From mboxrd@z Thu Jan 1 00:00:00 1970 From: Masami Hiramatsu Subject: Re: [PATCH -tip 4/6 V4.1] x86: kprobes checks safeness of insertion address. Date: Fri, 03 Apr 2009 15:20:06 -0400 Message-ID: <49D66166.9040002@redhat.com> References: <49D4F4E9.2030809@redhat.com> <20090403051854.GA4846@in.ibm.com> <49D63327.8020009@redhat.com> <1238779686.3568.18.camel@dyn9047018139.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Cc: ananth@in.ibm.com, Ingo Molnar , LKML , systemtap-ml , kvm@vger.kernel.org, Andi Kleen , Andrew Morton , Arnaldo Carvalho de Melo , Steven Rostedt , Frederic Weisbecker To: Jim Keniston Return-path: In-Reply-To: <1238779686.3568.18.camel@dyn9047018139.beaverton.ibm.com> List-Unsubscribe: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org List-Id: kvm.vger.kernel.org Jim Keniston wrote: > On Fri, 2009-04-03 at 12:02 -0400, Masami Hiramatsu wrote: >> Ensure safeness of inserting kprobes by checking whether the specified >> address is at the first byte of a instruction. This is done by decoding >> probed function from its head to the probe point. >> >> changes from v4: >> - change a comment according to Ananth's suggestion. >> >> Signed-off-by: Masami Hiramatsu >> Cc: Ananth N Mavinakayanahalli >> Cc: Jim Keniston >> Cc: Ingo Molnar >> --- >> >> arch/x86/kernel/kprobes.c | 51 +++++++++++++++++++++++++++++++++++++++++++++ >> 1 files changed, 51 insertions(+), 0 deletions(-) >> >> >> diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c > ... >> +/* Recover original instruction */ > > /* Recover the probed instruction at addr for further analysis. */ > See below. Sure. > >> +static int recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) >> +{ >> + struct kprobe *kp; >> + kp = get_kprobe((void *)addr); >> + if (!kp) >> + return -EINVAL; >> + >> + /* Don't use p->ainsn.insn; which will be modified by fix_riprel */ > > fix_riprel doesn't affect the instruction's length, which is what > concerns this patch. But we want this function to be useful for > unforeseen uses as well, so I like the code you have. Just consider the > suggested comment changes. > > /* > * Don't use p->ainsn.insn, which could be modified -- e.g., > * by fix_riprel(). > */ Thanks, I'll update comments then! > >> + memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); >> + buf[0] = kp->opcode; >> + return 0; >> +} > > Jim Keniston > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America) Inc. Software Solutions Division e-mail: mhiramat@redhat.com