forked from rostedt/trace-cmd
/
trace-blk-hack.c
163 lines (148 loc) · 4.81 KB
/
trace-blk-hack.c
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/*
* Copyright (C) 2009 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License (not later!)
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
#include <stdio.h>
#include "trace-cmd.h"
#include "trace-local.h"
static const char blk_event_start[] =
"name: blktrace\n"
"ID: %d\n"
"format:\n"
"\tfield:unsigned short common_type;\toffset:0;\tsize:2;\n"
"\tfield:unsigned char common_flags;\toffset:2;\tsize:1;\n"
"\tfield:unsigned char common_preempt_count;\toffset:3;\tsize:1;\n"
"\tfield:int common_pid;\toffset:4;\tsize:4;\n";
static const char blk_body[] = "\n"
"\tfield:u64 sector;\toffset:16;\tsize:8;\n"
"\tfield:int bytes;\toffset:24;\tsize:4;\n"
"\tfield:int action;\toffset:28;\tsize:4;\n"
"\tfield:int pid;\toffset:32;\tsize:4;\n"
"\tfield:int device;\toffset:36;\tsize:4;\n"
"\tfield:int cpu;\toffset:40;\tsize:4;\n"
"\tfield:short error;\toffset:44;\tsize:2;\n"
"\tfield:short pdu_len;\toffset:46;\tsize:2;\n"
"\tfield:void data;\toffset:48;\tsize:0;\n"
"\n"
"print fmt: \"%%d\", REC->pid\n";
int tracecmd_blk_hack(struct tracecmd_input *handle)
{
struct pevent *pevent;
struct event_format *event;
struct format_field *field;
char buf[4096]; /* way more than enough! */
int id;
int l;
int r;
pevent = tracecmd_get_pevent(handle);
/*
* Unfortunately, the TRACE_BLK has changed a bit.
* We need to test if various events exist to try
* to guess what event id TRACE_BLK would be.
*/
/* It was originally behind the "power" event */
event = pevent_find_event_by_name(pevent, "ftrace", "power");
if (event) {
id = event->id + 1;
goto found;
}
/*
* But the power tracer is now in perf.
* Then it was after kmem_free
*/
event = pevent_find_event_by_name(pevent, "ftrace", "kmem_free");
if (event) {
id = event->id + 1;
goto found;
}
/*
* But that then went away.
* Currently it should be behind the user stack.
*/
event = pevent_find_event_by_name(pevent, "ftrace", "user_stack");
if (event) {
id = event->id + 1;
goto found;
}
/* Give up :( */
return -1;
found:
/*
* Blk events are not exported in the events directory.
* This is a hack to attempt to create a block event
* that we can read.
*
* We'll make a format file to look like this:
*
* name: blktrace
* ID: 13
* format:
* field:unsigned short common_type; offset:0; size:2;
* field:unsigned char common_flags; offset:2; size:1;
* field:unsigned char common_preempt_count; offset:3; size:1;
* field:int common_pid; offset:4; size:4;
* field:int common_lock_depth; offset:8; size:4;
*
* field:u64 sector; offset:16; size:8;
* field:int bytes; offset:32; size:4;
* field:int action; offset:36; size:4;
* field:int pid; offset:40; size:4;
* field:int device; offset:44; size:4;
* field:int cpu; offset:48; size:4;
* field:short error; offset:52; size:2;
* field:short pdu_len; offset:54; size:2;
* field:void data; offset:60; size:0;
*
* print fmt: "%d", REC->pid
*
* Note: the struct blk_io_trace is used directly and
* just the first parts of the struct are not used in order
* to not write over the ftrace data.
*/
/* Make sure the common fields exist */
field = pevent_find_common_field(event, "common_type");
if (!field || field->offset != 0 || field->size != 2)
goto fail;
field = pevent_find_common_field(event, "common_flags");
if (!field || field->offset != 2 || field->size != 1)
goto fail;
field = pevent_find_common_field(event, "common_preempt_count");
if (!field || field->offset != 3 || field->size != 1)
goto fail;
field = pevent_find_common_field(event, "common_pid");
if (!field || field->offset != 4 || field->size != 4)
goto fail;
r = sprintf(buf, blk_event_start, id);
l = r;
/* lock depth is optional */
field = pevent_find_common_field(event, "common_lock_depth");
if (field) {
if (field->offset != 8 || field->size != 4)
return -1;
r = sprintf(buf+l, "\tfield:int common_lock_depth;\toffset:8;\tsize:4;\n");
l += r;
}
r = sprintf(buf+l, blk_body);
/* Parse this event */
l += r;
pevent_parse_event(pevent, buf, l, "ftrace");
return 0;
fail:
return -1;
}