From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Prasanna S Panchamukhi <prasanna@in.ibm.com>,
Ingo Molnar <mingo@redhat.com>,
SystemTAP <systemtap@sources.redhat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
Satoshi Oshima <soshima@redhat.com>,
Hideo Aoki <haoki@redhat.com>,
Yumiko Sugita <yumiko.sugita.yf@hitachi.com>
Subject: [RFC][djprobe] djprobe examples
Date: Thu, 19 Oct 2006 09:04:00 -0000 [thread overview]
Message-ID: <45373F70.4020507@hitachi.com> (raw)
In-Reply-To: <45338593.6090207@hitachi.com>
[-- Attachment #1: Type: text/plain, Size: 2182 bytes --]
Hi,
Here are an example module of djprobe and a simple helper script.
NOTE:
Currently, this helper script can ONLY measure the *LENGTH* of the
instruction-block which will be overwritten by a jump code. It can
*NOT* check whether this instruction-block can be executed out of
line and no branch jumps into the target area.
However, now we're developing more useful helper tool which can
check it.
Here is the example of usage;
1) Analyze the kernel code by using the helper script.
$ ./disym.sh sys_symlink
sys_symlink
0xc017bbe0
/lib/modules/2.6.19-rc1-mm1/build/vmlinux: file format elf32-i386
Disassembly of section .text:
c017bbe0 <sys_symlink>:
c017bbe0: 83 ec 0c sub $0xc,%esp
c017bbe3: 8b 44 24 14 mov 0x14(%esp),%eax
Please be sure that the above-disassembled instructions are relocatable.
Parameter: addr=0xc017bbe0 size=7
2) If the instructions can be executed out of line (ex. load/store,
compare, add/sub, etc.) and no branch jumps into it (you can dump whole
of the function by using disym.sh with '-a' option),
Install the example module with the above parameters.
$ sudo /sbin/insmod ./djprobe_ex.ko addr=0xc017bbe0 size=7
3) and test it.
$ ln -s hoge huga
$ dmesg | tail -n 4
probe install at c017bbe0, size 7
Stopping tasks: =======================================|
Restarting tasks... done
probe call:c017bbe0, caller:c01030c5
$ rm huga
$ ln -s hoge huga
$ dmesg | tail -n 5
probe install at c017bbe0, size 7
Stopping tasks: =======================================|
Restarting tasks... done
probe call:c017bbe0, caller:c01030c5
probe call:c017bbe0, caller:c01030c5
4) Finally, remove the module.
$ sudo /sbin/rmmod djprobe_ex.ko
$ dmesg | tail -n 8
probe install at c017bbe0, size 7
Stopping tasks: =======================================|
Restarting tasks... done
probe call:c017bbe0, caller:c01030c5
probe call:c017bbe0, caller:c01030c5
probe uninstall at c017bbe0
Stopping tasks: =======================================|
Restarting tasks... done
Thanks,
--
Masami HIRAMATSU
Linux Technology Center
Hitachi, Ltd., Systems Development Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
[-- Attachment #2: disym.sh --]
[-- Type: text/plain, Size: 1743 bytes --]
#!/bin/sh
# Copyright (C) HITACHI, Ltd. 2005
# Created by M.Hiramatsu <hiramatu@sdl.hitachi.co.jp>
[ $# -gt 3 -o $# -lt 1 ] && echo "usage: disym.sh [-a] <kernel_symbol> [kernel-version]" && exit 0
DISALL=0
if [ $1 = "-a" ] ;then
DISALL=1
shift 1
fi
SYM=$1
KVER=$2
[ -z "$KVER" ] && KVER=`uname -r`
function cntarg () {
return $#
}
SYSMAP=/lib/modules/$KVER/build/System.map
[ -f $SYSMAP ] || SYSMAP=/boot/System.map-`uname -r`
[ -f $SYSMAP ] || SYSMAP=/proc/kallsyms
VMLINUX=/lib/modules/$KVER/build/vmlinux
[ -f $VMLINUX ] || VMLINUX=/boot/vmlinux-`uname -r`
[ -f $VMLINUX ] || VMLINUX=/usr/lib/debug/lib/modules/$KVER/vmlinux
setaddrs () {
XADDR=$1
XEADDR=$2
}
echo $SYM
case $SYM in
0x*)
XADDR=$SYM
SADDR=`printf "%d" $SYM`
EADDR=`expr $SADDR + 5`
;;
*)
if [ $DISALL -eq 1 ] ;then
setaddrs `sort $SYSMAP | grep -A1 " $SYM"$ | cut -f 1 -d\ `
if [ -z "$XADDR" ] ; then
echo "Error : $SYM was not found in "$SYSMAP
exit 0;
fi
XADDR=0x$XADDR
XEADDR=0x$XEADDR
SADDR=`printf "%d" $XADDR`
EADDR=`printf "%d" $XEADDR`
else
XADDR=0x`grep " $SYM"$ $SYSMAP | cut -f 1 -d\ `
if [ "$XADDR" = "0x" ] ; then
echo "Error : $SYM was not found in "$SYSMAP
exit 0;
fi
SADDR=`printf "%d" $XADDR`
EADDR=`expr $SADDR + 5`
fi
;;
esac
echo $XADDR
objdump -w --start-address=$SADDR --stop-address=$EADDR -j ".text" -d $VMLINUX
echo
LLINE=`objdump -w --start-address=$SADDR --stop-address=$EADDR -j ".text" -d $VMLINUX | tail -n 1 | sed s/" "/\:/g`
EXADDR=`echo $LLINE | cut -f 1 -d:`
cntarg `echo $LLINE | cut -f 3 -d:`
DIFF=$?
