linux-kernel - Re: [PATCH 1/3] uprobes: add trap variant helper

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Date:	Fri, 22 Mar 2013 15:54:06 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	benh@...nel.crashing.org, ppcdev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH 1/3] uprobes: add trap variant helper

On 03/22, Ananth N Mavinakayanahalli wrote:
>
> +/**
> + * is_trap_insn - check if instruction is breakpoint instruction.
> + * @insn: instruction to be checked.
> + * Default implementation of is_trap_insn
> + * Returns true if @insn is a breakpoint instruction.
> + *
> + * This function is needed for the case where an architecture has multiple
> + * trap instructions (like powerpc).
> + */
> +bool __weak is_trap_insn(uprobe_opcode_t *insn)
> +{
> +	return is_swbp_insn(insn);
> +}

OK, thanks, the whole series looks fine, just one note...

My patch also changed prepare_uprobe() to use is_trap_insn(), and I think
this is right. Exactly because of 3/3 which removes is_trap() from
arch_uprobe_analyze_insn().

If the original insn is_trap(), we do not want to singlestep it and get
another trap after we hit handle_swbp().

Oleg.

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