drivers/firmware/efi/libstub/efi-stub.c - linux/torvalds/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * EFI stub implementation that is shared by arm and arm64 architectures.
  * This should be #included by the EFI stub implementation files.
  *
  * Copyright (C) 2013,2014 Linaro Limited
  *     Roy Franz <roy.franz@linaro.org
  * Copyright (C) 2013 Red Hat, Inc.
  *     Mark Salter <msalter@redhat.com>
  */

 #include <linux/efi.h>
 #include <asm/efi.h>

 #include "efistub.h"

 /*
  * This is the base address at which to start allocating virtual memory ranges
  * for UEFI Runtime Services.
  *
  * For ARM/ARM64:
  * This is in the low TTBR0 range so that we can use
  * any allocation we choose, and eliminate the risk of a conflict after kexec.
  * The value chosen is the largest non-zero power of 2 suitable for this purpose
  * both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
  * be mapped efficiently.
  * Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
  * map everything below 1 GB. (512 MB is a reasonable upper bound for the
  * entire footprint of the UEFI runtime services memory regions)
  *
  * For RISC-V:
  * There is no specific reason for which, this address (512MB) can't be used
  * EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
  * services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
  * as well to minimize the code churn.
  */
 #define EFI_RT_VIRTUAL_BASE	SZ_512M

 /*
  * Some architectures map the EFI regions into the kernel's linear map using a
  * fixed offset.
  */
 #ifndef EFI_RT_VIRTUAL_OFFSET
 #define EFI_RT_VIRTUAL_OFFSET	0
 #endif

 static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
 static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);

 struct screen_info * __weak alloc_screen_info(void)
 {
 	return &screen_info;
 }

 void __weak free_screen_info(struct screen_info *si)
 {
 }

 static struct screen_info *setup_graphics(void)
 {
 	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
 	efi_status_t status;
 	unsigned long size;
 	void **gop_handle = NULL;
 	struct screen_info *si = NULL;

 	size = 0;
 	status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
 			     &gop_proto, NULL, &size, gop_handle);
 	if (status == EFI_BUFFER_TOO_SMALL) {
 		si = alloc_screen_info();
 		if (!si)
 			return NULL;
 		status = efi_setup_gop(si, &gop_proto, size);
 		if (status != EFI_SUCCESS) {
 			free_screen_info(si);
 			return NULL;
 		}
 	}
 	return si;
 }

 static void install_memreserve_table(void)
 {
 	struct linux_efi_memreserve *rsv;
 	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
 	efi_status_t status;

 	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
 			     (void **)&rsv);
 	if (status != EFI_SUCCESS) {
 		efi_err("Failed to allocate memreserve entry!\n");
 		return;
 	}

 	rsv->next = 0;
 	rsv->size = 0;
 	atomic_set(&rsv->count, 0);

 	status = efi_bs_call(install_configuration_table,
 			     &memreserve_table_guid, rsv);
 	if (status != EFI_SUCCESS)
 		efi_err("Failed to install memreserve config table!\n");
 }

 static u32 get_supported_rt_services(void)
 {
 	const efi_rt_properties_table_t *rt_prop_table;
 	u32 supported = EFI_RT_SUPPORTED_ALL;

 	rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
 	if (rt_prop_table)
 		supported &= rt_prop_table->runtime_services_supported;

 	return supported;
 }

 efi_status_t efi_handle_cmdline(efi_loaded_image_t *image, char **cmdline_ptr)
 {
 	int cmdline_size = 0;
 	efi_status_t status;
 	char *cmdline;

 	/*
 	 * Get the command line from EFI, using the LOADED_IMAGE
 	 * protocol. We are going to copy the command line into the
 	 * device tree, so this can be allocated anywhere.
 	 */
 	cmdline = efi_convert_cmdline(image, &cmdline_size);
 	if (!cmdline) {
 		efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
 		return EFI_OUT_OF_RESOURCES;
 	}

 	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) ||
 	    IS_ENABLED(CONFIG_CMDLINE_FORCE) ||
 	    cmdline_size == 0) {
 		status = efi_parse_options(CONFIG_CMDLINE);
 		if (status != EFI_SUCCESS) {
 			efi_err("Failed to parse options\n");
 			goto fail_free_cmdline;
 		}
 	}

 	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
 		status = efi_parse_options(cmdline);
 		if (status != EFI_SUCCESS) {
 			efi_err("Failed to parse options\n");
 			goto fail_free_cmdline;
 		}
 	}

 	*cmdline_ptr = cmdline;
 	return EFI_SUCCESS;

 fail_free_cmdline:
 	efi_bs_call(free_pool, cmdline_ptr);
 	return status;
 }

 efi_status_t efi_stub_common(efi_handle_t handle,
 			     efi_loaded_image_t *image,
 			     unsigned long image_addr,
 			     char *cmdline_ptr)
 {
 	struct screen_info *si;
 	efi_status_t status;

 	status = check_platform_features();
 	if (status != EFI_SUCCESS)
 		return status;

 	si = setup_graphics();

 	efi_retrieve_tpm2_eventlog();

