From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4849732B13A for ; Wed, 15 Jul 2026 02:13:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784081619; cv=none; b=GLTaCQCNvIo4eO4dY61uQCprP1O7OeKxxmhFvrr07L8Fn0gMUqjm3j6YfLDG+c/60Hn7MZAM+tOvWDCHHGjsrVbW4yKtjrOw0/8gvaqXHyBeTicMHViAm0cgSPVUbmj2I2YOAnyQbuqnE6AObYrplagZbCYILvTRlZEEhocEr5I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784081619; c=relaxed/simple; bh=NZptgngmdCWPSHbyuccMz0lQCuKBN1gfDbIl37AV0y0=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=oSbOjaypEdMZVcej/kxLZRaHHpG8zP8ciIdH0ekg7s3i74uYuARfChOn7AEakZqarnY8gyEvEyqeeZBy/yzCkuMcsMuKwsEt/CElYMGcLI1cHmydls+BaEytI8t36GRfzQg42Pl1GxUKKWHjcemEYDrt2Gf7+ILVoWDW6gTl2Pc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VyyFRUz0; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="VyyFRUz0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9D0F1F000E9; Wed, 15 Jul 2026 02:13:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784081618; bh=oNMnJlFGawsihn6MvT+t84jY5ga+yhTwJlKRA3hNyQU=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=VyyFRUz0RwFQZUtCaokqQgZrt1EWuzvnM3Eq8ek38D+K4yzQOZWyT/1k/TzC2B8hk dMrnSwZncFSv4CMxxOtGMrF7z91v2Hwccz20pD+SqzrhR/RYBQZOYGVjuMjYElnNnh aiw2gYIofFyK108isde2/rluMwD1tFjD3LmDpttBjwmnGJlF0NbhQUU3XHW6NYKnLc iHRH9JR3zyusL6/STWx8B/Ce7hV+XY7RsXezVBFhdys3dGD6Y8j67xhED9H40DwlzZ 9FBL96IDwnfqMXxTX6xztELHihYr6LCiQglgdS/lw/PWJcFT08F/AZefr85dwjDS0m P7P+d6U8cLjwA== From: sashiko-bot@kernel.org Subject: Re: [PATCH v7 07/10] x86/hw_breakpoint: Add arch_reinstall_hw_breakpoint Reply-To: sashiko-reviews@lists.linux.dev To: =?utf-8?b?TWFzYW1pIEhpcmFtYXRzdSAoR29vZ2xlKQ==?= Cc: linux-perf-users@vger.kernel.org In-Reply-To: <178407992003.95826.8437044383333615344.stgit@devnote2> References: <178407983818.95826.12714571928538799781.stgit@devnote2> <178407992003.95826.8437044383333615344.stgit@devnote2> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 15 Jul 2026 02:13:37 +0000 Message-Id: <20260715021337.E9D0F1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [Medium] arch_reinstall_hw_breakpoint() fails to clear old DR7 length and= type bits before applying new attributes, causing hardware state corruptio= n if breakpoint parameters are modified. -- --- Patch [7]: [PATCH v7 07/10] x86/hw_breakpoint: Add arch_reinstall_hw_br= eakpoint --- commit 6bcf7b8e474f5683afc4564b0a92754b65b43406 Author: Jinchao Wang x86/hw_breakpoint: Add arch_reinstall_hw_breakpoint This commit introduces arch_reinstall_hw_breakpoint() to allow callers to efficiently re-establish existing hardware breakpoints in an atomic context without needing the full free and re-allocation path. > diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpo= int.c > index 877509539300c..9af8d81075db7 100644 > --- a/arch/x86/kernel/hw_breakpoint.c > +++ b/arch/x86/kernel/hw_breakpoint.c [ ... ] > @@ -188,6 +192,11 @@ int arch_install_hw_breakpoint(struct perf_event *bp) > return arch_manage_bp(bp, BP_SLOT_ACTION_INSTALL); > } > =20 > +int arch_reinstall_hw_breakpoint(struct perf_event *bp) > +{ > + return arch_manage_bp(bp, BP_SLOT_ACTION_REINSTALL); > +} [Severity: Medium] When callers use this new function to update an existing breakpoint's length or type attributes, will this cause hardware state corruption in the DR7 control register? The execution path goes through arch_manage_bp() and calls setup_hwbp() with enable =3D true. Looking at setup_hwbp(), it appears the new control b= its are bitwise OR'ed with the existing mask: arch/x86/kernel/hw_breakpoint.c:setup_hwbp() { ... if (enable) dr7 |=3D encode_dr7(slot, info->len, info->type); ... } Because the old DR7 configuration bits for this slot are never cleared firs= t, could the combination of old and new bits create an invalid breakpoint configuration mask? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/178407983818.95826.= 12714571928538799781.stgit@devnote2?part=3D7