// SPDX-License-Identifier: GPL-2.0 /* * * Function graph tracer. * Copyright (c) 2008-2009 Frederic Weisbecker * Mostly borrowed from function tracer which * is Copyright (c) Steven Rostedt * */ #include #include #include #include #include #include "trace.h" #include "trace_output.h" static bool kill_ftrace_graph; /** * ftrace_graph_is_dead - returns true if ftrace_graph_stop() was called * * ftrace_graph_stop() is called when a severe error is detected in * the function graph tracing. This function is called by the critical * paths of function graph to keep those paths from doing any more harm. */ bool ftrace_graph_is_dead(void) { return kill_ftrace_graph; } /** * ftrace_graph_stop - set to permanently disable function graph tracincg * * In case of an error int function graph tracing, this is called * to try to keep function graph tracing from causing any more harm. * Usually this is pretty severe and this is called to try to at least * get a warning out to the user. */ void ftrace_graph_stop(void) { kill_ftrace_graph = true; } /* When set, irq functions will be ignored */ static int ftrace_graph_skip_irqs; struct fgraph_cpu_data { pid_t last_pid; int depth; int depth_irq; int ignore; unsigned long enter_funcs[FTRACE_RETFUNC_DEPTH]; }; struct fgraph_data { struct fgraph_cpu_data __percpu *cpu_data; /* Place to preserve last processed entry. */ struct ftrace_graph_ent_entry ent; struct ftrace_graph_ret_entry ret; int failed; int cpu; }; #define TRACE_GRAPH_INDENT 2 unsigned int fgraph_max_depth; static struct tracer_opt trace_opts[] = { /* Display overruns? (for self-debug purpose) */ { TRACER_OPT(funcgraph-overrun, TRACE_GRAPH_PRINT_OVERRUN) }, /* Display CPU ? */ { TRACER_OPT(funcgraph-cpu, TRACE_GRAPH_PRINT_CPU) }, /* Display Overhead ? */ { TRACER_OPT(funcgraph-overhead, TRACE_GRAPH_PRINT_OVERHEAD) }, /* Display proc name/pid */ { TRACER_OPT(funcgraph-proc, TRACE_GRAPH_PRINT_PROC) }, /* Display duration of execution */ { TRACER_OPT(funcgraph-duration, TRACE_GRAPH_PRINT_DURATION) }, /* Display absolute time of an entry */ { TRACER_OPT(funcgraph-abstime, TRACE_GRAPH_PRINT_ABS_TIME) }, /* Display interrupts */ { TRACER_OPT(funcgraph-irqs, TRACE_GRAPH_PRINT_IRQS) }, /* Display function name after trailing } */ { TRACER_OPT(funcgraph-tail, TRACE_GRAPH_PRINT_TAIL) }, /* Include sleep time (scheduled out) between entry and return */ { TRACER_OPT(sleep-time, TRACE_GRAPH_SLEEP_TIME) }, /* Include time within nested functions */ { TRACER_OPT(graph-time, TRACE_GRAPH_GRAPH_TIME) }, { } /* Empty entry */ }; static struct tracer_flags tracer_flags = { /* Don't display overruns, proc, or tail by default */ .val = TRACE_GRAPH_PRINT_CPU | TRACE_GRAPH_PRINT_OVERHEAD | TRACE_GRAPH_PRINT_DURATION | TRACE_GRAPH_PRINT_IRQS | TRACE_GRAPH_SLEEP_TIME | TRACE_GRAPH_GRAPH_TIME, .opts = trace_opts }; static struct trace_array *graph_array; /* * DURATION column is being also used to display IRQ signs, * following values are used by print_graph_irq and others * to fill in space into DURATION column. */ enum { FLAGS_FILL_FULL = 1 << TRACE_GRAPH_PRINT_FILL_SHIFT, FLAGS_FILL_START = 2 << TRACE_GRAPH_PRINT_FILL_SHIFT, FLAGS_FILL_END = 3 << TRACE_GRAPH_PRINT_FILL_SHIFT, }; static void print_graph_duration(struct trace_array *tr, unsigned long long duration, struct trace_seq *s, u32 flags); /* Add a function return address to the trace stack on thread info.*/ static int ftrace_push_return_trace(unsigned long ret, unsigned long func, unsigned long frame_pointer, unsigned long *retp) { unsigned long long calltime; int index; if (unlikely(ftrace_graph_is_dead())) return -EBUSY; if (!current->ret_stack) return -EBUSY; /* * We must make sure the ret_stack is tested before we read * anything else. */ smp_rmb(); /* The return trace stack is full */ if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) { atomic_inc(¤t->trace_overrun); return -EBUSY; } /* * The curr_ret_stack is an index to ftrace return stack of * current task. Its value should be in [0, FTRACE_RETFUNC_ * DEPTH) when the function graph tracer is used. To support * filtering out specific functions, it makes the index * negative by subtracting huge value (FTRACE_NOTRACE_DEPTH) * so when it sees a negative index the ftrace will ignore * the record. And the index gets recovered when returning * from the filtered function by adding the FTRACE_NOTRACE_ * DEPTH and then it'll continue to record functions normally. * * The curr_ret_stack is initialized to -1 and get increased * in this function. So it can be less than -1 only if it was * filtered out via ftrace_graph_notrace_addr() which can be * set from set_graph_notrace file in tracefs by user. */ if (current->curr_ret_stack < -1) return -EBUSY; calltime = trace_clock_local(); index = ++current->curr_ret_stack; if (ftrace_graph_notrace_addr(func)) current->curr_ret_stack -= FTRACE_NOTRACE_DEPTH; barrier(); current->ret_stack[index].ret = ret; current->ret_stack[index].func = func; current->ret_stack[index].calltime = calltime; #ifdef HAVE_FUNCTION_GRAPH_FP_TEST current->ret_stack[index].fp = frame_pointer; #endif #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR current->ret_stack[index].retp = retp; #endif return 0; } int function_graph_enter(unsigned long ret, unsigned long func, unsigned long frame_pointer, unsigned long *retp) { struct ftrace_graph_ent trace; trace.func = func; trace.depth = ++current->curr_ret_depth; if (ftrace_push_return_trace(ret, func, frame_pointer, retp)) goto out; /* Only trace if the calling function expects to */ if (!ftrace_graph_entry(&trace)) goto out_ret; return 0; out_ret: current->curr_ret_stack--; out: current->curr_ret_depth--; return -EBUSY; } /* Retrieve a function return address to the trace stack on thread info.*/ static void ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret, unsigned long frame_pointer) { int index; index = current->curr_ret_stack; /* * A negative index here means that it's just returned from a * notrace'd function. Recover index to get an original * return address. See ftrace_push_return_trace(). * * TODO: Need to check whether the stack gets corrupted. */ if (index < 0) index += FTRACE_NOTRACE_DEPTH; if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) { ftrace_graph_stop(); WARN_ON(1); /* Might as well panic, otherwise we have no where to go */ *ret = (unsigned long)panic; return; } #ifdef HAVE_FUNCTION_GRAPH_FP_TEST /* * The arch may choose to record the frame pointer used * and check it here to make sure that it is what we expect it * to be. If gcc does not set the place holder of the return * address in the frame pointer, and does a copy instead, then * the function graph trace will fail. This test detects this * case. * * Currently, x86_32 with optimize for size (-Os) makes the latest * gcc do the above. * * Note, -mfentry does not use frame pointers, and this test * is not needed if CC_USING_FENTRY is set. */ if (unlikely(current->ret_stack[index].fp != frame_pointer)) { ftrace_graph_stop(); WARN(1, "Bad frame pointer: expected %lx, received %lx\n" " from func %ps return to %lx\n", current->ret_stack[index].fp, frame_pointer, (void *)current->ret_stack[index].func, current->ret_stack[index].ret); *ret = (unsigned long)panic; return; } #endif *ret = current->ret_stack[index].ret; trace->func = current->ret_stack[index].func; trace->calltime = current->ret_stack[index].calltime; trace->overrun = atomic_read(¤t->trace_overrun); trace->depth = current->curr_ret_depth--; /* * We still want to trace interrupts coming in if * max_depth is set to 1. Make sure the decrement is * seen before ftrace_graph_return. */ barrier(); } /* * Send the trace to the ring-buffer. * @return the original return address. */ unsigned long ftrace_return_to_handler(unsigned long frame_pointer) { struct ftrace_graph_ret trace; unsigned long ret; ftrace_pop_return_trace(&trace, &ret, frame_pointer); trace.rettime = trace_clock_local(); ftrace_graph_return(&trace); /* * The ftrace_graph_return() may still access the current * ret_stack structure, we need to make sure the update of * curr_ret_stack is after that. */ barrier(); current->curr_ret_stack--; /* * The curr_ret_stack can be less than -1 only if it was * filtered out and it's about to return from the function. * Recover the index and continue to trace normal functions. */ if (current->curr_ret_stack < -1) { current->curr_ret_stack += FTRACE_NOTRACE_DEPTH; return ret; } if (unlikely(!ret)) { ftrace_graph_stop(); WARN_ON(1); /* Might as well panic. What else to do? */ ret = (unsigned long)panic; } return ret; } /** * ftrace_graph_ret_addr - convert a potentially modified stack return address * to its original value * * This function can be called by stack unwinding code to convert a found stack * return address ('ret') to its original value, in case the function graph * tracer has modified it to be 'return_to_handler'. If the address hasn't * been modified, the unchanged value of 'ret' is returned. * * 'idx' is a state variable which should be initialized by the caller to zero * before the first call. * * 'retp' is a pointer to the return address on the stack. It's ignored if * the arch doesn't have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR defined. */ #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, unsigned long ret, unsigned long *retp) { int index = task->curr_ret_stack; int i; if (ret != (unsigned long)return_to_handler) return ret; if (index < -1) index += FTRACE_NOTRACE_DEPTH; if (index < 0) return ret; for (i = 0; i <= index; i++) if (task->ret_stack[i].retp == retp) return task->ret_stack[i].ret; return ret; } #else /* !HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx, unsigned long ret, unsigned long *retp) { int task_idx; if (ret != (unsigned long)return_to_handler) return ret; task_idx = task->curr_ret_stack; if (!task->ret_stack || task_idx < *idx) return ret; task_idx -= *idx; (*idx)++; return task->ret_stack[task_idx].ret; } #endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */ int __trace_graph_entry(struct trace_array *tr, struct ftrace_graph_ent *trace, unsigned long flags, int pc) { struct trace_event_call *call = &event_funcgraph_entry; struct ring_buffer_event *event; struct ring_buffer *buffer = tr->trace_buffer.buffer; struct ftrace_graph_ent_entry *entry; event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_ENT, sizeof(*entry), flags, pc); if (!event) return 0; entry = ring_buffer_event_data(event); entry->graph_ent = *trace; if (!call_filter_check_discard(call, entry, buffer, event)) trace_buffer_unlock_commit_nostack(buffer, event); return 1; } static inline int ftrace_graph_ignore_irqs(void) { if (!ftrace_graph_skip_irqs || trace_recursion_test(TRACE_IRQ_BIT)) return 0; return in_irq(); } int trace_graph_entry(struct ftrace_graph_ent *trace) { struct trace_array *tr = graph_array; struct trace_array_cpu *data; unsigned long flags; long disabled; int ret; int cpu; int pc; if (!ftrace_trace_task(tr)) return 0; if (ftrace_graph_ignore_func(trace)) return 0; if (ftrace_graph_ignore_irqs()) return 0; /* * Do not trace a function if it's filtered by set_graph_notrace. * Make the index of ret stack negative to indicate that it should * ignore further functions. But it needs its own ret stack entry * to recover the original index in order to continue tracing after * returning from the function. */ if (ftrace_graph_notrace_addr(trace->func)) return 1; /* * Stop here if tracing_threshold is set. We only write function return * events to the ring buffer. */ if (tracing_thresh) return 1; local_irq_save(flags); cpu = raw_smp_processor_id(); data = per_cpu_ptr(tr->trace_buffer.data, cpu); disabled = atomic_inc_return(&data->disabled); if (likely(disabled == 1)) { pc = preempt_count(); ret = __trace_graph_entry(tr, trace, flags, pc); } else { ret = 0; } atomic_dec(&data->disabled); local_irq_restore(flags); return ret; } static void __trace_graph_function(struct trace_array *tr, unsigned long ip, unsigned long flags, int pc) { u64 time = trace_clock_local(); struct ftrace_graph_ent ent = { .func = ip, .depth = 0, }; struct ftrace_graph_ret ret = { .func = ip, .depth = 0, .calltime = time, .rettime = time, }; __trace_graph_entry(tr, &ent, flags, pc); __trace_graph_return(tr, &ret, flags, pc); } void trace_graph_function(struct trace_array *tr, unsigned long ip, unsigned long parent_ip, unsigned long flags, int pc) { __trace_graph_function(tr, ip, flags, pc); } void __trace_graph_return(struct trace_array *tr, struct ftrace_graph_ret *trace, unsigned long flags, int pc) { struct trace_event_call *call = &event_funcgraph_exit; struct ring_buffer_event *event; struct ring_buffer *buffer = tr->trace_buffer.buffer; struct ftrace_graph_ret_entry *entry; event = trace_buffer_lock_reserve(buffer, TRACE_GRAPH_RET, sizeof(*entry), flags, pc); if (!event) return; entry = ring_buffer_event_data(event); entry->ret = *trace; if (!call_filter_check_discard(call, entry, buffer, event)) trace_buffer_unlock_commit_nostack(buffer, event); } void trace_graph_return(struct ftrace_graph_ret *trace) { struct trace_array *tr = graph_array; struct trace_array_cpu *data; unsigned long flags; long disabled; int cpu; int pc; local_irq_save(flags); cpu = raw_smp_processor_id(); data = per_cpu_ptr(tr->trace_buffer.data, cpu); disabled = atomic_inc_return(&data->disabled); if (likely(disabled == 1)) { pc = preempt_count(); __trace_graph_return(tr, trace, flags, pc); } atomic_dec(&data->disabled); local_irq_restore(flags); } void set_graph_array(struct trace_array *tr) { graph_array = tr; /* Make graph_array visible before we start tracing */ smp_mb(); } static void trace_graph_thresh_return(struct ftrace_graph_ret *trace) { if (tracing_thresh && (trace->rettime - trace->calltime < tracing_thresh)) return; else trace_graph_return(trace); } static int graph_trace_init(struct trace_array *tr) { int ret; set_graph_array(tr); if (tracing_thresh) ret = register_ftrace_graph(&trace_graph_thresh_return, &trace_graph_entry); else ret = register_ftrace_graph(&trace_graph_return, &trace_graph_entry); if (ret) return ret; tracing_start_cmdline_record(); return 0; } static void graph_trace_reset(struct trace_array *tr) { tracing_stop_cmdline_record(); unregister_ftrace_graph(); } static int graph_trace_update_thresh(struct trace_array *tr) { graph_trace_reset(tr); return graph_trace_init(tr); } static int max_bytes_for_cpu; static void print_graph_cpu(struct trace_seq *s, int cpu) { /* * Start with a space character - to make it stand out * to the right a bit when trace output is pasted into * email: */ trace_seq_printf(s, " %*d) ", max_bytes_for_cpu, cpu); } #define TRACE_GRAPH_PROCINFO_LENGTH 14 static void print_graph_proc(struct trace_seq *s, pid_t pid) { char comm[TASK_COMM_LEN]; /* sign + log10(MAX_INT) + '\0' */ char pid_str[11]; int spaces = 0; int len; int i; trace_find_cmdline(pid, comm); comm[7] = '\0'; sprintf(pid_str, "%d", pid); /* 1 stands for the "-" character */ len = strlen(comm) + strlen(pid_str) + 1; if (len < TRACE_GRAPH_PROCINFO_LENGTH) spaces = TRACE_GRAPH_PROCINFO_LENGTH - len; /* First spaces to align center */ for (i = 0; i < spaces / 2; i++) trace_seq_putc(s, ' '); trace_seq_printf(s, "%s-%s", comm, pid_str); /* Last spaces to align center */ for (i = 0; i < spaces - (spaces / 2); i++) trace_seq_putc(s, ' '); } static void print_graph_lat_fmt(struct trace_seq *s, struct trace_entry *entry) { trace_seq_putc(s, ' '); trace_print_lat_fmt(s, entry); } /* If the pid changed since the last trace, output this event */ static void verif_pid(struct trace_seq *s, pid_t pid, int cpu, struct fgraph_data *data) { pid_t prev_pid; pid_t *last_pid; if (!data) return; last_pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid); if (*last_pid == pid) return; prev_pid = *last_pid; *last_pid = pid; if (prev_pid == -1) return; /* * Context-switch trace line: ------------------------------------------ | 1) migration/0--1 => sshd-1755 ------------------------------------------ */ trace_seq_puts(s, " ------------------------------------------\n"); print_graph_cpu(s, cpu); print_graph_proc(s, prev_pid); trace_seq_puts(s, " => "); print_graph_proc(s, pid); trace_seq_puts(s, "\n ------------------------------------------\n\n"); } static struct ftrace_graph_ret_entry * get_return_for_leaf(struct trace_iterator *iter, struct ftrace_graph_ent_entry *curr) { struct fgraph_data *data = iter->private; struct ring_buffer_iter *ring_iter = NULL; struct ring_buffer_event *event; struct ftrace_graph_ret_entry *next; /* * If the previous output failed to write to the seq buffer, * then we just reuse the data from before. */ if (data && data->failed) { curr = &data->ent; next = &data->ret; } else { ring_iter = trace_buffer_iter(iter, iter->cpu); /* First peek to compare current entry and the next one */ if (ring_iter) event = ring_buffer_iter_peek(ring_iter, NULL); else { /* * We need to consume the current entry to see * the next one. */ ring_buffer_consume(iter->trace_buffer->buffer, iter->cpu, NULL, NULL); event = ring_buffer_peek(iter->trace_buffer->buffer, iter->cpu, NULL, NULL); } if (!event) return NULL; next = ring_buffer_event_data(event); if (data) { /* * Save current and next entries for later reference * if the output fails. */ data->ent = *curr; /* * If the next event is not a return type, then * we only care about what type it is. Otherwise we can * safely copy the entire event. */ if (next->ent.type == TRACE_GRAPH_RET) data->ret = *next; else data->ret.ent.type = next->ent.type; } } if (next->ent.type != TRACE_GRAPH_RET) return NULL; if (curr->ent.pid != next->ent.pid || curr->graph_ent.func != next->ret.func) return NULL; /* this is a leaf, now advance the iterator */ if (ring_iter) ring_buffer_read(ring_iter, NULL); return next; } static void print_graph_abs_time(u64 t, struct trace_seq *s) { unsigned long usecs_rem; usecs_rem = do_div(t, NSEC_PER_SEC); usecs_rem /= 1000; trace_seq_printf(s, "%5lu.%06lu | ", (unsigned long)t, usecs_rem); } static void print_graph_irq(struct trace_iterator *iter, unsigned long addr, enum trace_type type, int cpu, pid_t pid, u32 flags) { struct trace_array *tr = iter->tr; struct trace_seq *s = &iter->seq; struct trace_entry *ent = iter->ent; if (addr < (unsigned long)__irqentry_text_start || addr >= (unsigned long)__irqentry_text_end) return; if (tr->trace_flags & TRACE_ITER_CONTEXT_INFO) { /* Absolute time */ if (flags & TRACE_GRAPH_PRINT_ABS_TIME) print_graph_abs_time(iter->ts, s); /* Cpu */ if (flags & TRACE_GRAPH_PRINT_CPU) print_graph_cpu(s, cpu); /* Proc */ if (flags & TRACE_GRAPH_PRINT_PROC) { print_graph_proc(s, pid); trace_seq_puts(s, " | "); } /* Latency format */ if (tr->trace_flags & TRACE_ITER_LATENCY_FMT) print_graph_lat_fmt(s, ent); } /* No overhead */ print_graph_duration(tr, 0, s, flags | FLAGS_FILL_START); if (type == TRACE_GRAPH_ENT) trace_seq_puts(s, "==========>"); else trace_seq_puts(s, "<=========="); print_graph_duration(tr, 0, s, flags | FLAGS_FILL_END); trace_seq_putc(s, '\n'); } void trace_print_graph_duration(unsigned long long duration, struct trace_seq *s) { unsigned long nsecs_rem = do_div(duration, 1000); /* log10(ULONG_MAX) + '\0' */ char usecs_str[21]; char nsecs_str[5]; int len; int i; sprintf(usecs_str, "%lu", (unsigned long) duration); /* Print msecs */ trace_seq_printf(s, "%s", usecs_str); len = strlen(usecs_str); /* Print nsecs (we don't want to exceed 7 numbers) */ if (len < 7) { size_t slen = min_t(size_t, sizeof(nsecs_str), 8UL - len); snprintf(nsecs_str, slen, "%03lu", nsecs_rem); trace_seq_printf(s, ".%s", nsecs_str); len += strlen(nsecs_str) + 1; } trace_seq_puts(s, " us "); /* Print remaining spaces to fit the row's width */ for (i = len; i < 8; i++) trace_seq_putc(s, ' '); } static void print_graph_duration(struct trace_array *tr, unsigned long long duration, struct trace_seq *s, u32 flags) { if (!(flags & TRACE_GRAPH_PRINT_DURATION) || !(tr->trace_flags & TRACE_ITER_CONTEXT_INFO)) return; /* No real adata, just filling the column with spaces */ switch (flags & TRACE_GRAPH_PRINT_FILL_MASK) { case FLAGS_FILL_FULL: trace_seq_puts(s, " | "); return; case FLAGS_FILL_START: trace_seq_puts(s, " "); return; case FLAGS_FILL_END: trace_seq_puts(s, " |"); return; } /* Signal a overhead of time execution to the output */ if (flags & TRACE_GRAPH_PRINT_OVERHEAD) trace_seq_printf(s, "%c ", trace_find_mark(duration)); else trace_seq_puts(s, " "); trace_print_graph_duration(duration, s); trace_seq_puts(s, "| "); } /* Case of a leaf function on its call entry */ static enum print_line_t print_graph_entry_leaf(struct trace_iterator *iter, struct ftrace_graph_ent_entry *entry, struct ftrace_graph_ret_entry *ret_entry, struct trace_seq *s, u32 flags) { struct fgraph_data *data = iter->private; struct trace_array *tr = iter->tr; struct ftrace_graph_ret *graph_ret; struct ftrace_graph_ent *call; unsigned long long duration; int cpu = iter->cpu; int i; graph_ret = &ret_entry->ret; call = &entry->graph_ent; duration = graph_ret->rettime - graph_ret->calltime; if (data) { struct fgraph_cpu_data *cpu_data; cpu_data = per_cpu_ptr(data->cpu_data, cpu); /* If a graph tracer ignored set_graph_notrace */ if (call->depth < -1) call->depth += FTRACE_NOTRACE_DEPTH; /* * Comments display at + 1 to depth. Since * this is a leaf function, keep the comments * equal to this depth. */ cpu_data->depth = call->depth - 1; /* No need to keep this function around for this depth */ if (call->depth < FTRACE_RETFUNC_DEPTH && !WARN_ON_ONCE(call->depth < 0)) cpu_data->enter_funcs[call->depth] = 0; } /* Overhead and duration */ print_graph_duration(tr, duration, s, flags); /* Function */ for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) trace_seq_putc(s, ' '); trace_seq_printf(s, "%ps();\n", (void *)call->func); print_graph_irq(iter, graph_ret->func, TRACE_GRAPH_RET, cpu, iter->ent->pid, flags); return trace_handle_return(s); } static enum print_line_t print_graph_entry_nested(struct trace_iterator *iter, struct ftrace_graph_ent_entry *entry, struct trace_seq *s, int cpu, u32 flags) { struct ftrace_graph_ent *call = &entry->graph_ent; struct fgraph_data *data = iter->private; struct trace_array *tr = iter->tr; int i; if (data) { struct fgraph_cpu_data *cpu_data; int cpu = iter->cpu; /* If a graph tracer ignored set_graph_notrace */ if (call->depth < -1) call->depth += FTRACE_NOTRACE_DEPTH; cpu_data = per_cpu_ptr(data->cpu_data, cpu); cpu_data->depth = call->depth; /* Save this function pointer to see if the exit matches */ if (call->depth < FTRACE_RETFUNC_DEPTH && !WARN_ON_ONCE(call->depth < 0)) cpu_data->enter_funcs[call->depth] = call->func; } /* No time */ print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL); /* Function */ for (i = 0; i < call->depth * TRACE_GRAPH_INDENT; i++) trace_seq_putc(s, ' '); trace_seq_printf(s, "%ps() {\n", (void *)call->func); if (trace_seq_has_overflowed(s)) return TRACE_TYPE_PARTIAL_LINE; /* * we already consumed the current entry to check the next one * and see if this is a leaf. */ return TRACE_TYPE_NO_CONSUME; } static void print_graph_prologue(struct trace_iterator *iter, struct trace_seq *s, int type, unsigned long addr, u32 flags) { struct fgraph_data *data = iter->private; struct trace_entry *ent = iter->ent; struct trace_array *tr = iter->tr; int cpu = iter->cpu; /* Pid */ verif_pid(s, ent->pid, cpu, data); if (type) /* Interrupt */ print_graph_irq(iter, addr, type, cpu, ent->pid, flags); if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO)) return; /* Absolute time */ if (flags & TRACE_GRAPH_PRINT_ABS_TIME) print_graph_abs_time(iter->ts, s); /* Cpu */ if (flags & TRACE_GRAPH_PRINT_CPU) print_graph_cpu(s, cpu); /* Proc */ if (flags & TRACE_GRAPH_PRINT_PROC) { print_graph_proc(s, ent->pid); trace_seq_puts(s, " | "); } /* Latency format */ if (tr->trace_flags & TRACE_ITER_LATENCY_FMT) print_graph_lat_fmt(s, ent); return; } /* * Entry check for irq code * * returns 1 if * - we are inside irq code * - we just entered irq code * * retunns 0 if * - funcgraph-interrupts option is set * - we are not inside irq code */ static int check_irq_entry(struct trace_iterator *iter, u32 flags, unsigned long addr, int depth) { int cpu = iter->cpu; int *depth_irq; struct fgraph_data *data = iter->private; /* * If we are either displaying irqs, or we got called as * a graph event and private data does not exist, * then we bypass the irq check. */ if ((flags & TRACE_GRAPH_PRINT_IRQS) || (!data)) return 0; depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq); /* * We are inside the irq code */ if (*depth_irq >= 0) return 1; if ((addr < (unsigned long)__irqentry_text_start) || (addr >= (unsigned long)__irqentry_text_end)) return 0; /* * We are entering irq code. */ *depth_irq = depth; return 1; } /* * Return check for irq code * * returns 1 if * - we are inside irq code * - we just left irq code * * returns 0 if * - funcgraph-interrupts option is set * - we are not inside irq code */ static int check_irq_return(struct trace_iterator *iter, u32 flags, int depth) { int cpu = iter->cpu; int *depth_irq; struct fgraph_data *data = iter->private; /* * If we are either displaying irqs, or we got called as * a graph event and private data does not exist, * then we bypass the irq check. */ if ((flags & TRACE_GRAPH_PRINT_IRQS) || (!data)) return 0; depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq); /* * We are not inside the irq code. */ if (*depth_irq == -1) return 0; /* * We are inside the irq code, and this is returning entry. * Let's not trace it and clear the entry depth, since * we are out of irq code. * * This condition ensures that we 'leave the irq code' once * we are out of the entry depth. Thus protecting us from * the RETURN entry loss. */ if (*depth_irq >= depth) { *depth_irq = -1; return 1; } /* * We are inside the irq code, and this is not the entry. */ return 1; } static enum print_line_t print_graph_entry(struct ftrace_graph_ent_entry *field, struct trace_seq *s, struct trace_iterator *iter, u32 flags) { struct fgraph_data *data = iter->private; struct ftrace_graph_ent *call = &field->graph_ent; struct ftrace_graph_ret_entry *leaf_ret; static enum print_line_t ret; int cpu = iter->cpu; if (check_irq_entry(iter, flags, call->func, call->depth)) return TRACE_TYPE_HANDLED; print_graph_prologue(iter, s, TRACE_GRAPH_ENT, call->func, flags); leaf_ret = get_return_for_leaf(iter, field); if (leaf_ret) ret = print_graph_entry_leaf(iter, field, leaf_ret, s, flags); else ret = print_graph_entry_nested(iter, field, s, cpu, flags); if (data) { /* * If we failed to write our output, then we need to make * note of it. Because we already consumed our entry. */ if (s->full) { data->failed = 1; data->cpu = cpu; } else data->failed = 0; } return ret; } static enum print_line_t print_graph_return(struct ftrace_graph_ret *trace, struct trace_seq *s, struct trace_entry *ent, struct trace_iterator *iter, u32 flags) { unsigned long long duration = trace->rettime - trace->calltime; struct fgraph_data *data = iter->private; struct trace_array *tr = iter->tr; pid_t pid = ent->pid; int cpu = iter->cpu; int func_match = 1; int i; if (check_irq_return(iter, flags, trace->depth)) return TRACE_TYPE_HANDLED; if (data) { struct fgraph_cpu_data *cpu_data; int cpu = iter->cpu; cpu_data = per_cpu_ptr(data->cpu_data, cpu); /* * Comments display at + 1 to depth. This is the * return from a function, we now want the comments * to display at the same level of the bracket. */ cpu_data->depth = trace->depth - 1; if (trace->depth < FTRACE_RETFUNC_DEPTH && !WARN_ON_ONCE(trace->depth < 0)) { if (cpu_data->enter_funcs[trace->depth] != trace->func) func_match = 0; cpu_data->enter_funcs[trace->depth] = 0; } } print_graph_prologue(iter, s, 0, 0, flags); /* Overhead and duration */ print_graph_duration(tr, duration, s, flags); /* Closing brace */ for (i = 0; i < trace->depth * TRACE_GRAPH_INDENT; i++) trace_seq_putc(s, ' '); /* * If the return function does not have a matching entry, * then the entry was lost. Instead of just printing * the '}' and letting the user