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path: root/drivers/firmware/efi/libstub/x86-stub.c
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Diffstat (limited to 'drivers/firmware/efi/libstub/x86-stub.c')
-rw-r--r--drivers/firmware/efi/libstub/x86-stub.c837
1 files changed, 837 insertions, 0 deletions
diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
new file mode 100644
index 000000000000..8d3a707789de
--- /dev/null
+++ b/drivers/firmware/efi/libstub/x86-stub.c
@@ -0,0 +1,837 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/* -----------------------------------------------------------------------
+ *
+ * Copyright 2011 Intel Corporation; author Matt Fleming
+ *
+ * ----------------------------------------------------------------------- */
+
+#include <linux/efi.h>
+#include <linux/pci.h>
+
+#include <asm/efi.h>
+#include <asm/e820/types.h>
+#include <asm/setup.h>
+#include <asm/desc.h>
+#include <asm/boot.h>
+
+#include "efistub.h"
+
+/* Maximum physical address for 64-bit kernel with 4-level paging */
+#define MAXMEM_X86_64_4LEVEL (1ull << 46)
+
+static efi_system_table_t *sys_table;
+extern const bool efi_is64;
+extern u32 image_offset;
+
+__pure efi_system_table_t *efi_system_table(void)
+{
+ return sys_table;
+}
+
+__attribute_const__ bool efi_is_64bit(void)
+{
+ if (IS_ENABLED(CONFIG_EFI_MIXED))
+ return efi_is64;
+ return IS_ENABLED(CONFIG_X86_64);
+}
+
+static efi_status_t
+preserve_pci_rom_image(efi_pci_io_protocol_t *pci, struct pci_setup_rom **__rom)
+{
+ struct pci_setup_rom *rom = NULL;
+ efi_status_t status;
+ unsigned long size;
+ uint64_t romsize;
+ void *romimage;
+
+ /*
+ * Some firmware images contain EFI function pointers at the place where
+ * the romimage and romsize fields are supposed to be. Typically the EFI
+ * code is mapped at high addresses, translating to an unrealistically
+ * large romsize. The UEFI spec limits the size of option ROMs to 16
+ * MiB so we reject any ROMs over 16 MiB in size to catch this.
+ */
+ romimage = efi_table_attr(pci, romimage);
+ romsize = efi_table_attr(pci, romsize);
+ if (!romimage || !romsize || romsize > SZ_16M)
+ return EFI_INVALID_PARAMETER;
+
+ size = romsize + sizeof(*rom);
+
+ status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
+ (void **)&rom);
+ if (status != EFI_SUCCESS) {
+ efi_printk("Failed to allocate memory for 'rom'\n");
+ return status;
+ }
+
+ memset(rom, 0, sizeof(*rom));
+
+ rom->data.type = SETUP_PCI;
+ rom->data.len = size - sizeof(struct setup_data);
+ rom->data.next = 0;
+ rom->pcilen = pci->romsize;
+ *__rom = rom;
+
+ status = efi_call_proto(pci, pci.read, EfiPciIoWidthUint16,
+ PCI_VENDOR_ID, 1, &rom->vendor);
+
+ if (status != EFI_SUCCESS) {
+ efi_printk("Failed to read rom->vendor\n");
+ goto free_struct;
+ }
+
+ status = efi_call_proto(pci, pci.read, EfiPciIoWidthUint16,
+ PCI_DEVICE_ID, 1, &rom->devid);
+
+ if (status != EFI_SUCCESS) {
+ efi_printk("Failed to read rom->devid\n");
+ goto free_struct;
+ }
+
+ status = efi_call_proto(pci, get_location, &rom->segment, &rom->bus,
+ &rom->device, &rom->function);
+
+ if (status != EFI_SUCCESS)
+ goto free_struct;
+
+ memcpy(rom->romdata, romimage, romsize);
+ return status;
+
+free_struct:
+ efi_bs_call(free_pool, rom);
+ return status;
+}
+
+/*
+ * There's no way to return an informative status from this function,
+ * because any analysis (and printing of error messages) needs to be
+ * done directly at the EFI function call-site.
+ *
+ * For example, EFI_INVALID_PARAMETER could indicate a bug or maybe we
+ * just didn't find any PCI devices, but there's no way to tell outside
+ * the context of the call.
