/* * ring buffer based function tracer * * Copyright (C) 2007-2012 Steven Rostedt * Copyright (C) 2008 Ingo Molnar * * Originally taken from the RT patch by: * Arnaldo Carvalho de Melo * * Based on code from the latency_tracer, that is: * Copyright (C) 2004-2006 Ingo Molnar * Copyright (C) 2004 Nadia Yvette Chambers */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "trace.h" #include "trace_output.h" /* * On boot up, the ring buffer is set to the minimum size, so that * we do not waste memory on systems that are not using tracing. */ bool ring_buffer_expanded; /* * We need to change this state when a selftest is running. * A selftest will lurk into the ring-buffer to count the * entries inserted during the selftest although some concurrent * insertions into the ring-buffer such as trace_printk could occurred * at the same time, giving false positive or negative results. */ static bool __read_mostly tracing_selftest_running; /* * If a tracer is running, we do not want to run SELFTEST. */ bool __read_mostly tracing_selftest_disabled; /* Pipe tracepoints to printk */ struct trace_iterator *tracepoint_print_iter; int tracepoint_printk; static DEFINE_STATIC_KEY_FALSE(tracepoint_printk_key); /* For tracers that don't implement custom flags */ static struct tracer_opt dummy_tracer_opt[] = { { } }; static int dummy_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) { return 0; } /* * To prevent the comm cache from being overwritten when no * tracing is active, only save the comm when a trace event * occurred. */ static DEFINE_PER_CPU(bool, trace_cmdline_save); /* * Kill all tracing for good (never come back). * It is initialized to 1 but will turn to zero if the initialization * of the tracer is successful. But that is the only place that sets * this back to zero. */ static int tracing_disabled = 1; cpumask_var_t __read_mostly tracing_buffer_mask; /* * ftrace_dump_on_oops - variable to dump ftrace buffer on oops * * If there is an oops (or kernel panic) and the ftrace_dump_on_oops * is set, then ftrace_dump is called. This will output the contents * of the ftrace buffers to the console. This is very useful for * capturing traces that lead to crashes and outputing it to a * serial console. * * It is default off, but you can enable it with either specifying * "ftrace_dump_on_oops" in the kernel command line, or setting * /proc/sys/kernel/ftrace_dump_on_oops * Set 1 if you want to dump buffers of all CPUs * Set 2 if you want to dump the buffer of the CPU that triggered oops */ enum ftrace_dump_mode ftrace_dump_on_oops; /* When set, tracing will stop when a WARN*() is hit */ int __disable_trace_on_warning; #ifdef CONFIG_TRACE_ENUM_MAP_FILE /* Map of enums to their values, for "enum_map" file */ struct trace_enum_map_head { struct module *mod; unsigned long length; }; union trace_enum_map_item; struct trace_enum_map_tail { /* * "end" is first and points to NULL as it must be different * than "mod" or "enum_string" */ union trace_enum_map_item *next; const char *end; /* points to NULL */ }; static DEFINE_MUTEX(trace_enum_mutex); /* * The trace_enum_maps are saved in an array with two extra elements, * one at the beginning, and one at the end. The beginning item contains * the count of the saved maps (head.length), and the module they * belong to if not built in (head.mod). The ending item contains a * pointer to the next array of saved enum_map items. */ union trace_enum_map_item { struct trace_enum_map map; struct trace_enum_map_head head; struct trace_enum_map_tail tail; }; static union trace_enum_map_item *trace_enum_maps; #endif /* CONFIG_TRACE_ENUM_MAP_FILE */ static int tracing_set_tracer(struct trace_array *tr, const char *buf); #define MAX_TRACER_SIZE 100 static char bootup_tracer_buf[MAX_TRACER_SIZE] __initdata; static char *default_bootup_tracer; static bool allocate_snapshot; static int __init set_cmdline_ftrace(char *str) { strlcpy(bootup_tracer_buf, str, MAX_TRACER_SIZE); default_bootup_tracer = bootup_tracer_buf; /* We are using ftrace early, expand it */ ring_buffer_expanded = true; return 1; } __setup("ftrace=", set_cmdline_ftrace); static int __init set_ftrace_dump_on_oops(char *str) { if (*str++ != '=' || !*str) { ftrace_dump_on_oops = DUMP_ALL; return 1; } if (!strcmp("orig_cpu", str)) { ftrace_dump_on_oops = DUMP_ORIG; return 1; } return 0; } __setup("ftrace_dump_on_oops", set_ftrace_dump_on_oops); static int __init stop_trace_on_warning(char *str) { if ((strcmp(str, "=0") != 0 && strcmp(str, "=off") != 0)) __disable_trace_on_warning = 1; return 1; } __setup("traceoff_on_warning", stop_trace_on_warning); static int __init boot_alloc_snapshot(char *str) { allocate_snapshot = true; /* We also need the main ring buffer expanded */ ring_buffer_expanded = true; return 1; } __setup("alloc_snapshot", boot_alloc_snapshot); static char trace_boot_options_buf[MAX_TRACER_SIZE] __initdata; static int __init set_trace_boot_options(char *str) { strlcpy(trace_boot_options_buf, str, MAX_TRACER_SIZE); return 0; } __setup("trace_options=", set_trace_boot_options); static char trace_boot_clock_buf[MAX_TRACER_SIZE] __initdata; static char *trace_boot_clock __initdata; static int __init set_trace_boot_clock(char *str) { strlcpy(trace_boot_clock_buf, str, MAX_TRACER_SIZE); trace_boot_clock = trace_boot_clock_buf; return 0; } __setup("trace_clock=", set_trace_boot_clock); static int __init set_tracepoint_printk(char *str) { if ((strcmp(str, "=0") != 0 && strcmp(str, "=off") != 0)) tracepoint_printk = 1; return 1; } __setup("tp_printk", set_tracepoint_printk); unsigned long long ns2usecs(u64 nsec) { nsec += 500; do_div(nsec, 1000); return nsec; } /* trace_flags holds trace_options default values */ #define TRACE_DEFAULT_FLAGS \ (FUNCTION_DEFAULT_FLAGS | \ TRACE_ITER_PRINT_PARENT | TRACE_ITER_PRINTK | \ TRACE_ITER_ANNOTATE | TRACE_ITER_CONTEXT_INFO | \ TRACE_ITER_RECORD_CMD | TRACE_ITER_OVERWRITE | \ TRACE_ITER_IRQ_INFO | TRACE_ITER_MARKERS) /* trace_options that are only supported by global_trace */ #define TOP_LEVEL_TRACE_FLAGS (TRACE_ITER_PRINTK | \ TRACE_ITER_PRINTK_MSGONLY | TRACE_ITER_RECORD_CMD) /* trace_flags that are default zero for instances */ #define ZEROED_TRACE_FLAGS \ (TRACE_ITER_EVENT_FORK | TRACE_ITER_FUNC_FORK) /* * The global_trace is the descriptor that holds the top-level tracing * buffers for the live tracing. */ static struct trace_array global_trace = { .trace_flags = TRACE_DEFAULT_FLAGS, }; LIST_HEAD(ftrace_trace_arrays); int trace_array_get(struct trace_array *this_tr) { struct trace_array *tr; int ret = -ENODEV; mutex_lock(&trace_types_lock); list_for_each_entry(tr, &ftrace_trace_arrays, list) { if (tr == this_tr) { tr->ref++; ret = 0; break; } } mutex_unlock(&trace_types_lock); return ret; } static void __trace_array_put(struct trace_array *this_tr) { WARN_ON(!this_tr->ref); this_tr->ref--; } void trace_array_put(struct trace_array *this_tr) { mutex_lock(&trace_types_lock); __trace_array_put(this_tr); mutex_unlock(&trace_types_lock); } int call_filter_check_discard(struct trace_event_call *call, void *rec, struct ring_buffer *buffer, struct ring_buffer_event *event) { if (unlikely(call->flags & TRACE_EVENT_FL_FILTERED) && !filter_match_preds(call->filter, rec)) { __trace_event_discard_commit(buffer, event); return 1; } return 0; } void trace_free_pid_list(struct trace_pid_list *pid_list) { vfree(pid_list->pids); kfree(pid_list); } /** * trace_find_filtered_pid - check if a pid exists in a filtered_pid list * @filtered_pids: The list of pids to check * @search_pid: The PID to find in @filtered_pids * * Returns true if @search_pid is fonud in @filtered_pids, and false otherwis. */ bool trace_find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid) { /* * If pid_max changed after filtered_pids was created, we * by default ignore all pids greater than the previous pid_max. */ if (search_pid >= filtered_pids->pid_max) return false; return test_bit(search_pid, filtered_pids->pids); } /** * trace_ignore_this_task - should a task be ignored for tracing * @filtered_pids: The list of pids to check * @task: The task that should be ignored if not filtered * * Checks if @task should be traced or not from @filtered_pids. * Returns true if @task should *NOT* be traced. * Returns false if @task should be traced. */ bool trace_ignore_this_task(struct trace_pid_list *filtered_pids, struct task_struct *task) { /* * Return false, because if filtered_pids does not exist, * all pids are good to trace. */ if (!filtered_pids) return false; return !trace_find_filtered_pid(filtered_pids, task->pid); } /** * trace_pid_filter_add_remove - Add or remove a task from a pid_list * @pid_list: The list to modify * @self: The current task for fork or NULL for exit * @task: The task to add or remove * * If adding a task, if @self is defined, the task is only added if @self * is also included in @pid_list. This happens on fork and tasks should * only be added when the parent is listed. If @self is NULL, then the * @task pid will be removed from the list, which would happen on exit * of a task. */ void trace_filter_add_remove_task(struct trace_pid_list *pid_list, struct task_struct *self, struct task_struct *task) { if (!pid_list) return; /* For forks, we only add if the forking task is listed */ if (self) { if (!trace_find_filtered_pid(pid_list, self->pid)) return; } /* Sorry, but we don't support pid_max changing after setting */ if (task->pid >= pid_list->pid_max) return; /* "self" is set for forks, and NULL for exits */ if (self) set_bit(task->pid, pid_list->pids); else clear_bit(task->pid, pid_list->pids); } /** * trace_pid_next - Used for seq_file to get to the next pid of a pid_list * @pid_list: The pid list to show * @v: The last pid that was shown (+1 the actual pid to let zero be displayed) * @pos: The position of the file * * This is used by the seq_file "next" operation to iterate the pids * listed in a trace_pid_list structure. * * Returns the pid+1 as we want to display pid of zero, but NULL would * stop the iteration. */ void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos) { unsigned long pid = (unsigned long)v; (*pos)++; /* pid already is +1 of the actual prevous bit */ pid = find_next_bit(pid_list->pids, pid_list->pid_max, pid); /* Return pid + 1 to allow zero to be represented */ if (pid < pid_list->pid_max) return (void *)(pid + 1); return NULL; } /** * trace_pid_start - Used for seq_file to start reading pid lists * @pid_list: The pid list to show * @pos: The position of the file * * This is used by seq_file "start" operation to start the iteration * of listing pids. * * Returns the pid+1 as we want to display pid of zero, but NULL would * stop the iteration. */ void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos) { unsigned long pid; loff_t l = 0; pid = find_first_bit(pid_list->pids, pid_list->pid_max); if (pid >= pid_list->pid_max) return NULL; /* Return pid + 1 so that zero can be the exit value */ for (pid++; pid && l < *pos; pid = (unsigned long)trace_pid_next(pid_list, (void *)pid, &l)) ; return (void *)pid; } /** * trace_pid_show - show the current pid in seq_file processing * @m: The seq_file structure to write into * @v: A void pointer of the pid (+1) value to display * * Can be directly used by seq_file operations to display the current * pid value. */ int trace_pid_show(struct seq_file *m, void *v) { unsigned long pid = (unsigned long)v - 1; seq_printf(m, "%lu\n", pid); return 0; } /* 128 should be much more than enough */ #define PID_BUF_SIZE 127 int trace_pid_write(struct trace_pid_list *filtered_pids, struct trace_pid_list **new_pid_list, const char __user *ubuf, size_t cnt) { struct trace_pid_list *pid_list; struct trace_parser parser; unsigned long val; int nr_pids = 0; ssize_t read = 0; ssize_t ret = 0; loff_t pos; pid_t pid; if (trace_parser_get_init(&parser, PID_BUF_SIZE + 1)) return -ENOMEM; /* * Always recreate a new array. The write is an all or nothing * operation. Always create a new array when adding new pids by * the user. If the operation fails, then the current list is * not modified. */ pid_list = kmalloc(sizeof(*pid_list), GFP_KERNEL); if (!pid_list) return -ENOMEM; pid_list->pid_max = READ_ONCE(pid_max); /* Only truncating will shrink pid_max */ if (filtered_pids && filtered_pids->pid_max > pid_list->pid_max) pid_list->pid_max = filtered_pids->pid_max; pid_list->pids = vzalloc((pid_list->pid_max + 7) >> 3); if (!pid_list->pids) { kfree(pid_list); return -ENOMEM; } if (filtered_pids) { /* copy the current bits to the new max */ for_each_set_bit(pid, filtered_pids->pids, filtered_pids->pid_max) { set_bit(pid, pid_list->pids); nr_pids++; } } while (cnt > 0) { pos = 0; ret = trace_get_user(&parser, ubuf, cnt, &pos); if (ret < 0 || !trace_parser_loaded(&parser)) break; read += ret; ubuf += ret; cnt -= ret; parser.buffer[parser.idx] = 0; ret = -EINVAL; if (kstrtoul(parser.buffer, 0, &val)) break; if (val >= pid_list->pid_max) break; pid = (pid_t)val; set_bit(pid, pid_list->pids); nr_pids++; trace_parser_clear(&parser); ret = 0; } trace_parser_put(&parser); if (ret < 0) { trace_free_pid_list(pid_list); return ret; } if (!nr_pids) { /* Cleared the list of pids */ trace_free_pid_list(pid_list); read = ret; pid_list = NULL; } *new_pid_list = pid_list; return read; } static u64 buffer_ftrace_now(struct trace_buffer *buf, int cpu) { u64 ts; /* Early boot up does not have a buffer yet */ if (!buf->buffer) return trace_clock_local(); ts = ring_buffer_time_stamp(buf->buffer, cpu); ring_buffer_normalize_time_stamp(buf->buffer, cpu, &ts); return ts; } u64 ftrace_now(int cpu) { return buffer_ftrace_now(&global_trace.trace_buffer, cpu); } /** * tracing_is_enabled - Show if global_trace has been disabled * * Shows if the global trace has been enabled or not. It uses the * mirror flag "buffer_disabled" to be used in fast paths such as for * the irqsoff tracer. But it may be inaccurate due to races. If you * need to know the accurate state, use tracing_is_on() which is a little * slower, but accurate. */ int tracing_is_enabled(void) { /* * For quick access (irqsoff uses this in fast path), just * return the mirror variable of the state of the ring buffer. * It's a little racy, but we don't really care. */ smp_rmb(); return !global_trace.buffer_disabled; } /* * trace_buf_size is the size in bytes that is allocated * for a buffer. Note, the number of bytes is always rounded * to page size. * * This number is purposely set to a low number of 16384. * If the dump on oops happens, it will be much appreciated * to not have to wait for all that output. Anyway this can be * boot time and run time configurable. */ #define TRACE_BUF_SIZE_DEFAULT 1441792UL /* 16384 * 88 (sizeof(entry)) */ static unsigned long trace_buf_size = TRACE_BUF_SIZE_DEFAULT; /* trace_types holds a link list of available tracers. */ static struct tracer *trace_types __read_mostly; /* * trace_types_lock is used to protect the trace_types list. */ DEFINE_MUTEX(trace_types_lock); /* * serialize the access of the ring buffer * * ring buffer serializes readers, but it is low level protection. * The validity of the events (which returns by ring_buffer_peek() ..etc) * are not protected by ring buffer. * * The content of events may