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[192.237.175.120]) by mx.google.com with ESMTPS id y7si64604107jai.31.2019.07.22.14.43.15 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 22 Jul 2019 14:43:15 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of xen-devel-bounces@lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of xen-devel-bounces@lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hpg30-0003Sc-SF; Mon, 22 Jul 2019 21:40:42 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hpg2u-0003CT-CQ for xen-devel@lists.xenproject.org; Mon, 22 Jul 2019 21:40:36 +0000 X-Inumbo-ID: 5642fb6e-acc9-11e9-b4fb-3fed55cc5072 Received: from foss.arm.com (unknown [217.140.110.172]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTP id 5642fb6e-acc9-11e9-b4fb-3fed55cc5072; Mon, 22 Jul 2019 21:40:34 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 97362153B; Mon, 22 Jul 2019 14:40:34 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.196.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E56193F71F; Mon, 22 Jul 2019 14:40:33 -0700 (PDT) From: Julien Grall To: xen-devel@lists.xenproject.org Date: Mon, 22 Jul 2019 22:39:55 +0100 Message-Id: <20190722213958.5761-33-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190722213958.5761-1-julien.grall@arm.com> References: <20190722213958.5761-1-julien.grall@arm.com> Subject: [Xen-devel] [PATCH v2 32/35] xen/arm32: head: Rework and document setup_fixmap() X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Julien Grall , Stefano Stabellini , Volodymyr Babchuk MIME-Version: 1.0 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" At the moment, the fixmap table is only hooked when earlyprintk is used. This is fine today because in C land, the fixmap is not used by anyone until the the boot CPU is switching to the runtime page-tables. In the future, the boot CPU will not switch between page-tables to avoid TLB incoherency. Thus, the fixmap table will need to be always hooked beofre any use. Let's start doing it now in setup_fixmap(). Lastly, document the behavior and the main registers usage within the function. Signed-off-by: Julien Grall Reviewed-by: Stefano Stabellini --- Changes in v2: - Patch added --- xen/arch/arm/arm32/head.S | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S index 56e2d09ed4..e0f8c2e0cb 100644 --- a/xen/arch/arm/arm32/head.S +++ b/xen/arch/arm/arm32/head.S @@ -536,8 +536,21 @@ identity_mapping_removed: mov pc, lr ENDPROC(remove_identity_mapping) +/* + * Map the UART in the fixmap (when earlyprintk is used) and hook the + * fixmap table in the page tables. + * + * The fixmap cannot be mapped in create_page_tables because it may + * clash with the 1:1 mapping. + * + * Inputs: + * r10: Physical offset + * r11: Early UART base physical address + * + * Clobbers r1 - r4 + */ setup_fixmap: -#if defined(CONFIG_EARLY_PRINTK) /* Fixmap is only used by early printk */ +#if defined(CONFIG_EARLY_PRINTK) /* Add UART to the fixmap table */ ldr r1, =xen_fixmap /* r1 := vaddr (xen_fixmap) */ lsr r2, r11, #THIRD_SHIFT @@ -546,7 +559,7 @@ setup_fixmap: orr r2, r2, #PT_LOWER(DEV_L3) /* r2:r3 := 4K dev map including UART */ mov r3, #0x0 strd r2, r3, [r1, #(FIXMAP_CONSOLE*8)] /* Map it in the first fixmap's slot */ -1: +#endif /* Map fixmap into boot_second */ ldr r1, =boot_second /* r1 := vaddr (boot_second) */ @@ -561,7 +574,7 @@ setup_fixmap: /* Ensure any page table updates made above have occurred. */ dsb nshst -#endif + mov pc, lr ENDPROC(setup_fixmap)