Messages in this thread Patch in this message | | | From | Chao Fan <> | Subject | [PATCH v15 3/6] x86/boot: Introduce efi_get_rsdp_addr() to find RSDP from EFI table | Date | Mon, 7 Jan 2019 11:22:40 +0800 |
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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 <fanc.fnst@cn.fujitsu.com> --- arch/x86/boot/compressed/acpi.c | 83 +++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+)
diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c index 7ca5001d7639..f74c5d033d79 100644 --- a/arch/x86/boot/compressed/acpi.c +++ b/arch/x86/boot/compressed/acpi.c @@ -5,6 +5,8 @@ #include "../string.h" #include <linux/acpi.h> +#include <linux/efi.h> +#include <asm/efi.h> /* * Max length of 64-bit hex address string is 19, prefix "0x" + 16 hex @@ -28,3 +30,84 @@ 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 *ei; + bool efi_64; + char *sig; + int size; + int i; + + ei = &boot_params->efi_info; + sig = (char *)&ei->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 *)(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; +#endif + + if (!systab) + error("EFI system table is not found."); + + /* + * 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; + u64 table64; + + tmp_table = config_tables; + guid = tmp_table->guid; + table64 = tmp_table->table; + table = table64; + + if (!IS_ENABLED(CONFIG_X86_64) && table64 >> 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 = config_tables; + guid = tmp_table->guid; + table = tmp_table->table; + } + + if (!(efi_guidcmp(guid, ACPI_TABLE_GUID))) + rsdp_addr = table; + else if (!(efi_guidcmp(guid, ACPI_20_TABLE_GUID))) + return table; + } +#endif + return rsdp_addr; +} -- 2.20.1
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