From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 324EFC433FE for ; Thu, 3 Nov 2022 01:23:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229975AbiKCBXz (ORCPT ); Wed, 2 Nov 2022 21:23:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229436AbiKCBXw (ORCPT ); Wed, 2 Nov 2022 21:23:52 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 12A0F62D7 for ; Wed, 2 Nov 2022 18:23:51 -0700 (PDT) Received: from kwepemi500012.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4N2mHN2JRVzbcCw; Thu, 3 Nov 2022 09:23:44 +0800 (CST) Received: from [10.67.110.108] (10.67.110.108) by kwepemi500012.china.huawei.com (7.221.188.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Thu, 3 Nov 2022 09:23:48 +0800 Message-ID: <9cee98fa-fa5c-9b3e-505b-6e86f526a027@huawei.com> Date: Thu, 3 Nov 2022 09:23:47 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH 1/8] riscv/kprobe: Prepare the skeleton to implement RISCV OPTPROBES feature To: Conor Dooley CC: Chen Guokai , , , , , , , , References: <20221030090141.2550837-1-chenguokai17@mails.ucas.ac.cn> <20221030090141.2550837-2-chenguokai17@mails.ucas.ac.cn> <1fe22055-7458-e052-4438-0338da9e369c@huawei.com> From: "liaochang (A)" In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.110.108] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemi500012.china.huawei.com (7.221.188.12) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/11/2 7:30, Conor Dooley 写道: > On Tue, Nov 01, 2022 at 07:07:44PM +0800, liaochang (A) wrote: >> Hi，Conor, >> >> 在 2022/11/1 3:42, Conor Dooley 写道: >>> Hey Chen Guokai, >>> >>> On Sun, Oct 30, 2022 at 05:01:34PM +0800, Chen Guokai wrote: >>>> From: Liao Chang >>>> >>>> Prepare skeleton to implement optimized kprobe on RISCV, it consists >>>> of Makfile, Kconfig and some architecture specific files: kprobe.h and >>>> opt.c opt.c includes some macro, type definition and functions required >>>> by kprobe framework, opt_trampoline.S provides a piece of assembly code >>>> template used to construct the detour buffer as the target of long jump >>>> instruction(s) for each optimzed kprobe. >>>> >>>> Since the jump range of PC-relative instruction JAL is +/-1M, that is >>>> too small to reach the detour buffer, hence the foudamental idea to >>>> address OPTPROBES on RISCV is to replace 'EBREAK' with 'AUIPC+JALR'. which >>>> means it needs to clobber one more instruction beside the kprobe >>>> instruction, furthermore, RISCV supports hybird RVI and RVC in single >>>> kernel binary, so in theory a pair of 'AUIPC/JALR' is about to clobber >>>> 10 bytes(3 RVC and 1 RVI, 2 bytes is padding for alignment) at worst >>>> case. The second hardsome problem is looking for one integer register as >>>> the destination of 'AUIPC/JALR' without any side-effect. >>>> >>>> More solution details will be introduced in the coming commits. >>> >>> nit: you can drop this reference to future commits. >>> >>>> >>>> Co-developed-by: Chen Guokai >>>> Signed-off-by: Chen Guokai >>>> Signed-off-by: Liao Chang >>> >>> FYI, your signoff should come last since you're sending the patches, so >>> this would become: >>> >>>> Signed-off-by: Liao Chang >>>> Co-developed-by: Chen