 	/* Ask the firmware to clear memory on unclean shutdown */
 	efi_enable_reset_attack_mitigation();

 	efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr),
 			NULL);

 	efi_random_get_seed();

 	/* force efi_novamap if SetVirtualAddressMap() is unsupported */
 	efi_novamap |= !(get_supported_rt_services() &
 			 EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);

 	install_memreserve_table();

 	status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);

 	free_screen_info(si);
 	return status;
 }

 /*
  * efi_allocate_virtmap() - create a pool allocation for the virtmap
  *
  * Create an allocation that is of sufficient size to hold all the memory
  * descriptors that will be passed to SetVirtualAddressMap() to inform the
  * firmware about the virtual mapping that will be used under the OS to call
  * into the firmware.
  */
 efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap,
 			       unsigned long *desc_size, u32 *desc_ver)
 {
 	unsigned long size, mmap_key;
 	efi_status_t status;

 	/*
 	 * Use the size of the current memory map as an upper bound for the
 	 * size of the buffer we need to pass to SetVirtualAddressMap() to
 	 * cover all EFI_MEMORY_RUNTIME regions.
 	 */
 	size = 0;
 	status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size,
 			     desc_ver);
 	if (status != EFI_BUFFER_TOO_SMALL)
 		return EFI_LOAD_ERROR;

 	return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
 			   (void **)virtmap);
 }

 /*
  * efi_get_virtmap() - create a virtual mapping for the EFI memory map
  *
  * This function populates the virt_addr fields of all memory region descriptors
  * in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
  * are also copied to @runtime_map, and their total count is returned in @count.
  */
 void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
 		     unsigned long desc_size, efi_memory_desc_t *runtime_map,
 		     int *count)
 {
 	u64 efi_virt_base = virtmap_base;
 	efi_memory_desc_t *in, *out = runtime_map;
 	int l;

 	*count = 0;

 	for (l = 0; l < map_size; l += desc_size) {
 		u64 paddr, size;

 		in = (void *)memory_map + l;
 		if (!(in->attribute & EFI_MEMORY_RUNTIME))
 			continue;

 		paddr = in->phys_addr;
 		size = in->num_pages * EFI_PAGE_SIZE;

 		in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
 		if (efi_novamap) {
 			continue;
 		}

 		/*
 		 * Make the mapping compatible with 64k pages: this allows
 		 * a 4k page size kernel to kexec a 64k page size kernel and
 		 * vice versa.
 		 */
 		if (!flat_va_mapping) {

 			paddr = round_down(in->phys_addr, SZ_64K);
 			size += in->phys_addr - paddr;

 			/*
 			 * Avoid wasting memory on PTEs by choosing a virtual
 			 * base that is compatible with section mappings if this
 			 * region has the appropriate size and physical
 			 * alignment. (Sections are 2 MB on 4k granule kernels)
 			 */
 			if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
 				efi_virt_base = round_up(efi_virt_base, SZ_2M);
 			else
 				efi_virt_base = round_up(efi_virt_base, SZ_64K);

 			in->virt_addr += efi_virt_base - paddr;
 			efi_virt_base += size;
 		}

 		memcpy(out, in, desc_size);
 		out = (void *)out + desc_size;
 		++*count;
 	}
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* EFI stub implementation that is shared by arm and arm64 architectures.
	* This should be #included by the EFI stub implementation files.
	*
	* Copyright (C) 2013,2014 Linaro Limited
	* Roy Franz <roy.franz@linaro.org
	* Copyright (C) 2013 Red Hat, Inc.
	* Mark Salter <msalter@redhat.com>
	*/

	#include <linux/efi.h>
	#include <asm/efi.h>

	#include "efistub.h"

	/*
	* This is the base address at which to start allocating virtual memory ranges
	* for UEFI Runtime Services.
	*
	* For ARM/ARM64:
	* This is in the low TTBR0 range so that we can use
	* any allocation we choose, and eliminate the risk of a conflict after kexec.
	* The value chosen is the largest non-zero power of 2 suitable for this purpose
	* both on 32-bit and 64-bit ARM CPUs, to maximize the likelihood that it can
	* be mapped efficiently.
	* Since 32-bit ARM could potentially execute with a 1G/3G user/kernel split,
	* map everything below 1 GB. (512 MB is a reasonable upper bound for the
	* entire footprint of the UEFI runtime services memory regions)
	*
	* For RISC-V:
	* There is no specific reason for which, this address (512MB) can't be used
	* EFI runtime virtual address for RISC-V. It also helps to use EFI runtime
	* services on both RV32/RV64. Keep the same runtime virtual address for RISC-V
	* as well to minimize the code churn.
	*/
	#define EFI_RT_VIRTUAL_BASE SZ_512M