+ */
+static void setup_efi_pci(struct boot_params *params)
+{
+ efi_status_t status;
+ void **pci_handle = NULL;
+ efi_guid_t pci_proto = EFI_PCI_IO_PROTOCOL_GUID;
+ unsigned long size = 0;
+ struct setup_data *data;
+ efi_handle_t h;
+ int i;
+
+ status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
+ &pci_proto, NULL, &size, pci_handle);
+
+ if (status == EFI_BUFFER_TOO_SMALL) {
+ status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
+ (void **)&pci_handle);
+
+ if (status != EFI_SUCCESS) {
+ efi_printk("Failed to allocate memory for 'pci_handle'\n");
+ return;
+ }
+
+ status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
+ &pci_proto, NULL, &size, pci_handle);
+ }
+
+ if (status != EFI_SUCCESS)
+ goto free_handle;
+
+ data = (struct setup_data *)(unsigned long)params->hdr.setup_data;
+
+ while (data && data->next)
+ data = (struct setup_data *)(unsigned long)data->next;
+
+ for_each_efi_handle(h, pci_handle, size, i) {
+ efi_pci_io_protocol_t *pci = NULL;
+ struct pci_setup_rom *rom;
+
+ status = efi_bs_call(handle_protocol, h, &pci_proto,
+ (void **)&pci);
+ if (status != EFI_SUCCESS || !pci)
+ continue;
+
+ status = preserve_pci_rom_image(pci, &rom);
+ if (status != EFI_SUCCESS)
+ continue;
+
+ if (data)
+ data->next = (unsigned long)rom;
+ else
+ params->hdr.setup_data = (unsigned long)rom;
+
+ data = (struct setup_data *)rom;
+ }
+
+free_handle:
+ efi_bs_call(free_pool, pci_handle);
+}
+
+static void retrieve_apple_device_properties(struct boot_params *boot_params)
+{
+ efi_guid_t guid = APPLE_PROPERTIES_PROTOCOL_GUID;
+ struct setup_data *data, *new;
+ efi_status_t status;
+ u32 size = 0;
+ apple_properties_protocol_t *p;
+
+ status = efi_bs_call(locate_protocol, &guid, NULL, (void **)&p);
+ if (status != EFI_SUCCESS)
+ return;
+
+ if (efi_table_attr(p, version) != 0x10000) {
+ efi_printk("Unsupported properties proto version\n");
+ return;
+ }
+
+ efi_call_proto(p, get_all, NULL, &size);
+ if (!size)
+ return;
+
+ do {
+ status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
+ size + sizeof(struct setup_data),
+ (void **)&new);
+ if (status != EFI_SUCCESS) {
+ efi_printk("Failed to allocate memory for 'properties'\n");
+ return;
+ }
+
+ status = efi_call_proto(p, get_all, new->data, &size);
+
+ if (status == EFI_BUFFER_TOO_SMALL)
+ efi_bs_call(free_pool, new);
+ } while (status == EFI_BUFFER_TOO_SMALL);
+
+ new->type = SETUP_APPLE_PROPERTIES;
+ new->len = size;
+ new->next = 0;
+
+ data = (struct setup_data *)(unsigned long)boot_params->hdr.setup_data;
+ if (!data) {
+ boot_params->hdr.setup_data = (unsigned long)new;
+ } else {
+ while (data->next)
+ data = (struct setup_data *)(unsigned long)data->next;
+ data->next = (unsigned long)new;
+ }
+}
+
+static const efi_char16_t apple[] = L"Apple";
+
+static void setup_quirks(struct boot_params *boot_params)
+{
+ efi_char16_t *fw_vendor = (efi_char16_t *)(unsigned long)
+ efi_table_attr(efi_system_table(), fw_vendor);
+
+ if (!memcmp(fw_vendor, apple, sizeof(apple))) {
+ if (IS_ENABLED(CONFIG_APPLE_PROPERTIES))
