1 /* 2 * kdb helper for dumping the ftrace buffer 3 * 4 * Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com> 5 * 6 * ftrace_dump_buf based on ftrace_dump: 7 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> 8 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com> 9 * 10 */ 11 #include <linux/init.h> 12 #include <linux/kgdb.h> 13 #include <linux/kdb.h> 14 #include <linux/ftrace.h> 15 16 #include "trace.h" 17 #include "trace_output.h" 18 19 static void ftrace_dump_buf(int skip_lines, long cpu_file) 20 { 21 /* use static because iter can be a bit big for the stack */ 22 static struct trace_iterator iter; 23 unsigned int old_userobj; 24 int cnt = 0, cpu; 25 26 trace_init_global_iter(&iter); 27 28 for_each_tracing_cpu(cpu) { 29 atomic_inc(&iter.tr->data[cpu]->disabled); 30 } 31 32 old_userobj = trace_flags; 33 34 /* don't look at user memory in panic mode */ 35 trace_flags &= ~TRACE_ITER_SYM_USEROBJ; 36 37 kdb_printf("Dumping ftrace buffer:\n"); 38 39 /* reset all but tr, trace, and overruns */ 40 memset(&iter.seq, 0, 41 sizeof(struct trace_iterator) - 42 offsetof(struct trace_iterator, seq)); 43 iter.iter_flags |= TRACE_FILE_LAT_FMT; 44 iter.pos = -1; 45 46 if (cpu_file == TRACE_PIPE_ALL_CPU) { 47 for_each_tracing_cpu(cpu) { 48 iter.buffer_iter[cpu] = 49 ring_buffer_read_prepare(iter.tr->buffer, cpu); 50 ring_buffer_read_start(iter.buffer_iter[cpu]); 51 tracing_iter_reset(&iter, cpu); 52 } 53 } else { 54 iter.cpu_file = cpu_file; 55 iter.buffer_iter[cpu_file] = 56 ring_buffer_read_prepare(iter.tr->buffer, cpu_file); 57 ring_buffer_read_start(iter.buffer_iter[cpu_file]); 58 tracing_iter_reset(&iter, cpu_file); 59 } 60 if (!trace_empty(&iter)) 61 trace_find_next_entry_inc(&iter); 62 while (!trace_empty(&iter)) { 63 if (!cnt) 64 kdb_printf("---------------------------------\n"); 65 cnt++; 66 67 if (trace_find_next_entry_inc(&iter) != NULL && !skip_lines) 68 print_trace_line(&iter); 69 if (!skip_lines) 70 trace_printk_seq(&iter.seq); 71 else 72 skip_lines--; 73 if (KDB_FLAG(CMD_INTERRUPT)) 74 goto out; 75 } 76 77 if (!cnt) 78 kdb_printf(" (ftrace buffer empty)\n"); 79 else 80 kdb_printf("---------------------------------\n"); 81 82 out: 83 trace_flags = old_userobj; 84 85 for_each_tracing_cpu(cpu) { 86 atomic_dec(&iter.tr->data[cpu]->disabled); 87 } 88 89 for_each_tracing_cpu(cpu) 90 if (iter.buffer_iter[cpu]) 91 ring_buffer_read_finish(iter.buffer_iter[cpu]); 92 } 93 94 /* 95 * kdb_ftdump - Dump the ftrace log buffer 96 */ 97 static int kdb_ftdump(int argc, const char **argv) 98 { 99 int skip_lines = 0; 100 long cpu_file; 101 char *cp; 102 103 if (argc > 2) 104 return KDB_ARGCOUNT; 105 106 if (argc) { 107 skip_lines = simple_strtol(argv[1], &cp, 0); 108 if (*cp) 109 skip_lines = 0; 110 } 111 112 if (argc == 2) { 113 cpu_file = simple_strtol(argv[2], &cp, 0); 114 if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 || 115 !cpu_online(cpu_file)) 116 return KDB_BADINT; 117 } else { 118 cpu_file = TRACE_PIPE_ALL_CPU; 119 } 120 121 kdb_trap_printk++; 122 ftrace_dump_buf(skip_lines, cpu_file); 123 kdb_trap_printk--; 124 125 return 0; 126 } 127 128 static __init int kdb_ftrace_register(void) 129 { 130 kdb_register_repeat("ftdump", kdb_ftdump, "[skip_#lines] [cpu]", 131 "Dump ftrace log", 0, KDB_REPEAT_NONE); 132 return 0; 133 } 134 135 late_initcall(kdb_ftrace_register); 136