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 static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS]; 24 struct trace_array *tr; 25 unsigned int old_userobj; 26 int cnt = 0, cpu; 27 28 trace_init_global_iter(&iter); 29 iter.buffer_iter = buffer_iter; 30 tr = iter.tr; 31 32 for_each_tracing_cpu(cpu) { 33 atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled); 34 } 35 36 old_userobj = tr->trace_flags; 37 38 /* don't look at user memory in panic mode */ 39 tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ; 40 41 kdb_printf("Dumping ftrace buffer:\n"); 42 43 /* reset all but tr, trace, and overruns */ 44 memset(&iter.seq, 0, 45 sizeof(struct trace_iterator) - 46 offsetof(struct trace_iterator, seq)); 47 iter.iter_flags |= TRACE_FILE_LAT_FMT; 48 iter.pos = -1; 49 50 if (cpu_file == RING_BUFFER_ALL_CPUS) { 51 for_each_tracing_cpu(cpu) { 52 iter.buffer_iter[cpu] = 53 ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu); 54 ring_buffer_read_start(iter.buffer_iter[cpu]); 55 tracing_iter_reset(&iter, cpu); 56 } 57 } else { 58 iter.cpu_file = cpu_file; 59 iter.buffer_iter[cpu_file] = 60 ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu_file); 61 ring_buffer_read_start(iter.buffer_iter[cpu_file]); 62 tracing_iter_reset(&iter, cpu_file); 63 } 64 65 while (trace_find_next_entry_inc(&iter)) { 66 if (!cnt) 67 kdb_printf("---------------------------------\n"); 68 cnt++; 69 70 if (!skip_lines) { 71 print_trace_line(&iter); 72 trace_printk_seq(&iter.seq); 73 } else { 74 skip_lines--; 75 } 76 77 if (KDB_FLAG(CMD_INTERRUPT)) 78 goto out; 79 } 80 81 if (!cnt) 82 kdb_printf(" (ftrace buffer empty)\n"); 83 else 84 kdb_printf("---------------------------------\n"); 85 86 out: 87 tr->trace_flags = old_userobj; 88 89 for_each_tracing_cpu(cpu) { 90 atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled); 91 } 92 93 for_each_tracing_cpu(cpu) { 94 if (iter.buffer_iter[cpu]) { 95 ring_buffer_read_finish(iter.buffer_iter[cpu]); 96 iter.buffer_iter[cpu] = NULL; 97 } 98 } 99 } 100 101 /* 102 * kdb_ftdump - Dump the ftrace log buffer 103 */ 104 static int kdb_ftdump(int argc, const char **argv) 105 { 106 int skip_lines = 0; 107 long cpu_file; 108 char *cp; 109 110 if (argc > 2) 111 return KDB_ARGCOUNT; 112 113 if (argc) { 114 skip_lines = simple_strtol(argv[1], &cp, 0); 115 if (*cp) 116 skip_lines = 0; 117 } 118 119 if (argc == 2) { 120 cpu_file = simple_strtol(argv[2], &cp, 0); 121 if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 || 122 !cpu_online(cpu_file)) 123 return KDB_BADINT; 124 } else { 125 cpu_file = RING_BUFFER_ALL_CPUS; 126 } 127 128 kdb_trap_printk++; 129 ftrace_dump_buf(skip_lines, cpu_file); 130 kdb_trap_printk--; 131 132 return 0; 133 } 134 135 static __init int kdb_ftrace_register(void) 136 { 137 kdb_register_flags("ftdump", kdb_ftdump, "[skip_#lines] [cpu]", 138 "Dump ftrace log", 0, KDB_ENABLE_ALWAYS_SAFE); 139 return 0; 140 } 141 142 late_initcall(kdb_ftrace_register); 143