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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 80861C433EF for ; Fri, 22 Jul 2022 23:11:03 +0000 (UTC) Received: from localhost ([::1]:41464 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oF1nS-0003qe-Cj for qemu-devel@archiver.kernel.org; Fri, 22 Jul 2022 19:11:02 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56128) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oF1m6-0002x5-5i; Fri, 22 Jul 2022 19:09:38 -0400 Received: from zero.eik.bme.hu ([152.66.115.2]:57722) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oF1m3-0003O0-As; Fri, 22 Jul 2022 19:09:37 -0400 Received: from zero.eik.bme.hu (blah.eik.bme.hu [152.66.115.182]) by localhost (Postfix) with SMTP id 9575C746381; Sat, 23 Jul 2022 01:09:29 +0200 (CEST) Received: by zero.eik.bme.hu (Postfix, from userid 432) id 5718A74637E; Sat, 23 Jul 2022 01:09:29 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by zero.eik.bme.hu (Postfix) with ESMTP id 55535745702; Sat, 23 Jul 2022 01:09:29 +0200 (CEST) Date: Sat, 23 Jul 2022 01:09:29 +0200 (CEST) From: BALATON Zoltan To: Daniel Henrique Barboza cc: qemu-devel@nongnu.org, Alistair Francis , David Gibson , Peter Maydell , qemu-arm@nongnu.org Subject: Re: [PATCH for-7.2 01/10] hw/arm/boot.c: do not free machine->fdt in arm_load_dtb() In-Reply-To: <20220722200007.1602174-2-danielhb413@gmail.com> Message-ID: References: <20220722200007.1602174-1-danielhb413@gmail.com> <20220722200007.1602174-2-danielhb413@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Received-SPF: pass client-ip=152.66.115.2; envelope-from=balaton@eik.bme.hu; helo=zero.eik.bme.hu X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, 22 Jul 2022, Daniel Henrique Barboza wrote: > At this moment, arm_load_dtb() can free machine->fdt when > binfo->dtb_filename is NULL. If there's no 'dtb_filename', 'fdt' will be > retrieved by binfo->get_dtb(). If get_dtb() returns machine->fdt, as is > the case of machvirt_dtb() from hw/arm/virt.c, fdt now has a pointer to > machine->fdt. And, in that case, the existing g_free(fdt) at the end of > arm_load_dtb() will make machine->fdt point to an invalid memory region. > > This is not an issue right now because there's no code that access > machine->fdt after arm_load_dtb(), but we're going to add a couple do > FDT HMP commands that will rely on machine->fdt being valid. > > Instead of freeing 'fdt' at the end of arm_load_dtb(), assign it to > machine->fdt. This will allow the FDT of ARM machines that relies on > arm_load_dtb() to be accessed later on. > > Since all ARM machines allocates the FDT only once, we don't need to > worry about leaking the existing FDT during a machine reset (which is > something that other machines have to look after, e.g. the ppc64 pSeries > machine). > > Cc: Peter Maydell > Cc: qemu-arm@nongnu.org > Signed-off-by: Daniel Henrique Barboza > --- > hw/arm/boot.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/hw/arm/boot.c b/hw/arm/boot.c > index ada2717f76..1d9c6047b1 100644 > --- a/hw/arm/boot.c > +++ b/hw/arm/boot.c > @@ -684,7 +684,8 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo, > */ > rom_add_blob_fixed_as("dtb", fdt, size, addr, as); > > - g_free(fdt); > + /* Update ms->fdt pointer */ > + ms->fdt = fdt; Not sure this comment is useful as it just states what the assignment does so provides no further info. Regards, BALATON Zoltan > > return size; > >