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 575EB2853FD; Tue, 23 Jun 2026 16:49:13 +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=1782233354; cv=none; b=i3UKSfTMHNv7dp04DNvBTluQ9XqaornSaEv0Q5SOtK1qBxkV7XhRaRWqGj1R9k6EYZpBKmN39O8LzaS6hZzR4yykVFa55tzG2OvEWqMtV5xYuYec7DFXer84q8m4NMopRa/nC5506+zSX4f5ejKPD0JkMILvJPTnMmaFDGH6AyA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782233354; c=relaxed/simple; bh=uJESZwzQetj7bsP1Y5YB4Rky1pTFuKDm1eTLjrcKgD4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=QxSegIDaKpNCwkgiqgBtXsJS8kbmKmfORRz5wd++cfjIO2daZTKPGHXAhE+p/OJUqyosOrFAALHPwksMp9cjPTWrEqb1MaLe1En6yAOzC+vdHwPZG23Qnxanvba6gYTZltU59kr2+f3AQfdGBwj7hMXv3+NiYt8y53SCid7T4Mw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=FPIsYuJZ; 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="FPIsYuJZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9BF51F000E9; Tue, 23 Jun 2026 16:49:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782233353; bh=UAIuZzJVuMknDux/bEzPsZD71ovTlDxXumqdgDrt0ro=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=FPIsYuJZMGuNFb42/8CgB2rsdvqjeyPAE9jDG55eYI6/yUBXW4b0e4N7MBjr6GcoT LDTTDrmyYI3+Y3RMAGlHFVYanMN3h6m3fjvpKFTSY5Lj06rTBPDEj0DcGs9VcgWC4t S3Yg5EZf0r1xnd+3opAAidwlQij8Z34ESDxD5CiiB6VHl0tOdWPE4mDnh8yz7fBN9H GSOTcvSLyhkaUPwbfhgbXB4bcXzrL4RMmwQch9oEPG6P9DGRbtGHUj+EXSq/6/V4im 0jiaVUeLYYEmSUIzVfp8idRaLjGKrSm8N0tKIBQ3KUFq24bJgVdohJaH1RRco2UoLz zJH1PsSUg7Mzg== Date: Tue, 23 Jun 2026 09:49:10 -0700 From: Namhyung Kim To: sashiko-reviews@lists.linux.dev Cc: linux-perf-users@vger.kernel.org Subject: Re: [PATCH 2/4] perf kvm: Check kvm_need_default_arch_event() early Message-ID: References: <20260623070313.55225-1-namhyung@kernel.org> <20260623070313.55225-3-namhyung@kernel.org> <20260623071657.7D2E61F00A3A@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260623071657.7D2E61F00A3A@smtp.kernel.org> On Tue, Jun 23, 2026 at 07:16:57AM +0000, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > - [High] BUG_ON() unconditionally triggers and crashes `perf kvm record` on architectures where default arch events are not added (e.g., ARM64, RISC-V, s390). > -- > > commit e180ad0afcd0778bb15a60785a0b08bfd2f76a50 > Author: Namhyung Kim > > perf kvm: Check kvm_need_default_arch_event() early > > This commit modifies perf kvm record to check if default options are needed > before allocating arguments and passing the extra command line, preventing > the default event from being incorrectly passed to the external command. > > > diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c > > index c236093eac473..acc6f2a706b35 100644 > > --- a/tools/perf/builtin-kvm.c > > +++ b/tools/perf/builtin-kvm.c > > @@ -1996,13 +1996,14 @@ static int __cmd_record(const char *file_name, int argc, const char **argv) > > { > > int rec_argc, i = 0, j, ret; > > const char **rec_argv; > > + int need_arch_event = !!kvm_need_default_arch_event(argc, argv); > > > > /* > > * Besides the 2 more options "-o" and "filename", > > * kvm_add_default_arch_event() may add 2 extra options, > > - * so allocate 4 more items. > > + * so allocate more items conditionally. > > */ > > - rec_argc = argc + 2 + 2; > > + rec_argc = argc + 2 + (2 * need_arch_event); > > [ ... ] > > > - if (kvm_need_default_arch_event(argc, argv)) { > > + if (need_arch_event) { > > ret = kvm_add_default_arch_event(EM_HOST, &i, rec_argv); > > if (ret) > > goto EXIT; > > } > > > > + for (j = 1; j < argc; j++, i++) > > + rec_argv[i] = STRDUP_FAIL_EXIT(argv[j]); > > + > > - BUG_ON(i + 2 != rec_argc); > > + BUG_ON(i != rec_argc); > > [Severity: High] > Could this BUG_ON() cause a regression for perf kvm record on architectures > that do not add default events? > > If kvm_need_default_arch_event() returns true, rec_argc is set to argc + 4. > > However, on architectures like ARM64, RISC-V, or s390, it appears > kvm_add_default_arch_event() can return 0 without actually appending any > events or incrementing i. > > If that happens, i will only equal argc + 2 after the loop, causing this > assertion to unconditionally fail and abort the process. I'll check those arch and make sure they return 0 in kvm_need_default_arch_event(). Thanks, Namhyung