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 2AE1AC46CD2 for ; Tue, 2 Jan 2024 23:42:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=Yeq6BZULTzxWOFIKU5cd9+0S7JW9PT+b7qEpO8XEQIk=; b=PES+m3yCpYoYhc Kph1t2MHlu7srvoWryJzJ4hLVz1WAH+BJqbgV2ynekObNtRze/GV1fb95M39ftQ8RrDfO41iVIEVZ E+Hang+3NyWcz7JOEYW81TOctRbx19+arViG10ESWBrlplvtAmSvtsrJDajz3iJu3oZklHsYr6NfI zs3kZ8k/E3DrpM/igcYRj0cg4Fu3A0D+EeeIMsaDDhJDUgbu9IJJXzu1NFrmbjgv8vp0npHCArOZ0 LuswxezPzuvUYZHF8L5r6RQgzlGYM2P77EpxU9jga1qNrKRWtU4dFEqJX2KTmLtGoSpAP1AS3dqu8 Yc1ThN+BB0vL5T4M48jQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rKoOo-009K77-1X; Tue, 02 Jan 2024 23:42:18 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rKoOk-009K6h-2n for kexec@lists.infradead.org; Tue, 02 Jan 2024 23:42:16 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1704238933; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=UjYTBnUjGAihRalbH8/D8jyPDwibjRZBox8xXLoEF/I=; b=SjQDDbVBABgqWbKNeT/y3tSO76fD5asPKskBx4fJFHBtCDdLHWihnDTfshJr1xn/BX+Edx pCArvJT+lQYUBbxi6zaYSwc584DhALXgtW2UKiTju1I1pQmJZZB2j5+qV84X86/hm69pw4 Mqsragj9v7dUjmIWsDh2dS7sRLA9lkg= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-393-sSwRajKQN0aNxm2Hr1yK_A-1; Tue, 02 Jan 2024 18:42:10 -0500 X-MC-Unique: sSwRajKQN0aNxm2Hr1yK_A-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 5E3871C5407F; Tue, 2 Jan 2024 23:42:09 +0000 (UTC) Received: from localhost (unknown [10.72.116.129]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4C24040C6EB9; Tue, 2 Jan 2024 23:42:08 +0000 (UTC) Date: Wed, 3 Jan 2024 07:42:05 +0800 From: Baoquan He To: Yuntao Wang Cc: linux-kernel@vger.kernel.org, kexec@lists.infradead.org, x86@kernel.org, Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Vivek Goyal , Dave Young , Hari Bathini , Sourabh Jain , Takashi Iwai Subject: Re: [PATCH v2 3/3] crash_core: fix and simplify the logic of crash_exclude_mem_range() Message-ID: References: <20240102144905.110047-1-ytcoode@gmail.com> <20240102144905.110047-4-ytcoode@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240102144905.110047-4-ytcoode@gmail.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240102_154215_000827_F4E171C2 X-CRM114-Status: GOOD ( 30.00 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 01/02/24 at 10:49pm, Yuntao Wang wrote: > The purpose of crash_exclude_mem_range() is to remove all memory ranges > that overlap with [mstart-mend]. However, the current logic only removes > the first overlapping memory range. > > Commit a2e9a95d2190 ("kexec: Improve & fix crash_exclude_mem_range() to > handle overlapping ranges") attempted to address this issue, but it did not > fix all error cases. > > Let's fix and simplify the logic of crash_exclude_mem_range(). Thanks, this makes the code logic much clearer and easier to follow. Acked-by: Baoquan He > > Signed-off-by: Yuntao Wang > --- > kernel/crash_core.c | 80 ++++++++++++++++----------------------------- > 1 file changed, 29 insertions(+), 51 deletions(-) > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index efe87d501c8c..c51d0a54296b 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -565,9 +565,8 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map, > int crash_exclude_mem_range(struct crash_mem *mem, > unsigned long long mstart, unsigned long long mend) > { > - int i, j; > + int i; > unsigned long long start, end, p_start, p_end; > - struct range temp_range = {0, 0}; > > for (i = 0; i < mem->nr_ranges; i++) { > start = mem->ranges[i].start; > @@ -575,72 +574,51 @@ int crash_exclude_mem_range(struct crash_mem *mem, > p_start = mstart; > p_end = mend; > > - if (mstart > end || mend < start) > + if (p_start > end) > continue; > > + /* > + * Because the memory ranges in mem->ranges are stored in > + * ascending order, when we detect `p_end < start`, we can > + * immediately exit the for loop, as the subsequent memory > + * ranges will definitely be outside the range we are looking > + * for. > + */ > + if (p_end < start) > + break; > + > /* Truncate any area outside of range */ > - if (mstart < start) > + if (p_start < start) > p_start = start; > - if (mend > end) > + if (p_end > end) > p_end = end; > > /* Found completely overlapping range */ > if (p_start == start && p_end == end) { > - mem->ranges[i].start = 0; > - mem->ranges[i].end = 0; > - if (i < mem->nr_ranges - 1) { > - /* Shift rest of the ranges to left */ > - for (j = i; j < mem->nr_ranges - 1; j++) { > - mem->ranges[j].start = > - mem->ranges[j+1].start; > - mem->ranges[j].end = > - mem->ranges[j+1].end; > - } > - > - /* > - * Continue to check if there are another overlapping ranges > - * from the current position because of shifting the above > - * mem ranges. > - */ > - i--; > - mem->nr_ranges--; > - continue; > - } > + memmove(&mem->ranges[i], &mem->ranges[i + 1], > + (mem->nr_ranges - (i + 1)) * sizeof(mem->ranges[i])); > + i--; > mem->nr_ranges--; > - return 0; > - } > - > - if (p_start > start && p_end < end) { > + } else if (p_start > start && p_end < end) { > /* Split original range */ > + if (mem->nr_ranges >= mem->max_nr_ranges) > + return -ENOMEM; > + > + memmove(&mem->ranges[i + 2], &mem->ranges[i + 1], > + (mem->nr_ranges - (i + 1)) * sizeof(mem->ranges[i])); > + > mem->ranges[i].end = p_start - 1; > - temp_range.start = p_end + 1; > - temp_range.end = end; > + mem->ranges[i + 1].start = p_end + 1; > + mem->ranges[i + 1].end = end; > + > + i++; > + mem->nr_ranges++; > } else if (p_start != start) > mem->ranges[i].end = p_start - 1; > else > mem->ranges[i].start = p_end + 1; > - break; > - } > - > - /* If a split happened, add the split to array */ > - if (!temp_range.end) > - return 0; > - > - /* Split happened */ > - if (i == mem->max_nr_ranges - 1) > - return -ENOMEM; > - > - /* Location where new range should go */ > - j = i + 1; > - if (j < mem->nr_ranges) { > - /* Move over all ranges one slot towards the end */ > - for (i = mem->nr_ranges - 1; i >= j; i--) > - mem->ranges[i + 1] = mem->ranges[i]; > } > > - mem->ranges[j].start = temp_range.start; > - mem->ranges[j].end = temp_range.end; > - mem->nr_ranges++; > return 0; > } > > -- > 2.43.0 > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec