From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0D151C5B549 for ; Wed, 28 May 2025 16:48:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: Content-Transfer-Encoding:Content-Type:In-Reply-To:From:References:To:Subject :MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=vzwBUHMTTLY4KfyYe7Oqmpldgz8NbjWW+e3wXEyxA+U=; b=iHADIya6U4zrQi 0VTqDUuUjxjYMQZmG/4YbU3o9ntW0c9E+41Va7P83yWUeeUnFDuyaTilyTtwesSNq/lwzzV+CapuW iLSKsR0Q+kCmLTIlanLIXQno3OK1+UZDJwnpZariQ6sZUKWWgzSVCideDoWMvusSAlt7NF4MPJWCM DJBDekmd4Ovl042TeSolrCTLAbCc7IAak51qT9AlCQm0HoHz4bg4fyazisrGGZsruQqCJZmbMyKRi 4Q0qwHmBfcK9AYyuzd8eeskspaIYCAdmy+rwGHLLIKKYl5lRpQCLE3WZTTeNUltjgrCTj8QKlyFwx wMlG6IspNfy2rGc8DD9Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uKJx5-0000000Djgl-1HoN; Wed, 28 May 2025 16:48:27 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uKJqd-0000000DizC-1qzv for linux-arm-kernel@lists.infradead.org; Wed, 28 May 2025 16:41:48 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2C4B11FC7; Wed, 28 May 2025 09:41:30 -0700 (PDT) Received: from [10.1.34.177] (e137867.arm.com [10.1.34.177]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3EE7F3F673; Wed, 28 May 2025 09:41:45 -0700 (PDT) Message-ID: <7d856e23-2697-4ba1-ab80-a658a9b84d9a@arm.com> Date: Wed, 28 May 2025 17:41:43 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 11/11] arm64: debug: remove debug exception registration infrastructure To: Will Deacon References: <20250512174326.133905-1-ada.coupriediaz@arm.com> <20250512174326.133905-12-ada.coupriediaz@arm.com> <20250521093817.GA20245@willie-the-truck> From: Ada Couprie Diaz Content-Language: en-US, en-GB Organization: Arm Ltd. In-Reply-To: <20250521093817.GA20245@willie-the-truck> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250528_094147_531865_C096D1D3 X-CRM114-Status: GOOD ( 12.92 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , "Luis Claudio R. Goncalves" , Catalin Marinas , Sebastian Andrzej Siewior , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 21/05/2025 10:38, Will Deacon wrote: > On Mon, May 12, 2025 at 06:43:26PM +0100, Ada Couprie Diaz wrote: >> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c >> index 50d7a6a75f45..ce20f46e08cb 100644 >> --- a/arch/arm64/kernel/traps.c >> +++ b/arch/arm64/kernel/traps.c >> @@ -1101,29 +1101,5 @@ int ubsan_brk_handler(struct pt_regs *regs, unsigned long esr) >> } >> #endif >> >> -/* >> - * Initial handler for AArch64 BRK exceptions >> - * This handler only used until debug_traps_init(). >> - */ >> -int __init early_brk64(unsigned long addr, unsigned long esr, >> - struct pt_regs *regs) >> -{ >> -#ifdef CONFIG_CFI_CLANG >> - if (esr_is_cfi_brk(esr)) >> - return cfi_brk_handler(regs, esr) != DBG_HOOK_HANDLED; >> -#endif >> -#ifdef CONFIG_KASAN_SW_TAGS >> - if ((esr_brk_comment(esr) & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) >> - return kasan_brk_handler(regs, esr) != DBG_HOOK_HANDLED; >> -#endif >> -#ifdef CONFIG_UBSAN_TRAP >> - if ((esr_brk_comment(esr) & ~UBSAN_BRK_MASK) == UBSAN_BRK_IMM) >> - return ubsan_brk_handler(regs, esr) != DBG_HOOK_HANDLED; >> -#endif >> - return bug_brk_handler(regs, esr) != DBG_HOOK_HANDLED; > The early bug handler is now only called if the brk immediate matches, > but I couldn't spot any problems with that. Correct, as far as I can tell the behaviour is unchanged for a fall-through : `bug_brk_handler()` would have called `report_bug()`, which would not have found a non-BUG BRK and bailed early with BUG_TRAP_TYPE_NONE, leading `bug_brk_handler()` to return `DBG_HOOK_ERROR`. Now, we would return `DBG_HOOK_ERROR` anyway if it's not an immediate we know how to handle. (This also seems to match better with the expectations of the comment in `is_valid_bugaddr()`, in `kernel/traps.c` !) > Will Happy to have my logic checked or add a mention in a commit message (either this one, or patch 02 ?) Thanks, Ada