diff options
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 167 |
1 files changed, 85 insertions, 82 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 95ede1f7ffdf..fd8e1ec39c27 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1723,8 +1723,15 @@ void tracing_reset_all_online_cpus(void) } } +/* + * The tgid_map array maps from pid to tgid; i.e. the value stored at index i + * is the tgid last observed corresponding to pid=i. + */ static int *tgid_map; +/* The maximum valid index into tgid_map. */ +static size_t tgid_map_max; + #define SAVED_CMDLINES_DEFAULT 128 #define NO_CMDLINE_MAP UINT_MAX static arch_spinlock_t trace_cmdline_lock = __ARCH_SPIN_LOCK_UNLOCKED; @@ -1737,9 +1744,6 @@ struct saved_cmdlines_buffer { }; static struct saved_cmdlines_buffer *savedcmd; -/* temporary disable recording */ -static atomic_t trace_record_taskinfo_disabled __read_mostly; - static inline char *get_saved_cmdlines(int idx) { return &savedcmd->saved_cmdlines[idx * TASK_COMM_LEN]; @@ -1928,14 +1932,13 @@ static void tracing_stop_tr(struct trace_array *tr) static int trace_save_cmdline(struct task_struct *tsk) { - unsigned pid, idx; + unsigned tpid, idx; /* treat recording of idle task as a success */ if (!tsk->pid) return 1; - if (unlikely(tsk->pid > PID_MAX_DEFAULT)) - return 0; + tpid = tsk->pid & (PID_MAX_DEFAULT - 1); /* * It's not the end of the world if we don't get @@ -1946,26 +1949,15 @@ static int trace_save_cmdline(struct task_struct *tsk) if (!arch_spin_trylock(&trace_cmdline_lock)) return 0; - idx = savedcmd->map_pid_to_cmdline[tsk->pid]; + idx = savedcmd->map_pid_to_cmdline[tpid]; 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->map_pid_to_cmdline[tpid] = idx; savedcmd->cmdline_idx = idx; } + savedcmd->map_cmdline_to_pid[idx] = tsk->pid; set_cmdline(idx, tsk->comm); arch_spin_unlock(&trace_cmdline_lock); @@ -1976,6 +1968,7 @@ static int trace_save_cmdline(struct task_struct *tsk) static void __trace_find_cmdline(int pid, char comm[]) { unsigned map; + int tpid; if (!pid) { strcpy(comm, "<idle>"); @@ -1987,16 +1980,16 @@ static void __trace_find_cmdline(int pid, char comm[]) return; } - if (pid > PID_MAX_DEFAULT) { - strcpy(comm, "<...>"); - return; + tpid = pid & (PID_MAX_DEFAULT - 1); + map = savedcmd->map_pid_to_cmdline[tpid]; + if (map != NO_CMDLINE_MAP) { + tpid = savedcmd->map_cmdline_to_pid[map]; + if (tpid == pid) { + strlcpy(comm, get_saved_cmdlines(map), TASK_COMM_LEN); + 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, "<...>"); + strcpy(comm, "<...>"); } void trace_find_cmdline(int pid, char comm[]) @@ -2010,24 +2003,41 @@ void trace_find_cmdline(int pid, char comm[]) preempt_enable(); } +static int *trace_find_tgid_ptr(int pid) +{ + /* + * Pairs with the smp_store_release in set_tracer_flag() to ensure that + * if we observe a non-NULL tgid_map then we also observe the correct + * tgid_map_max. + */ + int *map = smp_load_acquire(&tgid_map); + + if (unlikely(!map || pid > tgid_map_max)) + return NULL; + + return &map[pid]; +} + int trace_find_tgid(int pid) { - if (unlikely(!tgid_map || !pid || pid > PID_MAX_DEFAULT)) - return 0; + int *ptr = trace_find_tgid_ptr(pid); - return tgid_map[pid]; + return ptr ? *ptr : 0; } static int trace_save_tgid(struct task_struct *tsk) { + int *ptr; + /* treat recording of idle task as a success */ if (!tsk->pid) return 1; - if (unlikely(!tgid_map || tsk->pid > PID_MAX_DEFAULT)) + ptr = trace_find_tgid_ptr(tsk->pid); + if (!ptr) return 0; - tgid_map[tsk->pid] = tsk->tgid; + *ptr = tsk->tgid; return 1; } @@ -2035,8 +2045,6 @@ static bool tracing_record_taskinfo_skip(int flags) { if (unlikely(!(flags & (TRACE_RECORD_CMDLINE | TRACE_RECORD_TGID)))) return true; - if (atomic_read(&trace_record_taskinfo_disabled) || !tracing_is_on()) - return true; if (!__this_cpu_read(trace_taskinfo_save)) return true; return false; @@ -2285,7 +2293,7 @@ trace_event_buffer_lock_reserve(struct ring_buffer **current_rb, (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) { + if ((len < (PAGE_SIZE - sizeof(*entry) - sizeof(entry->array[0]))) && val == 1) { trace_event_setup(entry, type, flags, pc); entry->array[0] = len; return entry; @@ -2404,7 +2412,7 @@ void trace_buffer_unlock_commit_regs(struct trace_array *tr, * two. They are that meaningful. */ ftrace_trace_stack(tr, buffer, flags, regs ? 0 : 4, pc, regs); - ftrace_trace_userstack(buffer, flags, pc); + ftrace_trace_userstack(tr, buffer, flags, pc); } /* @@ -2631,7 +2639,8 @@ static void __ftrace_trace_stack(struct ring_buffer *buffer, size *= sizeof(unsigned long); event = __trace_buffer_lock_reserve(buffer, TRACE_STACK, - sizeof(*entry) + size, flags, pc); + (sizeof(*entry) - sizeof(entry->caller)) + size, + flags, pc); if (!event) goto out; entry = ring_buffer_event_data(event); @@ -2734,14 +2743,15 @@ void trace_dump_stack(int skip) static DEFINE_PER_CPU(int, user_stack_count); void -ftrace_trace_userstack(struct ring_buffer *buffer, unsigned long flags, int pc) +ftrace_trace_userstack(struct trace_array *tr, + struct ring_buffer *buffer, unsigned long flags, int pc) { struct trace_event_call *call = &event_user_stack; struct ring_buffer_event *event; struct userstack_entry *entry; struct stack_trace trace; - if (!(global_trace.trace_flags & TRACE_ITER_USERSTACKTRACE)) + if (!(tr->trace_flags & TRACE_ITER_USERSTACKTRACE)) return; /* @@ -2800,7 +2810,7 @@ struct trace_buffer_struct { char buffer[4][TRACE_BUF_SIZE]; }; -static struct trace_buffer_struct *trace_percpu_buffer; +static struct trace_buffer_struct __percpu *trace_percpu_buffer; /* * Thise allows for lockless recording. If we're nested too deeply, then @@ -2810,14 +2820,14 @@ static char *get_trace_buf(void) { struct trace_buffer_struct *buffer = this_cpu_ptr(trace_percpu_buffer); - if (!buffer || buffer->nesting >= 4) + if (!trace_percpu_buffer || buffer->nesting >= 4) return NULL; buffer->nesting++; /* Interrupts must see nesting incremented before we use the buffer */ barrier(); - return &buffer->buffer[buffer->nesting][0]; + return &buffer->buffer[buffer->nesting - 1][0]; } static void put_trace_buf(void) @@ -2829,7 +2839,7 @@ static void put_trace_buf(void) static int alloc_percpu_trace_buffer(void) { - struct trace_buffer_struct *buffers; + struct trace_buffer_struct __percpu *buffers; buffers = alloc_percpu(struct trace_buffer_struct); if (WARN(!buffers, "Could not allocate percpu trace_printk buffer")) @@ -3035,6 +3045,9 @@ int trace_array_printk(struct trace_array *tr, if (!