become garbage if we allow other process consumes * these events concurrently: * A) the page of the consumed events may become a normal page * (not reader page) in ring buffer, and this page will be rewrited * by events producer. * B) The page of the consumed events may become a page for splice_read, * and this page will be returned to system. * * These primitives allow multi process access to different cpu ring buffer * concurrently. * * These primitives don't distinguish read-only and read-consume access. * Multi read-only access are also serialized. */ #ifdef CONFIG_SMP static DECLARE_RWSEM(all_cpu_access_lock); static DEFINE_PER_CPU(struct mutex, cpu_access_lock); static inline void trace_access_lock(int cpu) { if (cpu == RING_BUFFER_ALL_CPUS) { /* gain it for accessing the whole ring buffer. */ down_write(&all_cpu_access_lock); } else { /* gain it for accessing a cpu ring buffer. */ /* Firstly block other trace_access_lock(RING_BUFFER_ALL_CPUS). */ down_read(&all_cpu_access_lock); /* Secondly block other access to this @cpu ring buffer. */ mutex_lock(&per_cpu(cpu_access_lock, cpu)); } } static inline void trace_access_unlock(int cpu) { if (cpu == RING_BUFFER_ALL_CPUS) { up_write(&all_cpu_access_lock); } else { mutex_unlock(&per_cpu(cpu_access_lock, cpu)); up_read(&all_cpu_access_lock); } } static inline void trace_access_lock_init(void) { int cpu; for_each_possible_cpu(cpu) mutex_init(&per_cpu(cpu_access_lock, cpu)); } #else static DEFINE_MUTEX(access_lock); static inline void trace_access_lock(int cpu) { (void)cpu; mutex_lock(&access_lock); } static inline void trace_access_unlock(int cpu) { (void)cpu; mutex_unlock(&access_lock); } static inline void trace_access_lock_init(void) { } #endif #ifdef CONFIG_STACKTRACE static void __ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags, int skip, int pc, struct pt_regs *regs); static inline void ftrace_trace_stack(struct trace_array *tr, struct ring_buffer *buffer, unsigned long flags, int skip, int pc, struct pt_regs *regs); #else static inline void __ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags, int skip, int pc, struct pt_regs *regs) { } static inline void ftrace_trace_stack(struct trace_array *tr, struct ring_buffer *buffer, unsigned long flags, int skip, int pc, struct pt_regs *regs) { } #endif static __always_inline void trace_event_setup(struct ring_buffer_event *event, int type, unsigned long flags, int pc) { struct trace_entry *ent = ring_buffer_event_data(event); tracing_generic_entry_update(ent, flags, pc); ent->type = type; } static __always_inline struct ring_buffer_event * __trace_buffer_lock_reserve(struct ring_buffer *buffer, int type, unsigned long len, unsigned long flags, int pc) { struct ring_buffer_event *event; event = ring_buffer_lock_reserve(buffer, len); if (event != NULL) trace_event_setup(event, type, flags, pc); return event; } void tracer_tracing_on(struct trace_array *tr) { if (tr->trace_buffer.buffer) ring_buffer_record_on(tr->trace_buffer.buffer); /* * This flag is looked at when buffers haven't been allocated * yet, or by some tracers (like irqsoff), that just want to * know if the ring buffer has been disabled, but it can handle * races of where it gets disabled but we still do a record. * As the check is in the fast path of the tracers, it is more * important to be fast than accurate. */ tr->buffer_disabled = 0; /* Make the flag seen by readers */ smp_wmb(); } /** * tracing_on - enable tracing buffers * * This function enables tracing buffers that may have been * disabled with tracing_off. */ void tracing_on(void) { tracer_tracing_on(&global_trace); } EXPORT_SYMBOL_GPL(tracing_on); static __always_inline void __buffer_unlock_commit(struct ring_buffer *buffer, struct ring_buffer_event *event) { __this_cpu_write(trace_cmdline_save, true); /* If this is the temp buffer, we need to commit fully */ if (this_cpu_read(trace_buffered_event) == event) { /* Length is in event->array[0] */ ring_buffer_write(buffer, event->array[0], &event->array[1]); /* Release the temp buffer */ this_cpu_dec(trace_buffered_event_cnt); } else ring_buffer_unlock_commit(buffer, event); } /** * __trace_puts - write a constant string into the trace buffer. * @ip: The address of the caller * @str: The constant string to write * @size: The size of the string. */ int __trace_puts(unsigned long ip, const char *str, int size) { struct ring_buffer_event *event; struct ring_buffer *buffer; struct print_entry *entry; unsigned long irq_flags; int alloc; int pc; if (!(global_trace.trace_flags & TRACE_ITER_PRINTK)) return 0; pc = preempt_count(); if (unlikely(tracing_selftest_running || tracing_disabled)) return 0; alloc = sizeof(*entry) + size + 2; /* possible \n added */ local_save_flags(irq_flags); buffer = global_trace.trace_buffer.buffer; event = __trace_buffer_lock_reserve(buffer, TRACE_PRINT, alloc, irq_flags, pc); if (!event) return 0; entry = ring_buffer_event_data(event); entry->ip = ip; memcpy(&entry->buf, str, size); /* Add a newline if necessary */ if (entry->buf[size - 1] != '\n') { entry->buf[size] = '\n'; entry->buf[size + 1] = '\0'; } else entry->buf[size] = '\0'; __buffer_unlock_commit(buffer, event); ftrace_trace_stack(&global_trace, buffer, irq_flags, 4, pc, NULL); return size; } EXPORT_SYMBOL_GPL(__trace_puts); /** * __trace_bputs - write the pointer to a constant string into trace buffer * @ip: The address of the caller * @str: The constant string to write to the buffer to */ int __trace_bputs(unsigned long ip, const char *str) { struct ring_buffer_event *event; struct ring_buffer *buffer; struct bputs_entry *entry; unsigned long irq_flags; int size = sizeof(struct bputs_entry); int pc; if (!(global_trace.trace_flags & TRACE_ITER_PRINTK)) return 0; pc = preempt_count(); if (unlikely(tracing_selftest_running || tracing_disabled)) return 0; local_save_flags(irq_flags); buffer = global_trace.trace_buffer.buffer; event = __trace_buffer_lock_reserve(buffer, TRACE_BPUTS, size, irq_flags, pc); if (!event) return 0; entry = ring_buffer_event_data(event); entry->ip = ip; entry->str = str; __buffer_unlock_commit(buffer, event); ftrace_trace_stack(&global_trace, buffer, irq_flags, 4, pc, NULL); return 1; } EXPORT_SYMBOL_GPL(__trace_bputs); #ifdef CONFIG_TRACER_SNAPSHOT static void tracing_snapshot_instance(struct trace_array *tr) { struct tracer *tracer = tr->current_trace; unsigned long flags; if (in_nmi()) { internal_trace_puts("*** SNAPSHOT CALLED FROM NMI CONTEXT ***\n"); internal_trace_puts("*** snapshot is being ignored ***\n"); return; } if (!tr->allocated_snapshot) { internal_trace_puts("*** SNAPSHOT NOT ALLOCATED ***\n"); internal_trace_puts("*** stopping trace here! ***\n"); tracing_off(); return; } /* Note, snapshot can not be used when the tracer uses it */ if (tracer->use_max_tr) { internal_trace_puts("*** LATENCY TRACER ACTIVE ***\n"); internal_trace_puts("*** Can not use snapshot (sorry) ***\n"); return; } local_irq_save(flags); update_max_tr(tr, current, smp_processor_id()); local_irq_restore(flags); } /** * trace_snapshot - take a snapshot of the current buffer. * * This causes a swap between the snapshot buffer and the current live * tracing buffer. You can use this to take snapshots of the live * trace when some condition is triggered, but continue to trace. * * Note, make sure to allocate the snapshot with either * a tracing_snapshot_alloc(), or by doing it manually * with: echo 1 > /sys/kernel/debug/tracing/snapshot * * If the snapshot buffer is not allocated, it will stop tracing. * Basically making a permanent snapshot. */ void tracing_snapshot(void) { struct trace_array *tr = &global_trace; tracing_snapshot_instance(tr); } EXPORT_SYMBOL_GPL(tracing_snapshot); static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf, struct trace_buffer *size_buf, int cpu_id); static void set_buffer_entries(struct trace_buffer *buf, unsigned long val); static int alloc_snapshot(struct trace_array *tr) { int ret; if (!tr->allocated_snapshot) { /* allocate spare buffer */ ret = resize_buffer_duplicate_size(&tr->max_buffer, &tr->trace_buffer, RING_BUFFER_ALL_CPUS); if (ret < 0) return ret; tr->allocated_snapshot = true; } return 0; } static void free_snapshot(struct trace_array *tr) { /* * We don't free the ring buffer. instead, resize it because * The max_tr ring buffer has some state (e.g. ring->clock) and * we want preserve it. */ ring_buffer_resize(tr->max_buffer.buffer, 1, RING_BUFFER_ALL_CPUS); set_buffer_entries(&tr->max_buffer, 1); tracing_reset_online_cpus(&tr->max_buffer); tr->allocated_snapshot = false; } /** * tracing_alloc_snapshot - allocate snapshot buffer. * * This only allocates the snapshot buffer if it isn't already * allocated - it doesn't also take a snapshot. * * This is meant to be used in cases where the snapshot buffer needs * to be set up for events that can't sleep but need to be able to * trigger a snapshot. */ int tracing_alloc_snapshot(void) { struct trace_array *tr = &global_trace; int ret; ret = alloc_snapshot(tr); WARN_ON(ret < 0); return ret; } EXPORT_SYMBOL_GPL(tracing_alloc_snapshot); /** * trace_snapshot_alloc - allocate and take a snapshot of the current buffer. * * This is similar to trace_snapshot(), but it will allocate the * snapshot buffer if it isn't already allocated. Use this only * where it is safe to sleep, as the allocation may sleep. * * This causes a swap between the snapshot buffer and the current live * tracing buffer. You can use this to take snapshots of the live * trace when some condition is triggered, but continue to trace. */ void tracing_snapshot_alloc(void) { int ret; ret = tracing_alloc_snapshot(); if (ret < 0) return; tracing_snapshot(); } EXPORT_SYMBOL_GPL(tracing_snapshot_alloc); #else void tracing_snapshot(void) { WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used"); } EXPORT_SYMBOL_GPL(tracing_snapshot); int tracing_alloc_snapshot(void) { WARN_ONCE(1, "Snapshot feature not enabled, but snapshot allocation used"); return -ENODEV; } EXPORT_SYMBOL_GPL(tracing_alloc_snapshot); void tracing_snapshot_alloc(void) { /* Give warning */ tracing_snapshot(); } EXPORT_SYMBOL_GPL(tracing_snapshot_alloc); #endif /* CONFIG_TRACER_SNAPSHOT */ void tracer_tracing_off(struct trace_array *tr) { if (tr->trace_buffer.buffer) ring_buffer_record_off(tr->trace_buffer.buffer); /* * This flag is looked at when buffers haven't been allocated * yet, or by some tracers (like irqsoff), that just want to * know if the ring buffer has been disabled, but it can handle * races of where it gets disabled but we still do a record. * As the check is in the fast path of the tracers, it is more * important to be fast than accurate. */ tr->buffer_disabled = 1; /* Make the flag seen by readers */ smp_wmb(); } /** * tracing_off - turn off tracing buffers * * This function stops the tracing buffers from recording data. * It does not disable any overhead the tracers themselves may * be causing. This function simply causes all recording to * the ring buffers to fail. */ void tracing_off(void) { tracer_tracing_off(&global_trace); } EXPORT_SYMBOL_GPL(tracing_off); void disable_trace_on_warning(void) { if (__disable_trace_on_warning) tracing_off(); } /** * tracer_tracing_is_on - show real state of ring buffer enabled * @tr : the trace array to know if ring buffer is enabled * * Shows real state of the ring buffer if it is enabled or not. */ int tracer_tracing_is_on(struct trace_array *tr) { if (tr->trace_buffer.buffer) return ring_buffer_record_is_on(tr->trace_buffer.buffer); return !tr->buffer_disabled; } /** * tracing_is_on - show state of ring buffers enabled */ int tracing_is_on(void) { return tracer_tracing_is_on(&global_trace); } EXPORT_SYMBOL_GPL(tracing_is_on); static int __init set_buf_size(char *str) { unsigned long buf_size; if (!str) return 0; buf_size = memparse(str, &str); /* nr_entries can not be zero */ if (buf_size == 0) return 0; trace_buf_size = buf_size; return 1; } __setup("trace_buf_size=", set_buf_size); static int __init set_tracing_thresh(char *str) { unsigned long threshold; int ret; if (!str) return 0; ret = kstrtoul(str, 0, &threshold); if (ret < 0) return 0; tracing_thresh = threshold * 1000; return 1; } __setup("tracing_thresh=", set_tracing_thresh); unsigned long nsecs_to_usecs(unsigned long nsecs) { return nsecs / 1000; } /* * TRACE_FLAGS is defined as a tuple matching bit masks with strings. * It uses C(a, b) where 'a' is the enum name and 'b' is the string that * matches it. By defining "C(a, b) b", TRACE_FLAGS becomes a list * of strings in the order that the enums were defined. */ #undef C #define C(a, b) b /* These must match the bit postions in trace_iterator_flags */ static const char *trace_options[] = { TRACE_FLAGS NULL }; static struct { u64 (*func)(void); const char *name; int in_ns; /* is this clock in nanoseconds? */ } trace_clocks[] = { { trace_clock_local, "local", 1 }, { trace_clock_global, "global", 1 }, { trace_clock_counter, "counter", 0 }, { trace_clock_jiffies, "uptime", 0 }, { trace_clock, "perf", 1 }, { ktime_get_mono_fast_ns, "mono", 1 }, { ktime_get_raw_fast_ns, "mono_raw", 1 }, { ktime_get_boot_fast_ns, "boot", 1 }, ARCH_TRACE_CLOCKS }; /* * trace_parser_get_init - gets the buffer for trace parser */ int trace_parser_get_init(struct trace_parser *parser, int size) { memset(parser, 0, sizeof(*parser)); parser->buffer = kmalloc(size, GFP_KERNEL); if (!parser->buffer) return 1; parser->size = size; return 0; } /* * trace_parser_put - frees the buffer for trace parser */ void trace_parser_put(struct trace_parser *parser) { kfree(parser->buffer); parser->buffer = NULL; } /* * trace_get_user - reads the user input string separated by space * (matched by isspace(ch)) * * For each string found the 'struct trace_parser' is updated, * and the function returns. * * Returns number of bytes read. * * See kernel/trace/trace.h for 'struct trace_parser' details. */ int trace_get_user(struct trace_parser *parser, const char __user *ubuf, size_t cnt, loff_t *ppos) { char ch; size_t read = 0; ssize_t ret; if (!*ppos) trace_parser_clear(parser); ret = get_user(ch, ubuf++); if (ret) goto out; read++; cnt--; /* * The parser is not finished with the last write, * continue reading the user input without skipping spaces. */ if (!parser->cont) { /* skip white space */ while (cnt && isspace(ch)) { ret = get_user(ch, ubuf++); if (ret) goto out; read++; cnt--; } /* only spaces were written */ if (isspace(ch)) { *ppos += read; ret = read; goto out; } parser->idx = 0; } /* read the non-space input */ while (cnt && !isspace(ch)) { if (parser->idx < parser->size - 1) parser->buffer[parser->idx++] = ch; else { ret = -EINVAL; goto out; } ret = get_user(ch, ubuf++); if (ret) goto out; read++; cnt--; } /* We either got finished input or we have to wait for another call. */ if (isspace(ch)) { parser->buffer[parser->idx] = 0; parser->cont = false; } else if (parser->idx < parser->size - 1) { parser->cont = true; parser->buffer[parser->idx++] = ch; } else { ret = -EINVAL; goto out; } *ppos += read; ret = read; out: return ret; } /* TODO add a seq_buf_to_buffer() */ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt) { int len; if (trace_seq_used(s) <= s->seq.readpos) return -EBUSY; len = trace_seq_used(s) - s->seq.readpos; if (cnt > len) cnt = len; memcpy(buf, s->buffer + s->seq.readpos, cnt); s->seq.readpos += cnt; return cnt; } unsigned long __read_mostly tracing_thresh; #ifdef CONFIG_TRACER_MAX_TRACE /* * Copy the new maximum trace into the separate maximum-trace * structure. (this way the maximum trace is permanently saved, * for later retrieval via /sys/kernel/debug/tracing/latency_trace) */ static void __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) { struct trace_buffer *trace_buf = &tr->trace_buffer; struct trace_buffer *max_buf = &tr->max_buffer; struct trace_array_cpu *data = per_cpu_ptr(trace_buf->data, cpu); struct trace_array_cpu *max_data = per_cpu_ptr(max_buf->data, cpu); max_buf->cpu = cpu; max_buf->time_start = data->preempt_timestamp; max_data->saved_latency = tr->max_latency; max_data->critical_start = data->critical_start; max_data->critical_end = data->critical_end; memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN); max_data->pid = tsk->pid; /* * If tsk == current, then use current_uid(), as that does not use * RCU. The irq tracer can be called out of RCU scope. */ if (tsk == current) max_data->uid = current_uid(); else max_data->uid = task_uid(tsk); max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO; max_data->policy = tsk->policy; max_data->rt_priority = tsk->rt_priority; /* record this tasks comm */ tracing_record_cmdline(tsk); } /** * update_max_tr - snapshot all trace buffers from global_trace to max_tr * @tr: tracer * @tsk: the task with the latency * @cpu: The cpu that initiated the trace. * * Flip the buffers between the @tr and the max_tr and record information * about which task was the cause of this latency. */ void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) { struct ring_buffer *buf; if (tr->stop_count) return; WARN_ON_ONCE(!irqs_disabled()); if (!tr->allocated_snapshot) { /* Only the nop tracer should hit this when disabling */ WARN_ON_ONCE(tr->current_trace != &nop_trace); return; } arch_spin_lock(&tr->max_lock); buf = tr->trace_buffer.buffer; tr->trace_buffer.buffer = tr->max_buffer.buffer; tr->max_buffer.buffer = buf; __update_max_tr(tr, tsk, cpu); arch_spin_unlock(&tr->max_lock); } /** * update_max_tr_single - only copy one trace over, and reset the rest * @tr - tracer * @tsk - task with the latency * @cpu - the cpu of the buffer to copy. * * Flip the trace of a single CPU buffer between the @tr and the max_tr. */ void update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu) { int ret; if (tr->stop_count) return; WARN_ON_ONCE(!irqs_disabled()); if (!tr->allocated_snapshot) { /* Only the nop tracer should hit this when disabling */ WARN_ON_ONCE(tr->current_trace != &nop_trace); return; } arch_spin_lock(&tr->max_lock); ret = ring_buffer_swap_cpu(tr->max_buffer.buffer, tr->trace_buffer.buffer, cpu); if (ret == -EBUSY) { /* * We failed to swap the buffer due to a commit taking * place on this CPU. We fail to record, but we reset * the max trace buffer (no one writes directly to it) * and flag that it failed. */ trace_array_printk_buf(tr->max_buffer.buffer, _THIS_IP_, "Failed to swap buffers due to commit in progress\n"); } WARN_ON_ONCE(ret && ret != -EAGAIN && ret != -EBUSY); __update_max_tr(tr, tsk, cpu); arch_spin_unlock(&tr->max_lock); } #endif /* CONFIG_TRACER_MAX_TRACE */ static int wait_on_pipe(struct trace_iterator *iter, bool full) { /* Iterators are static, they should be filled or empty */ if (trace_buffer_iter(iter, iter->cpu_file)) return 0; return ring_buffer_wait(iter->trace_buffer->buffer, iter->cpu_file, full); } #ifdef CONFIG_FTRACE_STARTUP_TEST static bool selftests_can_run; struct trace_selftests { struct list_head list; struct tracer *type; }; static LIST_HEAD(postponed_selftests); static int save_selftest(struct tracer *type) { struct trace_selftests *selftest; selftest = kmalloc(sizeof(*selftest), GFP_KERNEL); if (!selftest) return -ENOMEM; selftest->type = type; list_add(&selftest->list, &postponed_selftests); return 0; } static int run_tracer_selftest(struct tracer *type) { struct trace_array *tr = &global_trace; struct tracer *saved_tracer = tr->current_trace; int ret; if (!type->selftest || tracing_selftest_disabled) return 0; /* * If a tracer registers early in boot up (before scheduling is * initialized and such), then do not run its selftests yet. * Instead, run it a little later in the boot process. */ if (!selftests_can_run) return save_selftest(type); /* * Run a selftest on this tracer. * Here we reset the trace buffer, and set the current * tracer to be this tracer. The tracer can then run some * internal tracing to verify that everything is in order. * If we fail, we do not register this tracer. */ tracing_reset_online_cpus(&tr->trace_buffer); tr->current_trace = type; #ifdef CONFIG_TRACER_MAX_TRACE if (type->use_max_tr) { /* If we expanded the buffers, make sure the max is expanded too */ if (ring_buffer_expanded) ring_buffer_resize(tr->max_buffer.buffer, trace_buf_size, RING_BUFFER_ALL_CPUS); tr->allocated_snapshot = true; } #endif /* the test is responsible for initializing and enabling */ pr_info("Testing tracer %s: ", type->name); ret = type->selftest(type, tr); /* the test is responsible for resetting too */ tr->current_trace = saved_tracer; if (ret) { printk(KERN_CONT "FAILED!\n"); /* Add the warning after printing 'FAILED' */ WARN_ON(1); return -1; } /* Only reset on passing, to avoid touching corrupted buffers */ tracing_reset_online_cpus(&tr->trace_buffer); #ifdef CONFIG_TRACER_MAX_TRACE if (type->use_max_tr) { tr->allocated_snapshot = false; /* Shrink the max buffer again */ if (ring_buffer_expanded) ring_buffer_resize(tr->max_buffer.buffer, 1, RING_BUFFER_ALL_CPUS); } #endif printk(KERN_CONT "PASSED\n"); return 0; } static __init int init_trace_selftests(void) { struct trace_selftests *p, *n; struct tracer *t, **last; int ret; selftests_can_run = true; mutex_lock(&trace_types_lock); if (list_empty(&postponed_selftests)) goto out; pr_info("Running postponed tracer tests:\n"); list_for_each_entry_safe(p, n, &postponed_selftests, list) { ret = run_tracer_selftest(p->type); /* If the test fails, then warn and remove from available_tracers */ if (ret < 0) { WARN(1, "tracer: %s failed selftest, disabling\n", p->type->name); last = &trace_types; for (t = trace_types; t; t = t->next) { if (t == p->type) { *last = t->next; break; } last = &t->next; } } list_del(&p->list); kfree(p); } out: mutex_unlock(&trace_types_lock); return 0; } core_initcall(init_trace_selftests); #else static inline int run_tracer_selftest(struct tracer *type) { return 0; } #endif /* CONFIG_FTRACE_STARTUP_TEST */ static void add_tracer_options(struct trace_array *tr, struct tracer *t); static void __init apply_trace_boot_options(void); /** * register_tracer - register a tracer with the ftrace system. * @type - the plugin for the tracer * * Register a new plugin tracer. */ int __init register_tracer(struct tracer *type) { struct tracer *t; int ret = 0; if (!type->name) { pr_info("Tracer must have a name\n"); return -1; } if (strlen(type->name) >= MAX_TRACER_SIZE) { pr_info("Tracer has a name longer than %d\n", MAX_TRACER_SIZE); return -1; } mutex_lock(&trace_types_lock); tracing_selftest_running = true; for (t = trace_types; t; t = t->next) { if (strcmp(type->name, t->name) == 0) { /* already found */ pr_info("Tracer %s already registered\n", type->name); ret = -1; goto out; } } if (!type->set_flag) type->set_flag = &dummy_set_flag; if (!type->flags) { /*allocate a dummy tracer_flags*/ type->flags = kmalloc(sizeof(*type->flags), GFP_KERNEL); if (!type->flags) { ret = -ENOMEM; goto