linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Masami Hiramatsu <mhiramat@kernel.org>
To: David Long <dave.long@linaro.org>
Cc: "Catalin Marinas" <catalin.marinas@arm.com>,
	"Huang Shijie" <shijie.huang@arm.com>,
	"James Morse" <james.morse@arm.com>,
	"Marc Zyngier" <marc.zyngier@arm.com>,
	"Pratyush Anand" <panand@redhat.com>,
	"Sandeepa Prabhu" <sandeepa.s.prabhu@gmail.com>,
	"Will Deacon" <will.deacon@arm.com>,
	"William Cohen" <wcohen@redhat.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	"Steve Capper" <steve.capper@linaro.org>,
	"Li Bin" <huawei.libin@huawei.com>,
	"Adam Buchbinder" <adam.buchbinder@gmail.com>,
	"Alex Bennée" <alex.bennee@linaro.org>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Andrey Ryabinin" <ryabinin.a.a@gmail.com>,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	"Christoffer Dall" <christoffer.dall@linaro.org>,
	"Daniel Thompson" <daniel.thompson@linaro.org>,
	"Dave P Martin" <Dave.Martin@arm.com>,
	"Jens Wiklander" <jens.wiklander@linaro.org>,
	"Jisheng Zhang" <jszhang@marvell.com>,
	"John Blackwood" <john.blackwood@ccur.com>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Petr Mladek" <pmladek@suse.com>,
	"Robin Murphy" <robin.murphy@arm.com>,
	"Suzuki K Poulose" <suzuki.poulose@arm.com>,
	"Vladimir Murzin" <Vladimir.Murzin@arm.com>,
	"Yang Shi" <yang.shi@linaro.org>,
	"Zi Shen Lim" <zlim.lnx@gmail.com>,
	"yalin wang" <yalin.wang2010@gmail.com>,
	"Mark Brown" <broonie@kernel.org>
Subject: Re: [PATCH v13 05/10] arm64: Kprobes with single stepping support
Date: Mon, 13 Jun 2016 15:50:17 +0900	[thread overview]
Message-ID: <20160613155017.860097875e8bc86563a065ce@kernel.org> (raw)
In-Reply-To: <575E3235.1020904@linaro.org>

On Mon, 13 Jun 2016 00:10:29 -0400
David Long <dave.long@linaro.org> wrote:

> >> ---
> >>   arch/arm64/Kconfig                      |   1 +
> >>   arch/arm64/include/asm/debug-monitors.h |   5 +
> >>   arch/arm64/include/asm/insn.h           |   4 +-
> >>   arch/arm64/include/asm/kprobes.h        |  60 ++++
> >>   arch/arm64/include/asm/probes.h         |  44 +++
> >>   arch/arm64/kernel/Makefile              |   1 +
> >>   arch/arm64/kernel/debug-monitors.c      |  18 +-
> >>   arch/arm64/kernel/kprobes-arm64.c       | 144 +++++++++
> >>   arch/arm64/kernel/kprobes-arm64.h       |  35 +++
> >>   arch/arm64/kernel/kprobes.c             | 526 ++++++++++++++++++++++++++++++++
> >
> > Not sure why kprobes.c and kprobes-arm64.c are splitted.
> >
> >
> 
> This comes from the model of the arm32 kprobes code where handling of 
> the low-level instruction simulation is implemented in separate files 
> for 32-bit vs. thumb instructions.  It should make a little more sense 
> in the future when additional instruction simulation code will hopefully 
> be added for those instructions we cannot currently single-step 
> out-of-line.  It also probably *could* be merged into one file.

Hmm, at least the name of arch/arm64/kernel/kprobes-arm64.c is
meaningless. As we've done in x86, I think we can make it 
arch/arm64/kernel/kprobes/decode-insn.{c,h}


[..]
> >> +
> >> +/* Return:
> >> + *   INSN_REJECTED     If instruction is one not allowed to kprobe,
> >> + *   INSN_GOOD         If instruction is supported and uses instruction slot,
> >> + *   INSN_GOOD_NO_SLOT If instruction is supported but doesn't use its slot.
> >
> > Is there any chance to return INSN_GOOD_NO_SLOT?
> >
> 
> Ah, that gets used later when simulation support is added.  I've removed 
> this enum value from this commit and will add it to the later one. 
> Please no one complain about using an enum instead of a bool, it will 
> eventually have three possible values.

OK :)

