From patchwork Sun Jun 25 20:49:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 13292186 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.xenproject.org (lists.xenproject.org [192.237.175.120]) (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 8F09BEB64DC for ; Sun, 25 Jun 2023 20:49:38 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.554873.866303 (Exim 4.92) (envelope-from ) id 1qDWff-00035x-Pk; Sun, 25 Jun 2023 20:49:19 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 554873.866303; Sun, 25 Jun 2023 20:49:19 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qDWff-00035q-Ms; Sun, 25 Jun 2023 20:49:19 +0000 Received: by outflank-mailman (input) for mailman id 554873; Sun, 25 Jun 2023 20:49:18 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qDWfe-0002fU-7G for xen-devel@lists.xenproject.org; Sun, 25 Jun 2023 20:49:18 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qDWfd-0003M4-Ut; Sun, 25 Jun 2023 20:49:17 +0000 Received: from 54-240-197-232.amazon.com ([54.240.197.232] helo=dev-dsk-jgrall-1b-035652ec.eu-west-1.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1qDWfd-00021M-Mu; Sun, 25 Jun 2023 20:49:17 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:MIME-Version:References: In-Reply-To:Message-Id:Date:Subject:Cc:To:From; bh=pIp2Ocf+duFQJxu0URFuhairXV4FCYWfRGikcKVLzqU=; b=qfck+/QFFLkk2WdsWO3K9gtgeW CUyhCCbYpAl5g7ea+HY5mE5aTKWMIldZc7meMakKcwPAC/RAL6UjxXfsMgiUZcmgTdYfyRMyPdepx ipCi91YDVkJvYWGQm9J5CF0/WU6SWZiMOvO7Y6Ke02fWhZLGaz62hTsSoc794BnUXHvA=; From: Julien Grall To: xen-devel@lists.xenproject.org Cc: Luca.Fancellu@arm.com, michal.orzel@amd.com, Henry.Wang@arm.com, Julien Grall , Stefano Stabellini , Julien Grall , Bertrand Marquis , Volodymyr Babchuk Subject: [PATCH 2/9] xen/arm64: head: Don't map too much in boot_third Date: Sun, 25 Jun 2023 21:49:00 +0100 Message-Id: <20230625204907.57291-3-julien@xen.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230625204907.57291-1-julien@xen.org> References: <20230625204907.57291-1-julien@xen.org> MIME-Version: 1.0 From: Julien Grall At the moment, we are mapping the size of the reserved area for Xen (i.e. 2MB) even if the binary is smaller. We don't exactly know what's after Xen, so it is not a good idea to map more than necessary for a couple of reasons: * We would need to use break-before-make if the extra PTE needs to be updated to point to another region * The extra area mapped may be mapped again by Xen with different memory attribute. This would result to attribue mismatch. Therefore, rework the logic in create_page_tables() to map only what's necessary. To simplify the logic, we also want to make sure _end is page-aligned. So align the symbol in the linker and add an assert to catch any change. Signed-off-by: Julien Grall Reviewed-by: Michal Orzel --- xen/arch/arm/arm64/head.S | 15 ++++++++++++++- xen/arch/arm/xen.lds.S | 3 +++ 2 files changed, 17 insertions(+), 1 deletion(-) diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S index f37133cf7ccd..66bc85d4c39e 100644 --- a/xen/arch/arm/arm64/head.S +++ b/xen/arch/arm/arm64/head.S @@ -572,6 +572,19 @@ create_page_tables: create_table_entry boot_first, boot_second, x0, 1, x1, x2, x3 create_table_entry boot_second, boot_third, x0, 2, x1, x2, x3 + /* + * Find the size of Xen in pages and multiply by the size of a + * PTE. This will then be compared in the mapping loop below. + * + * Note the multiplication is just to avoid using an extra + * register/instruction per iteration. + */ + ldr x0, =_start /* x0 := vaddr(_start) */ + ldr x1, =_end /* x1 := vaddr(_end) */ + sub x0, x1, x0 /* x0 := effective size of Xen */ + lsr x0, x0, #PAGE_SHIFT /* x0 := Number of pages for Xen */ + lsl x0, x0, #3 /* x0 := Number of pages * PTE size */ + /* Map Xen */ adr_l x4, boot_third @@ -585,7 +598,7 @@ create_page_tables: 1: str x2, [x4, x1] /* Map vaddr(start) */ add x2, x2, #PAGE_SIZE /* Next page */ add x1, x1, #8 /* Next slot */ - cmp x1, #(XEN_PT_LPAE_ENTRIES<<3) /* 512 entries per page */ + cmp x1, x0 /* Loop until we map all of Xen */ b.lt 1b /* diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S index c5d8c6201423..c4627cea7482 100644 --- a/xen/arch/arm/xen.lds.S +++ b/xen/arch/arm/xen.lds.S @@ -212,6 +212,7 @@ SECTIONS . = ALIGN(POINTER_ALIGN); __bss_end = .; } :text + . = ALIGN(PAGE_SIZE); _end = . ; /* Section for the device tree blob (if any). */ @@ -241,4 +242,6 @@ ASSERT(IS_ALIGNED(__init_begin, 4), "__init_begin is misaligned") ASSERT(IS_ALIGNED(__init_end, 4), "__init_end is misaligned") ASSERT(IS_ALIGNED(__bss_start, POINTER_ALIGN), "__bss_start is misaligned") ASSERT(IS_ALIGNED(__bss_end, POINTER_ALIGN), "__bss_end is misaligned") +/* To simplify the logic in head.S, we want to _end to be page aligned */ +ASSERT(IS_ALIGNED(_end, PAGE_SIZE), "_end is not page aligned") ASSERT((_end - start) <= XEN_VIRT_SIZE, "Xen is too big")