Guokai >>>> Signed-off-by: Chen Guokai >>> >>> I noticed on some of the other patches that your SoB is missing there, >>> for example patch 2. >> >> Yes, i have sent patch 2 to mailing list long time ago, got some feedback from >> Palmer Debbelt. Because that patch is designed for riscv optprobe, so i bring it >> to this patchset. > > Not sure if you understood the point I was making - you need to have a > Signed-off-by: Chen Guokai > at the end of every patch that Chen sends. Patch 2 does not have one. > For the other patches, the order should be you, followed by Chen since > they are the one that sent the patch to the list this time. > > See: > https://www.kernel.org/doc/html/latest/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by > Or: > Documentation/translations/zh_CN/process/submitting-patches.rst > > In the zh_CN document, the relevant section is: > 何时使用Acked-by:，CC:，和Co-Developed by: Thanks for your explanation, it is very clear and helpful, i will make SoB correct. Thanks. > > Hope that helps, > Conor. > >>>> --- >>>> arch/riscv/Kconfig | 1 + >>>> arch/riscv/include/asm/kprobes.h | 32 ++++++++++++++ >>>> arch/riscv/kernel/probes/Makefile | 1 + >>>> arch/riscv/kernel/probes/opt.c | 51 +++++++++++++++++++++++ >>>> arch/riscv/kernel/probes/opt_trampoline.S | 12 ++++++ >>>> 5 files changed, 97 insertions(+) >>>> create mode 100644 arch/riscv/kernel/probes/opt.c >>>> create mode 100644 arch/riscv/kernel/probes/opt_trampoline.S >>>> >>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig >>>> index 6b48a3ae9843..ca29306c93e2 100644 >>>> --- a/arch/riscv/Kconfig >>>> +++ b/arch/riscv/Kconfig >>>> @@ -99,6 +99,7 @@ config RISCV >>>> select HAVE_KPROBES if !XIP_KERNEL >>>> select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL >>>> select HAVE_KRETPROBES if !XIP_KERNEL >>>> + select HAVE_OPTPROBES if !XIP_KERNEL >>>> select HAVE_MOVE_PMD >>>> select HAVE_MOVE_PUD >>>> select HAVE_PCI >>>> diff --git a/arch/riscv/include/asm/kprobes.h b/arch/riscv/include/asm/kprobes.h >>>> index 217ef89f22b9..22b73a2fd1fd 100644 >>>> --- a/arch/riscv/include/asm/kprobes.h >>>> +++ b/arch/riscv/include/asm/kprobes.h >>>> @@ -43,5 +43,37 @@ bool kprobe_single_step_handler(struct pt_regs *regs); >>>> void __kretprobe_trampoline(void); >>>> void __kprobes *trampoline_probe_handler(struct pt_regs *regs); >>>> >>>> +#ifdef CONFIG_OPTPROBES >>>> + >>>> +/* optinsn template addresses */ >>>> +extern __visible kprobe_opcode_t optprobe_template_entry[]; >>>> +extern __visible kprobe_opcode_t optprobe_template_end[]; >>>> + >>>> +#define MAX_OPTINSN_SIZE \ >>>> + ((unsigned long)optprobe_template_end - \ >>>> + (unsigned long)optprobe_template_entry) >>>> + >>>> +/* >>>> + * For RVI and RVC hybird encoding kernel, althought long jump just needs >>>> + * 2 RVI instructions(AUIPC+JALR), optimized instructions is 10 bytes long >>>> + * at most to ensure no RVI would be truncated actually, so it means four >>>> + * combinations: >>>> + * - 2 RVI >>>> + * - 4 RVC >>>> + * - 2 RVC + 1 RVI >>>> + * - 3 RVC + 1 RVI (truncated, need padding) >>>> + */ >>>> +#define MAX_COPIED_INSN 4 >>>> +#define MAX_OPTIMIZED_LENGTH 10 >>>> + >>>> +struct