+ retrieve_apple_device_properties(boot_params);
+ }
+}
+
+/*
+ * See if we have Universal Graphics Adapter (UGA) protocol
+ */
+static efi_status_t
+setup_uga(struct screen_info *si, efi_guid_t *uga_proto, unsigned long size)
+{
+ efi_status_t status;
+ u32 width, height;
+ void **uga_handle = NULL;
+ efi_uga_draw_protocol_t *uga = NULL, *first_uga;
+ efi_handle_t handle;
+ int i;
+
+ status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
+ (void **)&uga_handle);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
+ uga_proto, NULL, &size, uga_handle);
+ if (status != EFI_SUCCESS)
+ goto free_handle;
+
+ height = 0;
+ width = 0;
+
+ first_uga = NULL;
+ for_each_efi_handle(handle, uga_handle, size, i) {
+ efi_guid_t pciio_proto = EFI_PCI_IO_PROTOCOL_GUID;
+ u32 w, h, depth, refresh;
+ void *pciio;
+
+ status = efi_bs_call(handle_protocol, handle, uga_proto,
+ (void **)&uga);
+ if (status != EFI_SUCCESS)
+ continue;
+
+ pciio = NULL;
+ efi_bs_call(handle_protocol, handle, &pciio_proto, &pciio);
+
+ status = efi_call_proto(uga, get_mode, &w, &h, &depth, &refresh);
+ if (status == EFI_SUCCESS && (!first_uga || pciio)) {
+ width = w;
+ height = h;
+
+ /*
+ * Once we've found a UGA supporting PCIIO,
+ * don't bother looking any further.
+ */
+ if (pciio)
+ break;
+
+ first_uga = uga;
+ }
+ }
+
+ if (!width && !height)
+ goto free_handle;
+
+ /* EFI framebuffer */
+ si->orig_video_isVGA = VIDEO_TYPE_EFI;
+
+ si->lfb_depth = 32;
+ si->lfb_width = width;
+ si->lfb_height = height;
+
+ si->red_size = 8;
+ si->red_pos = 16;
+ si->green_size = 8;
+ si->green_pos = 8;
+ si->blue_size = 8;
+ si->blue_pos = 0;
+ si->rsvd_size = 8;
+ si->rsvd_pos = 24;
+
+free_handle:
+ efi_bs_call(free_pool, uga_handle);
+
+ return status;
+}
+
+static void setup_graphics(struct boot_params *boot_params)
+{
+ efi_guid_t graphics_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
+ struct screen_info *si;
+ efi_guid_t uga_proto = EFI_UGA_PROTOCOL_GUID;
+ efi_status_t status;
+ unsigned long size;
+ void **gop_handle = NULL;
+ void **uga_handle = NULL;
+
+ si = &boot_params->screen_info;
+ memset(si, 0, sizeof(*si));
+
+ size = 0;
+ status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
+ &graphics_proto, NULL, &size, gop_handle);
+ if (status == EFI_BUFFER_TOO_SMALL)
+ status = efi_setup_gop(si, &graphics_proto, size);
+
+ if (status != EFI_SUCCESS) {
+ size = 0;
+ status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
+ &uga_proto, NULL, &size, uga_handle);
+ if (status == EFI_BUFFER_TOO_SMALL)
+ setup_uga(si, &uga_proto, size);
+ }
+}
+
+
+static void __noreturn efi_exit(efi_handle_t handle, efi_status_t status)
+{
+ efi_bs_call(exit, handle, status, 0, NULL);
+ for(;;)
+ asm("hlt");
+}
+
+void startup_32(struct boot_params *boot_params);
+
+void __noreturn efi_stub_entry(efi_handle_t handle,
+ efi_system_table_t *sys_table_arg,
+ struct boot_params *boot_params);
+
+/*
+ * Because the x86 boot code expects to be passed a boot_params we
+ * need to create one ourselves (usually the bootloader would create
+ * one for us).
