From: Masami Hiramatsu <mhiramat@kernel.org> To: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org> Cc: x86@kernel.org, Masami Hiramatsu <mhiramat@kernel.org>, Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org, Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, Steven Rostedt <rostedt@goodmis.org>, Laura Abbott <labbott@redhat.com>, Josef Bacik <jbacik@fb.com>, Alexei Starovoitov <ast@kernel.org>, Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>, Vineet Gupta <vgupta@synopsys.com>, Russell King <linux@armlinux.org.uk>, Arnd Bergmann <arnd@arndb.de>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Tony Luck <tony.luck@intel.com>, Fenghua Yu <fenghua.yu@intel.com>, Ralf Baechle <ralf@linux-mips.org>, James Hogan <jhogan@kernel.org>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Yoshinori Sato <ysato@users.sourceforge.jp>, Rich Felker <dalias@libc.org>, "David S . Miller" <davem@davemloft.net>, linux-arch@vger.kernel.org Subject: [PATCH -tip v4 26/27] Documentation: kprobes: Add how to change the execution path Date: Mon, 28 May 2018 16:12:40 +0900 [thread overview] Message-ID: <152749156011.15132.15417205958490100087.stgit@devbox> (raw) In-Reply-To: <152749074878.15132.16693721906742461289.stgit@devbox> Add a section that explaining how to change the execution path with kprobes. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> --- Documentation/kprobes.txt | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt index 3e9e99ea751b..8a98eed1521b 100644 --- a/Documentation/kprobes.txt +++ b/Documentation/kprobes.txt @@ -80,6 +80,26 @@ After the instruction is single-stepped, Kprobes executes the "post_handler," if any, that is associated with the kprobe. Execution then continues with the instruction following the probepoint. +Changing Execution Path +----------------------- + +Since the kprobes can probe into a running kernel code, it can change +the register set, including instruction pointer. This operation +requires maximum attention, such as keeping the stack frame, recovering +execution path etc. Since it is operated on running kernel and need deep +knowladge of the archtecture and concurrent computing, you can easily +shot your foot. + +If you change the instruction pointer (and set up other related +registers) in pre_handler, you must return !0 so that the kprobes +stops single stepping and just returns to given address. +This also means post_handler should not be called anymore. + +Note that this operation may be harder on some architectures which +use TOC (Table of Contents) for function call, since you have to +setup new TOC for your function in your module, and recover old +one after back from it. + Return Probes -------------
WARNING: multiple messages have this Message-ID (diff)
From: Masami Hiramatsu <mhiramat@kernel.org> To: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org> Cc: x86@kernel.org, Masami Hiramatsu <mhiramat@kernel.org>, Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>, linux-kernel@vger.kernel.org, Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, Steven Rostedt <rostedt@goodmis.org>, Laura Abbott <labbott@redhat.com>, Josef Bacik <jbacik@fb.com>, Alexei Starovoitov <ast@kernel.org>, Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>, Vineet Gupta <vgupta@synopsys.com>, Russell King <linux@armlinux.org.uk>, Arnd Bergmann <arnd@arndb.de>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Tony Luck <tony.luck@intel.com>, Fenghua Yu <fenghua.yu@intel.com>, Ralf Baechle <ralf@linux-mips.org>, James Hogan <jhogan@kernel.org> Subject: [PATCH -tip v4 26/27] Documentation: kprobes: Add how to change the execution path Date: Mon, 28 May 2018 16:12:40 +0900 [thread overview] Message-ID: <152749156011.15132.15417205958490100087.stgit@devbox> (raw) In-Reply-To: <152749074878.15132.16693721906742461289.stgit@devbox> Add a section that explaining how to change the execution path with kprobes. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> --- Documentation/kprobes.txt | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt index 3e9e99ea751b..8a98eed1521b 100644 --- a/Documentation/kprobes.txt +++ b/Documentation/kprobes.txt @@ -80,6 +80,26 @@ After the instruction is single-stepped, Kprobes executes the "post_handler," if any, that is associated with the kprobe. Execution then continues with the instruction following the probepoint. +Changing Execution Path +----------------------- + +Since the kprobes can probe into a running kernel code, it can change +the register set, including instruction pointer. This operation +requires maximum attention, such as keeping the stack frame, recovering +execution path etc. Since it is operated on running kernel and need deep +knowladge of the archtecture and concurrent computing, you can easily +shot your foot. + +If you change the instruction pointer (and set up other related +registers) in pre_handler, you must return !0 so that the kprobes +stops single stepping and just returns to given address. +This also means post_handler should not be called anymore. + +Note that this operation may be harder on some architectures which +use TOC (Table of Contents) for function call, since you have to +setup new TOC for your function in your module, and recover old +one after back from it. + Return Probes -------------
