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From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>, Andi Kleen <andi@firstfloor.org>,
	Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
	Sandeepa Prabhu <sandeepa.prabhu@linaro.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
	fche@redhat.com, mingo@redhat.com, systemtap@sourceware.org,
	"H. Peter Anvin" <hpa@zytor.com>,
	Sasha Levin <sasha.levin@oracle.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Seiji Aguchi <seiji.aguchi@hds.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH -tip v9 08/26] kprobes/x86: Call exception handlers directly from do_int3/do_debug
Date: Thu, 17 Apr 2014 17:17:33 +0900
Message-ID: <20140417081733.26341.24423.stgit@ltc230.yrl.intra.hitachi.co.jp> (raw)
In-Reply-To: <20140417081636.26341.87858.stgit@ltc230.yrl.intra.hitachi.co.jp>

To avoid a kernel crash by probing on lockdep code, call
kprobe_int3_handler() and kprobe_debug_handler()(which was
formerly called post_kprobe_handler()) directly from
do_int3 and do_debug.

Currently kprobes uses notify_die() to hook the int3/debug
exceptoins. Since there is a locking code in notify_die,
the lockdep code can be invoked. And because the lockdep involves
printk() related things, theoretically, we need to prohibit probing
on such code, which means much longer blacklist we'll have.
Instead, hooking the int3/debug for kprobes before notify_die()
can avoid this problem.

Anyway, most of the int3 handlers in the kernel are already
called from do_int3 directly, e.g. ftrace_int3_handler,
poke_int3_handler, kgdb_ll_trap. Actually only
kprobe_exceptions_notify is on the notifier_call_chain.

Changes from v8:
 - Update the patch description.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
---
 arch/x86/include/asm/kprobes.h |    2 ++
 arch/x86/kernel/kprobes/core.c |   24 +++---------------------
 arch/x86/kernel/traps.c        |   10 ++++++++++
 3 files changed, 15 insertions(+), 21 deletions(-)

diff --git a/arch/x86/include/asm/kprobes.h b/arch/x86/include/asm/kprobes.h
index 9454c16..53cdfb2 100644
--- a/arch/x86/include/asm/kprobes.h
+++ b/arch/x86/include/asm/kprobes.h
@@ -116,4 +116,6 @@ struct kprobe_ctlblk {
 extern int kprobe_fault_handler(struct pt_regs *regs, int trapnr);
 extern int kprobe_exceptions_notify(struct notifier_block *self,
 				    unsigned long val, void *data);
+extern int kprobe_int3_handler(struct pt_regs *regs);
+extern int kprobe_debug_handler(struct pt_regs *regs);
 #endif /* _ASM_X86_KPROBES_H */
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 181bdde..4157d648 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -559,7 +559,7 @@ reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb
  * Interrupts are disabled on entry as trap3 is an interrupt gate and they
  * remain disabled throughout this function.
  */
-static int __kprobes kprobe_handler(struct pt_regs *regs)
+int __kprobes kprobe_int3_handler(struct pt_regs *regs)
 {
 	kprobe_opcode_t *addr;
 	struct kprobe *p;
@@ -857,7 +857,7 @@ no_change:
  * Interrupts are disabled on entry as trap1 is an interrupt gate and they
  * remain disabled throughout this function.
  */
-static int __kprobes post_kprobe_handler(struct pt_regs *regs)
+int __kprobes kprobe_debug_handler(struct pt_regs *regs)
 {
 	struct kprobe *cur = kprobe_running();
 	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
@@ -963,22 +963,7 @@ kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *d
 	if (args->regs && user_mode_vm(args->regs))
 		return ret;
 
-	switch (val) {
-	case DIE_INT3:
-		if (kprobe_handler(args->regs))
-			ret = NOTIFY_STOP;
-		break;
-	case DIE_DEBUG:
-		if (post_kprobe_handler(args->regs)) {
-			/*
-			 * Reset the BS bit in dr6 (pointed by args->err) to
-			 * denote completion of processing
-			 */
-			(*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
-			ret = NOTIFY_STOP;
-		}
-		break;
-	case DIE_GPF:
+	if (val == DIE_GPF) {
 		/*
 		 * To be potentially processing a kprobe fault and to
 		 * trust the result from kprobe_running(), we have
@@ -987,9 +972,6 @@ kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *d
 		if (!preemptible() && kprobe_running() &&
 		    kprobe_fault_handler(args->regs, args->trapnr))
 			ret = NOTIFY_STOP;
-		break;
-	default:
-		break;
 	}
 	return ret;
 }
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 57409f6..e5d4a70 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -334,6 +334,11 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_co
 		goto exit;
 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
 
+#ifdef CONFIG_KPROBES
+	if (kprobe_int3_handler(regs))
+		return;
+#endif
+
 	if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 			SIGTRAP) == NOTIFY_STOP)
 		goto exit;
@@ -440,6 +445,11 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 	/* Store the virtualized DR6 value */
 	tsk->thread.debugreg6 = dr6;
 