out; } type->flags->val = 0; type->flags->opts = dummy_tracer_opt; } else if (!type->flags->opts) type->flags->opts = dummy_tracer_opt; /* store the tracer for __set_tracer_option */ type->flags->trace = type; ret = run_tracer_selftest(type); if (ret < 0) goto out; type->next = trace_types; trace_types = type; add_tracer_options(&global_trace, type); out: tracing_selftest_running = false; mutex_unlock(&trace_types_lock); if (ret || !default_bootup_tracer) goto out_unlock; if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE)) goto out_unlock; printk(KERN_INFO "Starting tracer '%s'\n", type->name); /* Do we want this tracer to start on bootup? */ tracing_set_tracer(&global_trace, type->name); default_bootup_tracer = NULL; apply_trace_boot_options(); /* disable other selftests, since this will break it. */ tracing_selftest_disabled = true; #ifdef CONFIG_FTRACE_STARTUP_TEST printk(KERN_INFO "Disabling FTRACE selftests due to running tracer '%s'\n", type->name); #endif out_unlock: return ret; } void tracing_reset(struct trace_buffer *buf, int cpu) { struct ring_buffer *buffer = buf->buffer; if (!buffer) return; ring_buffer_record_disable(buffer); /* Make sure all commits have finished */ synchronize_sched(); ring_buffer_reset_cpu(buffer, cpu); ring_buffer_record_enable(buffer); } void tracing_reset_online_cpus(struct trace_buffer *buf) { struct ring_buffer *buffer = buf->buffer; int cpu; if (!buffer) return; ring_buffer_record_disable(buffer); /* Make sure all commits have finished */ synchronize_sched(); buf->time_start = buffer_ftrace_now(buf, buf->cpu); for_each_online_cpu(cpu) ring_buffer_reset_cpu(buffer, cpu); ring_buffer_record_enable(buffer); } /* Must have trace_types_lock held */ void tracing_reset_all_online_cpus(void) { struct trace_array *tr; list_for_each_entry(tr, &ftrace_trace_arrays, list) { tracing_reset_online_cpus(&tr->trace_buffer); #ifdef CONFIG_TRACER_MAX_TRACE tracing_reset_online_cpus(&tr->max_buffer); #endif } } #define SAVED_CMDLINES_DEFAULT 128 #define NO_CMDLINE_MAP UINT_MAX static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED; struct saved_cmdlines_buffer { unsigned map_pid_to_cmdline[PID_MAX_DEFAULT+1]; unsigned *map_cmdline_to_pid; unsigned cmdline_num; int cmdline_idx; char *saved_cmdlines; }; static struct saved_cmdlines_buffer *savedcmd; /* temporary disable recording */ static atomic_t trace_record_cmdline_disabled __read_mostly; static inline char *get_saved_cmdlines(int idx) { return &savedcmd->saved_cmdlines[idx * TASK_COMM_LEN]; } static inline void set_cmdline(int idx, const char *cmdline) { memcpy(get_saved_cmdlines(idx), cmdline, TASK_COMM_LEN); } static int allocate_cmdlines_buffer(unsigned int val, struct saved_cmdlines_buffer *s) { s->map_cmdline_to_pid = kmalloc(val * sizeof(*s->map_cmdline_to_pid), GFP_KERNEL); if (!s->map_cmdline_to_pid) return -ENOMEM; s->saved_cmdlines = kmalloc(val * TASK_COMM_LEN, GFP_KERNEL); if (!s->saved_cmdlines) { kfree(s->map_cmdline_to_pid); return -ENOMEM; } s->cmdline_idx = 0; s->cmdline_num = val; memset(&s->map_pid_to_cmdline, NO_CMDLINE_MAP, sizeof(s->map_pid_to_cmdline)); memset(s->map_cmdline_to_pid, NO_CMDLINE_MAP, val * sizeof(*s->map_cmdline_to_pid)); return 0; } static int trace_create_savedcmd(void) { int ret; savedcmd = kmalloc(sizeof(*savedcmd), GFP_KERNEL); if (!savedcmd) return -ENOMEM; ret = allocate_cmdlines_buffer(SAVED_CMDLINES_DEFAULT, savedcmd); if (ret < 0) { kfree(savedcmd); savedcmd = NULL; return -ENOMEM; } return 0; } int is_tracing_stopped(void) { return global_trace.stop_count; } /** * tracing_start - quick start of the tracer * * If tracing is enabled but was stopped by tracing_stop, * this will start the tracer back up. */ void tracing_start(void) { struct ring_buffer *buffer; unsigned long flags; if (tracing_disabled) return; raw_spin_lock_irqsave(&global_trace.start_lock, flags); if (--global_trace.stop_count) { if (global_trace.stop_count < 0) { /* Someone screwed up their debugging */ WARN_ON_ONCE(1); global_trace.stop_count = 0; } goto out; } /* Prevent the buffers from switching */ arch_spin_lock(&global_trace.max_lock); buffer = global_trace.trace_buffer.buffer; if (buffer) ring_buffer_record_enable(buffer); #ifdef CONFIG_TRACER_MAX_TRACE buffer = global_trace.max_buffer.buffer; if (buffer) ring_buffer_record_enable(buffer); #endif arch_spin_unlock(&global_trace.max_lock); out: raw_spin_unlock_irqrestore(&global_trace.start_lock, flags); } static void tracing_start_tr(struct trace_array *tr) { struct ring_buffer *buffer; unsigned long flags; if (tracing_disabled) return; /* If global, we need to also start the max tracer */ if (tr->flags & TRACE_ARRAY_FL_GLOBAL) return tracing_start(); raw_spin_lock_irqsave(&tr->start_lock, flags); if (--tr->stop_count) { if (tr->stop_count < 0) { /* Someone screwed up their debugging */ WARN_ON_ONCE(1); tr->stop_count = 0; } goto out; } buffer = tr->trace_buffer.buffer; if (buffer) ring_buffer_record_enable(buffer); out: raw_spin_unlock_irqrestore(&tr->start_lock, flags); } /** * tracing_stop - quick stop of the tracer * * Light weight way to stop tracing. Use in conjunction with * tracing_start. */ void tracing_stop(void) { struct ring_buffer *buffer; unsigned long flags; raw_spin_lock_irqsave(&global_trace.start_lock, flags); if (global_trace.stop_count++) goto out; /* Prevent the buffers from switching */ arch_spin_lock(&global_trace.max_lock); buffer = global_trace.trace_buffer.buffer; if (buffer) ring_buffer_record_disable(buffer); #ifdef CONFIG_TRACER_MAX_TRACE buffer = global_trace.max_buffer.buffer; if (buffer) ring_buffer_record_disable(buffer); #endif arch_spin_unlock(&global_trace.max_lock); out: raw_spin_unlock_irqrestore(&global_trace.start_lock, flags); } static void tracing_stop_tr(struct trace_array *tr) { struct ring_buffer *buffer; unsigned long flags; /* If global, we need to also stop the max tracer */ if (tr->flags & TRACE_ARRAY_FL_GLOBAL) return tracing_stop(); raw_spin_lock_irqsave(&tr->start_lock, flags); if (tr->stop_count++) goto out; buffer = tr->trace_buffer.buffer; if (buffer) ring_buffer_record_disable(buffer); out: raw_spin_unlock_irqrestore(&tr->start_lock, flags); } void trace_stop_cmdline_recording(void); static int trace_save_cmdline(struct task_struct *tsk) { unsigned pid, idx; if (!tsk->pid || unlikely(tsk->pid > PID_MAX_DEFAULT)) return 0; /* * It's not the end of the world if we don't get * the lock, but we also don't want to spin * nor do we want to disable interrupts, * so if we miss here, then better luck next time. */ if (!arch_spin_trylock(&trace_cmdline_lock)) return 0; idx = savedcmd->map_pid_to_cmdline[tsk->pid]; if (idx == NO_CMDLINE_MAP) { idx = (savedcmd->cmdline_idx + 1) % savedcmd->cmdline_num; /* * Check whether the cmdline buffer at idx has a pid * mapped. We are going to overwrite that entry so we * need to clear the map_pid_to_cmdline. Otherwise we * would read the new comm for the old pid. */ pid = savedcmd->map_cmdline_to_pid[idx]; if (pid != NO_CMDLINE_MAP) savedcmd->map_pid_to_cmdline[pid] = NO_CMDLINE_MAP; savedcmd->map_cmdline_to_pid[idx] = tsk->pid; savedcmd->map_pid_to_cmdline[tsk->pid] = idx; savedcmd->cmdline_idx = idx; } set_cmdline(idx, tsk->comm); arch_spin_unlock(&trace_cmdline_lock); return 1; } static void __trace_find_cmdline(int pid, char comm[]) { unsigned map; if (!pid) { strcpy(comm, ""); return; } if (WARN_ON_ONCE(pid < 0)) { strcpy(comm, ""); return; } if (pid > PID_MAX_DEFAULT) { strcpy(comm, "<...>"); return; } map = savedcmd->map_pid_to_cmdline[pid]; if (map != NO_CMDLINE_MAP) strlcpy(comm, get_saved_cmdlines(map), TASK_COMM_LEN); else strcpy(comm, "<...