next prev parent reply other threads:[~2018-05-28 7:13 UTC|newest] Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-05-28 6:59 [PATCH -tip v4 00/27] kprobes: Cleanup jprobe implementation Masami Hiramatsu 2018-05-28 6:59 ` Masami Hiramatsu 2018-05-28 6:59 ` [PATCH -tip v4 01/27] Documentation/kprobes: Fix to remove remaining jprobe Masami Hiramatsu 2018-05-28 6:59 ` Masami Hiramatsu 2018-05-28 7:00 ` [PATCH -tip v4 02/27] kprobes: Remove jprobe API implementation Masami Hiramatsu 2018-05-28 7:00 ` Masami Hiramatsu 2018-05-28 7:00 ` [PATCH -tip v4 03/27] kprobes/x86: Remove jprobe implementation Masami Hiramatsu 2018-05-28 7:00 ` Masami Hiramatsu 2018-05-28 7:01 ` [PATCH -tip v4 04/27] ARC: kprobes: " Masami Hiramatsu 2018-05-28 7:01 ` Masami Hiramatsu 2018-05-28 7:01 ` [PATCH -tip v4 05/27] ARM: kprobes: Remove jprobe arm implementation Masami Hiramatsu 2018-05-28 7:01 ` Masami Hiramatsu 2018-05-28 7:02 ` [PATCH -tip v4 06/27] arm64: kprobes: Remove jprobe implementation Masami Hiramatsu 2018-05-28 7:02 ` Masami Hiramatsu 2018-05-28 7:02 ` [PATCH -tip v4 07/27] powerpc/kprobes: Remove jprobe powerpc implementation Masami Hiramatsu 2018-05-28 7:02 ` Masami Hiramatsu 2018-05-28 7:03 ` [PATCH -tip v4 08/27] ia64: kprobes: Remove jprobe implementation Masami Hiramatsu 2018-05-28 7:03 ` Masami Hiramatsu 2018-05-28 7:03 ` [PATCH -tip v4 09/27] MIPS: " Masami Hiramatsu 2018-05-28 7:03 ` Masami Hiramatsu 2018-05-28 7:04 ` [PATCH -tip v4 10/27] s390/kprobes: " Masami Hiramatsu 2018-05-28 7:04 ` Masami Hiramatsu 2018-05-28 7:04 ` [PATCH -tip v4 11/27] sh: kprobes: " Masami Hiramatsu 2018-05-28 7:04 ` Masami Hiramatsu 2018-05-28 7:05 ` [PATCH -tip v4 12/27] sparc64: " Masami Hiramatsu 2018-05-28 7:05 ` Masami Hiramatsu 2018-05-28 7:05 ` [PATCH -tip v4 13/27] kprobes: Don't check the ->break_handler() in generic kprobes code Masami Hiramatsu 2018-05-28 7:05 ` Masami Hiramatsu 2018-05-28 7:06 ` [PATCH -tip v4 14/27] kprobes/x86: Don't call ->break_handler() in x86 kprobes Masami Hiramatsu 2018-05-28 7:06 ` Masami Hiramatsu 2018-05-28 7:06 ` [PATCH -tip v4 15/27] ARC: kprobes: Don't call the ->break_handler() in ARC kprobes code Masami Hiramatsu 2018-05-28 7:06 ` Masami Hiramatsu 2018-05-28 7:07 ` [PATCH -tip v4 16/27] ARM: kprobes: Don't call the ->break_handler() in arm " Masami Hiramatsu 2018-05-28 7:07 ` Masami Hiramatsu 2018-05-28 7:08 ` [PATCH -tip v4 17/27] arm64: " Masami Hiramatsu 2018-05-28 7:08 ` Masami Hiramatsu 2018-05-28 7:08 ` [PATCH -tip v4 18/27] powerpc/kprobes: " Masami Hiramatsu 2018-05-28 7:08 ` Masami Hiramatsu 2018-05-28 7:09 ` [PATCH -tip v4 19/27] ia64: kprobes: Don't call the ->break_handler() in ia64 " Masami Hiramatsu 2018-05-28 7:09 ` Masami Hiramatsu 2018-05-28 7:09 ` [PATCH -tip v4 20/27] MIPS: kprobes: Don't call the ->break_handler() in MIPS " Masami Hiramatsu 2018-05-28 7:09 ` Masami Hiramatsu 2018-05-28 7:10 ` [PATCH -tip v4 21/27] s390/kprobes: Don't call the ->break_handler() in s390 " Masami Hiramatsu 2018-05-28 7:10 ` Masami Hiramatsu 2018-05-28 7:10 ` [PATCH -tip v4 22/27] sh: kprobes: Don't call the ->break_handler() in SH " Masami Hiramatsu 2018-05-28 7:10 ` Masami Hiramatsu 2018-05-28 7:11 ` [PATCH -tip v4 23/27] sparc64: kprobes: Don't call the ->break_handler() in sparc64 " Masami Hiramatsu 2018-05-28 7:11 ` Masami Hiramatsu 2018-05-28 7:11 ` [PATCH -tip v4 24/27] bpf: error-inject: kprobes: Clear current_kprobe and enable preempt in kprobe Masami Hiramatsu 2018-05-28 7:11 ` Masami Hiramatsu 2018-05-31 10:55 ` Naveen N. Rao 2018-06-01 23:36 ` Masami Hiramatsu 2018-06-02 11:58 ` Naveen N. Rao 2018-06-04 9:08 ` Masami Hiramatsu 2018-05-28 7:12 ` [PATCH -tip v4 25/27] x86: kprobes: Do not disable preempt on int3 path Masami Hiramatsu 2018-05-28 7:12 ` Masami Hiramatsu 2018-05-28 7:12 ` Masami Hiramatsu [this message] 2018-05-28 7:12 ` [PATCH -tip v4 26/27] Documentation: kprobes: Add how to change the execution path Masami Hiramatsu 2018-05-28 7:13 ` [PATCH -tip v4 27/27] kprobes: Remove jprobe stub API Masami Hiramatsu 2018-05-28 7:13 ` Masami Hiramatsu 2018-05-30 9:01 ` [PATCH -tip v4 00/27] kprobes: Cleanup jprobe implementation Masami Hiramatsu 2018-05-30 9:01 ` Masami Hiramatsu 2018-05-31 10:43 ` Naveen N. Rao 2018-05-31 10:43 ` Naveen N. Rao
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