1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * kdb helper for dumping the ftrace buffer 4 * 5 * Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com> 6 * 7 * ftrace_dump_buf based on ftrace_dump: 8 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> 9 * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com> 10 * 11 */ 12 #include <linux/init.h> 13 #include <linux/kgdb.h> 14 #include <linux/kdb.h> 15 #include <linux/ftrace.h> 16 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 static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS]; 25 struct trace_array *tr; 26 unsigned int old_userobj; 27 int cnt = 0, cpu; 28 29 trace_init_global_iter(&iter); 30 iter.buffer_iter = buffer_iter; 31 tr = iter.tr; 32 33 for_each_tracing_cpu(cpu) { 34 atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled); 35 } 36 37 old_userobj = tr->trace_flags; 38 39 /* don't look at user memory in panic mode */ 40 tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ; 41 42 kdb_printf("Dumping ftrace buffer:\n"); 43 44 /* reset all but tr, trace, and overruns */ 45 memset(&iter.seq, 0, 46 sizeof(struct trace_iterator) - 47 offsetof(struct trace_iterator, seq)); 48 iter.iter_flags |= TRACE_FILE_LAT_FMT; 49 iter.pos = -1; 50 51 if (cpu_file == RING_BUFFER_ALL_CPUS) { 52 for_each_tracing_cpu(cpu) { 53 iter.buffer_iter[cpu] = 54 ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu); 55 ring_buffer_read_start(iter.buffer_iter[cpu]); 56 tracing_iter_reset(&iter, cpu); 57 } 58 } else { 59 iter.cpu_file = cpu_file; 60 iter.buffer_iter[cpu_file] = 61 ring_buffer_read_prepare(iter.trace_buffer->buffer, cpu_file); 62 ring_buffer_read_start(iter.buffer_iter[cpu_file]); 63 tracing_iter_reset(&iter, cpu_file); 64 } 65 66 while (trace_find_next_entry_inc(&iter)) { 67 if (!cnt) 68 kdb_printf("---------------------------------\n"); 69 cnt++; 70 71 if (!skip_lines) { 72 print_trace_line(&iter); 73 trace_printk_seq(&iter.seq); 74 } else { 75 skip_lines--; 76 } 77 78 if (KDB_FLAG(CMD_INTERRUPT)) 79 goto out; 80 } 81 82 if (!cnt) 83 kdb_printf(" (ftrace buffer empty)\n"); 84 else 85 kdb_printf("---------------------------------\n"); 86 87 out: 88 tr->trace_flags = old_userobj; 89 90 for_each_tracing_cpu(cpu) { 91 atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled); 92 } 93 94 for_each_tracing_cpu(cpu) { 95 if (iter.buffer_iter[cpu]) { 96 ring_buffer_read_finish(iter.buffer_iter[cpu]); 97 iter.buffer_iter[cpu] = NULL; 98 } 99 } 100 } 101 102 /* 103 * kdb_ftdump - Dump the ftrace log buffer 104 */ 105 static int kdb_ftdump(int argc, const char **argv) 106 { 107 int skip_lines = 0; 108 long cpu_file; 109 char *cp; 110 111 if (argc > 2) 112 return KDB_ARGCOUNT; 113 114 if (argc) { 115 skip_lines = simple_strtol(argv[1], &cp, 0); 116 if (*cp) 117 skip_lines = 0; 118 } 119 120 if (argc == 2) { 121 cpu_file = simple_strtol(argv[2], &cp, 0); 122 if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 || 123 !cpu_online(cpu_file)) 124 return KDB_BADINT; 125 } else { 126 cpu_file = RING_BUFFER_ALL_CPUS; 127 } 128 129 kdb_trap_printk++; 130 ftrace_dump_buf(skip_lines, cpu_file); 131 kdb_trap_printk--; 132 133 return 0; 134 } 135 136 static __init int kdb_ftrace_register(void) 137 { 138 kdb_register_flags("ftdump", kdb_ftdump, "[skip_#lines] [cpu]", 139 "Dump ftrace log", 0, KDB_ENABLE_ALWAYS_SAFE); 140 return 0; 141 } 142 143 late_initcall(kdb_ftrace_register); 144