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 "../debug/kdb/kdb_private.h" 17 #include "trace.h" 18 #include "trace_output.h" 19 20 static void ftrace_dump_buf(int skip_lines, long cpu_file) 21 { 22 /* use static because iter can be a bit big for the stack */ 23 static struct trace_iterator iter; 24 unsigned int old_userobj; 25 int cnt = 0, cpu; 26 27 trace_init_global_iter(&iter); 28 29 for_each_tracing_cpu(cpu) { 30 atomic_inc(&iter.tr->data[cpu]->disabled); 31 } 32 33 old_userobj = trace_flags; 34 35 /* don't look at user memory in panic mode */ 36 trace_flags &= ~TRACE_ITER_SYM_USEROBJ; 37 38 kdb_printf("Dumping ftrace buffer:\n"); 39 40 /* reset all but tr, trace, and overruns */ 41 memset(&iter.seq, 0, 42 sizeof(struct trace_iterator) - 43 offsetof(struct trace_iterator, seq)); 44 iter.iter_flags |= TRACE_FILE_LAT_FMT; 45 iter.pos = -1; 46 47 if (cpu_file == TRACE_PIPE_ALL_CPU) { 48 for_each_tracing_cpu(cpu) { 49 iter.buffer_iter[cpu] = 50 ring_buffer_read_prepare(iter.tr->buffer, cpu); 51 ring_buffer_read_start(iter.buffer_iter[cpu]); 52 tracing_iter_reset(&iter, cpu); 53 } 54 } else { 55 iter.cpu_file = cpu_file; 56 iter.buffer_iter[cpu_file] = 57 ring_buffer_read_prepare(iter.tr->buffer, cpu_file); 58 ring_buffer_read_start(iter.buffer_iter[cpu_file]); 59 tracing_iter_reset(&iter, cpu_file); 60 } 61 if (!trace_empty(&iter)) 62 trace_find_next_entry_inc(&iter); 63 while (!trace_empty(&iter)) { 64 if (!cnt) 65 kdb_printf("---------------------------------\n"); 66 cnt++; 67 68 if (trace_find_next_entry_inc(&iter) != NULL && !skip_lines) 69 print_trace_line(&iter); 70 if (!skip_lines) 71 trace_printk_seq(&iter.seq); 72 else 73 skip_lines--; 74 if (KDB_FLAG(CMD_INTERRUPT)) 75 goto out; 76 } 77 78 if (!cnt) 79 kdb_printf(" (ftrace buffer empty)\n"); 80 else 81 kdb_printf("---------------------------------\n"); 82 83 out: 84 trace_flags = old_userobj; 85 86 for_each_tracing_cpu(cpu) { 87 atomic_dec(&iter.tr->data[cpu]->disabled); 88 } 89 90 for_each_tracing_cpu(cpu) 91 if (iter.buffer_iter[cpu]) 92 ring_buffer_read_finish(iter.buffer_iter[cpu]); 93 } 94 95 /* 96 * kdb_ftdump - Dump the ftrace log buffer 97 */ 98 static int kdb_ftdump(int argc, const char **argv) 99 { 100 int skip_lines = 0; 101 long cpu_file; 102 char *cp; 103 104 if (argc > 2) 105 return KDB_ARGCOUNT; 106 107 if (argc) { 108 skip_lines = simple_strtol(argv[1], &cp, 0); 109 if (*cp) 110 skip_lines = 0; 111 } 112 113 if (argc == 2) { 114 cpu_file = simple_strtol(argv[2], &cp, 0); 115 if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 || 116 !cpu_online(cpu_file)) 117 return KDB_BADINT; 118 } else { 119 cpu_file = TRACE_PIPE_ALL_CPU; 120 } 121 122 kdb_trap_printk++; 123 ftrace_dump_buf(skip_lines, cpu_file); 124 kdb_trap_printk--; 125 126 return 0; 127 } 128 129 static __init int kdb_ftrace_register(void) 130 { 131 kdb_register_repeat("ftdump", kdb_ftdump, "[skip_#lines] [cpu]", 132 "Dump ftrace log", 0, KDB_REPEAT_NONE); 133 return 0; 134 } 135 136 late_initcall(kdb_ftrace_register); 137