From patchwork Wed Nov 1 23:30:11 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Julien Grall X-Patchwork-Id: 13443119 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 50F7DC4167D for ; Wed, 1 Nov 2023 23:30:51 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.626673.977148 (Exim 4.92) (envelope-from ) id 1qyKfJ-0004Ld-96; Wed, 01 Nov 2023 23:30:25 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 626673.977148; Wed, 01 Nov 2023 23:30:25 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qyKfJ-0004LS-5w; Wed, 01 Nov 2023 23:30:25 +0000 Received: by outflank-mailman (input) for mailman id 626673; Wed, 01 Nov 2023 23:30:24 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qyKfI-00048C-Dn for xen-devel@lists.xenproject.org; Wed, 01 Nov 2023 23:30:24 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1qyKfI-0008Dy-4m; Wed, 01 Nov 2023 23:30:24 +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 1qyKfH-0007xN-PI; Wed, 01 Nov 2023 23:30:24 +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=o8VZQgPoWYFxMhNL2bV9PEPd6/WmxcCBwhJiRXA0y5U=; b=dWLDcstJOp/FVw1s1VBEJSCLBY rSmScWiJNUdCspgFdGubUEFuoFxJMrOxorzuIvpKfE0l4qlPQ1uwcnDU2A8JlQrJWO+JIdge0N5Hm bHIPQZP9gqDK48hS1Fwvk3uAx0JTxaXpcEro7N/EaWH2rhL8IdLSVoZAZS//eV+6ckvA=; From: Julien Grall To: xen-devel@lists.xenproject.org Cc: Henry.Wang@arm.com, michal.orzel@amd.com, ayan.kumar.halder@amd.com, Julien Grall , Stefano Stabellini , Julien Grall , Bertrand Marquis , Volodymyr Babchuk Subject: [PATCH 2/2] xen/arm32: head: Improve logging in head.S Date: Wed, 1 Nov 2023 23:30:11 +0000 Message-Id: <20231101233011.83098-3-julien@xen.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231101233011.83098-1-julien@xen.org> References: <20231101233011.83098-1-julien@xen.org> MIME-Version: 1.0 From: Julien Grall The sequence to enable the MMU on arm32 is quite complex as we may need to jump to a temporary mapping to map Xen. Recently, we had one bug in the logic (see f5a49eb7f8b3 ("xen/arm32: head: Add mising isb in switch_to_runtime_mapping()") and it was a pain to debug because there are no logging. In order to improve the logging in the MMU switch we need to add support for early printk while running on the identity mapping and also on the temporary mapping. For the identity mapping, we have only the first page of Xen mapped. So all the strings should reside in the first page. For that purpose a new macro PRINT_ID is introduced. For the temporary mapping, the fixmap is already linked the temporary area (and so does the UART). So we just need to update the register storing the UART address (i.e. r11) to point to the UART temporary mapping. Take the opportunity to introduce mov_w_on_cond in order to conditionally execute mov_w and avoid branches. Signed-off-by: Julien Grall --- xen/arch/arm/arm32/head.S | 68 ++++++++++++++++++++----- xen/arch/arm/include/asm/asm_defns.h | 6 ++- xen/arch/arm/include/asm/early_printk.h | 3 ++ xen/arch/arm/include/asm/mmu/layout.h | 4 ++ xen/arch/arm/mm.c | 5 ++ xen/arch/arm/xen.lds.S | 1 + 6 files changed, 71 insertions(+), 16 deletions(-) diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S index fec2433e568f..bd61521a9dea 100644 --- a/xen/arch/arm/arm32/head.S +++ b/xen/arch/arm/arm32/head.S @@ -46,9 +46,13 @@ * Move an immediate constant into a 32-bit register using movw/movt * instructions. */ +.macro mov_w_on_cond cond, reg, word + movw\cond \reg, #:lower16:\word + movt\cond \reg, #:upper16:\word +.endm + .macro mov_w reg, word - movw \reg, #:lower16:\word - movt \reg, #:upper16:\word + mov_w_on_cond al, \reg, \word .endm /* @@ -104,16 +108,26 @@ */ #ifdef CONFIG_EARLY_PRINTK /* - * Macro to print a string to the UART, if there is one. + * Macros to print a string to the UART, if there is one. + * + * There are multiple flavors: + * - PRINT_SECT(section, string): The @string will be located in @section + * - PRINT(): The string will be located in .rodata.str. + * - PRINT_ID(): When Xen is running on the Identity Mapping, it is + * only possible to have a limited amount of Xen. This will create + * the string in .rodata.idmap which will always be mapped. * * Clobbers r0 - r3 */ -#define PRINT(_s) \ - mov r3, lr ;\ - adr_l r0, 98f ;\ - bl puts ;\ - mov lr, r3 ;\ - RODATA_STR(98, _s) +#define PRINT_SECT(section, string) \ + mov r3, lr ;\ + adr_l r0, 98f ;\ + bl puts ;\ + mov lr, r3 ;\ + RODATA_SECT(section, 98, string) + +#define PRINT(string) PRINT_SECT(.rodata.str, string) +#define PRINT_ID(string) PRINT_SECT(.rodata.idmap, string) /* * Macro to print the value of register \rb @@ -129,6 +143,7 @@ #else /* CONFIG_EARLY_PRINTK */ #define PRINT(s) +#define PRINT_ID(s) .macro print_reg rb .endm @@ -183,11 +198,6 @@ past_zImage: bl check_cpu_mode bl cpu_init bl create_page_tables - /* Add the UART mapping if requested */ -#ifdef CONFIG_EARLY_PRINTK - mov_w r0, EARLY_UART_VIRTUAL_ADDRESS - create_mapping_entry xen_fixmap, r0, r11, type=PT_DEV_L3 -#endif /* Address in the runtime mapping to jump to after the MMU is enabled */ mov_w lr, primary_switched @@ -593,6 +603,21 @@ enable_mmu: mcr CP32(r0, HSCTLR) /* now paging is enabled */ isb /* Now, flush the icache */ + /* + * At this stage, the UART address will depend on whether the + * temporary mapping was created or not. + * + * If it was, then the UART will be mapped in the temporary + * area. Otherwise, it will be mapped at runtime virtual + * mapping. + */ +#ifdef CONFIG_EARLY_PRINTK + teq r12, #1 /* Was the temporary mapping created? */ + mov_w_on_cond eq, r11, TEMPORARY_EARLY_UART_VIRTUAL_ADDRESS + mov_w_on_cond ne, r11, EARLY_UART_VIRTUAL_ADDRESS +#endif + PRINT_ID("- Paging turned on -\r\n") + /* * The MMU is turned on and we are in the 1:1 mapping. Switch * to the runtime mapping. @@ -643,12 +668,14 @@ switch_to_runtime_mapping: teq r12, #0 beq ready_to_switch + PRINT_ID("- Switching to the temporary mapping -\r\n") /* We are still in the 1:1 mapping. Jump to the temporary Virtual address. */ mov_w r0, 1f add r0, r0, #XEN_TEMPORARY_OFFSET /* r0 := address in temporary mapping */ mov pc, r0 1: + PRINT("- Running on the temporary mapping -\r\n") /* Remove boot_second_id */ mov r2, #0 mov r3, #0 @@ -659,6 +686,8 @@ switch_to_runtime_mapping: flush_xen_tlb_local r0 + PRINT("- 1:1 mapping removed -\r\n") + /* Map boot_second into boot_pgtable */ mov_w r0, XEN_VIRT_START create_table_entry boot_pgtable, boot_second, r0, 1 @@ -671,7 +700,10 @@ switch_to_runtime_mapping: */ isb + PRINT("- Runtime mapping mapped -\r\n") ready_to_switch: + PRINT("- Jumping to runtime address -\r\n") + mov pc, lr ENDPROC(switch_to_runtime_mapping) @@ -795,6 +827,14 @@ init_uart: early_uart_init r11, r1, r2 #endif PRINT("- UART enabled -\r\n") + + /* + * Add the UART mapping to the fixmap so the UART can be used + * as the MMU is on. + */ + mov_w r0, EARLY_UART_VIRTUAL_ADDRESS + create_mapping_entry xen_fixmap, r0, r11, type=PT_DEV_L3 + mov pc, lr ENDPROC(init_uart) diff --git a/xen/arch/arm/include/asm/asm_defns.h b/xen/arch/arm/include/asm/asm_defns.h index 29a9dbb002fa..ec803c0a370c 100644 --- a/xen/arch/arm/include/asm/asm_defns.h +++ b/xen/arch/arm/include/asm/asm_defns.h @@ -22,11 +22,13 @@ # error "unknown ARM variant" #endif -#define RODATA_STR(label, msg) \ -.pushsection .rodata.str, "aMS", %progbits, 1 ; \ +#define RODATA_SECT(section, label, msg) \ +.pushsection section, "aMS", %progbits, 1 ; \ label: .asciz msg; \ .popsection +#define RODATA_STR(label, msg) RODATA_SECT(.rodata.str, label, msg) + #define ASM_INT(label, val) \ .p2align 2; \ label: .long (val); \ diff --git a/xen/arch/arm/include/asm/early_printk.h b/xen/arch/arm/include/asm/early_printk.h index c5149b2976da..c1e84f8b0009 100644 --- a/xen/arch/arm/include/asm/early_printk.h +++ b/xen/arch/arm/include/asm/early_printk.h @@ -19,6 +19,9 @@ #define EARLY_UART_VIRTUAL_ADDRESS \ (FIXMAP_ADDR(FIXMAP_CONSOLE) + (CONFIG_EARLY_UART_BASE_ADDRESS & ~PAGE_MASK)) +#define TEMPORARY_EARLY_UART_VIRTUAL_ADDRESS \ + (TEMPORARY_FIXMAP_ADDR(FIXMAP_CONSOLE) + (CONFIG_EARLY_UART_BASE_ADDRESS & ~PAGE_MASK)) + #endif /* !CONFIG_EARLY_PRINTK */ #endif diff --git a/xen/arch/arm/include/asm/mmu/layout.h b/xen/arch/arm/include/asm/mmu/layout.h index da6be276ac5f..68855c4f3184 100644 --- a/xen/arch/arm/include/asm/mmu/layout.h +++ b/xen/arch/arm/include/asm/mmu/layout.h @@ -113,6 +113,10 @@ (TEMPORARY_AREA_FIRST_SLOT << XEN_PT_LEVEL_SHIFT(1))) #define TEMPORARY_XEN_VIRT_START TEMPORARY_AREA_ADDR(XEN_VIRT_START) +#define TEMPORARY_FIXMAP_VIRT_START TEMPORARY_AREA_ADDR(FIXMAP_VIRT_START) + +#define TEMPORARY_FIXMAP_ADDR(n) \ + (TEMPORARY_FIXMAP_VIRT_START + (n) * PAGE_SIZE) #else /* ARM_64 */ diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c index c34cc94c907a..6ffa45c53be6 100644 --- a/xen/arch/arm/mm.c +++ b/xen/arch/arm/mm.c @@ -193,7 +193,12 @@ static void __init __maybe_unused build_assertions(void) #ifdef CONFIG_ARM_32 CHECK_SAME_SLOT(first, TEMPORARY_XEN_VIRT_START, DOMHEAP_VIRT_START); CHECK_DIFFERENT_SLOT(first, XEN_VIRT_START, TEMPORARY_XEN_VIRT_START); + CHECK_SAME_SLOT(first, TEMPORARY_XEN_VIRT_START, + TEMPORARY_FIXMAP_VIRT_START); + CHECK_SAME_SLOT(first, TEMPORARY_XEN_VIRT_START, + TEMPORARY_FIXMAP_VIRT_START); CHECK_SAME_SLOT(second, XEN_VIRT_START, TEMPORARY_XEN_VIRT_START); + CHECK_SAME_SLOT(second, FIXMAP_VIRT_START, TEMPORARY_FIXMAP_VIRT_START); #endif #undef CHECK_SAME_SLOT diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S index 59b80d122fd0..20598c6963ce 100644 --- a/xen/arch/arm/xen.lds.S +++ b/xen/arch/arm/xen.lds.S @@ -35,6 +35,7 @@ SECTIONS _idmap_start = .; *(.text.header) *(.text.idmap) + *(.rodata.idmap) _idmap_end = .; *(.text.cold)