linux-kernel - Re: [PATCH v4 03/21] HWBP: Add modify_wide_hw_breakpoint

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Message-ID: <6b5e5d3e-5db8-44f2-8dca-42f317be8e0d@infradead.org>
Date: Fri, 12 Sep 2025 21:13:07 -0700
From: Randy Dunlap <rdunlap@...radead.org>
To: Jinchao Wang <wangjinchao600@...il.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Masami Hiramatsu <mhiramat@...nel.org>, Peter Zijlstra
 <peterz@...radead.org>, Mike Rapoport <rppt@...nel.org>,
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 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
 Juri Lelli <juri.lelli@...hat.com>,
 Vincent Guittot <vincent.guittot@...aro.org>,
 Dietmar Eggemann <dietmar.eggemann@....com>,
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 linux-perf-users@...r.kernel.org, linux-mm@...ck.org, llvm@...ts.linux.dev,
 Andrey Ryabinin <ryabinin.a.a@...il.com>,
 Andrey Konovalov <andreyknvl@...il.com>, Dmitry Vyukov <dvyukov@...gle.com>,
 Vincenzo Frascino <vincenzo.frascino@....com>, kasan-dev@...glegroups.com,
 "David S. Miller" <davem@...emloft.net>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH v4 03/21] HWBP: Add modify_wide_hw_breakpoint_local() API

On 9/12/25 3:11 AM, Jinchao Wang wrote:
> +/**
> + * modify_wide_hw_breakpoint_local - update breakpoint config for local cpu
> + * @bp: the hwbp perf event for this cpu
> + * @attr: the new attribute for @bp
> + *
> + * This does not release and reserve the slot of HWBP, just reuse the current

                                                 of a HWBP; it just reuses

and preferable s/cpu/CPU/ in comments.

> + * slot on local CPU. So the users must update the other CPUs by themselves.
> + * Also, since this does not release/reserve the slot, this can not change the
> + * type to incompatible type of the HWBP.
> + * Return err if attr is invalid or the cpu fails to update debug register
> + * for new @attr.
> + */
> +#ifdef CONFIG_HAVE_REINSTALL_HW_BREAKPOINT
> +int modify_wide_hw_breakpoint_local(struct perf_event *bp,
> +				    struct perf_event_attr *attr)
> +{

-- 
~Randy