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From: Sandeepa Prabhu <sandeepa.prabhu@linaro.org>
To: Will Deacon <will.deacon@arm.com>
Cc: David Long <dave.long@linaro.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Russell King <linux@arm.linux.org.uk>,
	William Cohen <wcohen@redhat.com>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	"Jon Medhurst (Tixy)" <tixy@linaro.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
	Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
	Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 1/5] arm64: Kprobes with single stepping support
Date: Wed, 19 Nov 2014 16:51:24 +0530	[thread overview]
Message-ID: <CA+b37P337jcTCPTg4Ydxh6TKwqmyMngt-eEowzfsTNBDZ7-NEg@mail.gmail.com> (raw)
In-Reply-To: <20141118145643.GO18842@arm.com>

On 18 November 2014 20:26, Will Deacon <will.deacon@arm.com> wrote:

> One thing I noticed looking through this patch is that we're effectively
> reinventing a bunch of the instruction decoding logic that we already have
> in the kernel (introduced since Sandeepa last sent his patch).
>
> Could you take a look at include/asm/insn.h and kernel/insn.c please, and
> see if you can at least consolidate some of this? Some of it should be easy
> (i.e. reusing masks, using existing #defines to construct BRK encodings),
> but I appreciate there may be places where kprobes needs to add extra bits,
> in which case I'd really like to keep this all together if at all possible.
>
> We're currently in a position where the module loader, BPF jit, ftrace and
> the proposed alternative patching scheme are all using the same instruction
> manipulation functions, so we should try to continue that trend if we can.
Will,

kernel/insn.c support generating instruction encodings(forming opcodes
with given specifications), so for kprobes, only BRK encoding can use
this mechanism.
For instruction simulation, the instruction behavior should be
simulated on saved pt_regs, which is not supported on insn.c routines,
so still need probes-simulate-insn.c. Please point me if I am missing
something here.

>
> Thanks,
>
> Will

WARNING: multiple messages have this Message-ID (diff)
From: sandeepa.prabhu@linaro.org (Sandeepa Prabhu)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 1/5] arm64: Kprobes with single stepping support
Date: Wed, 19 Nov 2014 16:51:24 +0530	[thread overview]
Message-ID: <CA+b37P337jcTCPTg4Ydxh6TKwqmyMngt-eEowzfsTNBDZ7-NEg@mail.gmail.com> (raw)
In-Reply-To: <20141118145643.GO18842@arm.com>

On 18 November 2014 20:26, Will Deacon <will.deacon@arm.com> wrote:

> One thing I noticed looking through this patch is that we're effectively
> reinventing a bunch of the instruction decoding logic that we already have
> in the kernel (introduced since Sandeepa last sent his patch).
>
> Could you take a look at include/asm/insn.h and kernel/insn.c please, and
> see if you can at least consolidate some of this? Some of it should be easy
> (i.e. reusing masks, using existing #defines to construct BRK encodings),
> but I appreciate there may be places where kprobes needs to add extra bits,
> in which case I'd really like to keep this all together if at all possible.
>
> We're currently in a position where the module loader, BPF jit, ftrace and
> the proposed alternative patching scheme are all using the same instruction
> manipulation functions, so we should try to continue that trend if we can.
Will,

kernel/insn.c support generating instruction encodings(forming opcodes
with given specifications), so for kprobes, only BRK encoding can use
this mechanism.
For instruction simulation, the instruction behavior should be
simulated on saved pt_regs, which is not supported on insn.c routines,
so still need probes-simulate-insn.c. Please point me if I am missing
something here.

>
> Thanks,
>
> Will

  reply	other threads:[~2014-11-19 11:21 UTC|newest]

