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234 lines
6.0 KiB
234 lines
6.0 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Helpers for early access to EFI configuration table. |
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* |
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* Originally derived from arch/x86/boot/compressed/acpi.c |
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*/ |
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#include "misc.h" |
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/** |
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* efi_get_type - Given a pointer to boot_params, determine the type of EFI environment. |
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* |
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* @bp: pointer to boot_params |
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* |
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* Return: EFI_TYPE_{32,64} for valid EFI environments, EFI_TYPE_NONE otherwise. |
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*/ |
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enum efi_type efi_get_type(struct boot_params *bp) |
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{ |
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struct efi_info *ei; |
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enum efi_type et; |
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const char *sig; |
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ei = &bp->efi_info; |
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sig = (char *)&ei->efi_loader_signature; |
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if (!strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) { |
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et = EFI_TYPE_64; |
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} else if (!strncmp(sig, EFI32_LOADER_SIGNATURE, 4)) { |
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et = EFI_TYPE_32; |
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} else { |
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debug_putstr("No EFI environment detected.\n"); |
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et = EFI_TYPE_NONE; |
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} |
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#ifndef CONFIG_X86_64 |
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/* |
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* Existing callers like acpi.c treat this case as an indicator to |
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* fall-through to non-EFI, rather than an error, so maintain that |
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* functionality here as well. |
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*/ |
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if (ei->efi_systab_hi || ei->efi_memmap_hi) { |
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debug_putstr("EFI system table is located above 4GB and cannot be accessed.\n"); |
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et = EFI_TYPE_NONE; |
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} |
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#endif |
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return et; |
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} |
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/** |
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* efi_get_system_table - Given a pointer to boot_params, retrieve the physical address |
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* of the EFI system table. |
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* |
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* @bp: pointer to boot_params |
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* |
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* Return: EFI system table address on success. On error, return 0. |
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*/ |
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unsigned long efi_get_system_table(struct boot_params *bp) |
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{ |
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unsigned long sys_tbl_pa; |
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struct efi_info *ei; |
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enum efi_type et; |
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/* Get systab from boot params. */ |
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ei = &bp->efi_info; |
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#ifdef CONFIG_X86_64 |
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sys_tbl_pa = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32); |
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#else |
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sys_tbl_pa = ei->efi_systab; |
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#endif |
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if (!sys_tbl_pa) { |
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debug_putstr("EFI system table not found."); |
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return 0; |
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} |
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return sys_tbl_pa; |
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} |
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/* |
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* EFI config table address changes to virtual address after boot, which may |
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* not be accessible for the kexec'd kernel. To address this, kexec provides |
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* the initial physical address via a struct setup_data entry, which is |
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* checked for here, along with some sanity checks. |
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*/ |
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static struct efi_setup_data *get_kexec_setup_data(struct boot_params *bp, |
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enum efi_type et) |
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{ |
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#ifdef CONFIG_X86_64 |
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struct efi_setup_data *esd = NULL; |
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struct setup_data *data; |
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u64 pa_data; |
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pa_data = bp->hdr.setup_data; |
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while (pa_data) { |
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data = (struct setup_data *)pa_data; |
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if (data->type == SETUP_EFI) { |
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esd = (struct efi_setup_data *)(pa_data + sizeof(struct setup_data)); |
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break; |
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} |
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pa_data = data->next; |
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} |
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/* |
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* Original ACPI code falls back to attempting normal EFI boot in these |
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* cases, so maintain existing behavior by indicating non-kexec |
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* environment to the caller, but print them for debugging. |
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*/ |
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if (esd && !esd->tables) { |
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debug_putstr("kexec EFI environment missing valid configuration table.\n"); |
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return NULL; |
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} |
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return esd; |
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#endif |
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return NULL; |
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} |
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/** |
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* efi_get_conf_table - Given a pointer to boot_params, locate and return the physical |
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* address of EFI configuration table. |
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* |
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* @bp: pointer to boot_params |
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* @cfg_tbl_pa: location to store physical address of config table |
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* @cfg_tbl_len: location to store number of config table entries |
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* |
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* Return: 0 on success. On error, return params are left unchanged. |
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*/ |
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int efi_get_conf_table(struct boot_params *bp, unsigned long *cfg_tbl_pa, |
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unsigned int *cfg_tbl_len) |
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{ |
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unsigned long sys_tbl_pa; |
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enum efi_type et; |
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int ret; |
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if (!cfg_tbl_pa || !cfg_tbl_len) |
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return -EINVAL; |
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sys_tbl_pa = efi_get_system_table(bp); |
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if (!sys_tbl_pa) |
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return -EINVAL; |
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/* Handle EFI bitness properly */ |
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et = efi_get_type(bp); |
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if (et == EFI_TYPE_64) { |
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efi_system_table_64_t *stbl = (efi_system_table_64_t *)sys_tbl_pa; |
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struct efi_setup_data *esd; |
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/* kexec provides an alternative EFI conf table, check for it. */ |
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esd = get_kexec_setup_data(bp, et); |
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*cfg_tbl_pa = esd ? esd->tables : stbl->tables; |
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*cfg_tbl_len = stbl->nr_tables; |
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} else if (et == EFI_TYPE_32) { |
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efi_system_table_32_t *stbl = (efi_system_table_32_t *)sys_tbl_pa; |
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*cfg_tbl_pa = stbl->tables; |
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*cfg_tbl_len = stbl->nr_tables; |
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} else { |
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return -EINVAL; |
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} |
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return 0; |
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} |
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/* Get vendor table address/guid from EFI config table at the given index */ |
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static int get_vendor_table(void *cfg_tbl, unsigned int idx, |
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unsigned long *vendor_tbl_pa, |
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efi_guid_t *vendor_tbl_guid, |
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enum efi_type et) |
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{ |
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if (et == EFI_TYPE_64) { |
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efi_config_table_64_t *tbl_entry = (efi_config_table_64_t *)cfg_tbl + idx; |
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if (!IS_ENABLED(CONFIG_X86_64) && tbl_entry->table >> 32) { |
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debug_putstr("Error: EFI config table entry located above 4GB.\n"); |
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return -EINVAL; |
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} |
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*vendor_tbl_pa = tbl_entry->table; |
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*vendor_tbl_guid = tbl_entry->guid; |
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} else if (et == EFI_TYPE_32) { |
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efi_config_table_32_t *tbl_entry = (efi_config_table_32_t *)cfg_tbl + idx; |
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*vendor_tbl_pa = tbl_entry->table; |
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*vendor_tbl_guid = tbl_entry->guid; |
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} else { |
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return -EINVAL; |
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} |
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return 0; |
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} |
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/** |
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* efi_find_vendor_table - Given EFI config table, search it for the physical |
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* address of the vendor table associated with GUID. |
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* |
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* @bp: pointer to boot_params |
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* @cfg_tbl_pa: pointer to EFI configuration table |
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* @cfg_tbl_len: number of entries in EFI configuration table |
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* @guid: GUID of vendor table |
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* |
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* Return: vendor table address on success. On error, return 0. |
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*/ |
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unsigned long efi_find_vendor_table(struct boot_params *bp, |
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unsigned long cfg_tbl_pa, |
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unsigned int cfg_tbl_len, |
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efi_guid_t guid) |
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{ |
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enum efi_type et; |
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unsigned int i; |
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et = efi_get_type(bp); |
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if (et == EFI_TYPE_NONE) |
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return 0; |
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for (i = 0; i < cfg_tbl_len; i++) { |
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unsigned long vendor_tbl_pa; |
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efi_guid_t vendor_tbl_guid; |
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int ret; |
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ret = get_vendor_table((void *)cfg_tbl_pa, i, |
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&vendor_tbl_pa, |
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&vendor_tbl_guid, et); |
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if (ret) |
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return 0; |
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if (!efi_guidcmp(guid, vendor_tbl_guid)) |
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return vendor_tbl_pa; |
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} |
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return 0; |
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}
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