arch_optimized_insn { >>>> + kprobe_opcode_t copied_insn[MAX_COPIED_INSN]; >>>> + /* detour code buffer */ >>>> + kprobe_opcode_t *insn; >>>> + unsigned long length; >>>> + int rd; >>>> +}; >>>> + >>>> +#endif /* CONFIG_OPTPROBES */ >>>> #endif /* CONFIG_KPROBES */ >>>> #endif /* _ASM_RISCV_KPROBES_H */ >>>> diff --git a/arch/riscv/kernel/probes/Makefile b/arch/riscv/kernel/probes/Makefile >>>> index 7f0840dcc31b..6255b4600875 100644 >>>> --- a/arch/riscv/kernel/probes/Makefile >>>> +++ b/arch/riscv/kernel/probes/Makefile >>>> @@ -3,4 +3,5 @@ obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o simulate-insn.o >>>> obj-$(CONFIG_KPROBES) += kprobes_trampoline.o >>>> obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o >>>> obj-$(CONFIG_UPROBES) += uprobes.o decode-insn.o simulate-insn.o >>>> +obj-$(CONFIG_OPTPROBES) += opt.o opt_trampoline.o >>>> CFLAGS_REMOVE_simulate-insn.o = $(CC_FLAGS_FTRACE) >>>> diff --git a/arch/riscv/kernel/probes/opt.c b/arch/riscv/kernel/probes/opt.c >>>> new file mode 100644 >>>> index 000000000000..56c8a227c857 >>>> --- /dev/null >>>> +++ b/arch/riscv/kernel/probes/opt.c >>>> @@ -0,0 +1,51 @@ >>>> +// SPDX-License-Identifier: GPL-2.0-or-later >>>> +/* >>>> + * Kernel Probes Jump Optimization (Optprobes) >>>> + * >>>> + * Copyright (C) Guokai Chen, 2022 >>>> + * Author: Guokai Chen chenguokai17@mails.ucas.ac.cn >>>> + */ >>>> + >>>> +#define pr_fmt(fmt) "optprobe: " fmt >>>> + >>>> +#include >>>> +#include >>>> + >>>> +int arch_prepared_optinsn(struct arch_optimized_insn *optinsn) >>>> +{ >>>> + return 0; >>>> +} >>>> + >>>> +int arch_check_optimized_kprobe(struct optimized_kprobe *op) >>>> +{ >>>> + return 0; >>>> +} >>>> + >>>> +int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, >>>> + struct kprobe *orig) >>>> +{ >>>> + return 0; >>>> +} >>>> + >>>> +void arch_remove_optimized_kprobe(struct optimized_kprobe *op) >>>> +{ >>>> +} >>>> + >>>> +void arch_optimize_kprobes(struct list_head *oplist) >>>> +{ >>>> +} >>>> + >>>> +void arch_unoptimize_kprobes(struct list_head *oplist, >>>> + struct list_head *done_list) >>>> +{ >>>> +} >>>> + >>>> +void arch_unoptimize_kprobe(struct optimized_kprobe *op) >>>> +{ >>>> +} >>>> + >>>> +int arch_within_optimized_kprobe(struct optimized_kprobe *op, >>>> + kprobe_opcode_t *addr) >>>> +{ >>>> + return 0; >>>> +} >>>> diff --git a/arch/riscv/kernel/probes/opt_trampoline.S b/arch/riscv/kernel/probes/opt_trampoline.S >>>> new file mode 100644 >>>> index 000000000000..16160c4367ff >>>> --- /dev/null >>>> +++ b/arch/riscv/kernel/probes/opt_trampoline.S >>>> @@ -0,0 +1,12 @@ >>>> +/* SPDX-License-Identifier: GPL-2.0-only */ >>>> +/* >>>> + * Copyright (C) 2022 Guokai Chen >>>> + */ >>>> + >>>> +#include >>>> + >>>> +#incldue >>>> +#include >>>> + >>>> +SYM_ENTRY(optprobe_template_entry, SYM_L_GLOBAL, SYM_A_NONE) >>>> +SYM_ENTRY(optprobe_template_end, SYM_L_GLOBAL, SYM_A_NONE) >>>> -- >>>> 2.25.1 >>>> >>>> >>>> _______________________________________________ >>>> linux-riscv mailing list >>>> linux-riscv@lists.infradead.org >>>> http://lists.infradead.org/mailman/listinfo/linux-riscv >>> . >> >> -- >> BR, >> Liao, Chang > . -- BR, Liao, Chang