+#ifdef CONFIG_KPROBES
+	if (kprobe_debug_handler(regs))
+		goto exit;
+#endif
+
 	if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
 							SIGTRAP) == NOTIFY_STOP)
 		goto exit;



  parent reply index

Thread overview: 103+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-17  8:16 [PATCH -tip v9 00/26] kprobes: introduce NOKPROBE_SYMBOL, bugfixes and scalbility efforts Masami Hiramatsu
2014-04-17  8:16 ` [PATCH -tip v9 01/26] [BUGFIX]kprobes/x86: Fix page-fault handling logic Masami Hiramatsu
2014-04-17  9:58   ` [tip:perf/urgent] kprobes/x86: " tip-bot for Masami Hiramatsu
2014-04-17  8:16 ` [PATCH -tip v9 02/26] kprobes/x86: Allow to handle reentered kprobe on singlestepping Masami Hiramatsu
2014-04-24 10:57   ` [tip:perf/kprobes] kprobes/x86: Allow to handle reentered kprobe on single-stepping tip-bot for Masami Hiramatsu
2014-04-17  8:16 ` [PATCH -tip v9 03/26] kprobes: Prohibit probing on .entry.text code Masami Hiramatsu
2014-04-24 10:57   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 04/26] kprobes: Introduce NOKPROBE_SYMBOL() macro for blacklist Masami Hiramatsu
2014-04-24 10:58   ` [tip:perf/kprobes] kprobes: Introduce NOKPROBE_SYMBOL() macro to maintain kprobes blacklist tip-bot for Masami Hiramatsu
2014-05-01  5:26     ` kprobes broken in linux-next (was Re: [tip:perf/kprobes] kprobes: Introduce NOKPROBE_SYMBOL() macro to maintain kprobes blacklist) Vineet Gupta
2014-05-02  1:13       ` Masami Hiramatsu
2014-05-07  4:56         ` Vineet Gupta
2014-05-07 19:18       ` [tip:perf/kprobes] kprobes: Ensure blacklist data is aligned tip-bot for Vineet Gupta
2014-05-05 20:48     ` [tip:perf/kprobes] kprobes: Introduce NOKPROBE_SYMBOL() macro to maintain kprobes blacklist Tony Luck
2014-05-06  9:25       ` Masami Hiramatsu
2014-05-06 10:03       ` Masami Hiramatsu
2014-05-07 11:19         ` Masami Hiramatsu
2014-05-07 11:55           ` [RFT PATCH -next ] [BUGFIX] kprobes: Fix "Failed to find blacklist" error on ia64 and ppc64 Masami Hiramatsu
2014-05-07 11:59             ` Masami Hiramatsu
2014-05-14  8:19               ` Masami Hiramatsu
2014-05-08  4:47             ` Ananth N Mavinakayanahalli
2014-05-08  5:40               ` Masami Hiramatsu
2014-05-08  6:16                 ` Ananth N Mavinakayanahalli
2014-05-09  8:06                   ` Masami Hiramatsu
2014-05-26 11:25             ` Suzuki K. Poulose
2014-05-26 11:48               ` Masami Hiramatsu
2014-05-27  6:31               ` [RFT PATCH -next v2] " Masami Hiramatsu
2014-05-29 19:13                 ` Suzuki K. Poulose
2014-05-30  2:47                   ` Masami Hiramatsu
2014-05-30  3:18                     ` [RFT PATCH -next v3] " Masami Hiramatsu
2014-06-06  6:38                       ` Masami Hiramatsu
2014-06-17 23:03                         ` Tony Luck
2014-06-18  7:56                         ` Michael Ellerman
2014-06-18  8:46                           ` Masami Hiramatsu
2014-06-19  1:30                             ` Michael Ellerman
2014-06-19  4:52                               ` Masami Hiramatsu
2014-06-19  6:40                                 ` Suzuki K. Poulose
2014-06-19  7:26                                   ` Masami Hiramatsu
2014-06-19  9:45                                     ` Suzuki K. Poulose
2014-06-19 11:01                                       ` Masami Hiramatsu
2014-06-19 11:20                                         ` Masami Hiramatsu
2014-06-20  0:37                                           ` Michael Ellerman
2014-06-20  2:13                                             ` Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 05/26] [BUGFIX] kprobes/x86: Prohibit probing on debug_stack_* Masami Hiramatsu
2014-04-24 10:58   ` [tip:perf/kprobes] kprobes, x86: Prohibit probing on debug_stack_*() tip-bot for Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 06/26] [BUGFIX] x86: Prohibit probing on native_set_debugreg/load_idt Masami Hiramatsu
2014-04-24 10:58   ` [tip:perf/kprobes] kprobes, x86: Prohibit probing on native_set_debugreg()/load_idt() tip-bot for Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 07/26] [BUGFIX] x86: Prohibit probing on thunk functions and restore Masami Hiramatsu
2014-04-24 10:58   ` [tip:perf/kprobes] kprobes, " tip-bot for Masami Hiramatsu
2014-04-17  8:17 ` Masami Hiramatsu [this message]
2014-04-24 10:59   ` [tip:perf/kprobes] kprobes/x86: Call exception handlers directly from do_int3/do_debug tip-bot for Masami Hiramatsu
2014-04-24 11:26     ` Jiri Kosina
2014-04-17  8:17 ` [PATCH -tip v9 09/26] x86: Call exception_enter after kprobes handled Masami Hiramatsu
2014-04-24 10:59   ` [tip:perf/kprobes] kprobes, " tip-bot for Masami Hiramatsu
2014-06-13 17:14     ` Frederic Weisbecker
2014-06-14  5:44       ` Masami Hiramatsu
2014-06-14  6:47         ` [PATCH -tip ] [Bugfix] x86/kprobes: Fix build errors and blacklist context_track_user Masami Hiramatsu
2014-06-14  8:58           ` [tip:perf/urgent] " tip-bot for Masami Hiramatsu
2014-06-16 15:52           ` [PATCH -tip ] [Bugfix] " Frederic Weisbecker
2014-04-17  8:17 ` [PATCH -tip v9 10/26] kprobes/x86: Allow probe on some kprobe preparation functions Masami Hiramatsu
2014-04-24 10:59   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-17  8:17 ` [PATCH -tip v9 11/26] kprobes: Allow probe on some kprobe functions Masami Hiramatsu
2014-04-24 10:59   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 12/26] ftrace/*probes: Allow probing on some functions Masami Hiramatsu
2014-04-24 10:59   ` [tip:perf/kprobes] kprobes, ftrace: " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 13/26] x86: Allow kprobes on text_poke/hw_breakpoint Masami Hiramatsu
2014-04-24 11:00   ` [tip:perf/kprobes] kprobes, x86: Allow kprobes on text_poke/ hw_breakpoint tip-bot for Masami Hiramatsu
2014-04-24 11:26     ` Jiri Kosina
2014-04-17  8:18 ` [PATCH -tip v9 14/26] x86: Use NOKPROBE_SYMBOL() instead of __kprobes annotation Masami Hiramatsu
2014-04-24 11:00   ` [tip:perf/kprobes] kprobes, " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 15/26] kprobes: Use NOKPROBE_SYMBOL macro instead of __kprobes Masami Hiramatsu
2014-04-24 11:00   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 16/26] ftrace/kprobes: Use NOKPROBE_SYMBOL macro in ftrace Masami Hiramatsu
2014-04-24 11:00   ` [tip:perf/kprobes] kprobes, ftrace: " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 17/26] notifier: Use NOKPROBE_SYMBOL macro in notifier Masami Hiramatsu
2014-04-17 14:40   ` Josh Triplett
2014-04-24 11:00   ` [tip:perf/kprobes] kprobes, " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 18/26] sched: Use NOKPROBE_SYMBOL macro in sched Masami Hiramatsu
2014-04-24 11:01   ` [tip:perf/kprobes] kprobes, " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 19/26] kprobes: Show blacklist entries via debugfs Masami Hiramatsu
2014-04-24 11:01   ` [tip:perf/kprobes] " tip-bot for Masami Hiramatsu
2014-04-17  8:18 ` [PATCH -tip v9 20/26] kprobes: Support blacklist functions in module Masami Hiramatsu
2014-04-24  8:56   ` Ingo Molnar
2014-04-24 11:24     ` Masami Hiramatsu
2014-04-25  8:19       ` Ingo Molnar
2014-04-25 10:12         ` Masami Hiramatsu
2014-04-25 10:55           ` Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 21/26] kprobes: Use NOKPROBE_SYMBOL() in sample modules Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 22/26] kprobes/x86: Use kprobe_blacklist for .kprobes.text and .entry.text Masami Hiramatsu
2014-04-24  8:58   ` Ingo Molnar
2014-04-24 11:22     ` Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 23/26] kprobes/x86: Remove unneeded preempt_disable/enable in interrupt handlers Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 24/26] kprobes: Enlarge hash table to 512 entries Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 25/26] kprobes: Introduce kprobe cache to reduce cache misshits Masami Hiramatsu
2014-04-24  9:01   ` Ingo Molnar
2014-04-24 11:38     ` Masami Hiramatsu
2014-04-25  8:20       ` Ingo Molnar
2014-04-25  9:43         ` Masami Hiramatsu
2014-04-26  7:12           ` Ingo Molnar
2014-04-27 12:49             ` Masami Hiramatsu
2014-04-17  8:19 ` [PATCH -tip v9 26/26] ftrace: Introduce FTRACE_OPS_FL_SELF_FILTER for ftrace-kprobe Masami Hiramatsu
2014-04-17  8:37 ` [PATCH -tip v9 00/26] kprobes: introduce NOKPROBE_SYMBOL, bugfixes and scalbility efforts Ingo Molnar
2014-04-17  8:53   ` Masami Hiramatsu

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