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ftrace,kdb: Extend kdb to be able to dump the ftrace buffer
Add in a helper function to allow the kdb shell to dump the ftrace buffer. Modify trace.c to expose the capability to iterate over the ftrace buffer in a read only capacity. Signed-off-by: Jason Wessel <[email protected]> Acked-by: Steven Rostedt <[email protected]> CC: Frederic Weisbecker <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,119 @@ | ||
| /* | ||
| * kdb helper for dumping the ftrace buffer | ||
| * | ||
| * Copyright (C) 2010 Jason Wessel <[email protected]> | ||
| * | ||
| * ftrace_dump_buf based on ftrace_dump: | ||
| * Copyright (C) 2007-2008 Steven Rostedt <[email protected]> | ||
| * Copyright (C) 2008 Ingo Molnar <[email protected]> | ||
| * | ||
| */ | ||
| #include <linux/init.h> | ||
| #include <linux/kgdb.h> | ||
| #include <linux/kdb.h> | ||
| #include <linux/ftrace.h> | ||
|
|
||
| #include "../debug/kdb/kdb_private.h" | ||
| #include "trace.h" | ||
| #include "trace_output.h" | ||
|
|
||
| static void ftrace_dump_buf(int skip_lines) | ||
| { | ||
| /* use static because iter can be a bit big for the stack */ | ||
| static struct trace_iterator iter; | ||
| unsigned int old_userobj; | ||
| int cnt = 0, cpu; | ||
|
|
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| trace_init_global_iter(&iter); | ||
|
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| for_each_tracing_cpu(cpu) { | ||
| atomic_inc(&iter.tr->data[cpu]->disabled); | ||
| } | ||
|
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| old_userobj = trace_flags; | ||
|
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| /* don't look at user memory in panic mode */ | ||
| trace_flags &= ~TRACE_ITER_SYM_USEROBJ; | ||
|
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| kdb_printf("Dumping ftrace buffer:\n"); | ||
|
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| /* reset all but tr, trace, and overruns */ | ||
| memset(&iter.seq, 0, | ||
| sizeof(struct trace_iterator) - | ||
| offsetof(struct trace_iterator, seq)); | ||
| iter.iter_flags |= TRACE_FILE_LAT_FMT; | ||
| iter.pos = -1; | ||
|
|
||
| for_each_tracing_cpu(cpu) { | ||
| iter.buffer_iter[cpu] = | ||
| ring_buffer_read_prepare(iter.tr->buffer, cpu); | ||
| ring_buffer_read_start(iter.buffer_iter[cpu]); | ||
| tracing_iter_reset(&iter, cpu); | ||
| } | ||
|
|
||
| if (!trace_empty(&iter)) | ||
| trace_find_next_entry_inc(&iter); | ||
| while (!trace_empty(&iter)) { | ||
| if (!cnt) | ||
| kdb_printf("---------------------------------\n"); | ||
| cnt++; | ||
|
|
||
| if (trace_find_next_entry_inc(&iter) != NULL && !skip_lines) | ||
| print_trace_line(&iter); | ||
| if (!skip_lines) | ||
| trace_printk_seq(&iter.seq); | ||
| else | ||
| skip_lines--; | ||
| if (KDB_FLAG(CMD_INTERRUPT)) | ||
| goto out; | ||
| } | ||
|
|
||
| if (!cnt) | ||
| kdb_printf(" (ftrace buffer empty)\n"); | ||
| else | ||
| kdb_printf("---------------------------------\n"); | ||
|
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| out: | ||
| trace_flags = old_userobj; | ||
|
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| for_each_tracing_cpu(cpu) { | ||
| atomic_dec(&iter.tr->data[cpu]->disabled); | ||
| } | ||
|
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| for_each_tracing_cpu(cpu) | ||
| if (iter.buffer_iter[cpu]) | ||
| ring_buffer_read_finish(iter.buffer_iter[cpu]); | ||
| } | ||
|
|
||
| /* | ||
| * kdb_ftdump - Dump the ftrace log buffer | ||
| */ | ||
| static int kdb_ftdump(int argc, const char **argv) | ||
| { | ||
| int skip_lines = 0; | ||
| char *cp; | ||
|
|
||
| if (argc > 1) | ||
| return KDB_ARGCOUNT; | ||
|
|
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| if (argc) { | ||
| skip_lines = simple_strtol(argv[1], &cp, 0); | ||
| if (*cp) | ||
| skip_lines = 0; | ||
| } | ||
|
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| kdb_trap_printk++; | ||
| ftrace_dump_buf(skip_lines); | ||
| kdb_trap_printk--; | ||
|
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| return 0; | ||
| } | ||
|
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| static __init int kdb_ftrace_register(void) | ||
| { | ||
| kdb_register_repeat("ftdump", kdb_ftdump, "", "Dump ftrace log", | ||
| 0, KDB_REPEAT_NONE); | ||
| return 0; | ||
| } | ||
|
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| late_initcall(kdb_ftrace_register); |