[..]
> >> +enum kprobe_insn __kprobes
> >> +arm_kprobe_decode_insn(kprobe_opcode_t *addr, struct arch_specific_insn *asi)
> >> +{
> >> +	enum kprobe_insn decoded;
> >> +	kprobe_opcode_t insn = le32_to_cpu(*addr);
> >> +	kprobe_opcode_t *scan_start = addr - 1;
> >> +	kprobe_opcode_t *scan_end = addr - MAX_ATOMIC_CONTEXT_SIZE;
> >> +#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
> >> +	struct module *mod;
> >> +#endif
> >> +
> >> +	if (addr >= (kprobe_opcode_t *)_text &&
> >> +	    scan_end < (kprobe_opcode_t *)_text)
> >> +		scan_end = (kprobe_opcode_t *)_text;
> >> +#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
> >> +	else {
> >> +		preempt_disable();
> >> +		mod = __module_address((unsigned long)addr);
> >> +		if (mod && within_module_init((unsigned long)addr, mod) &&
> >> +			!within_module_init((unsigned long)scan_end, mod))
> >> +			scan_end = (kprobe_opcode_t *)mod->init_layout.base;
> >> +		else if (mod && within_module_core((unsigned long)addr, mod) &&
> >> +			!within_module_core((unsigned long)scan_end, mod))
> >> +			scan_end = (kprobe_opcode_t *)mod->core_layout.base;
> >
> > What happen if mod == NULL? it should be return error, isn't it?
> >
> 
> No, it should be fine.  It just means it didn't have to do either of the 
> extra checks to limit the end of the search through the code to the 
> boundary of one of the corresponding module text sections. It means the 
> instruction is in the regular kernel (non-module) text segment.

Ah, I see. It is OK then. :)

Thank you,


-- 
Masami Hiramatsu <mhiramat@kernel.org>

  reply	other threads:[~2016-06-13  6:50 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-03  3:26 [PATCH v13 00/10] arm64: Add kernel probes (kprobes) support David Long
2016-06-03  3:26 ` [PATCH v13 01/10] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature David Long
2016-06-03 11:36   ` Masami Hiramatsu
2016-06-20  2:43   ` Li Bin
2016-06-23 13:48     ` David Long
2016-06-03  3:26 ` [PATCH v13 02/10] arm64: Add more test functions to insn.c David Long
2016-06-08  1:14   ` Masami Hiramatsu
2016-06-10 14:54     ` David Long
2016-06-03  3:26 ` [PATCH v13 03/10] arm64: add conditional instruction simulation support David Long
2016-06-04  3:53   ` Masami Hiramatsu
2016-06-13  4:19     ` David Long
2016-06-03  3:26 ` [PATCH v13 04/10] arm64: Blacklist non-kprobe-able symbol David Long
2016-06-04  3:40   ` Masami Hiramatsu
2016-06-07  3:52     ` David Long
2016-06-10 19:16     ` David Long
2016-06-03  3:26 ` [PATCH v13 05/10] arm64: Kprobes with single stepping support David Long
2016-06-08  1:07   ` Masami Hiramatsu
2016-06-13  4:10     ` David Long
2016-06-13  6:50       ` Masami Hiramatsu [this message]
2016-06-13 15:22         ` David Long
2016-06-14  0:45           ` Masami Hiramatsu
2016-06-22 18:28             ` David Long
2016-06-14  1:42   ` Masami Hiramatsu
2016-06-03  3:26 ` [PATCH v13 06/10] arm64: Treat all entry code as non-kprobe-able David Long
2016-06-07  0:34   ` Masami Hiramatsu
2016-06-03  3:26 ` [PATCH v13 07/10] arm64: kprobes instruction simulation support David Long
2016-06-03  3:26 ` [PATCH v13 08/10] arm64: Add trampoline code for kretprobes David Long
2016-06-07 10:38   ` Masami Hiramatsu
2016-06-13  4:23     ` David Long
2016-06-03  3:26 ` [PATCH v13 09/10] arm64: Add kernel return probes support (kretprobes) David Long
2016-06-07 10:28   ` Masami Hiramatsu
2016-06-22 18:16     ` David Long
2016-06-03  3:26 ` [PATCH v13 10/10] kprobes: Add arm64 case in kprobe example module David Long
2016-06-07 10:12   ` Masami Hiramatsu
2016-06-08  5:49   ` Huang Shijie
2016-06-27  2:54     ` David Long

Reply instructions:

You may reply publicly 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=20160613155017.860097875e8bc86563a065ce@kernel.org \
    --to=mhiramat@kernel.org \
    --cc=Dave.Martin@arm.com \
    --cc=Vladimir.Murzin@arm.com \
    --cc=adam.buchbinder@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=alex.bennee@linaro.org \
    --cc=ard.biesheuvel@linaro.org \
    --cc=broonie@kernel.org \
    --cc=catalin.marinas@arm.com \
    --cc=christoffer.dall@linaro.org \
    --cc=daniel.thompson@linaro.org \
    --cc=dave.long@linaro.org \
    --cc=huawei.libin@huawei.com \
    --cc=james.morse@arm.com \
    --cc=jens.wiklander@linaro.org \
    --cc=john.blackwood@ccur.com \
    --cc=jszhang@marvell.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=marc.zyngier@arm.com \
    --cc=mark.rutland@arm.com \
    --cc=panand@redhat.com \
    --cc=pmladek@suse.com \
    --cc=robin.murphy@arm.com \
    --cc=ryabinin.a.a@gmail.com \
    --cc=sandeepa.s.prabhu@gmail.com \
    --cc=shijie.huang@arm.com \
    --cc=steve.capper@linaro.org \
    --cc=suzuki.poulose@arm.com \
    --cc=wcohen@redhat.com \
    --cc=will.deacon@arm.com \
    --cc=yalin.wang2010@gmail.com \
    --cc=yang.shi@linaro.org \
    --cc=zlim.lnx@gmail.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
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).