From: "Björn Töpel" <bjorn@kernel.org>
To: Chen Guokai <chenguokai17@mails.ucas.ac.cn>,
paul.walmsley@sifive.com, palmer@dabbelt.com,
aou@eecs.berkeley.edu, rostedt@goodmis.org, mingo@redhat.com,
sfr@canb.auug.org.au
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
liaochang1@huawei.com,
Chen Guokai <chenguokai17@mails.ucas.ac.cn>
Subject: Re: [PATCH v5 7/9] riscv/kprobe: Prepare detour buffer for optimized kprobe
Date: Mon, 02 Jan 2023 19:04:18 +0100 [thread overview]
Message-ID: <87r0wcvmn1.fsf@all.your.base.are.belong.to.us> (raw)
In-Reply-To: <20221224114315.850130-8-chenguokai17@mails.ucas.ac.cn>
Chen Guokai <chenguokai17@mails.ucas.ac.cn> writes:
> From: Liao Chang <liaochang1@huawei.com>
> diff --git a/arch/riscv/kernel/probes/opt.c b/arch/riscv/kernel/probes/opt.c
> index 258a283c906d..bc232fce5b39 100644
> --- a/arch/riscv/kernel/probes/opt.c
> +++ b/arch/riscv/kernel/probes/opt.c
> @@ -11,9 +11,37 @@
> #include <linux/kprobes.h>
> #include <asm/kprobes.h>
> #include <asm/patch.h>
> +#include <asm/asm-offsets.h>
>
> #include "simulate-insn.h"
> #include "decode-insn.h"
> +#include "../../net/bpf_jit.h"
> +
> +static void
Super-nit, but I really prefer *not* breaking function name and return
value, for grepability.
> diff --git a/arch/riscv/kernel/probes/opt_trampoline.S b/arch/riscv/kernel/probes/opt_trampoline.S
> index 16160c4367ff..75e34e373cf2 100644
> --- a/arch/riscv/kernel/probes/opt_trampoline.S
> +++ b/arch/riscv/kernel/probes/opt_trampoline.S
> @@ -1,12 +1,137 @@
> /* SPDX-License-Identifier: GPL-2.0-only */
> /*
> * Copyright (C) 2022 Guokai Chen
> + * Copyright (C) 2022 Liao, Chang <liaochang1@huawei.com>
> */
>
> #include <linux/linkage.h>
>
> +#include <asm/asm.h>
> #incldue <asm/csr.h>
> #include <asm/asm-offsets.h>
>
> SYM_ENTRY(optprobe_template_entry, SYM_L_GLOBAL, SYM_A_NONE)
> + addi sp, sp, -(PT_SIZE_ON_STACK)
> + REG_S x1, PT_RA(sp)
> + REG_S x2, PT_SP(sp)
> + REG_S x3, PT_GP(sp)
> + REG_S x4, PT_TP(sp)
> + REG_S x5, PT_T0(sp)
> + REG_S x6, PT_T1(sp)
> + REG_S x7, PT_T2(sp)
> + REG_S x8, PT_S0(sp)
> + REG_S x9, PT_S1(sp)
> + REG_S x10, PT_A0(sp)
> + REG_S x11, PT_A1(sp)
> + REG_S x12, PT_A2(sp)
> + REG_S x13, PT_A3(sp)
> + REG_S x14, PT_A4(sp)
> + REG_S x15, PT_A5(sp)
> + REG_S x16, PT_A6(sp)
> + REG_S x17, PT_A7(sp)
> + REG_S x18, PT_S2(sp)
> + REG_S x19, PT_S3(sp)
> + REG_S x20, PT_S4(sp)
> + REG_S x21, PT_S5(sp)
> + REG_S x22, PT_S6(sp)
> + REG_S x23, PT_S7(sp)
> + REG_S x24, PT_S8(sp)
> + REG_S x25, PT_S9(sp)
> + REG_S x26, PT_S10(sp)
> + REG_S x27, PT_S11(sp)
> + REG_S x28, PT_T3(sp)
> + REG_S x29, PT_T4(sp)
> + REG_S x30, PT_T5(sp)
> + REG_S x31, PT_T6(sp)
> + /* Update fp is friendly for stacktrace */
> + addi s0, sp, (PT_SIZE_ON_STACK)
> + j 1f
> +
> +SYM_ENTRY(optprobe_template_save, SYM_L_GLOBAL, SYM_A_NONE)
> + /*
> + * Step1:
> + * Filled with the pointer to optimized_kprobe data
> + */
> + .dword 0
> +1:
> + /* Load optimize_kprobe pointer from .dword below */
> + auipc a0, 0
> + REG_L a0, -8(a0)
> + add a1, sp, x0
> +
> +SYM_ENTRY(optprobe_template_call, SYM_L_GLOBAL, SYM_A_NONE)
> + /*
> + * Step2:
> + * <IMME> of AUIPC/JALR are modified to the offset to optimized_callback
> + * jump target is loaded from above .dword.