>"); } void trace_find_cmdline(int pid, char comm[]) { preempt_disable(); arch_spin_lock(&trace_cmdline_lock); __trace_find_cmdline(pid, comm); arch_spin_unlock(&trace_cmdline_lock); preempt_enable(); } void tracing_record_cmdline(struct task_struct *tsk) { if (atomic_read(&trace_record_cmdline_disabled) || !tracing_is_on()) return; if (!__this_cpu_read(trace_cmdline_save)) return; if (trace_save_cmdline(tsk)) __this_cpu_write(trace_cmdline_save, false); } /* * Several functions return TRACE_TYPE_PARTIAL_LINE if the trace_seq * overflowed, and TRACE_TYPE_HANDLED otherwise. This helper function * simplifies those functions and keeps them in sync. */ enum print_line_t trace_handle_return(struct trace_seq *s) { return trace_seq_has_overflowed(s) ? TRACE_TYPE_PARTIAL_LINE : TRACE_TYPE_HANDLED; } EXPORT_SYMBOL_GPL(trace_handle_return); void tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags, int pc) { struct task_struct *tsk = current; entry->preempt_count = pc & 0xff; entry->pid = (tsk) ? tsk->pid : 0; entry->flags = #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) | #else TRACE_FLAG_IRQS_NOSUPPORT | #endif ((pc & NMI_MASK ) ? TRACE_FLAG_NMI : 0) | ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) | ((pc & SOFTIRQ_OFFSET) ? TRACE_FLAG_SOFTIRQ : 0) | (tif_need_resched() ? TRACE_FLAG_NEED_RESCHED : 0) | (test_preempt_need_resched() ? TRACE_FLAG_PREEMPT_RESCHED : 0); } EXPORT_SYMBOL_GPL(tracing_generic_entry_update); struct ring_buffer_event * trace_buffer_lock_reserve(struct ring_buffer *buffer, int type, unsigned long len, unsigned long flags, int pc) { return __trace_buffer_lock_reserve(buffer, type, len, flags, pc); } DEFINE_PER_CPU(struct ring_buffer_event *, trace_buffered_event); DEFINE_PER_CPU(int, trace_buffered_event_cnt); static int trace_buffered_event_ref; /** * trace_buffered_event_enable - enable buffering events * * When events are being filtered, it is quicker to use a temporary * buffer to write the event data into if there's a likely chance * that it will not be committed. The discard of the ring buffer * is not as fast as committing, and is much slower than copying * a commit. * * When an event is to be filtered, allocate per cpu buffers to * write the event data into, and if the event is filtered and discarded * it is simply dropped, otherwise, the entire data is to be committed * in one shot. */ void trace_buffered_event_enable(void) { struct ring_buffer_event *event; struct page *page; int cpu; WARN_ON_ONCE(!mutex_is_locked(&event_mutex)); if (trace_buffered_event_ref++) return; for_each_tracing_cpu(cpu) { page = alloc_pages_node(cpu_to_node(cpu), GFP_KERNEL | __GFP_NORETRY, 0); if (!page) goto failed; event = page_address(page); memset(event, 0, sizeof(*event)); per_cpu(trace_buffered_event, cpu) = event; preempt_disable(); if (cpu == smp_processor_id() && this_cpu_read(trace_buffered_event) != per_cpu(trace_buffered_event, cpu)) WARN_ON_ONCE(1); preempt_enable(); } return; failed: trace_buffered_event_disable(); } static void enable_trace_buffered_event(void *data) { /* Probably not needed, but do it anyway */ smp_rmb(); this_cpu_dec(trace_buffered_event_cnt); } static void disable_trace_buffered_event(void *data) { this_cpu_inc(trace_buffered_event_cnt); } /** * trace_buffered_event_disable - disable buffering events * * When a filter is removed, it is faster to not use the buffered * events, and to commit directly into the ring buffer. Free up * the temp buffers when there are no more users. This requires * special synchronization with current events. */ void trace_buffered_event_disable(void) { int cpu; WARN_ON_ONCE(!mutex_is_locked(&event_mutex)); if (WARN_ON_ONCE(!trace_buffered_event_ref)) return; if (--trace_buffered_event_ref) return; preempt_disable(); /* For each CPU, set the buffer as used. */ smp_call_function_many(tracing_buffer_mask, disable_trace_buffered_event, NULL, 1); preempt_enable(); /* Wait for all current users to finish */ synchronize_sched(); for_each_tracing_cpu(cpu) { free_page((unsigned long)per_cpu(trace_buffered_event, cpu)); per_cpu(trace_buffered_event, cpu) = NULL; } /* * Make sure trace_buffered_event is NULL before clearing * trace_buffered_event_cnt. */ smp_wmb(); preempt_disable(); /* Do the work on each cpu */ smp_call_function_many(tracing_buffer_mask, enable_trace_buffered_event, NULL, 1); preempt_enable(); } static struct ring_buffer *temp_buffer; struct ring_buffer_event * trace_event_buffer_lock_reserve(struct ring_buffer **current_rb, struct trace_event_file *trace_file, int type, unsigned long len, unsigned long flags, int pc) { struct ring_buffer_event *entry; int val; *current_rb = trace_file->tr->trace_buffer.buffer; if ((trace_file->flags & (EVENT_FILE_FL_SOFT_DISABLED | EVENT_FILE_FL_FILTERED)) && (entry = this_cpu_read(trace_buffered_event))) { /* Try to use the per cpu buffer first */ val = this_cpu_inc_return(trace_buffered_event_cnt); if (val == 1) { trace_event_setup(entry, type, flags, pc); entry->array[0] = len; return entry; } this_cpu_dec(trace_buffered_event_cnt); } entry = __trace_buffer_lock_reserve(*current_rb, type, len, flags, pc); /* * If tracing is off, but we have triggers enabled * we still need to look at the event data. Use the temp_buffer * to store the trace event for the tigger to use. It's recusive * safe and will not be recorded anywhere. */ if (!entry && trace_file->flags & EVENT_FILE_FL_TRIGGER_COND) { *current_rb = temp_buffer; entry = __trace_buffer_lock_reserve(*current_rb, type, len, flags, pc); } return entry; } EXPORT_SYMBOL_GPL(trace_event_buffer_lock_reserve); static DEFINE_SPINLOCK(tracepoint_iter_lock); static DEFINE_MUTEX(tracepoint_printk_mutex); static void output_printk(struct trace_event_buffer *fbuffer) { struct trace_event_call *event_call; struct trace_event *event; unsigned long flags; struct trace_iterator *iter = tracepoint_print_iter; /* We should never get here if iter is NULL */ if (WARN_ON_ONCE(!iter)) return; event_call = fbuffer->trace_file->event_call; if (!event_call || !event_call->event.funcs || !event_call->event.funcs->trace) return; event = &fbuffer->trace_file->event_call->event; spin_lock_irqsave(&tracepoint_iter_lock, flags); trace_seq_init(&iter->seq); iter->ent = fbuffer->entry; event_call->event.funcs->trace(iter, 0, event); trace_seq_putc(&iter->seq, 0); printk("%s", iter->seq.buffer); spin_unlock_irqrestore(&tracepoint_iter_lock, flags); } int tracepoint_printk_sysctl(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { int save_tracepoint_printk; int ret; mutex_lock(&tracepoint_printk_mutex); save_tracepoint_printk = tracepoint_printk; ret = proc_dointvec(table, write, buffer, lenp, ppos); /* * This will force exiting early, as tracepoint_printk * is always zero when tracepoint_printk_iter is not allocated */ if (!tracepoint_print_iter) tracepoint_printk = 0; if (save_tracepoint_printk == tracepoint_printk) goto out; if (tracepoint_printk) static_key_enable(&tracepoint_printk_key.key); else static_key_disable(&tracepoint_printk_key.key); out: mutex_unlock(&tracepoint_printk_mutex); return ret; } void trace_event_buffer_commit(struct trace_event_buffer *fbuffer) { if (static_key_false(&tracepoint_printk_key.key)) output_printk(fbuffer); event_trigger_unlock_commit(fbuffer->trace_file, fbuffer->buffer, fbuffer->event, fbuffer->entry, fbuffer->flags, fbuffer->pc); } EXPORT_SYMBOL_GPL(trace_event_buffer_commit); void trace_buffer_unlock_commit_regs(struct trace_array *tr, struct ring_buffer *buffer, struct ring_buffer_event *event, unsigned long flags, int pc, struct pt_regs *regs) { __buffer_unlock_commit(buffer, event); /* * If regs is not set, then skip the following callers: * trace_buffer_unlock_commit_regs * event_trigger_unlock_commit * trace_event_buffer_commit * trace_event_raw_event_sched_switch * Note, we can still get here via blktrace, wakeup tracer * and mmiotrace, but that's ok if they lose a function or * two. They are that meaningful. */ ftrace_trace_stack(tr, buffer, flags, regs ? 