(global_trace.trace_flags & TRACE_ITER_PRINTK)) return 0; + if (!tr) + return -ENOENT; + va_start(ap, fmt); ret = trace_array_vprintk(tr, ip, fmt, ap); va_end(ap); @@ -3265,9 +3278,6 @@ static void *s_start(struct seq_file *m, loff_t *pos) return ERR_PTR(-EBUSY); #endif - if (!iter->snapshot) - atomic_inc(&trace_record_taskinfo_disabled); - if (*pos != iter->pos) { iter->ent = NULL; iter->cpu = 0; @@ -3310,9 +3320,6 @@ static void s_stop(struct seq_file *m, void *p) return; #endif - if (!iter->snapshot) - atomic_dec(&trace_record_taskinfo_disabled); - trace_access_unlock(iter->cpu_file); trace_event_read_unlock(); } @@ -4370,6 +4377,8 @@ int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set) int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled) { + int *map; + if ((mask == TRACE_ITER_RECORD_TGID) || (mask == TRACE_ITER_RECORD_CMD)) lockdep_assert_held(&event_mutex); @@ -4392,9 +4401,19 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled) trace_event_enable_cmd_record(enabled); if (mask == TRACE_ITER_RECORD_TGID) { - if (!tgid_map) - tgid_map = kzalloc((PID_MAX_DEFAULT + 1) * sizeof(*tgid_map), - GFP_KERNEL); + if (!tgid_map) { + tgid_map_max = pid_max; + map = kzalloc((tgid_map_max + 1) * sizeof(*tgid_map), + GFP_KERNEL); + + /* + * Pairs with smp_load_acquire() in + * trace_find_tgid_ptr() to ensure that if it observes + * the tgid_map we just allocated then it also observes + * the corresponding tgid_map_max value. + */ + smp_store_release(&tgid_map, map); + } if (!tgid_map) { tr->trace_flags &= ~TRACE_ITER_RECORD_TGID; return -ENOMEM; @@ -4767,37 +4786,16 @@ static const struct file_operations tracing_readme_fops = { static void *saved_tgids_next(struct seq_file *m, void *v, loff_t *pos) { - int *ptr = v; - - if (*pos || m->count) - ptr++; - - (*pos)++; + int pid = ++(*pos); - for (; ptr <= &tgid_map[PID_MAX_DEFAULT]; ptr++) { - if (trace_find_tgid(*ptr)) - return ptr; - } - - return NULL; + return trace_find_tgid_ptr(pid); } static void *saved_tgids_start(struct seq_file *m, loff_t *pos) { - void *v; - loff_t l = 0; - - if (!tgid_map) - return NULL; + int pid = *pos; - v = &tgid_map[0]; - while (l <= *pos) { - v = saved_tgids_next(m, v, &l); - if (!v) - return NULL; - } - - return v; + return trace_find_tgid_ptr(pid); } static void saved_tgids_stop(struct seq_file *m, void *v) @@ -4806,9 +4804,14 @@ static void saved_tgids_stop(struct seq_file *m, void *v) static int saved_tgids_show(struct seq_file *m, void *v) { - int pid = (int *)v - tgid_map; + int *entry = (int *)v; + int pid = entry - tgid_map; + int tgid = *entry; + + if (tgid == 0) + return SEQ_SKIP; - seq_printf(m, "%d %d\n", pid, trace_find_tgid(pid)); + seq_printf(m, "%d %d\n", pid, tgid); return 0; } @@ -8343,7 +8346,7 @@ __init static int tracer_alloc_buffers(void) goto out_free_buffer_mask; /* Only allocate trace_printk buffers if a trace_printk exists */ - if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt) + if (&__stop___trace_bprintk_fmt != &__start___trace_bprintk_fmt) /* Must be called before global_trace.buffer is allocated */ trace_printk_init_buffers(); |