linux-kernel - Re: [RFC PATCH 2/3] LoongArch: Add larch_insn_gen

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Date:   Fri, 7 Apr 2023 10:30:31 +0800
From:   Youling Tang <tangyouling@...ngson.cn>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc:     Huacai Chen <chenhuacai@...nel.org>,
        WANG Xuerui <kernel@...0n.name>, loongarch@...ts.linux.dev,
        linux-kernel@...r.kernel.org, loongson-kernel@...ts.loongnix.cn
Subject: Re: [RFC PATCH 2/3] LoongArch: Add larch_insn_gen_break() to generate
 break insn

/* snip */

> diff --git a/arch/loongarch/kernel/kprobes.c b/arch/loongarch/kernel/kprobes.c
> index 08c78d2..a5c3712 100644
> --- a/arch/loongarch/kernel/kprobes.c
> +++ b/arch/loongarch/kernel/kprobes.c
> @@ -4,19 +4,8 @@
>  #include <linux/preempt.h>
>  #include <asm/break.h>
>
> -static const union loongarch_instruction breakpoint_insn = {
> -	.reg0i15_format = {
> -		.opcode = break_op,
> -		.immediate = BRK_KPROBE_BP,
> -	}
> -};
> -
> -static const union loongarch_instruction singlestep_insn = {
> -	.reg0i15_format = {
> -		.opcode = break_op,
> -		.immediate = BRK_KPROBE_SSTEPBP,
> -	}
> -};
> +#define breakpoint_insn larch_insn_gen_break(BRK_KPROBE_BP)
> +#define singlestep_insn larch_insn_gen_break(BRK_KPROBE_SSTEPBP)

IMO, Defined as KPROBE_BP_INSN, KPROBE_SSTEPBP_INSN may be better.

Youling.
>
>  DEFINE_PER_CPU(struct kprobe *, current_kprobe);
>  DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
> @@ -253,7 +242,7 @@ bool kprobe_breakpoint_handler(struct pt_regs *regs)
>  		}
>  	}
>
> -	if (addr->word != breakpoint_insn.word) {
> +	if (*addr != breakpoint_insn) {
>  		/*
>  		 * The breakpoint instruction was removed right
>  		 * after we hit it.  Another cpu has removed
>