guess what function this * belongs to, write out the function name. Always do * that if the funcgraph-tail option is enabled. */ if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL)) trace_seq_puts(s, "}\n"); else trace_seq_printf(s, "} /* %ps */\n", (void *)trace->func); /* Overrun */ if (flags & TRACE_GRAPH_PRINT_OVERRUN) trace_seq_printf(s, " (Overruns: %lu)\n", trace->overrun); print_graph_irq(iter, trace->func, TRACE_GRAPH_RET, cpu, pid, flags); return trace_handle_return(s); } static enum print_line_t print_graph_comment(struct trace_seq *s, struct trace_entry *ent, struct trace_iterator *iter, u32 flags) { struct trace_array *tr = iter->tr; unsigned long sym_flags = (tr->trace_flags & TRACE_ITER_SYM_MASK); struct fgraph_data *data = iter->private; struct trace_event *event; int depth = 0; int ret; int i; if (data) depth = per_cpu_ptr(data->cpu_data, iter->cpu)->depth; print_graph_prologue(iter, s, 0, 0, flags); /* No time */ print_graph_duration(tr, 0, s, flags | FLAGS_FILL_FULL); /* Indentation */ if (depth > 0) for (i = 0; i < (depth + 1) * TRACE_GRAPH_INDENT; i++) trace_seq_putc(s, ' '); /* The comment */ trace_seq_puts(s, "/* "); switch (iter->ent->type) { case TRACE_BPUTS: ret = trace_print_bputs_msg_only(iter); if (ret != TRACE_TYPE_HANDLED) return ret; break; case TRACE_BPRINT: ret = trace_print_bprintk_msg_only(iter); if (ret != TRACE_TYPE_HANDLED) return ret; break; case TRACE_PRINT: ret = trace_print_printk_msg_only(iter); if (ret != TRACE_TYPE_HANDLED) return ret; break; default: event = ftrace_find_event(ent->type); if (!event) return TRACE_TYPE_UNHANDLED; ret = event->funcs->trace(iter, sym_flags, event); if (ret != TRACE_TYPE_HANDLED) return ret; } if (trace_seq_has_overflowed(s)) goto out; /* Strip ending newline */ if (s->buffer[s->seq.len - 1] == '\n') { s->buffer[s->seq.len - 1] = '\0'; s->seq.len--; } trace_seq_puts(s, " */\n"); out: return trace_handle_return(s); } enum print_line_t print_graph_function_flags(struct trace_iterator *iter, u32 flags) { struct ftrace_graph_ent_entry *field; struct fgraph_data *data = iter->private; struct trace_entry *entry = iter->ent; struct trace_seq *s = &iter->seq; int cpu = iter->cpu; int ret; if (data && per_cpu_ptr(data->cpu_data, cpu)->ignore) { per_cpu_ptr(data->cpu_data, cpu)->ignore = 0; return TRACE_TYPE_HANDLED; } /* * If the last output failed, there's a possibility we need * to print out the missing entry which would never go out. */ if (data && data->failed) { field = &data->ent; iter->cpu = data->cpu; ret = print_graph_entry(field, s, iter, flags); if (ret == TRACE_TYPE_HANDLED && iter->cpu != cpu) { per_cpu_ptr(data->cpu_data, iter->cpu)->ignore = 1; ret = TRACE_TYPE_NO_CONSUME; } iter->cpu = cpu; return ret; } switch (entry->type) { case TRACE_GRAPH_ENT: { /* * print_graph_entry() may consume the current event, * thus @field may become invalid, so we need to save it. * sizeof(struct ftrace_graph_ent_entry) is very small, * it can be safely saved at the stack. */ struct ftrace_graph_ent_entry saved; trace_assign_type(field, entry); saved = *field; return print_graph_entry(&saved, s, iter, flags); } case TRACE_GRAPH_RET: { struct ftrace_graph_ret_entry *field; trace_assign_type(field, entry); return print_graph_return(&field->ret, s, entry, iter, flags); } case TRACE_STACK: case TRACE_FN: /* dont trace stack and functions as comments */ return TRACE_TYPE_UNHANDLED; default: return print_graph_comment(s, entry, iter, flags); } return TRACE_TYPE_HANDLED; } static enum print_line_t print_graph_function(struct trace_iterator *iter) { return print_graph_function_flags(iter, tracer_flags.val); } static enum print_line_t print_graph_function_event(struct trace_iterator *iter, int flags, struct trace_event *event) { return print_graph_function(iter); } static void print_lat_header(struct seq_file *s, u32 flags) { static const char spaces[] = " " /* 16 spaces */ " " /* 4 spaces */ " "; /* 17 spaces */ int size = 0; if (flags & TRACE_GRAPH_PRINT_ABS_TIME) size += 16; if (flags & TRACE_GRAPH_PRINT_CPU) size += 4; if (flags & TRACE_GRAPH_PRINT_PROC) size += 17; seq_printf(s, "#%.*s _-----=> irqs-off \n", size, spaces); seq_printf(s, "#%.*s / _----=> need-resched \n", size, spaces); seq_printf(s, "#%.*s| / _---=> hardirq/softirq \n", size, spaces); seq_printf(s, "#%.*s|| / _--=> preempt-depth \n", size, spaces); seq_printf(s, "#%.