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 31DF0CD1292 for ; Thu, 4 Apr 2024 14:49:17 +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:References:To:From:Subject: Cc:Message-Id:Date:Mime-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=6vtS4jpHrVG/S9RhoPMw1+oMYtH/Xr6tR4YSzWbnU+8=; b=EXyOTxZqWIGCZa FxAeL53RgtF81pFVdmaX4tGs4aWTh15S9yNlMRSMpJLdNqAxStLh0soWlN0xgudmhA9mUyvIujZqG p+c1aowCnAETSdFydVC+PUfAL+k8g6iOotoD6SWxTqlI3rlvi/8o948Pc9NAz0tEai34/euC1Q1Cx fzPXNjhJoMBTo08HU6iRFyP8ftVDviV5+AAUZUyrlUf9YVcyfhIzR6HOhf8J5AFkRqkVsO69zTLG+ zsEfkaLoSZ5Noem+LvJh2cjIOkf4yJN5qZc5zCiXOwv7n/Y4xAzYkWPTrAF6O0yYKIpIINQwLfxjv QiN1lSK/Yvbl7kHeGkHQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rsOOl-0000000369p-18sh; Thu, 04 Apr 2024 14:49:03 +0000 Received: from sin.source.kernel.org ([145.40.73.55]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rsOOh-00000003687-0mTB for linux-arm-kernel@lists.infradead.org; Thu, 04 Apr 2024 14:49:01 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 779F2CE1FD1; Thu, 4 Apr 2024 14:48:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 57BE7C433C7; Thu, 4 Apr 2024 14:48:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1712242134; bh=a71wwcJR5TKYVGY9/88H+mkVOaP4piH5VNbwZOyifkE=; h=Date:Cc:Subject:From:To:References:In-Reply-To:From; b=dpM4E2ZiaPCeasQyfnx+ZLamawrdyUXqIFerCmPWI2+2xBoJ4Ju9WMclnQZxoS7NS +d4/MvGPr1yMZtcFmU7OpeH9rfERecy27D7Qs1n18hqXkCIXHPLORtP+YZNK7inNZE ZiQDZRy99DTShCW1sxY39JJRhJCKQlidOPCpucKnKFN+fZYKjteERrt1PaD6ngc3Fs ycf1Msm4Oooqxy625l7BuLHK8roupVPitFu8mDZ6XLeL2ZYXOmZhfibkqRN58eiCIG niktUXljafu/ZjYQZCCRw8tIB8IX7enUresYbk8QyBsnt6bS1BpZOrflPVKh8wB/yI iEVVRRT8FtePQ== Mime-Version: 1.0 Date: Thu, 04 Apr 2024 17:48:50 +0300 Message-Id: Cc: , "Catalin Marinas" , "Will Deacon" , , , , , , , , Subject: Re: [PATCH v2 1/4] arm64: patching: always use fixmap From: "Jarkko Sakkinen" To: "Mark Rutland" X-Mailer: aerc 0.17.0 References: <20240403150154.667649-1-mark.rutland@arm.com> <20240403150154.667649-2-mark.rutland@arm.com> In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240404_074900_038407_E666FDF8 X-CRM114-Status: GOOD ( 36.76 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed Apr 3, 2024 at 7:51 PM EEST, Mark Rutland wrote: > On Wed, Apr 03, 2024 at 07:20:31PM +0300, Jarkko Sakkinen wrote: > > On Wed Apr 3, 2024 at 6:01 PM EEST, Mark Rutland wrote: > > > For historical reasons, patch_map() won't bother to fixmap non-image > > > addresses when CONFIG_STRICT_MODULE_RWX=n, matching the behaviour prior > > > to the introduction of CONFIG_STRICT_MODULE_RWX. However, as arm64 > > > doesn't select CONFIG_ARCH_OPTIONAL_KERNEL_RWX, CONFIG_MODULES implies > > > CONFIG_STRICT_MODULE_RWX, so any kernel built with module support will > > > use the fixmap for any non-image address. > > > > Not familiar with the config flag but I'd guess it is essentially > > w^x enforcement right for the sections? > > Essentially, yes. > > > > Historically we only used patch_map() for the kernel image and modules, > > > but these days its also used by BPF and KPROBES to write to read-only > > > pages of executable text. Currently these both depend on CONFIG_MODULES, > > > but we'd like to change that in subsequent patches, which will require > > > using the fixmap regardless of CONFIG_STRICT_MODULE_RWX. > > > > > > This patch changes patch_map() to always use the fixmap, and simplifies > > > the logic: > > > > > > * Use is_image_text() directly in the if-else, rather than using a > > > temporary boolean variable. > > > > > > * Use offset_in_page() to get the offset within the mapping. > > > > > > * Remove uintaddr and cast the address directly when using > > > is_image_text(). > > > > > > For kernels built with CONFIG_MODULES=y, there should be no functional > > > change as a result of this patch. > > > > > > For kernels built with CONFIG_MODULES=n, patch_map() will use the fixmap > > > for non-image addresses, but there are no extant users with non-image > > > addresses when CONFIG_MODULES=n, and hence there should be no functional > > > change as a result of this patch alone. > > > > > > Signed-off-by: Mark Rutland > > > Cc: Catalin Marinas > > > Cc: Will Deacon > > > --- > > > arch/arm64/kernel/patching.c | 10 +++------- > > > 1 file changed, 3 insertions(+), 7 deletions(-) > > > > > > Catalin, Will, this is a prerequisite for the final two patches in the > > > series. Are you happy for this go via the tracing tree? > > > > > > Mark. > > > > > > diff --git a/arch/arm64/kernel/patching.c b/arch/arm64/kernel/patching.c > > > index 2555349303684..f0f3a2a82ca5a 100644 > > > --- a/arch/arm64/kernel/patching.c > > > +++ b/arch/arm64/kernel/patching.c > > > @@ -30,20 +30,16 @@ static bool is_image_text(unsigned long addr) > > > > > > static void __kprobes *patch_map(void *addr, int fixmap) > > > { > > > - unsigned long uintaddr = (uintptr_t) addr; > > > - bool image = is_image_text(uintaddr); > > > struct page *page; > > > > > > - if (image) > > > + if (is_image_text((unsigned long)addr)) > > > page = phys_to_page(__pa_symbol(addr)); > > > - else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) > > > - page = vmalloc_to_page(addr); > > > else > > > - return addr; > > > + page = vmalloc_to_page(addr); > > > > > > BUG_ON(!page); > > > return (void *)set_fixmap_offset(fixmap, page_to_phys(page) + > > > - (uintaddr & ~PAGE_MASK)); > > > + offset_in_page(addr)); > > > > nit: could be a single line but i guess it is up to the taste (and > > subsystem maintainer). I.e. checkpatch will allow it at least. > > > > I don't mind it too much just mentioning for completeness. > > At that point it goes to 93 chars long, and I stuck with the existing line > wrapping at 80 chars. I'd rather have a temporary 'phys_addr_t phys' variable > and do: > > phys = page_to_phys(page) + offset_in_page(addr); > return (void *)set_fixmap(fixmap, phys); > > ... but I'll leave this as-is for now. > > > > } > > > > > > static void __kprobes patch_unmap(int fixmap) > > > > If my assumption about the config flag holds this makes sense: > > > > Reviewed-by: Jarkko Sakkinen > > Thanks! I assume that should be "kernel.org", with an 'o' ;) Yes, that's correct, not from Gibraltar :-) BR, Jarkko _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel