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