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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8995FC6FD20 for ; Fri, 24 Mar 2023 15:21:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232082AbjCXPVX (ORCPT ); Fri, 24 Mar 2023 11:21:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49396 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232058AbjCXPVX (ORCPT ); Fri, 24 Mar 2023 11:21:23 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FDF2132EC; Fri, 24 Mar 2023 08:21:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id BD2FAB82498; Fri, 24 Mar 2023 15:21:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C4A70C433A8; Fri, 24 Mar 2023 15:21:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679671279; bh=02GM7K6r27KRYha6EteRpwwTUBbmpkVxG9OyijKlG3g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fYn5+NeZtpXWi3nVp/4LLy8DH0H0ymzl9ykR3HGhR56lH3c2NdLc7Vq9e+nz6yGLM th3lEHNjAcHCBgVNwpsDAEfKQW4MaCEZmWtunHGlBnrfdjyrj6dtyckAVr4AytNWP5 YoHlcyh9EHZLpMUfNtTxyT/IdQV32XFdbRz500HJrCQ7B2f3DEU8EIcFjArKBTNnl5 ITOUHbY65mucoIZhCnBong68mCzbzpAFuGBESgTkskfci1G2VXWa9Q9j1pHIxiB916 XgrZ1tXUn9nCbsGi93+pKgYS81I77gF95DX3iMV+WeX4Qo/HnMj3ISRhs917M91OiX +DMCYejfbkXNw== Date: Fri, 24 Mar 2023 15:21:13 +0000 From: Will Deacon To: Alexandre Ghiti Cc: Catalin Marinas , Paul Walmsley , Palmer Dabbelt , Albert Ou , Rob Herring , Frank Rowand , Mike Rapoport , Andrew Morton , Anup Patel , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v8 3/4] arm64: Make use of memblock_isolate_memory for the linear mapping Message-ID: <20230324152112.GD27199@willie-the-truck> References: <20230316131711.1284451-1-alexghiti@rivosinc.com> <20230316131711.1284451-4-alexghiti@rivosinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230316131711.1284451-4-alexghiti@rivosinc.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Thu, Mar 16, 2023 at 02:17:10PM +0100, Alexandre Ghiti wrote: > In order to isolate the kernel text mapping and the crash kernel > region, we used some sort of hack to isolate thoses ranges which consisted > in marking them as not mappable with memblock_mark_nomap. > > Simply use the newly introduced memblock_isolate_memory function which does > exactly the same but does not uselessly mark the region as not mappable. But that's not what this patch does -- it's also adding special-case code for kexec and, honestly, I'm struggling to see why this is improving anything. Can we leave the code like it is, or is there something else going on? Will > Signed-off-by: Alexandre Ghiti > --- > arch/arm64/mm/mmu.c | 25 ++++++++++++++++--------- > 1 file changed, 16 insertions(+), 9 deletions(-) > > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 6f9d8898a025..387c2a065a09 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -548,19 +548,18 @@ static void __init map_mem(pgd_t *pgdp) > > /* > * Take care not to create a writable alias for the > - * read-only text and rodata sections of the kernel image. > - * So temporarily mark them as NOMAP to skip mappings in > - * the following for-loop > + * read-only text and rodata sections of the kernel image so isolate > + * those regions and map them after the for loop. > */ > - memblock_mark_nomap(kernel_start, kernel_end - kernel_start); > + memblock_isolate_memory(kernel_start, kernel_end - kernel_start); > > #ifdef CONFIG_KEXEC_CORE > if (crash_mem_map) { > if (defer_reserve_crashkernel()) > flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; > else if (crashk_res.end) > - memblock_mark_nomap(crashk_res.start, > - resource_size(&crashk_res)); > + memblock_isolate_memory(crashk_res.start, > + resource_size(&crashk_res)); > } > #endif > > @@ -568,6 +567,17 @@ static void __init map_mem(pgd_t *pgdp) > for_each_mem_range(i, &start, &end) { > if (start >= end) > break; > + > + if (start == kernel_start) > + continue; > + > +#ifdef CONFIG_KEXEC_CORE > + if (start == crashk_res.start && > + crash_mem_map && !defer_reserve_crashkernel() && > + crashk_res.end) > + continue; > +#endif > + > /* > * The linear map must allow allocation tags reading/writing > * if MTE is present. Otherwise, it has the same attributes as > @@ -589,7 +599,6 @@ static void __init map_mem(pgd_t *pgdp) > */ > __map_memblock(pgdp, kernel_start, kernel_end, > PAGE_KERNEL, NO_CONT_MAPPINGS); > - memblock_clear_nomap(kernel_start, kernel_end - kernel_start); > > /* > * Use page-level mappings here so that we can shrink the region > @@ -603,8 +612,6 @@ static void __init map_mem(pgd_t *pgdp) > crashk_res.end + 1, > PAGE_KERNEL, > NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS); > - memblock_clear_nomap(crashk_res.start, > - resource_size(&crashk_res)); > } > } > #endif > -- > 2.37.2 >