Thread overview: 104+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-18  6:32 [PATCH v3 0/5] ARM64: Add kernel probes(Kprobes) support David Long
2014-11-18  6:32 ` David Long
2014-11-18  6:32 ` [PATCH v3 1/5] arm64: Kprobes with single stepping support David Long
2014-11-18  6:32   ` David Long
2014-11-18 13:28   ` Jon Medhurst (Tixy)
2014-11-18 13:28     ` Jon Medhurst (Tixy)
2014-11-21  4:28     ` David Long
2014-11-21  4:28       ` David Long
2014-11-18 14:38   ` William Cohen
2014-11-18 14:38     ` William Cohen
2014-11-18 14:39   ` William Cohen
2014-11-18 14:39     ` William Cohen
2014-11-18 14:56   ` Will Deacon
2014-11-18 14:56     ` Will Deacon
2014-11-19 11:21     ` Sandeepa Prabhu [this message]
2014-11-19 11:21       ` Sandeepa Prabhu
2014-11-19 11:25       ` Will Deacon
2014-11-19 11:25         ` Will Deacon
2014-11-19 14:55         ` David Long
2014-11-19 14:55           ` David Long
2014-11-20  5:10           ` Sandeepa Prabhu
2014-11-20  5:10             ` Sandeepa Prabhu
2014-11-26  6:46           ` David Long
2014-11-26  6:46             ` David Long
2014-11-26 10:09             ` Will Deacon
2014-11-26 10:09               ` Will Deacon
2014-12-22 10:10   ` Pratyush Anand
2014-12-22 10:10     ` Pratyush Anand
2014-11-18  6:32 ` [PATCH v3 2/5] arm64: Kprobes instruction simulation support David Long
2014-11-18  6:32   ` David Long
2014-11-18 14:43   ` William Cohen
2014-11-18 14:43     ` William Cohen
2014-11-18  6:32 ` [PATCH v3 3/5] arm64: Add kernel return probes support(kretprobes) David Long
2014-11-18  6:32   ` David Long
2014-11-18 14:50   ` William Cohen
2014-11-18 14:50     ` William Cohen
2014-11-18  6:32 ` [PATCH v3 4/5] kprobes: Add arm64 case in kprobe example module David Long
2014-11-18  6:32   ` David Long
2014-11-18  6:32 ` [PATCH v3 5/5] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature David Long
2014-11-18  6:32   ` David Long
2014-11-18 14:52   ` Will Deacon
2014-11-18 14:52     ` Will Deacon
2014-11-20  7:20     ` Masami Hiramatsu
2014-11-20  7:20       ` Masami Hiramatsu
2014-11-21  6:16     ` David Long
2014-11-21  6:16       ` David Long
2014-11-20 15:02 ` [PATCH v3 0/5] ARM64: Add kernel probes(Kprobes) support Steve Capper
2014-11-20 15:02   ` Steve Capper
2014-11-26  8:33   ` Masami Hiramatsu
2014-11-26  8:33     ` Masami Hiramatsu
2014-11-26 10:03     ` Steve Capper
2014-11-26 10:03       ` Steve Capper
2014-11-26 17:46       ` David Long
2014-11-26 17:46         ` David Long
2014-11-26 18:59         ` Steve Capper
2014-11-26 18:59           ` Steve Capper
2014-11-27  6:07           ` Masami Hiramatsu
2014-11-27  6:07             ` Masami Hiramatsu
2014-11-28 16:01             ` Steve Capper
2014-11-28 16:01               ` Steve Capper
2014-12-01  9:37               ` Re: " Masami Hiramatsu
2014-12-01  9:37                 ` Masami Hiramatsu
2014-12-02 19:27                 ` William Cohen
2014-12-02 19:27                   ` William Cohen
2014-12-02 20:00                   ` William Cohen
2014-12-02 20:00                     ` William Cohen
2014-12-03  3:36                   ` Masami Hiramatsu
2014-12-03  3:36                     ` Masami Hiramatsu
2014-12-03 14:54                 ` William Cohen
2014-12-03 14:54                   ` William Cohen
2014-12-03 22:54                   ` David Long
2014-12-03 22:54                     ` David Long
2014-12-04  0:02                     ` David Long
2014-12-04  0:02                       ` David Long
2014-12-04  1:16                     ` William Cohen
2014-12-04  1:16                       ` William Cohen
2014-12-04  2:48                       ` David Long
2014-12-04  2:48                         ` David Long
2014-12-04 10:21                         ` Steve Capper
2014-12-04 10:21                           ` Steve Capper
2014-12-04 10:43                           ` Masami Hiramatsu
2014-12-04 10:43                             ` Masami Hiramatsu
2014-12-04 11:29                             ` Steve Capper
2014-12-04 11:29                               ` Steve Capper
2014-12-04 11:53                               ` Masami Hiramatsu
2014-12-04 11:53                                 ` Masami Hiramatsu
2014-12-09 13:33                                 ` Steve Capper
2014-12-09 13:33                                   ` Steve Capper
2014-12-09 14:27                                   ` David Long
2014-12-09 14:27                                     ` David Long
2014-12-10 16:38                                     ` Steve Capper
2014-12-10 16:38                                       ` Steve Capper
2014-12-12 22:42                                       ` David Long
2014-12-12 22:42                                         ` David Long
2014-12-12 23:10                                         ` Steve Capper
2014-12-12 23:10                                           ` Steve Capper
2014-12-15  5:58                                           ` Masami Hiramatsu
2014-12-15  5:58                                             ` Masami Hiramatsu
2014-12-15  6:29                                           ` David Long
2014-12-15  6:29                                             ` David Long
2014-12-05  5:08                       ` William Cohen
2014-12-05  5:08                         ` William Cohen
2014-11-27  5:13       ` Masami Hiramatsu
2014-11-27  5:13         ` Masami Hiramatsu

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