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,URIBL_BLOCKED, 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 43EDCC43441 for ; Mon, 12 Nov 2018 14:54:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1280D2241E for ; Mon, 12 Nov 2018 14:54:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1280D2241E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alien8.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729619AbeKMAsQ (ORCPT ); Mon, 12 Nov 2018 19:48:16 -0500 Received: from mail.skyhub.de ([5.9.137.197]:45740 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729281AbeKMAsQ (ORCPT ); Mon, 12 Nov 2018 19:48:16 -0500 X-Virus-Scanned: Nedap ESD1 at mail.skyhub.de Received: from mail.skyhub.de ([127.0.0.1]) by localhost (blast.alien8.de [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id A9eteMCz43Q9; Mon, 12 Nov 2018 15:54:38 +0100 (CET) Received: from zn.tnic (p200300EC2BE56F00329C23FFFEA6A903.dip0.t-ipconnect.de [IPv6:2003:ec:2be5:6f00:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 800521EC01F6; Mon, 12 Nov 2018 15:54:38 +0100 (CET) Date: Mon, 12 Nov 2018 15:54:33 +0100 From: Borislav Petkov To: Chao Fan Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-efi@vger.kernel.org, linux-acpi@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, keescook@chromium.org, bhe@redhat.com, msys.mizuma@gmail.com, indou.takao@jp.fujitsu.com, caoj.fnst@cn.fujitsu.com Subject: Re: [PATCH v11 1/5] x86/boot: Add efi_get_rsdp_addr() to dig out RSDP from EFI table Message-ID: <20181112145433.GF8167@zn.tnic> References: <20181112094645.4879-1-fanc.fnst@cn.fujitsu.com> <20181112094645.4879-2-fanc.fnst@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181112094645.4879-2-fanc.fnst@cn.fujitsu.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 12, 2018 at 05:46:41PM +0800, Chao Fan wrote: > In order to parse SRAT table and get memory information, RSDP pointer > should be found. In kernel, there are three methods to get RSDP: > EFI condition, BIOS condition and KEXEC condition. The first works > for EFI condition. "condition"? Also, please explain shortly what all those abbreviations mean: think of a person reading your commit message who doesn't have any clue from ACPI. > Imitate ACPI code and EFI code to dig RSDP pointer from EFI tables. > Process: boot_param->systab->efi_config_table->RSDP. > Based on efi_init(), efi_config_init(), efi_config_parse_tables(). > > Signed-off-by: Chao Fan > --- > arch/x86/boot/compressed/acpitb.c | 96 +++++++++++++++++++++++++++++++ > 1 file changed, 96 insertions(+) > create mode 100644 arch/x86/boot/compressed/acpitb.c > > diff --git a/arch/x86/boot/compressed/acpitb.c b/arch/x86/boot/compressed/acpitb.c > new file mode 100644 > index 000000000000..56b54b0e0889 > --- /dev/null > +++ b/arch/x86/boot/compressed/acpitb.c > @@ -0,0 +1,96 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#define BOOT_CTYPE_H > +#include "misc.h" > +#include "error.h" > + > +#include > +#include > +#include > +#include > + > +/* Search EFI table for RSDP table. */ > +static void efi_get_rsdp_addr(acpi_physical_address *rsdp_addr) This is just silly: the function returns void and has a single parameter which is an *output* parameter?! Why isn't the signature static acpi_physical_address *efi_get_rsdp_addr(void) instead? > +{ > +#ifdef CONFIG_EFI > + efi_system_table_t *systab; > + bool efi_64 = false; You're setting it below already, why here too? > + void *config_tables; > + struct efi_info *e; > + 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; > + } > + > + /* 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)); No ugly line breaks with open braces trailing like that, pls - just let it stick out. > +#else > + if (e->efi_systab_hi || e->efi_memmap_hi) { > + debug_putstr("Table located above 4GB. EFI should be disabled.\n"); You need to say here what really happens here: debug_putstr("Error getting RSDP address: EFI system table located above 4GB.\n"); The same below. > + return; > + } > + systab = (efi_system_table_t *)e->efi_systab; > +#endif > + > + if (!systab) > + return; > + > + /* > + * Get EFI tables from systab. Based on efi_config_init() and > + * efi_config_parse_tables(). Only dig out the config_table. > + */ > + size = efi_64 ? sizeof(efi_config_table_64_t) : > + sizeof(efi_config_table_32_t); > + > + for (i = 0; i < systab->nr_tables; i++) { > + efi_guid_t guid; > + unsigned long table; Put the void *config_tables declaration here. > + > + 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; > + guid = tmp_table->guid; > + table = tmp_table->table; > +#ifndef CONFIG_64BIT Above you have CONFIG_X86_64, here CONFIG_64BIT. Please use one only. Also, use IS_ENABLED() instead. > + if (table >> 32) { > + debug_putstr("Table located above 4G. EFI should be disabled.\n"); > + return; > + } > +#endif > + } else { > + efi_config_table_32_t *tmp_table; > + > + tmp_table = (efi_config_table_32_t *)config_tables; > + guid = tmp_table->guid; > + table = tmp_table->table; > + } > + > + /* > + * Get RSDP from EFI tables. > + * If ACPI20 table found, use it. > + * If ACPI20 table not found, but ACPI table found, > + * use the ACPI table. > + */ That comment is the opposite of what the code does. Also, why is that comment needed at all? If anything, it should say *why* ACPI_TABLE_GUID is preferred and then the fallback to ACPI_20_TABLE_GUID is done - not *what* it does. That's easily visible in the code. Thx. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.