+ */
+efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
+ efi_system_table_t *sys_table_arg)
+{
+ struct boot_params *boot_params;
+ struct setup_header *hdr;
+ efi_loaded_image_t *image;
+ void *image_base;
+ efi_guid_t proto = LOADED_IMAGE_PROTOCOL_GUID;
+ int options_size = 0;
+ efi_status_t status;
+ char *cmdline_ptr;
+ unsigned long ramdisk_addr;
+ unsigned long ramdisk_size;
+
+ sys_table = sys_table_arg;
+
+ /* Check if we were booted by the EFI firmware */
+ if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
+ efi_exit(handle, EFI_INVALID_PARAMETER);
+
+ status = efi_bs_call(handle_protocol, handle, &proto, (void **)&image);
+ if (status != EFI_SUCCESS) {
+ efi_printk("Failed to get handle for LOADED_IMAGE_PROTOCOL\n");
+ efi_exit(handle, status);
+ }
+
+ image_base = efi_table_attr(image, image_base);
+ image_offset = (void *)startup_32 - image_base;
+
+ hdr = &((struct boot_params *)image_base)->hdr;
+
+ status = efi_allocate_pages(0x4000, (unsigned long *)&boot_params, ULONG_MAX);
+ if (status != EFI_SUCCESS) {
+ efi_printk("Failed to allocate lowmem for boot params\n");
+ efi_exit(handle, status);
+ }
+
+ memset(boot_params, 0x0, 0x4000);
+
+ hdr = &boot_params->hdr;
+
+ /* Copy the second sector to boot_params */
+ memcpy(&hdr->jump, image_base + 512, 512);
+
+ /*
+ * Fill out some of the header fields ourselves because the
+ * EFI firmware loader doesn't load the first sector.
+ */
+ hdr->root_flags = 1;
+ hdr->vid_mode = 0xffff;
+ hdr->boot_flag = 0xAA55;
+
+ hdr->type_of_loader = 0x21;
+
+ /* Convert unicode cmdline to ascii */
+ cmdline_ptr = efi_convert_cmdline(image, &options_size, ULONG_MAX);
+ if (!cmdline_ptr)
+ goto fail;
+
+ hdr->cmd_line_ptr = (unsigned long)cmdline_ptr;
+ /* Fill in upper bits of command line address, NOP on 32 bit */
+ boot_params->ext_cmd_line_ptr = (u64)(unsigned long)cmdline_ptr >> 32;
+
+ hdr->ramdisk_image = 0;
+ hdr->ramdisk_size = 0;
+
+ if (efi_is_native()) {
+ status = efi_parse_options(cmdline_ptr);
+ if (status != EFI_SUCCESS)
+ goto fail2;
+
+ if (!noinitrd()) {
+ status = efi_load_initrd(image, &ramdisk_addr,
+ &ramdisk_size,
+ hdr->initrd_addr_max,
+ ULONG_MAX);
+ if (status != EFI_SUCCESS)
+ goto fail2;
+ hdr->ramdisk_image = ramdisk_addr & 0xffffffff;
+ hdr->ramdisk_size = ramdisk_size & 0xffffffff;
+ boot_params->ext_ramdisk_image = (u64)ramdisk_addr >> 32;
+ boot_params->ext_ramdisk_size = (u64)ramdisk_size >> 32;
+ }
+ }
+
+ efi_stub_entry(handle, sys_table, boot_params);
+ /* not reached */
+
+fail2:
+ efi_free(options_size, (unsigned long)cmdline_ptr);
+fail:
+ efi_free(0x4000, (unsigned long)boot_params);
+
+ efi_exit(handle, status);
+}
+
+static void add_e820ext(struct boot_params *params,
+ struct setup_data *e820ext, u32 nr_entries)
+{
+ struct setup_data *data;
+
+ e820ext->type = SETUP_E820_EXT;
+ e820ext->len = nr_entries * sizeof(struct boot_e820_entry);
+ e820ext->next = 0;
+
+ data = (struct setup_data *)(unsigned long)params->hdr.setup_data;
+
+ while (data && data->next)
+ data = (struct setup_data *)(unsigned long)data->next;
+
+ if (data)
+ data->next = (unsigned long)e820ext;
+ else
+ params->hdr.setup_data = (unsigned long)e820ext;
+}
+
+static efi_status_t
