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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 v6 07/13] riscv/kprobe: Prepare detour buffer for optimized kprobe
Date: Wed, 01 Feb 2023 14:30:28 +0100	[thread overview]
Message-ID: <87v8kltswb.fsf@all.your.base.are.belong.to.us> (raw)
In-Reply-To: <20230127130541.1250865-8-chenguokai17@mails.ucas.ac.cn>

Chen Guokai <chenguokai17@mails.ucas.ac.cn> writes:

> diff --git a/arch/riscv/kernel/probes/opt.c b/arch/riscv/kernel/probes/opt.c
> index d84aa1420fa2..a47f7d2bf3a6 100644
> --- a/arch/riscv/kernel/probes/opt.c
> +++ b/arch/riscv/kernel/probes/opt.c
> @@ -11,9 +11,32 @@
>  #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 optimized_callback(struct optimized_kprobe *op,
> +			       struct pt_regs *regs)
> +{
> +	if (kprobe_disabled(&op->kp))
> +		return;
> +
> +	preempt_disable();
> +	if (kprobe_running()) {
> +		kprobes_inc_nmissed_count(&op->kp);
> +	} else {
> +		__this_cpu_write(current_kprobe, &op->kp);
> +		/* Save skipped registers */
> +		instruction_pointer_set(regs, (unsigned long)op->kp.addr);
> +		get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
> +		opt_pre_handler(&op->kp, regs);
> +		__this_cpu_write(current_kprobe, NULL);
> +	}
> +	preempt_enable();
> +}
> +NOKPROBE_SYMBOL(optimized_callback)
>  
>  static int in_auipc_jalr_range(long val)
>  {
> @@ -30,6 +53,11 @@ static int in_auipc_jalr_range(long val)
>  #endif
>  }
>  
> +#define DETOUR_ADDR(code, offs) \
> +	((void *)((unsigned long)(code) + (offs)))
> +#define DETOUR_INSN(code, offs) \
> +	(*(kprobe_opcode_t *)((unsigned long)(code) + (offs)))

Can this cause a misaligned u32 load exception?


Björn

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WARNING: multiple messages have this Message-ID (diff)
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 v6 07/13] riscv/kprobe: Prepare detour buffer for optimized kprobe
Date: Wed, 01 Feb 2023 14:30:28 +0100	[thread overview]
Message-ID: <87v8kltswb.fsf@all.your.base.are.belong.to.us> (raw)
In-Reply-To: <20230127130541.1250865-8-chenguokai17@mails.ucas.ac.cn>

Chen Guokai <chenguokai17@mails.ucas.ac.cn> writes:

> diff --git a/arch/riscv/kernel/probes/opt.c b/arch/riscv/kernel/probes/opt.c
> index d84aa1420fa2..a47f7d2bf3a6 100644
> --- a/arch/riscv/kernel/probes/opt.c
> +++ b/arch/riscv/kernel/probes/opt.c
> @@ -11,9 +11,32 @@
>  #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 optimized_callback(struct optimized_kprobe *op,
> +			       struct pt_regs *regs)
> +{
> +	if (kprobe_disabled(&op->kp))
> +		return;
> +
> +	preempt_disable();
> +	if (kprobe_running()) {
> +		kprobes_inc_nmissed_count(&op->kp);
> +	} else {
> +		__this_cpu_write(current_kprobe, &op->kp);
> +		/* Save skipped registers */
> +		instruction_pointer_set(regs, (unsigned long)op->kp.addr);
> +		get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
> +		opt_pre_handler(&op->kp, regs);
> +		__this_cpu_write(current_kprobe, NULL);
> +	}
> +	preempt_enable();
> +}
> +NOKPROBE_SYMBOL(optimized_callback)
>  
>  static int in_auipc_jalr_range(long val)
>  {
> @@ -30,6 +53,11 @@ static int in_auipc_jalr_range(long val)
>  #endif
>  }
>  
> +#define DETOUR_ADDR(code, offs) \
> +	((void *)((unsigned long)(code) + (offs)))
> +#define DETOUR_INSN(code, offs) \
> +	(*(kprobe_opcode_t *)((unsigned long)(code) + (offs)))

Can this cause a misaligned u32 load exception?


Björn

  reply	other threads:[~2023-02-01 13:30 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-27 13:05 [PATCH v6 00/13] Add OPTPROBES feature on RISCV Chen Guokai
2023-01-27 13:05 ` Chen Guokai
2023-01-27 13:05 ` [PATCH v6 01/13] riscv/kprobe: Prepare the skeleton to implement RISCV OPTPROBES Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-01-27 13:05 ` [PATCH v6 02/13] riscv/kprobe: Allocate detour buffer from module region Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-01-27 13:05 ` [PATCH v6 03/13] riscv/kprobe: Add skeleton for preparing optimized kprobe Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-01-27 13:05 ` [PATCH v6 04/13] riscv/kprobe: Add common RVI and RVC instruction decoder code Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-02-01 13:29   ` Björn Töpel
2023-02-01 13:29     ` Björn Töpel
2023-02-02 10:16   ` Conor Dooley
2023-02-02 10:16     ` Conor Dooley
2023-01-27 13:05 ` [PATCH v6 05/13] riscv/kprobe: Introduce free register(s) searching algorithm Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-01-27 13:05 ` [PATCH v6 06/13] riscv/kprobe: Add code to check if kprobe can be optimized Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-02-01 13:30   ` Björn Töpel
2023-02-01 13:30     ` Björn Töpel
2023-01-27 13:05 ` [PATCH v6 07/13] riscv/kprobe: Prepare detour buffer for optimized kprobe Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-02-01 13:30   ` Björn Töpel [this message]
2023-02-01 13:30     ` Björn Töpel
2023-01-27 13:05 ` [PATCH v6 08/13] riscv/kprobe: Patch AUIPC/JALR pair to optimize kprobe Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-02-01 13:31   ` Björn Töpel
2023-02-01 13:31     ` Björn Töpel
2023-01-27 13:05 ` [PATCH v6 09/13] riscv/kprobe: Search free registers from unused caller-saved ones Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-02-01 13:31   ` Björn Töpel
2023-02-01 13:31     ` Björn Töpel
2023-02-02  9:08   ` Conor Dooley
2023-02-02  9:08     ` Conor Dooley
2023-01-27 13:05 ` [PATCH v6 10/13] riscv/kprobe: Add instruction boundary check for RVI/RVC hybrid kernel Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-01-27 13:05 ` [PATCH v6 11/13] riscv/kprobe: Fix instruction simulation of JALR Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-01-31 12:51   ` Björn Töpel
2023-01-31 12:51     ` Björn Töpel
2023-01-27 13:05 ` [PATCH v6 12/13] riscv/kprobe: Move exception related symbols to .kprobe_blacklist Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-02-01 13:30   ` Björn Töpel
2023-02-01 13:30     ` Björn Töpel
2023-01-27 13:05 ` [PATCH v6 13/13] selftest/kprobes: Add testcase for kprobe SYM[+offs] Chen Guokai
2023-01-27 13:05   ` Chen Guokai
2023-01-30 12:31 ` [PATCH v6 00/13] Add OPTPROBES feature on RISCV Björn Töpel
2023-01-30 12:31   ` Björn Töpel
2023-01-30 14:38   ` Xim
2023-01-30 14:38     ` Xim
2023-04-26 18:01     ` Palmer Dabbelt
2023-04-26 18:01       ` Palmer Dabbelt
2023-02-01 13:29 ` Björn Töpel
2023-02-01 13:29   ` Björn Töpel

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