> + */
> + auipc ra, 0
> + jalr ra, 0(ra)
> +
> + REG_L x1, PT_RA(sp)
> + REG_L x3, PT_GP(sp)
> + REG_L x4, PT_TP(sp)
> + REG_L x5, PT_T0(sp)
> + REG_L x6, PT_T1(sp)
> + REG_L x7, PT_T2(sp)
> + REG_L x8, PT_S0(sp)
> + REG_L x9, PT_S1(sp)
> + REG_L x10, PT_A0(sp)
> + REG_L x11, PT_A1(sp)
> + REG_L x12, PT_A2(sp)
> + REG_L x13, PT_A3(sp)
> + REG_L x14, PT_A4(sp)
> + REG_L x15, PT_A5(sp)
> + REG_L x16, PT_A6(sp)
> + REG_L x17, PT_A7(sp)
> + REG_L x18, PT_S2(sp)
> + REG_L x19, PT_S3(sp)
> + REG_L x20, PT_S4(sp)
> + REG_L x21, PT_S5(sp)
> + REG_L x22, PT_S6(sp)
> + REG_L x23, PT_S7(sp)
> + REG_L x24, PT_S8(sp)
> + REG_L x25, PT_S9(sp)
> + REG_L x26, PT_S10(sp)
> + REG_L x27, PT_S11(sp)
> + REG_L x28, PT_T3(sp)
> + REG_L x29, PT_T4(sp)
> + REG_L x30, PT_T5(sp)
> + REG_L x31, PT_T6(sp)
> + REG_L x2, PT_SP(sp)
> + addi sp, sp, (PT_SIZE_ON_STACK)
> +
> +SYM_ENTRY(optprobe_template_insn, SYM_L_GLOBAL, SYM_A_NONE)
> + /*
> + * Step3:
> + * NOPS will be replaced by the probed instruction, at worst case 3 RVC
> + * and 1 RVI instructions is about to execute out of line.
> + */
> + nop
A nop here will be either a compressed nop or a non-compressed,
depending on the build (C-enabled or not), right? Maybe be explicit to
the assembler what you want?
Björn
next prev parent reply other threads:[~2023-01-02 18:04 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-24 11:43 [PATCH v5 0/9] Add OPTPROBES feature on RISCV Chen Guokai
2022-12-24 11:43 ` [PATCH v5 1/9] riscv/kprobe: Prepare the skeleton to implement RISCV OPTPROBES feature Chen Guokai
2023-01-02 18:03 ` Björn Töpel
2023-01-04 8:34 ` liaochang (A)
2022-12-24 11:43 ` [PATCH v5 2/9] riscv/kprobe: Allocate detour buffer from module area Chen Guokai
2022-12-24 11:43 ` [PATCH v5 3/9] riscv/kprobe: Prepare the skeleton to prepare optimized kprobe Chen Guokai
2023-01-02 18:03 ` Björn Töpel
2023-01-04 8:34 ` liaochang (A)
2023-01-04 8:54 ` Björn Töpel
2023-01-03 8:27 ` Björn Töpel
2023-01-04 8:34 ` liaochang (A)
2022-12-24 11:43 ` [PATCH v5 4/9] riscv/kprobe: Add common RVI and RVC instruction decoder code Chen Guokai
2023-01-02 18:03 ` Björn Töpel
2023-01-04 8:35 ` liaochang (A)
2023-01-04 8:57 ` Björn Töpel
2022-12-24 11:43 ` [PATCH v5 5/9] riscv/kprobe: Search free register(s) to clobber for 'AUIPC/JALR' Chen Guokai
2022-12-24 11:43 ` [PATCH v5 6/9] riscv/kprobe: Add code to check if kprobe can be optimized Chen Guokai
2023-01-02 18:04 ` Björn Töpel
2023-01-04 8:35 ` liaochang (A)
2022-12-24 11:43 ` [PATCH v5 7/9] riscv/kprobe: Prepare detour buffer for optimized kprobe Chen Guokai
2023-01-02 18:04 ` Björn Töpel [this message]
2023-01-04 8:35 ` liaochang (A)
2023-01-04 9:12 ` Björn Töpel
2023-01-05 0:46 ` liaochang (A)
2022-12-24 11:43 ` [PATCH v5 8/9] riscv/kprobe: Patch AUIPC/JALR pair to optimize kprobe Chen Guokai
2022-12-24 11:43 ` [PATCH v5 9/9] riscv/kprobe: Search free registers from unused caller-saved ones Chen Guokai
2023-01-02 18:04 ` Björn Töpel
2023-01-04 8:35 ` liaochang (A)
2023-01-02 18:02 ` [PATCH v5 0/9] Add OPTPROBES feature on RISCV Björn Töpel
2023-01-04 8:30 ` Xim
2023-01-04 8:45 ` Björn Töpel
2023-01-04 8:34 ` liaochang (A)
2023-01-04 8:53 ` Björn Töpel
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