+setup_e820(struct boot_params *params, struct setup_data *e820ext, u32 e820ext_size)
+{
+ struct boot_e820_entry *entry = params->e820_table;
+ struct efi_info *efi = &params->efi_info;
+ struct boot_e820_entry *prev = NULL;
+ u32 nr_entries;
+ u32 nr_desc;
+ int i;
+
+ nr_entries = 0;
+ nr_desc = efi->efi_memmap_size / efi->efi_memdesc_size;
+
+ for (i = 0; i < nr_desc; i++) {
+ efi_memory_desc_t *d;
+ unsigned int e820_type = 0;
+ unsigned long m = efi->efi_memmap;
+
+#ifdef CONFIG_X86_64
+ m |= (u64)efi->efi_memmap_hi << 32;
+#endif
+
+ d = efi_early_memdesc_ptr(m, efi->efi_memdesc_size, i);
+ switch (d->type) {
+ case EFI_RESERVED_TYPE:
+ case EFI_RUNTIME_SERVICES_CODE:
+ case EFI_RUNTIME_SERVICES_DATA:
+ case EFI_MEMORY_MAPPED_IO:
+ case EFI_MEMORY_MAPPED_IO_PORT_SPACE:
+ case EFI_PAL_CODE:
+ e820_type = E820_TYPE_RESERVED;
+ break;
+
+ case EFI_UNUSABLE_MEMORY:
+ e820_type = E820_TYPE_UNUSABLE;
+ break;
+
+ case EFI_ACPI_RECLAIM_MEMORY:
+ e820_type = E820_TYPE_ACPI;
+ break;
+
+ case EFI_LOADER_CODE:
+ case EFI_LOADER_DATA:
+ case EFI_BOOT_SERVICES_CODE:
+ case EFI_BOOT_SERVICES_DATA:
+ case EFI_CONVENTIONAL_MEMORY:
+ if (efi_soft_reserve_enabled() &&
+ (d->attribute & EFI_MEMORY_SP))
+ e820_type = E820_TYPE_SOFT_RESERVED;
+ else
+ e820_type = E820_TYPE_RAM;
+ break;
+
+ case EFI_ACPI_MEMORY_NVS:
+ e820_type = E820_TYPE_NVS;
+ break;
+
+ case EFI_PERSISTENT_MEMORY:
+ e820_type = E820_TYPE_PMEM;
+ break;
+
+ default:
+ continue;
+ }
+
+ /* Merge adjacent mappings */
+ if (prev && prev->type == e820_type &&
+ (prev->addr + prev->size) == d->phys_addr) {
+ prev->size += d->num_pages << 12;
+ continue;
+ }
+
+ if (nr_entries == ARRAY_SIZE(params->e820_table)) {
+ u32 need = (nr_desc - i) * sizeof(struct e820_entry) +
+ sizeof(struct setup_data);
+
+ if (!e820ext || e820ext_size < need)
+ return EFI_BUFFER_TOO_SMALL;
+
+ /* boot_params map full, switch to e820 extended */
+ entry = (struct boot_e820_entry *)e820ext->data;
+ }
+
+ entry->addr = d->phys_addr;
+ entry->size = d->num_pages << PAGE_SHIFT;
+ entry->type = e820_type;
+ prev = entry++;
+ nr_entries++;
+ }
+
+ if (nr_entries > ARRAY_SIZE(params->e820_table)) {
+ u32 nr_e820ext = nr_entries - ARRAY_SIZE(params->e820_table);
+
+ add_e820ext(params, e820ext, nr_e820ext);
+ nr_entries -= nr_e820ext;
+ }
+
+ params->e820_entries = (u8)nr_entries;
+
+ return EFI_SUCCESS;
+}
+
+static efi_status_t alloc_e820ext(u32 nr_desc, struct setup_data **e820ext,
+ u32 *e820ext_size)
+{
+ efi_status_t status;
+ unsigned long size;
+
+ size = sizeof(struct setup_data) +
+ sizeof(struct e820_entry) * nr_desc;
+
+ if (*e820ext) {
+ efi_bs_call(free_pool, *e820ext);
+ *e820ext = NULL;
+ *e820ext_size = 0;
+ }
+
+ status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
+ (void **)e820ext);
+ if (status == EFI_SUCCESS)
+ *e820ext_size = size;
+
+ return status;
+}
+
+static efi_status_t allocate_e820(struct boot_params *params,
+ struct setup_data **e820ext,
+ u32 *e820ext_size)
+{
+ unsigned long map_size, desc_size, buff_size;
+ struct efi_boot_memmap boot_map;
+ efi_memory_desc_t *map;
+ efi_status_t status;
+ __u32 nr_desc;
+
+ boot_map.map = &map;
+ boot_map.map_size = &map_size;
+ boot_map.desc_size = &desc_size;
