ts, sample->addr, sample->time, ref, cp, - true, false); + 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__pop_cp(thread, ts, sample->addr, sample->time, ref, - to_al->sym); + return thread_stack__call_return(thread, ts, --ts->cnt, tm, ref, false); } static int thread_stack__trace_begin(struct thread *thread, @@ -680,8 +760,6 @@ static int thread_stack__trace_end(struct thread_stack *ts, 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; @@ -689,6 +767,70 @@ static int thread_stack__trace_end(struct thread_stack *ts, 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, @@ -696,6 +838,7 @@ int thread_stack__process(struct thread *thread, struct comm *comm, 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) { @@ -711,6 +854,10 @@ int thread_stack__process(struct thread *thread, struct comm *comm, 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); @@ -745,14 +892,27 @@ int thread_stack__process(struct thread *thread, struct comm *comm, 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, 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->ip || !sample->addr) 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) { @@ -765,6 +925,25 @@ int thread_stack__process(struct thread *thread, struct comm *comm, 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; |