EADDR=`printf "%d" 0x$EXADDR`
SIZE=`expr $EADDR - $SADDR + $DIFF`
echo "Please be sure that the above-disassembled instructions are relocatable."
echo "Parameter: addr=$XADDR size=$SIZE"
[-- Attachment #3: djprobe_ex.c --]
[-- Type: text/plain, Size: 2174 bytes --]
/*
djprobe_ex.c -- Direct Jump Probe Example
Copyright (c) 2005,2006 Hitachi,Ltd.,
Created by Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
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 General Public License for more details.
You should have received a copy of the GNU 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 <linux/version.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/djprobe.h>
#include <linux/rcupdate.h>
static long addr=0;
module_param(addr, long, 0444);
static long size=0;
module_param(size, long, 0444);
static long show_arg=0;
module_param(show_arg, long, 0444);
#define CALLER(regs) (((unsigned long *)®s->esp)[0])
#define ARG(n,regs) (((unsigned long *)®s->esp)[n]) /*arg1: ARG(1,stadr)*/
static void probe_func(struct djprobe *djp, struct pt_regs *regs)
{
int i;
printk("probe call:%p, caller:%lx",
(void*)djp->inst->kp.addr, CALLER(regs));
for (i = 1; i <= show_arg; i++) {
printk(" arg[%d]:%lx", i, ARG(i, regs));
}
printk("\n");
}
static struct djprobe djp = {0};
static int install_probe(void)
{
if (addr == 0 || size < 5 || size > 16 ) {
return -1;
}
printk("probe install at %p, size %ld\n", (void*)addr, size);
djp.handler = probe_func;
djprobe_param_address(&djp.param) = (void *)addr;
djprobe_param_length(&djp.param) = size;
if (register_djprobe(&djp) != 0) return -1;
return 0;
}
static void uninstall_probe(void)
{
unregister_djprobe(&djp);
printk("probe uninstall at %p\n", (void*)addr);
}
module_init(install_probe);
module_exit(uninstall_probe);
MODULE_AUTHOR("M.Hiramatsu <masami.hiramatsu.pt@hitachi.com>");
MODULE_LICENSE("GPL");
next prev parent reply other threads:[~2006-10-19 9:04 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-16 13:14 [RFC][PATCH][kprobe] enabling booster on the preemptible kernel, take 2 Masami Hiramatsu
2006-10-19 9:00 ` [PATCH 1/5][djprobe] generalize the length of the instruction slots Masami Hiramatsu
2006-10-19 9:03 ` [PATCH 2/5][djprobe] djprobe core patch Masami Hiramatsu
2006-10-27 23:34 ` Keshavamurthy, Anil S
2006-10-30 14:07 ` Masami Hiramatsu
2006-10-30 14:11 ` Ingo Molnar
2006-10-19 9:03 ` [PATCH 4/5][djprobe] djprobe for i386 architecture code Masami Hiramatsu
2006-10-19 9:03 ` [PATCH 3/5][djprobe] export set_jmp_op() for sharing Masami Hiramatsu
2006-10-19 9:04 ` [PATCH 5/5][djprobe] delayed invoking commit_djprobes() Masami Hiramatsu
2006-10-19 9:04 ` Masami Hiramatsu [this message]
2006-10-30 6:37 ` [RFC][PATCH][kprobe] enabling booster on the preemptible kernel, take 2 bibo,mao
2006-10-30 14:07 ` Masami Hiramatsu
2006-10-31 9:14 ` bibo,mao
2006-10-31 13:47 ` Masami Hiramatsu
2006-10-31 13:49 ` Ingo Molnar
2006-10-31 14:13 ` Ingo Molnar
2006-10-31 16:39 ` Masami Hiramatsu
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