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 X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5AA29C43387 for ; Tue, 18 Dec 2018 01:45:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 29E52214C6 for ; Tue, 18 Dec 2018 01:45:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726374AbeLRBpz (ORCPT ); Mon, 17 Dec 2018 20:45:55 -0500 Received: from mail.cn.fujitsu.com ([183.91.158.132]:3653 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726285AbeLRBpz (ORCPT ); Mon, 17 Dec 2018 20:45:55 -0500 X-IronPort-AV: E=Sophos;i="5.56,367,1539619200"; d="scan'208";a="50022410" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 18 Dec 2018 09:45:52 +0800 Received: from G08CNEXCHPEKD01.g08.fujitsu.local (unknown [10.167.33.80]) by cn.fujitsu.com (Postfix) with ESMTP id AA0504B75BD3; Tue, 18 Dec 2018 09:45:49 +0800 (CST) Received: from localhost.localdomain (10.167.225.56) by G08CNEXCHPEKD01.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.408.0; Tue, 18 Dec 2018 09:45:55 +0800 Date: Tue, 18 Dec 2018 09:45:26 +0800 From: Chao Fan To: Ingo Molnar CC: , , , , , , , , , , Subject: Re: [PATCH v14 2/5] x86/boot: Introduce efi_get_rsdp_addr() to find RSDP from EFI table Message-ID: <20181218014526.GC31775@localhost.localdomain> References: <20181214093013.13370-1-fanc.fnst@cn.fujitsu.com> <20181214093013.13370-3-fanc.fnst@cn.fujitsu.com> <20181217173032.GB90818@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20181217173032.GB90818@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Originating-IP: [10.167.225.56] X-yoursite-MailScanner-ID: AA0504B75BD3.AE4BF X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: fanc.fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 17, 2018 at 06:30:32PM +0100, Ingo Molnar wrote: > >* Chao Fan wrote: > >> Memory information in SRAT is necessary to fix the conflict between >> KASLR and memory-hotremove. So RSDP and SRAT should be parsed. >> >> When booting form KEXEC/EFI/BIOS, the methods to compute RSDP >> are different. When booting from EFI, EFI table points to RSDP. >> So parse the EFI table and find the RSDP. >> >> Signed-off-by: Chao Fan >> --- >> arch/x86/boot/compressed/acpi.c | 79 +++++++++++++++++++++++++++++++++ >> 1 file changed, 79 insertions(+) >> >> diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c >> index 44f19546c169..4151881d8713 100644 >> --- a/arch/x86/boot/compressed/acpi.c >> +++ b/arch/x86/boot/compressed/acpi.c >> @@ -28,3 +28,82 @@ static acpi_physical_address get_acpi_rsdp(void) >> #endif >> return 0; >> } >> + >> +/* Search EFI table for RSDP. */ >> +static acpi_physical_address efi_get_rsdp_addr(void) >> +{ >> + acpi_physical_address rsdp_addr = 0; >> +#ifdef CONFIG_EFI >> + efi_system_table_t *systab; >> + struct efi_info *e; > >'e' is pretty meaningless, the canonical name for efi_info local >variables is typically 'ei' (although this is not consistent across the >code). OK, will change it. > >> + bool efi_64; > >Is this a flag that shows whether the EFI loader is 64-bit? Yes, I use the signature to decide the size of EFI table. It's used here: + size = efi_64 ? sizeof(efi_config_table_64_t) : + sizeof(efi_config_table_32_t); > >> + char *sig; >> + int size; >> + int i; >> + >> + e = &boot_params->efi_info; >> + sig = (char *)&e->efi_loader_signature; >> + >> + if (!strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) { >> + efi_64 = true; >> + } else if (!strncmp(sig, EFI32_LOADER_SIGNATURE, 4)) { >> + efi_64 = false; >> + } else { >> + debug_putstr("Wrong EFI loader signature.\n"); >> + return 0; >> + } >> + >> + /* Get systab from boot params. Based on efi_init(). */ >> +#ifdef CONFIG_X86_64 >> + systab = (efi_system_table_t *)(e->efi_systab | ((__u64)e->efi_systab_hi<<32)); >> +#else >> + if (e->efi_systab_hi || e->efi_memmap_hi) { >> + debug_putstr("Error getting RSDP address: EFI system table located above 4GB.\n"); >> + return 0; >> + } >> + systab = (efi_system_table_t *)e->efi_systab; >> +#endif >> + >> + if (!systab) >> + return 0; > >Is it normal that EFI provides no 'systab'? I think not normal, to make sure the code run normally. We will use it below like: i < systab->nr_tables, if systab is wrong, the code will fail to work. > >> + /* >> + * Get EFI tables from systab. Based on efi_config_init() and >> + * efi_config_parse_tables(). >> + */ >> + size = efi_64 ? sizeof(efi_config_table_64_t) : >> + sizeof(efi_config_table_32_t); >> + >> + for (i = 0; i < systab->nr_tables; i++) { >> + void *config_tables; >> + unsigned long table; >> + efi_guid_t guid; >> + >> + config_tables = (void *)(systab->tables + size * i); >> + if (efi_64) { >> + efi_config_table_64_t *tmp_table; >> + >> + tmp_table = (efi_config_table_64_t *)config_tables; > >Since 'config_tables' is a void * there's no need to cast the type. > >> + guid = tmp_table->guid; >> + table = tmp_table->table; >> + >> + if (!IS_ENABLED(CONFIG_X86_64) && table >> 32) { >> + debug_putstr("Error getting RSDP address: EFI config table located above 4GB.\n"); >> + return 0; >> + } >> + } else { >> + efi_config_table_32_t *tmp_table; >> + >> + tmp_table = (efi_config_table_32_t *)config_tables; > >Ditto. > >> + guid = tmp_table->guid; >> + table = tmp_table->table; >> + } > >So it looks like > >> + >> + if (!(efi_guidcmp(guid, ACPI_TABLE_GUID))) >> + rsdp_addr = (acpi_physical_address)table; >> + else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID))) >> + return (acpi_physical_address)table; > >'return' is not a function. Got it, will clean the type cast. Thanks, Chao Fan > >Thanks, > > Ingo > >