LKML Archive on lore.kernel.org
 help / Atom feed
From: Masami Hiramatsu <mhiramat@kernel.org>
To: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
	"David S . Miller" <davem@davemloft.net>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Ye Xiaolong <xiaolong.ye@intel.com>,
	mhiramat@kernel.org
Subject: [RFC PATCH tip/master V3 4/8] kprobes/x86: Do not modify singlestep buffer while resuming
Date: Wed, 29 Mar 2017 14:00:25 +0900
Message-ID: <149076361560.22469.1610155860343077495.stgit@devbox> (raw)
In-Reply-To: <149076333370.22469.11135086121721120819.stgit@devbox>

Do not modify singlestep execution buffer (kprobe.ainsn.insn)
while resuming from single-stepping, instead, modifies
the buffer to add a jump back instruction at preparing
buffer.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
  Changes in v3:
   - Fix imbalance curly braces.
   - Remove unneeded (void *) casting.
---
 arch/x86/kernel/kprobes/core.c |   42 +++++++++++++++++++---------------------
 1 file changed, 20 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 6327f95..a654054 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -399,23 +399,36 @@ int __copy_instruction(u8 *dest, u8 *src)
 	return length;
 }
 
+/* Prepare reljump right after instruction to boost */
+static void prepare_boost(struct kprobe *p, int length)
+{
+	if (can_boost(p->ainsn.insn, p->addr) &&
+	    MAX_INSN_SIZE - length >= RELATIVEJUMP_SIZE) {
+		/*
+		 * These instructions can be executed directly if it
+		 * jumps back to correct address.
+		 */
+		synthesize_reljump(p->ainsn.insn + length, p->addr + length);
+		p->ainsn.boostable = 1;
+	} else {
+		p->ainsn.boostable = -1;
+	}
+}
+
 static int arch_copy_kprobe(struct kprobe *p)
 {
-	int ret;
+	int len;
 
 	/* Copy an instruction with recovering if other optprobe modifies it.*/
-	ret = __copy_instruction(p->ainsn.insn, p->addr);
-	if (!ret)
+	len = __copy_instruction(p->ainsn.insn, p->addr);
+	if (!len)
 		return -EINVAL;
 
 	/*
 	 * __copy_instruction can modify the displacement of the instruction,
 	 * but it doesn't affect boostable check.
 	 */
-	if (can_boost(p->ainsn.insn, p->addr))
-		p->ainsn.boostable = 0;
-	else
-		p->ainsn.boostable = -1;
+	prepare_boost(p, len);
 
 	/* Check whether the instruction modifies Interrupt Flag or not */
 	p->ainsn.if_modifier = is_IF_modifier(p->ainsn.insn);
@@ -878,21 +891,6 @@ static void resume_execution(struct kprobe *p, struct pt_regs *regs,
 		break;
 	}
 
-	if (p->ainsn.boostable == 0) {
-		if ((regs->ip > copy_ip) &&
-		    (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) {
-			/*
-			 * These instructions can be executed directly if it
-			 * jumps back to correct address.
-			 */
-			synthesize_reljump((void *)regs->ip,
-				(void *)orig_ip + (regs->ip - copy_ip));
-			p->ainsn.boostable = 1;
-		} else {
-			p->ainsn.boostable = -1;
-		}
-	}
-
 	regs->ip += orig_ip - copy_ip;
 
 no_change:

  parent reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-29  4:55 [RFC PATCH tip/master V3 0/8] kprobes/x86: Make kprobes instruction buffers read-only Masami Hiramatsu
2017-03-29  4:56 ` [RFC PATCH tip/master V3 1/8] kprobes/x86: Fix not to boost call far instruction Masami Hiramatsu
2017-04-12  7:32   ` [tip:perf/core] kprobes/x86: Fix kprobe-booster not to boost far call instructions tip-bot for Masami Hiramatsu
2017-03-29  4:58 ` [RFC PATCH tip/master V3 2/8] kprobes/x86: Fix the description of __copy_instruction() Masami Hiramatsu
2017-04-12  7:32   ` [tip:perf/core] " tip-bot for Masami Hiramatsu
2017-03-29  4:59 ` [RFC PATCH tip/master V3 3/8] kprobes/x86: Use instruction decoder for booster Masami Hiramatsu
2017-04-12  7:33   ` [tip:perf/core] " tip-bot for Masami Hiramatsu
2017-03-29  5:00 ` Masami Hiramatsu [this message]
2017-04-12  7:33   ` [tip:perf/core] kprobes/x86: Do not modify singlestep buffer while resuming tip-bot for Masami Hiramatsu
2017-03-29  5:01 ` [RFC PATCH tip/master V3 5/8] kprobes/x86: Make boostable flag boolean Masami Hiramatsu
2017-04-12  7:34   ` [tip:perf/core] " tip-bot for Masami Hiramatsu
2017-03-29  5:02 ` [RFC PATCH tip/master V3 6/8] kprobes/x86: Set kprobes pages readonly Masami Hiramatsu
2017-04-12  7:34   ` [tip:perf/core] kprobes/x86: Set kprobes pages read-only tip-bot for Masami Hiramatsu
2017-03-29  5:03 ` [RFC PATCH tip/master V3 7/8] kprobes/x86: Use probe_kernel_read instead of memcpy Masami Hiramatsu
2017-04-12  7:35   ` [tip:perf/core] kprobes/x86: Use probe_kernel_read() instead of memcpy() tip-bot for Masami Hiramatsu
2017-03-29  5:05 ` [RFC PATCH tip/master V3 8/8] kprobes/x86: Consolidate insn decoder users for copying code Masami Hiramatsu
2017-04-12  7:35   ` [tip:perf/core] " tip-bot for Masami Hiramatsu
2017-04-11  5:44 ` [RFC PATCH tip/master V3 0/8] kprobes/x86: Make kprobes instruction buffers read-only Masami Hiramatsu

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=149076361560.22469.1610155860343077495.stgit@devbox \
    --to=mhiramat@kernel.org \
    --cc=ananth@linux.vnet.ibm.com \
    --cc=anil.s.keshavamurthy@intel.com \
    --cc=aryabinin@virtuozzo.com \
    --cc=davem@davemloft.net \
    --cc=hpa@zytor.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=xiaolong.ye@intel.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org linux-kernel@archiver.kernel.org
	public-inbox-index lkml


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox