1 files changed, 136 insertions, 0 deletions

diff --git a/kernel/trace/trace_kdb.c b/kernel/trace/trace_kdb.c
new file mode 100644
index 000000000000..7b8ecd751d93
--- /dev/null
+++ b/kernel/trace/trace_kdb.c
@@ -0,0 +1,136 @@
+/*
+ * 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 "../debug/kdb/kdb_private.h"
+#include "trace.h"
+#include "trace_output.h"
+
+static void ftrace_dump_buf(int skip_lines, long cpu_file)
+{
+        /* 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;
+
+        trace_init_global_iter(&iter);
+
+        for_each_tracing_cpu(cpu) {
+                atomic_inc(&iter.tr->data[cpu]->disabled);
+        }
+
+        old_userobj = trace_flags;
+
+        /* don't look at user memory in panic mode */
+        trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
+
+        kdb_printf("Dumping ftrace buffer:\n");
+
+        /* 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;
+
+        if (cpu_file == TRACE_PIPE_ALL_CPU) {
+                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);
+                }
+        } else {
+                iter.cpu_file = cpu_file;
+                iter.buffer_iter[cpu_file] =
+                        ring_buffer_read_prepare(iter.tr->buffer, cpu_file);
+                ring_buffer_read_start(iter.buffer_iter[cpu_file]);
+                tracing_iter_reset(&iter, cpu_file);
+        }
+        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");
+
+out:
+        trace_flags = old_userobj;
+
+        for_each_tracing_cpu(cpu) {
+                atomic_dec(&iter.tr->data[cpu]->disabled);
+        }
+
+        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;
+        long cpu_file;
+        char *cp;
+
+        if (argc > 2)
+                return KDB_ARGCOUNT;
+
+        if (argc) {
+                skip_lines = simple_strtol(argv[1], &cp, 0);
+                if (*cp)
+                        skip_lines = 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 = TRACE_PIPE_ALL_CPU;
+        }
+
+        kdb_trap_printk++;
+        ftrace_dump_buf(skip_lines, cpu_file);
+        kdb_trap_printk--;
+
+        return 0;
+}
+
+static __init int kdb_ftrace_register(void)
+{
+        kdb_register_repeat("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
+                            "Dump ftrace log", 0, KDB_REPEAT_NONE);
+        return 0;
+}
+
+late_initcall(kdb_ftrace_register);