linux-kernel - Re: [tip:x86/boot] x86/boot: Early parse RSDP and save it in boot

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Date:   Mon, 11 Feb 2019 21:21:37 +0800
From:   Chao Fan <fanc.fnst@...fujitsu.com>
To:     Borislav Petkov <bp@...en8.de>
CC:     Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        "Lendacky, Thomas" <thomas.lendacky@....com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        <caoj.fnst@...fujitsu.com>, Juergen Gross <jgross@...e.com>,
        Ingo Molnar <mingo@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        <linux-tip-commits@...r.kernel.org>,
        Matt Fleming <matt@...eblueprint.co.uk>
Subject: Re: [tip:x86/boot] x86/boot: Early parse RSDP and save it in
 boot_params

On Mon, Feb 11, 2019 at 12:20:09PM +0100, Borislav Petkov wrote:
>On Mon, Feb 11, 2019 at 10:46:18AM +0000, Ard Biesheuvel wrote:
>> As I pointed out in my previous reply, systab will be the wrong type
>> on 32-bit firmware, it needs to be efi_system_table_32_t
>
>This seems to work. Chao, please run it too.

Ah, I will try and test more then reply to mail list.

Thanks,
Chao Fan

>
>Thx.
>
>---
>diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
>index c5a949335d8b..0d97aa8bd01f 100644
>--- a/arch/x86/boot/compressed/acpi.c
>+++ b/arch/x86/boot/compressed/acpi.c
>@@ -50,7 +50,8 @@ static acpi_physical_address efi_get_rsdp_addr(void)
> 	acpi_physical_address rsdp_addr = 0;
> 
> #ifdef CONFIG_EFI
>-	efi_system_table_t *systab;
>+	unsigned long systab, systab_tables, config_tables;
>+	unsigned int nr_tables;
> 	struct efi_info *ei;
> 	bool efi_64;
> 	int size, i;
>@@ -70,13 +71,13 @@ static acpi_physical_address efi_get_rsdp_addr(void)
> 
> 	/* Get systab from boot params. */
> #ifdef CONFIG_X86_64
>-	systab = (efi_system_table_t *)(ei->efi_systab | ((__u64)ei->efi_systab_hi<<32));
>+	systab = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32);
> #else
> 	if (ei->efi_systab_hi || ei->efi_memmap_hi) {
> 		debug_putstr("Error getting RSDP address: EFI system table located above 4GB.\n");
> 		return 0;
> 	}
>-	systab = (efi_system_table_t *)ei->efi_systab;
>+	systab = ei->efi_systab;
> #endif
> 	if (!systab)
> 		error("EFI system table not found.");
>@@ -87,16 +88,30 @@ static acpi_physical_address efi_get_rsdp_addr(void)
> 	size = efi_64 ? sizeof(efi_config_table_64_t) :
> 			sizeof(efi_config_table_32_t);
> 
>-	for (i = 0; i < systab->nr_tables; i++) {
>+	if (efi_64) {
>+		efi_system_table_64_t *st_tbl = (efi_system_table_64_t *)systab;
>+
>+		config_tables	= st_tbl->tables;
>+		nr_tables	= st_tbl->nr_tables;
>+	} else {
>+		efi_system_table_32_t *st_tbl = (efi_system_table_32_t *)systab;
>+
>+		config_tables	= st_tbl->tables;
>+		nr_tables	= st_tbl->nr_tables;
>+	}
>+
>+	if (!config_tables)
>+		error("EFI config tables not found.");
>+
>+	for (i = 0; i < nr_tables; i++) {
> 		acpi_physical_address table;
>-		void *config_tables;
> 		efi_guid_t guid;
> 
>-		config_tables = (void *)(systab->tables + size * i);
>+		config_tables += size * i;
>+
> 		if (efi_64) {
>-			efi_config_table_64_t *tmp_table;
>+			efi_config_table_64_t *tmp_table = (efi_config_table_64_t *)config_tables;
> 
>-			tmp_table = config_tables;
> 			guid = tmp_table->guid;
> 			table = tmp_table->table;
> 
>@@ -105,9 +120,8 @@ static acpi_physical_address efi_get_rsdp_addr(void)
> 				return 0;
> 			}
> 		} else {
>-			efi_config_table_32_t *tmp_table;
>+			efi_config_table_32_t *tmp_table = (efi_config_table_32_t *)config_tables;
> 
>-			tmp_table = config_tables;
> 			guid = tmp_table->guid;
> 			table = tmp_table->table;
> 		}
>
>-- 
>Regards/Gruss,
>    Boris.
>
>Good mailing practices for 400: avoid top-posting and trim the reply.
>
>