+ boot_map.desc_ver = NULL;
+ boot_map.key_ptr = NULL;
+ boot_map.buff_size = &buff_size;
+
+ status = efi_get_memory_map(&boot_map);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ nr_desc = buff_size / desc_size;
+
+ if (nr_desc > ARRAY_SIZE(params->e820_table)) {
+ u32 nr_e820ext = nr_desc - ARRAY_SIZE(params->e820_table);
+
+ status = alloc_e820ext(nr_e820ext, e820ext, e820ext_size);
+ if (status != EFI_SUCCESS)
+ return status;
+ }
+
+ return EFI_SUCCESS;
+}
+
+struct exit_boot_struct {
+ struct boot_params *boot_params;
+ struct efi_info *efi;
+};
+
+static efi_status_t exit_boot_func(struct efi_boot_memmap *map,
+ void *priv)
+{
+ const char *signature;
+ struct exit_boot_struct *p = priv;
+
+ signature = efi_is_64bit() ? EFI64_LOADER_SIGNATURE
+ : EFI32_LOADER_SIGNATURE;
+ memcpy(&p->efi->efi_loader_signature, signature, sizeof(__u32));
+
+ p->efi->efi_systab = (unsigned long)efi_system_table();
+ p->efi->efi_memdesc_size = *map->desc_size;
+ p->efi->efi_memdesc_version = *map->desc_ver;
+ p->efi->efi_memmap = (unsigned long)*map->map;
+ p->efi->efi_memmap_size = *map->map_size;
+
+#ifdef CONFIG_X86_64
+ p->efi->efi_systab_hi = (unsigned long)efi_system_table() >> 32;
+ p->efi->efi_memmap_hi = (unsigned long)*map->map >> 32;
+#endif
+
+ return EFI_SUCCESS;
+}
+
+static efi_status_t exit_boot(struct boot_params *boot_params, void *handle)
+{
+ unsigned long map_sz, key, desc_size, buff_size;
+ efi_memory_desc_t *mem_map;
+ struct setup_data *e820ext = NULL;
+ __u32 e820ext_size = 0;
+ efi_status_t status;
+ __u32 desc_version;
+ struct efi_boot_memmap map;
+ struct exit_boot_struct priv;
+
+ map.map = &mem_map;
+ map.map_size = &map_sz;
+ map.desc_size = &desc_size;
+ map.desc_ver = &desc_version;
+ map.key_ptr = &key;
+ map.buff_size = &buff_size;
+ priv.boot_params = boot_params;
+ priv.efi = &boot_params->efi_info;
+
+ status = allocate_e820(boot_params, &e820ext, &e820ext_size);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ /* Might as well exit boot services now */
+ status = efi_exit_boot_services(handle, &map, &priv, exit_boot_func);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ /* Historic? */
+ boot_params->alt_mem_k = 32 * 1024;
+
+ status = setup_e820(boot_params, e820ext, e820ext_size);
+ if (status != EFI_SUCCESS)
+ return status;
+
+ return EFI_SUCCESS;
+}
+
+/*
+ * On success, we return the address of startup_32, which has potentially been
+ * relocated by efi_relocate_kernel.
+ * On failure, we exit to the firmware via efi_exit instead of returning.
+ */
+unsigned long efi_main(efi_handle_t handle,
+ efi_system_table_t *sys_table_arg,
+ struct boot_params *boot_params)
+{
+ unsigned long bzimage_addr = (unsigned long)startup_32;
+ unsigned long buffer_start, buffer_end;
+ struct setup_header *hdr = &boot_params->hdr;
+ efi_status_t status;
+ unsigned long cmdline_paddr;
+
+ sys_table = sys_table_arg;
+
+ /* Check if we were booted by the EFI firmware */
+ if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE)
+ efi_exit(handle, EFI_INVALID_PARAMETER);
+
+ /*
+ * If the kernel isn't already loaded at a suitable address,
+ * relocate it.
+ *
+ * It must be loaded above LOAD_PHYSICAL_ADDR.