0 : 4, pc, regs); ftrace_trace_userstack(buffer, flags, pc); } /* * Similar to trace_buffer_unlock_commit_regs() but do not dump stack. */ void trace_buffer_unlock_commit_nostack(struct ring_buffer *buffer, struct ring_buffer_event *event) { __buffer_unlock_commit(buffer, event); } static void trace_process_export(struct trace_export *export, struct ring_buffer_event *event) { struct trace_entry *entry; unsigned int size = 0; entry = ring_buffer_event_data(event); size = ring_buffer_event_length(event); export->write(entry, size); } static DEFINE_MUTEX(ftrace_export_lock); static struct trace_export __rcu *ftrace_exports_list __read_mostly; static DEFINE_STATIC_KEY_FALSE(ftrace_exports_enabled); static inline void ftrace_exports_enable(void) { static_branch_enable(&ftrace_exports_enabled); } static inline void ftrace_exports_disable(void) { static_branch_disable(&ftrace_exports_enabled); } void ftrace_exports(struct ring_buffer_event *event) { struct trace_export *export; preempt_disable_notrace(); export = rcu_dereference_raw_notrace(ftrace_exports_list); while (export) { trace_process_export(export, event); export = rcu_dereference_raw_notrace(export->next); } preempt_enable_notrace(); } static inline void add_trace_export(struct trace_export **list, struct trace_export *export) { rcu_assign_pointer(export->next, *list); /* * We are entering export into the list but another * CPU might be walking that list. We need to make sure * the export->next pointer is valid before another CPU sees * the export pointer included into the list. */ rcu_assign_pointer(*list, export); } static inline int rm_trace_export(struct trace_export **list, struct trace_export *export) { struct trace_export **p; for (p = list; *p != NULL; p = &(*p)->next) if (*p == export) break; if (*p != export) return -1; rcu_assign_pointer(*p, (*p)->next); return 0; } static inline void add_ftrace_export(struct trace_export **list, struct trace_export *export) { if (*list == NULL) ftrace_exports_enable(); add_trace_export(list, export); } static inline int rm_ftrace_export(struct trace_export **list, struct trace_export *export) { int ret; ret = rm_trace_export(list, export); if (*list == NULL) ftrace_exports_disable(); return ret; } int register_ftrace_export(struct trace_export *export) { if (WARN_ON_ONCE(!export->write)) return -1; mutex_lock(&ftrace_export_lock); add_ftrace_export(&ftrace_exports_list, export); mutex_unlock(&ftrace_export_lock); return 0; } EXPORT_SYMBOL_GPL(register_ftrace_export); int unregister_ftrace_export(struct trace_export *export) { int ret; mutex_lock(&ftrace_export_lock); ret = rm_ftrace_export(&ftrace_exports_list, export); mutex_unlock(&ftrace_export_lock); return ret; } EXPORT_SYMBOL_GPL(unregister_ftrace_export); void trace_function(struct trace_array *tr, unsigned long ip, unsigned long parent_ip, unsigned long flags, int pc) { struct trace_event_call *call = &event_function; struct ring_buffer *buffer = tr->trace_buffer.buffer; struct ring_buffer_event *event; struct ftrace_entry *entry; event = __trace_buffer_lock_reserve(buffer, TRACE_FN, sizeof(*entry), flags, pc); if (!event) return; entry = ring_buffer_event_data(event); entry->ip = ip; entry->parent_ip = parent_ip; if (!call_filter_check_discard(call, entry, buffer, event)) { if (static_branch_unlikely(&ftrace_exports_enabled)) ftrace_exports(event); __buffer_unlock_commit(buffer, event); } } #ifdef CONFIG_STACKTRACE #define FTRACE_STACK_MAX_ENTRIES (PAGE_SIZE / sizeof(unsigned long)) struct ftrace_stack { unsigned long calls[FTRACE_STACK_MAX_ENTRIES]; }; static DEFINE_PER_CPU(struct ftrace_stack, ftrace_stack); static DEFINE_PER_CPU(int, ftrace_stack_reserve); static void __ftrace_trace_stack(struct ring_buffer *buffer, unsigned long flags, int skip, int pc, struct pt_regs *regs) { struct trace_event_call *call = &event_kernel_stack; struct ring_buffer_event *event; struct stack_entry *entry; struct stack_trace trace; int use_stack; int size = FTRACE_STACK_ENTRIES; trace.nr_entries = 0; trace.skip = skip; /* * Add two, for this function and the call to save_stack_trace() * If regs is set, then these functions will not be in the way. */ if (!regs) trace.skip += 2; /* * Since events can happen in NMIs there's no safe way to * use the per cpu ftrace_stacks. We reserve it and if an interrupt * or NMI comes in, it will just have to use the default * FTRACE_STACK_SIZE. */ preempt_disable_notrace(); use_stack = __this_cpu_inc_return(ftrace_stack_reserve); /* * We don't need any atomic variables, just a barrier. * If an interrupt comes in, we don't care, because it would * have exited and put the counter back to what we want. * We just need a barrier to keep gcc from moving things * around. */ barrier(); if (use_stack == 1) { trace.entries = this_cpu_ptr(ftrace_stack.calls); trace.max_entries = FTRACE_STACK_MAX_ENTRIES; if (regs) save_stack_trace_regs(regs, &trace); else save_stack_trace(&trace); if (trace.nr_entries > size) size = trace.nr_entries; } else /* From now on, use_stack is a boolean */ use_stack = 0; size *= sizeof(unsigned long); event = __trace_buffer_lock_reserve(buffer, TRACE_STACK, sizeof(*entry) + size, flags, pc); if (!event) goto out; entry = ring_buffer_event_data(event); memset(&entry->caller, 0, size); if (use_stack) memcpy(&entry->caller, trace.entries, trace.nr_entries * sizeof(unsigned long)); else { trace.max_entries = FTRACE_STACK_ENTRIES; trace.entries = entry->caller; if (regs) save_stack_trace_regs(regs, &trace); else save_stack_trace(&trace); } entry->size = trace.nr_entries; if (!call_filter_check_discard(call, entry, buffer, event)) __buffer_unlock_commit(buffer, event); out: /* Again, don't let gcc optimize things here */ barrier(); __this_cpu_dec(ftrace_stack_reserve); preempt_enable_notrace(); } static inline void ftrace_trace_stack(struct trace_array *tr, struct ring_buffer *buffer, unsigned long flags, int skip, int pc, struct pt_regs *regs) { if (!(tr->trace_flags & TRACE_ITER_STACKTRACE)) return; __ftrace_trace_stack(buffer, flags, skip, pc, regs); } void __trace_stack(struct trace_array *tr, unsigned long flags, int skip, int pc) { struct ring_buffer *buffer = tr->trace_buffer.buffer; if (rcu_is_watching()) { __ftrace_trace_stack(buffer, flags, skip, pc, NULL); return; } /* * When an NMI triggers, RCU is enabled via rcu_nmi_enter(), * but if the above rcu_is_watching() failed, then the NMI * triggered someplace critical, and rcu_irq_enter() should * not be called from NMI. */ if (unlikely(in_nmi())) return; /* * It is possible that a function is being traced in a * location that RCU is not watching. A call to * rcu_irq_enter() will make sure that it is, but there's * a few internal rcu functions that could be traced * where that wont work either. In those cases, we just * do nothing. */ if (unlikely(rcu_irq_enter_disabled())) return; rcu_irq_enter_irqson(); __ftrace_trace_stack(buffer, flags, skip, pc, NULL); rcu_irq_exit_irqson(); } /** * trace_dump_stack - record a stack back trace in the trace buffer * @skip: Number of functions to skip (helper handlers) */ void trace_dump_stack(int skip) { unsigned long flags; if (tracing_disabled || tracin