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// SPDX-License-Identifier: GPL-2.0
#define BOOT_CTYPE_H
#include "misc.h"
#include "error.h"
#include "../string.h"
#include <linux/efi.h>
#include <asm/efi.h>
/*
* Max length of 64-bit hex address string is 19, prefix "0x" + 16 hex
* digits, and '\0' for termination.
*/
#define MAX_ADDR_LEN 19
static acpi_physical_address get_acpi_rsdp(void)
{
acpi_physical_address addr = 0;
#ifdef CONFIG_KEXEC
char val[MAX_ADDR_LEN] = { };
int ret;
ret = cmdline_find_option("acpi_rsdp", val, MAX_ADDR_LEN);
if (ret < 0)
return 0;
if (kstrtoull(val, 16, &addr))
return 0;
#endif
return addr;
}
/* Search EFI system tables 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;
int size, i;
char *sig;
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. */
#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 not found.");
/*
* Get EFI tables from systab.
*/
size = efi_64 ? sizeof(efi_config_table_64_t) :
sizeof(efi_config_table_32_t);
for (i = 0; i < systab->nr_tables; i++) {
acpi_physical_address table;
void *config_tables;
efi_guid_t guid;
config_tables = (void *)(systab->tables + size * i);
if (efi_64) {
efi_config_table_64_t *tmp_table;
tmp_table = config_tables;
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 = 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;
}
static u8 compute_checksum(u8 *buffer, u32 length)
{
u8 *end = buffer + length;
u8 sum = 0;
while (buffer < end)
sum += *(buffer++);
return sum;
}
/* Search a block of memory for the RSDP signature. */
static u8 *scan_mem_for_rsdp(u8 *start, u32 length)
{
struct acpi_table_rsdp *rsdp;
u8 *address, *end;
end = start + length;
/* Search from given start address for the requested length */
for (address = start; address < end; address += ACPI_RSDP_SCAN_STEP) {
/*
* Both RSDP signature and checksum must be correct.
* Note: Sometimes there exists more than one RSDP in memory;
* the valid RSDP has a valid checksum, all others have an
* invalid checksum.
*/
rsdp = (struct acpi_table_rsdp *)address;
/* BAD Signature */
if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature))
continue;
/* Check the standard checksum */
if (compute_checksum((u8 *)rsdp, ACPI_RSDP_CHECKSUM_LENGTH))
continue;
/* Check extended checksum if table version >= 2 */
if ((rsdp->revision >= 2) &&
(compute_checksum((u8 *)rsdp, ACPI_RSDP_XCHECKSUM_LENGTH)))
continue;
/* Signature and checksum valid, we have found a real RSDP */
return address;
}
return NULL;
}
/* Search RSDP address in EBDA. */
static acpi_physical_address bios_get_rsdp_addr(void)
{
unsigned long address;
u8 *rsdp;
/* Get the location of the Extended BIOS Data Area (EBDA) */
address = *(u16 *)ACPI_EBDA_PTR_LOCATION;
address <<= 4;
/*
* Search EBDA paragraphs (EBDA is required to be a minimum of
* 1K length)
*/
if (address > 0x400) {
rsdp = scan_mem_for_rsdp((u8 *)address, ACPI_EBDA_WINDOW_SIZE);
if (rsdp)
return (acpi_physical_address)(unsigned long)rsdp;
}
/* Search upper memory: 16-byte boundaries in E0000h-FFFFFh */
rsdp = scan_mem_for_rsdp((u8 *) ACPI_HI_RSDP_WINDOW_BASE,
ACPI_HI_RSDP_WINDOW_SIZE);
if (rsdp)
return (acpi_physical_address)(unsigned long)rsdp;
return 0;
}
/* Return RSDP address on success, otherwise 0. */
acpi_physical_address get_rsdp_addr(void)
{
acpi_physical_address pa;
pa = get_acpi_rsdp();
if (!pa)
pa = boot_params->acpi_rsdp_addr;
if (!pa)
pa = efi_get_rsdp_addr();
if (!pa)
pa = bios_get_rsdp_addr();
return pa;
}
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