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 5BE83C5475B for ; Fri, 1 Mar 2024 06:52:56 +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=FZ0nzKWMiUX6zZePE425GjhTxatbYKsUK3d6BHn1hcI=; b=gAe3O2/DaL1vgz cUWJNq/veO0CJ9WzSiWE74mRegtM8rMrrezqBUvD18/S/ZvKrqeaot19DsGzEMy4Bokmjuurn2qZ4 7pxAHzixpuQclphC5V05+UyndtVJZmX8ym0rZ2i7E3Oo4jsbAtpIr2Aqs79DBobBV9WqP5vUymeQ3 LQx1L/IO5Yiw7U1U9JK8QgsZRlcoq3bJ8PfK+VwpuolNyg9xDAKInExlZqgLZybCrlSbW4X80888u BrvuN5lpJ/ys/vZ6qMfN9yZIxL+OY6XkVpm+SNelapMr1zSXYb2yRvukX73VL28finPziSQYmKKJA VgFERvuXyOffwntHHC1A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rfwlJ-0000000GdEP-3bNQ; Fri, 01 Mar 2024 06:52:53 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rfwlG-0000000GdCW-41Sd for kexec@lists.infradead.org; Fri, 01 Mar 2024 06:52:52 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1709275968; 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=1hAv7LCsa3iLqGJhJsJviM4n+BZxClj9lSP/nAIPeEE=; b=ZmFeYeafCN5TPui876iOjrQyDomNHY06yTBI4gCX5MdMBIH7/ivIv108GNUYrVtYQLU0q3 MEaUIdasntw0fJSXeJuJgV8id17A2aUHXs/HqcfFpu+FnnCrlp8X2ugVrxHyYG7GQV6nx/ 1dmOz4IxhwRbaMPnBnY0nojTe2WxRCI= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-223-k9AfNMFUM463nT0FJ3bfzg-1; Fri, 01 Mar 2024 01:52:44 -0500 X-MC-Unique: k9AfNMFUM463nT0FJ3bfzg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (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 2B95183FC6C; Fri, 1 Mar 2024 06:52:44 +0000 (UTC) Received: from localhost (unknown [10.72.116.6]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7D4C21BDB1; Fri, 1 Mar 2024 06:52:42 +0000 (UTC) Date: Fri, 1 Mar 2024 14:52:34 +0800 From: Baoquan He To: "yang.zhang" , akpm@linux-foundation.org Cc: ebiederm@xmission.com, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, "yang.zhang" Subject: Re: [PATCH V3] kexec: copy only happens before uchunk goes to zero Message-ID: References: <20240222092119.5602-1-gaoshanliukou@163.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240222092119.5602-1-gaoshanliukou@163.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240229_225251_111316_4B523D9B X-CRM114-Status: GOOD ( 20.38 ) 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 CC Andrew On 02/22/24 at 05:21pm, yang.zhang wrote: > From: "yang.zhang" > > When loading segments, ubytes is <= mbytes. When ubytes is exhausted, > there could be remaining mbytes. Then in the while loop, the buf pointer > advancing with mchunk will causing meaningless reading even though it > doesn't harm. > > So let's change to make sure that all of the copying and the rest only > happens before uchunk goes to zero. > > Acked-by: Baoquan He > Signed-off-by: yang.zhang > > --- > V2 -> V3: > - Add more detailed description in the commit message > v1 -> v2: > - Only copy before uchunk goes to zero > > V1: https://lore.kernel.org/lkml/20240130101802.23850-1-gaoshanliukou@163.com/ > --- > kernel/kexec_core.c | 44 ++++++++++++++++++++++++-------------------- > 1 file changed, 24 insertions(+), 20 deletions(-) > > diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c > index d08fc7b5db97..2fc3d0e3715a 100644 > --- a/kernel/kexec_core.c > +++ b/kernel/kexec_core.c > @@ -800,22 +800,24 @@ static int kimage_load_normal_segment(struct kimage *image, > PAGE_SIZE - (maddr & ~PAGE_MASK)); > uchunk = min(ubytes, mchunk); > > - /* For file based kexec, source pages are in kernel memory */ > - if (image->file_mode) > - memcpy(ptr, kbuf, uchunk); > - else > - result = copy_from_user(ptr, buf, uchunk); > + if (uchunk) { > + /* For file based kexec, source pages are in kernel memory */ > + if (image->file_mode) > + memcpy(ptr, kbuf, uchunk); > + else > + result = copy_from_user(ptr, buf, uchunk); > + ubytes -= uchunk; > + if (image->file_mode) > + kbuf += uchunk; > + else > + buf += uchunk; > + } > kunmap_local(ptr); > if (result) { > result = -EFAULT; > goto out; > } > - ubytes -= uchunk; > maddr += mchunk; > - if (image->file_mode) > - kbuf += mchunk; > - else > - buf += mchunk; > mbytes -= mchunk; > > cond_resched(); > @@ -866,11 +868,18 @@ static int kimage_load_crash_segment(struct kimage *image, > memset(ptr + uchunk, 0, mchunk - uchunk); > } > > - /* For file based kexec, source pages are in kernel memory */ > - if (image->file_mode) > - memcpy(ptr, kbuf, uchunk); > - else > - result = copy_from_user(ptr, buf, uchunk); > + if (uchunk) { > + /* For file based kexec, source pages are in kernel memory */ > + if (image->file_mode) > + memcpy(ptr, kbuf, uchunk); > + else > + result = copy_from_user(ptr, buf, uchunk); > + ubytes -= uchunk; > + if (image->file_mode) > + kbuf += uchunk; > + else > + buf += uchunk; > + } > kexec_flush_icache_page(page); > kunmap_local(ptr); > arch_kexec_pre_free_pages(page_address(page), 1); > @@ -878,12 +887,7 @@ static int kimage_load_crash_segment(struct kimage *image, > result = -EFAULT; > goto out; > } > - ubytes -= uchunk; > maddr += mchunk; > - if (image->file_mode) > - kbuf += mchunk; > - else > - buf += mchunk; > mbytes -= mchunk; > > cond_resched(); > -- > 2.25.1 > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec