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Diffstat (limited to 'arch/x86/boot/compressed/efi.c')
-rw-r--r--arch/x86/boot/compressed/efi.c234
1 files changed, 234 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c
new file mode 100644
index 000000000000..6edd034b0b30
--- /dev/null
+++ b/arch/x86/boot/compressed/efi.c
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Helpers for early access to EFI configuration table.
+ *
+ * Originally derived from arch/x86/boot/compressed/acpi.c
+ */
+
+#include "misc.h"
+
+/**
+ * efi_get_type - Given a pointer to boot_params, determine the type of EFI environment.
+ *
+ * @bp: pointer to boot_params
+ *
+ * Return: EFI_TYPE_{32,64} for valid EFI environments, EFI_TYPE_NONE otherwise.
+ */
+enum efi_type efi_get_type(struct boot_params *bp)
+{
+ struct efi_info *ei;
+ enum efi_type et;
+ const char *sig;
+
+ ei = &bp->efi_info;
+ sig = (char *)&ei->efi_loader_signature;
+
+ if (!strncmp(sig, EFI64_LOADER_SIGNATURE, 4)) {
+ et = EFI_TYPE_64;
+ } else if (!strncmp(sig, EFI32_LOADER_SIGNATURE, 4)) {
+ et = EFI_TYPE_32;
+ } else {
+ debug_putstr("No EFI environment detected.\n");
+ et = EFI_TYPE_NONE;
+ }
+
+#ifndef CONFIG_X86_64
+ /*
+ * Existing callers like acpi.c treat this case as an indicator to
+ * fall-through to non-EFI, rather than an error, so maintain that
+ * functionality here as well.
+ */
+ if (ei->efi_systab_hi || ei->efi_memmap_hi) {
+ debug_putstr("EFI system table is located above 4GB and cannot be accessed.\n");
+ et = EFI_TYPE_NONE;
+ }
+#endif
+
+ return et;
+}
+
+/**
+ * efi_get_system_table - Given a pointer to boot_params, retrieve the physical address
+ * of the EFI system table.
+ *
+ * @bp: pointer to boot_params
+ *
+ * Return: EFI system table address on success. On error, return 0.
+ */
+unsigned long efi_get_system_table(struct boot_params *bp)
+{
+ unsigned long sys_tbl_pa;
+ struct efi_info *ei;
+ enum efi_type et;
+
+ /* Get systab from boot params. */
+ ei = &bp->efi_info;
+#ifdef CONFIG_X86_64
+ sys_tbl_pa = ei->efi_systab | ((__u64)ei->efi_systab_hi << 32);
+#else
+ sys_tbl_pa = ei->efi_systab;
+#endif
+ if (!sys_tbl_pa) {
+ debug_putstr("EFI system table not found.");
+ return 0;
+ }
+
+ return sys_tbl_pa;
+}
+
+/*
+ * EFI config table address changes to virtual address after boot, which may
+ * not be accessible for the kexec'd kernel. To address this, kexec provides
+ * the initial physical address via a struct setup_data entry, which is
+ * checked for here, along with some sanity checks.
+ */
+static struct efi_setup_data *get_kexec_setup_data(struct boot_params *bp,
+ enum efi_type et)
+{
+#ifdef CONFIG_X86_64
+ struct efi_setup_data *esd = NULL;
+ struct setup_data *data;
+ u64 pa_data;
+
+ pa_data = bp->hdr.setup_data;
+ while (pa_data) {
+ data = (struct setup_data *)pa_data;
+ if (data->type == SETUP_EFI) {
+ esd = (struct efi_setup_data *)(pa_data + sizeof(struct setup_data));
+ break;
+ }
+
+ pa_data = data->next;
+ }
+
+ /*
+ * Original ACPI code falls back to attempting normal EFI boot in these
+ * cases, so maintain existing behavior by indicating non-kexec
+ * environment to the caller, but print them for debugging.
+ */
+ if (esd && !esd->tables) {
+ debug_putstr("kexec EFI environment missing valid configuration table.\n");
+ return NULL;
+ }
+
+ return esd;
+#endif
+ return NULL;
+}
+
+/**
+ * efi_get_conf_table - Given a pointer to boot_params, locate and return the physical
+ * address of EFI configuration table.
+ *
+ * @bp: pointer to boot_params
+ * @cfg_tbl_pa: location to store physical address of config table
+ * @cfg_tbl_len: location to store number of config table entries
+ *
+ * Return: 0 on success. On error, return params are left unchanged.
+ */
+int efi_get_conf_table(struct boot_params *bp, unsigned long *cfg_tbl_pa,
+ unsigned int *cfg_tbl_len)
+{
+ unsigned long sys_tbl_pa;
+ enum efi_type et;
+ int ret;
+
+ if (!cfg_tbl_pa || !cfg_tbl_len)
+ return -EINVAL;
+
+ sys_tbl_pa = efi_get_system_table(bp);
+ if (!sys_tbl_pa)
+ return -EINVAL;
+
+ /* Handle EFI bitness properly */
+ et = efi_get_type(bp);
+ if (et == EFI_TYPE_64) {
+ efi_system_table_64_t *stbl = (efi_system_table_64_t *)sys_tbl_pa;
+ struct efi_setup_data *esd;
+
+ /* kexec provides an alternative EFI conf table, check for it. */
+ esd = get_kexec_setup_data(bp, et);
+
+ *cfg_tbl_pa = esd ? esd->tables : stbl->tables;
+ *cfg_tbl_len = stbl->nr_tables;
+ } else if (et == EFI_TYPE_32) {
+ efi_system_table_32_t *stbl = (efi_system_table_32_t *)sys_tbl_pa;
+
+ *cfg_tbl_pa = stbl->tables;
+ *cfg_tbl_len = stbl->nr_tables;
+ } else {
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/* Get vendor table address/guid from EFI config table at the given index */
+static int get_vendor_table(void *cfg_tbl, unsigned int idx,
+ unsigned long *vendor_tbl_pa,
+ efi_guid_t *vendor_tbl_guid,
+ enum efi_type et)
+{
+ if (et == EFI_TYPE_64) {
+ efi_config_table_64_t *tbl_entry = (efi_config_table_64_t *)cfg_tbl + idx;
+
+ if (!IS_ENABLED(CONFIG_X86_64) && tbl_entry->table >> 32) {
+ debug_putstr("Error: EFI config table entry located above 4GB.\n");
+ return -EINVAL;
+ }
+
+ *vendor_tbl_pa = tbl_entry->table;
+ *vendor_tbl_guid = tbl_entry->guid;
+
+ } else if (et == EFI_TYPE_32) {
+ efi_config_table_32_t *tbl_entry = (efi_config_table_32_t *)cfg_tbl + idx;
+
+ *vendor_tbl_pa = tbl_entry->table;
+ *vendor_tbl_guid = tbl_entry->guid;
+ } else {
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/**
+ * efi_find_vendor_table - Given EFI config table, search it for the physical
+ * address of the vendor table associated with GUID.
+ *
+ * @bp: pointer to boot_params
+ * @cfg_tbl_pa: pointer to EFI configuration table
+ * @cfg_tbl_len: number of entries in EFI configuration table
+ * @guid: GUID of vendor table
+ *
+ * Return: vendor table address on success. On error, return 0.
+ */
+unsigned long efi_find_vendor_table(struct boot_params *bp,
+ unsigned long cfg_tbl_pa,
+ unsigned int cfg_tbl_len,
+ efi_guid_t guid)
+{
+ enum efi_type et;
+ unsigned int i;
+
+ et = efi_get_type(bp);
+ if (et == EFI_TYPE_NONE)
+ return 0;
+
+ for (i = 0; i < cfg_tbl_len; i++) {
+ unsigned long vendor_tbl_pa;
+ efi_guid_t vendor_tbl_guid;
+ int ret;
+
+ ret = get_vendor_table((void *)cfg_tbl_pa, i,
+ &vendor_tbl_pa,
+ &vendor_tbl_guid, et);
+ if (ret)
+ return 0;
+
+ if (!efi_guidcmp(guid, vendor_tbl_guid))
+ return vendor_tbl_pa;
+ }
+
+ return 0;
+}