diff options
Diffstat (limited to 'kernel/trace/trace_kdb.c')
| -rw-r--r-- | kernel/trace/trace_kdb.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c new file mode 100644 index 0000000000..59857a1ee4 --- /dev/null +++ b/kernel/trace/trace_kdb.c @@ -0,0 +1,164 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * kdb helper for dumping the ftrace buffer + * + * Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com> + * + * ftrace_dump_buf based on ftrace_dump: + * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> + * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com> + * + */ +#include <linux/init.h> +#include <linux/kgdb.h> +#include <linux/kdb.h> +#include <linux/ftrace.h> + +#include "trace.h" +#include "trace_output.h" + +static struct trace_iterator iter; +static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS]; + +static void ftrace_dump_buf(int skip_entries, long cpu_file) +{ + struct trace_array *tr; + unsigned int old_userobj; + int cnt = 0, cpu; + + tr = iter.tr; + + old_userobj = tr->trace_flags; + + /* don't look at user memory in panic mode */ + tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ; + + kdb_printf("Dumping ftrace buffer:\n"); + if (skip_entries) + kdb_printf("(skipping %d entries)\n", skip_entries); + + trace_iterator_reset(&iter); + iter.iter_flags |= TRACE_FILE_LAT_FMT; + + if (cpu_file == RING_BUFFER_ALL_CPUS) { + for_each_tracing_cpu(cpu) { + iter.buffer_iter[cpu] = + ring_buffer_read_prepare(iter.array_buffer->buffer, + cpu, GFP_ATOMIC); + ring_buffer_read_start(iter.buffer_iter[cpu]); + tracing_iter_reset(&iter, cpu); + } + } else { + iter.cpu_file = cpu_file; + iter.buffer_iter[cpu_file] = + ring_buffer_read_prepare(iter.array_buffer->buffer, + cpu_file, GFP_ATOMIC); + ring_buffer_read_start(iter.buffer_iter[cpu_file]); + tracing_iter_reset(&iter, cpu_file); + } + + while (trace_find_next_entry_inc(&iter)) { + if (!cnt) + kdb_printf("---------------------------------\n"); + cnt++; + + if (!skip_entries) { + print_trace_line(&iter); + trace_printk_seq(&iter.seq); + } else { + skip_entries--; + } + + if (KDB_FLAG(CMD_INTERRUPT)) + goto out; + } + + if (!cnt) + kdb_printf(" (ftrace buffer empty)\n"); + else + kdb_printf("---------------------------------\n"); + +out: + tr->trace_flags = old_userobj; + + for_each_tracing_cpu(cpu) { + if (iter.buffer_iter[cpu]) { + ring_buffer_read_finish(iter.buffer_iter[cpu]); + iter.buffer_iter[cpu] = NULL; + } + } +} + +/* + * kdb_ftdump - Dump the ftrace log buffer + */ +static int kdb_ftdump(int argc, const char **argv) +{ + int skip_entries = 0; + long cpu_file; + char *cp; + int cnt; + int cpu; + + if (argc > 2) + return KDB_ARGCOUNT; + + if (argc) { + skip_entries = simple_strtol(argv[1], &cp, 0); + if (*cp) + skip_entries = 0; + } + + if (argc == 2) { + cpu_file = simple_strtol(argv[2], &cp, 0); + if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 || + !cpu_online(cpu_file)) + return KDB_BADINT; + } else { + cpu_file = RING_BUFFER_ALL_CPUS; + } + + kdb_trap_printk++; + + trace_init_global_iter(&iter); + iter.buffer_iter = buffer_iter; + + for_each_tracing_cpu(cpu) { + atomic_inc(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); + } + + /* A negative skip_entries means skip all but the last entries */ + if (skip_entries < 0) { + if (cpu_file == RING_BUFFER_ALL_CPUS) + cnt = trace_total_entries(NULL); + else + cnt = trace_total_entries_cpu(NULL, cpu_file); + skip_entries = max(cnt + skip_entries, 0); + } + + ftrace_dump_buf(skip_entries, cpu_file); + + for_each_tracing_cpu(cpu) { + atomic_dec(&per_cpu_ptr(iter.array_buffer->data, cpu)->disabled); + } + + kdb_trap_printk--; + + return 0; +} + +static kdbtab_t ftdump_cmd = { + .name = "ftdump", + .func = kdb_ftdump, + .usage = "[skip_#entries] [cpu]", + .help = "Dump ftrace log; -skip dumps last #entries", + .flags = KDB_ENABLE_ALWAYS_SAFE, +}; + +static __init int kdb_ftrace_register(void) +{ + kdb_register(&ftdump_cmd); + return 0; +} + +late_initcall(kdb_ftrace_register); |