+ *
+ * The maximum address for 64-bit is 1 << 46 for 4-level paging. This
+ * is defined as the macro MAXMEM, but unfortunately that is not a
+ * compile-time constant if 5-level paging is configured, so we instead
+ * define our own macro for use here.
+ *
+ * For 32-bit, the maximum address is complicated to figure out, for
+ * now use KERNEL_IMAGE_SIZE, which will be 512MiB, the same as what
+ * KASLR uses.
+ *
+ * Also relocate it if image_offset is zero, i.e. we weren't loaded by
+ * LoadImage, but we are not aligned correctly.
+ */
+
+ buffer_start = ALIGN(bzimage_addr - image_offset,
+ hdr->kernel_alignment);
+ buffer_end = buffer_start + hdr->init_size;
+
+ if ((buffer_start < LOAD_PHYSICAL_ADDR) ||
+ (IS_ENABLED(CONFIG_X86_32) && buffer_end > KERNEL_IMAGE_SIZE) ||
+ (IS_ENABLED(CONFIG_X86_64) && buffer_end > MAXMEM_X86_64_4LEVEL) ||
+ (image_offset == 0 && !IS_ALIGNED(bzimage_addr,
+ hdr->kernel_alignment))) {
+ status = efi_relocate_kernel(&bzimage_addr,
+ hdr->init_size, hdr->init_size,
+ hdr->pref_address,
+ hdr->kernel_alignment,
+ LOAD_PHYSICAL_ADDR);
+ if (status != EFI_SUCCESS) {
+ efi_printk("efi_relocate_kernel() failed!\n");
+ goto fail;
+ }
+ /*
+ * Now that we've copied the kernel elsewhere, we no longer
+ * have a set up block before startup_32(), so reset image_offset
+ * to zero in case it was set earlier.
+ */
+ image_offset = 0;
+ }
+
+ /*
+ * efi_pe_entry() may have been called before efi_main(), in which
+ * case this is the second time we parse the cmdline. This is ok,
+ * parsing the cmdline multiple times does not have side-effects.
+ */
+ cmdline_paddr = ((u64)hdr->cmd_line_ptr |
+ ((u64)boot_params->ext_cmd_line_ptr << 32));
+ efi_parse_options((char *)cmdline_paddr);
+
+ /*
+ * At this point, an initrd may already have been loaded, either by
+ * the bootloader and passed via bootparams, or loaded from a initrd=
+ * command line option by efi_pe_entry() above. In either case, we
+ * permit an initrd loaded from the LINUX_EFI_INITRD_MEDIA_GUID device
+ * path to supersede it.
+ */
+ if (!noinitrd()) {
+ unsigned long addr, size;
+
+ status = efi_load_initrd_dev_path(&addr, &size, ULONG_MAX);
+ if (status == EFI_SUCCESS) {
+ hdr->ramdisk_image = (u32)addr;
+ hdr->ramdisk_size = (u32)size;
+ boot_params->ext_ramdisk_image = (u64)addr >> 32;
+ boot_params->ext_ramdisk_size = (u64)size >> 32;
+ } else if (status != EFI_NOT_FOUND) {
+ efi_printk("efi_load_initrd_dev_path() failed!\n");
+ goto fail;
+ }
+ }
+
+ /*
+ * If the boot loader gave us a value for secure_boot then we use that,
+ * otherwise we ask the BIOS.
+ */
+ if (boot_params->secure_boot == efi_secureboot_mode_unset)
+ boot_params->secure_boot = efi_get_secureboot();
+
+ /* Ask the firmware to clear memory on unclean shutdown */
+ efi_enable_reset_attack_mitigation();
+
+ efi_random_get_seed();
+
+ efi_retrieve_tpm2_eventlog();
+
+ setup_graphics(boot_params);
+
+ setup_efi_pci(boot_params);
+
+ setup_quirks(boot_params);
+
+ status = exit_boot(boot_params, handle);
+ if (status != EFI_SUCCESS) {
+ efi_printk("exit_boot() failed!\n");
+ goto fail;
+ }
+
+ return bzimage_addr;
+fail:
+ efi_printk("efi_main() failed!\n");
+
+ efi_exit(handle, status);
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.