*s||| / \n", size, spaces); } static void __print_graph_headers_flags(struct trace_array *tr, struct seq_file *s, u32 flags) { int lat = tr->trace_flags & TRACE_ITER_LATENCY_FMT; if (lat) print_lat_header(s, flags); /* 1st line */ seq_putc(s, '#'); if (flags & TRACE_GRAPH_PRINT_ABS_TIME) seq_puts(s, " TIME "); if (flags & TRACE_GRAPH_PRINT_CPU) seq_puts(s, " CPU"); if (flags & TRACE_GRAPH_PRINT_PROC) seq_puts(s, " TASK/PID "); if (lat) seq_puts(s, "||||"); if (flags & TRACE_GRAPH_PRINT_DURATION) seq_puts(s, " DURATION "); seq_puts(s, " FUNCTION CALLS\n"); /* 2nd line */ seq_putc(s, '#'); if (flags & TRACE_GRAPH_PRINT_ABS_TIME) seq_puts(s, " | "); if (flags & TRACE_GRAPH_PRINT_CPU) seq_puts(s, " | "); if (flags & TRACE_GRAPH_PRINT_PROC) seq_puts(s, " | | "); if (lat) seq_puts(s, "||||"); if (flags & TRACE_GRAPH_PRINT_DURATION) seq_puts(s, " | | "); seq_puts(s, " | | | |\n"); } static void print_graph_headers(struct seq_file *s) { print_graph_headers_flags(s, tracer_flags.val); } void print_graph_headers_flags(struct seq_file *s, u32 flags) { struct trace_iterator *iter = s->private; struct trace_array *tr = iter->tr; if (!(tr->trace_flags & TRACE_ITER_CONTEXT_INFO)) return; if (tr->trace_flags & TRACE_ITER_LATENCY_FMT) { /* print nothing if the buffers are empty */ if (trace_empty(iter)) return; print_trace_header(s, iter); } __print_graph_headers_flags(tr, s, flags); } void graph_trace_open(struct trace_iterator *iter) { /* pid and depth on the last trace processed */ struct fgraph_data *data; gfp_t gfpflags; int cpu; iter->private = NULL; /* We can be called in atomic context via ftrace_dump() */ gfpflags = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL; data = kzalloc(sizeof(*data), gfpflags); if (!data) goto out_err; data->cpu_data = alloc_percpu_gfp(struct fgraph_cpu_data, gfpflags); if (!data->cpu_data) goto out_err_free; for_each_possible_cpu(cpu) { pid_t *pid = &(per_cpu_ptr(data->cpu_data, cpu)->last_pid); int *depth = &(per_cpu_ptr(data->cpu_data, cpu)->depth); int *ignore = &(per_cpu_ptr(data->cpu_data, cpu)->ignore); int *depth_irq = &(per_cpu_ptr(data->cpu_data, cpu)->depth_irq); *pid = -1; *depth = 0; *ignore = 0; *depth_irq = -1; } iter->private = data; return; out_err_free: kfree(data); out_err: pr_warn("function graph tracer: not enough memory\n"); } void graph_trace_close(struct trace_iterator *iter) { struct fgraph_data *data = iter->private; if (data) { free_percpu(data->cpu_data); kfree(data); } } static int func_graph_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) { if (bit == TRACE_GRAPH_PRINT_IRQS) ftrace_graph_skip_irqs = !set; if (bit == TRACE_GRAPH_SLEEP_TIME) ftrace_graph_sleep_time_control(set); if (bit == TRACE_GRAPH_GRAPH_TIME) ftrace_graph_graph_time_control(set); return 0; } static struct trace_event_functions graph_functions = { .trace = print_graph_function_event, }; static struct trace_event graph_trace_entry_event = { .type = TRACE_GRAPH_ENT, .funcs = &graph_functions, }; static struct trace_event graph_trace_ret_event = { .type = TRACE_GRAPH_RET, .funcs = &graph_functions }; static struct tracer graph_trace __tracer_data = { .name = "function_graph", .update_thresh = graph_trace_update_thresh, .open = graph_trace_open, .pipe_open = graph_trace_open, .close = graph_trace_close, .pipe_close = graph_trace_close, .init = graph_trace_init, .reset = graph_trace_reset, .print_line = print_graph_function, .print_header = print_graph_headers, .flags = &tracer_flags, .set_flag = func_graph_set_flag, #ifdef CONFIG_FTRACE_SELFTEST .selftest = trace_selftest_startup_function_graph, #endif }; static ssize_t graph_depth_write(struct file *filp, const char __user *ubuf, size_t cnt, loff_t *ppos) { unsigned long val; int ret; ret = kstrtoul_from_user(ubuf, cnt, 10, &val); if (ret) return ret; fgraph_max_depth = val; *ppos += cnt; return cnt; } static ssize_t graph_depth_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) { char buf[15]; /* More than enough to hold UINT_MAX + "\n"*/ int n; n = sprintf(buf, "%d\n", fgraph_max_depth); return simple_read_from_buffer(ubuf, cnt, ppos, buf, n); } static const struct file_operations graph_depth_fops = { .open = tracing_open_generic, .write = graph_depth_write, .read = graph_depth_read, .llseek = generic_file_llseek, }; static __init int init_graph_tracefs(void) { struct dentry *d_tracer; d_tracer = tracing_init_dentry(); if (IS_ERR(d_tracer)) return 0; trace_create_file("max_graph_depth", 0644, d_tracer, NULL, &graph_depth_fops); return 0; } fs_initcall(init_graph_tracefs); static __init int init_graph_trace(void) { max_bytes_for_cpu = snprintf(NULL, 0, "%u", nr_cpu_ids - 1); if (!register_trace_event(&graph_trace_entry_event)) { pr_warn("Warning: could not register graph trace events\n"); return 1; } if (!register_trace_event(&graph_trace_ret_event)) { pr_warn("Warning: could not register graph trace events\n"); return 1; } return register_tracer(&graph_trace); } core_initcall(init_graph_trace);