	/*
	* Some architectures map the EFI regions into the kernel's linear map using a
	* fixed offset.
	*/
	#ifndef EFI_RT_VIRTUAL_OFFSET
	#define EFI_RT_VIRTUAL_OFFSET 0
	#endif

	static u64 virtmap_base = EFI_RT_VIRTUAL_BASE;
	static bool flat_va_mapping = (EFI_RT_VIRTUAL_OFFSET != 0);

	struct screen_info * __weak alloc_screen_info(void)
	{
	return &screen_info;
	}

	void __weak free_screen_info(struct screen_info *si)
	{
	}

	static struct screen_info *setup_graphics(void)
	{
	efi_guid_t gop_proto = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
	efi_status_t status;
	unsigned long size;
	void **gop_handle = NULL;
	struct screen_info *si = NULL;

	size = 0;
	status = efi_bs_call(locate_handle, EFI_LOCATE_BY_PROTOCOL,
	&gop_proto, NULL, &size, gop_handle);
	if (status == EFI_BUFFER_TOO_SMALL) {
	si = alloc_screen_info();
	if (!si)
	return NULL;
	status = efi_setup_gop(si, &gop_proto, size);
	if (status != EFI_SUCCESS) {
	free_screen_info(si);
	return NULL;
	}
	}
	return si;
	}

	static void install_memreserve_table(void)
	{
	struct linux_efi_memreserve *rsv;
	efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID;
	efi_status_t status;

	status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv),
	(void **)&rsv);
	if (status != EFI_SUCCESS) {
	efi_err("Failed to allocate memreserve entry!\n");
	return;
	}

	rsv->next = 0;
	rsv->size = 0;
	atomic_set(&rsv->count, 0);

	status = efi_bs_call(install_configuration_table,
	&memreserve_table_guid, rsv);
	if (status != EFI_SUCCESS)
	efi_err("Failed to install memreserve config table!\n");
	}

	static u32 get_supported_rt_services(void)
	{
	const efi_rt_properties_table_t *rt_prop_table;
	u32 supported = EFI_RT_SUPPORTED_ALL;

	rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID);
	if (rt_prop_table)
	supported &= rt_prop_table->runtime_services_supported;

	return supported;
	}

	efi_status_t efi_handle_cmdline(efi_loaded_image_t image, char *cmdline_ptr)
	{
	int cmdline_size = 0;
	efi_status_t status;
	char *cmdline;

	/*
	* Get the command line from EFI, using the LOADED_IMAGE
	* protocol. We are going to copy the command line into the
	* device tree, so this can be allocated anywhere.
	*/
	cmdline = efi_convert_cmdline(image, &cmdline_size);
	if (!cmdline) {
	efi_err("getting command line via LOADED_IMAGE_PROTOCOL\n");
	return EFI_OUT_OF_RESOURCES;
	}

	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) \|\|
	IS_ENABLED(CONFIG_CMDLINE_FORCE) \|\|
	cmdline_size == 0) {
	status = efi_parse_options(CONFIG_CMDLINE);
	if (status != EFI_SUCCESS) {
	efi_err("Failed to parse options\n");
	goto fail_free_cmdline;
	}
	}

	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && cmdline_size > 0) {
	status = efi_parse_options(cmdline);
	if (status != EFI_SUCCESS) {
	efi_err("Failed to parse options\n");
	goto fail_free_cmdline;
	}
	}

	*cmdline_ptr = cmdline;
	return EFI_SUCCESS;

	fail_free_cmdline:
	efi_bs_call(free_pool, cmdline_ptr);
	return status;
	}

	efi_status_t efi_stub_common(efi_handle_t handle,
	efi_loaded_image_t *image,
	unsigned long image_addr,
	char *cmdline_ptr)
	{
	struct screen_info *si;
	efi_status_t status;

	status = check_platform_features();
	if (status != EFI_SUCCESS)
	return status;

	si = setup_graphics();

	efi_retrieve_tpm2_eventlog();

	/* Ask the firmware to clear memory on unclean shutdown */
	efi_enable_reset_attack_mitigation();

	efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr),
	NULL);

	efi_random_get_seed();

	/* force efi_novamap if SetVirtualAddressMap() is unsupported */
	efi_novamap \|= !(get_supported_rt_services() &
	EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP);

	install_memreserve_table();

	status = efi_boot_kernel(handle, image, image_addr, cmdline_ptr);

	free_screen_info(si);
	return status;
	}

	/*
	* efi_allocate_virtmap() - create a pool allocation for the virtmap
	*
	* Create an allocation that is of sufficient size to hold all the memory
	* descriptors that will be passed to SetVirtualAddressMap() to inform the
	* firmware about the virtual mapping that will be used under the OS to call
	* into the firmware.
	*/
	efi_status_t efi_alloc_virtmap(efi_memory_desc_t **virtmap,
	unsigned long desc_size, u32 desc_ver)
	{
	unsigned long size, mmap_key;
	efi_status_t status;

	/*
	* Use the size of the current memory map as an upper bound for the
	* size of the buffer we need to pass to SetVirtualAddressMap() to
	* cover all EFI_MEMORY_RUNTIME regions.
	*/
	size = 0;
	status = efi_bs_call(get_memory_map, &size, NULL, &mmap_key, desc_size,
	desc_ver);
	if (status != EFI_BUFFER_TOO_SMALL)
	return EFI_LOAD_ERROR;

	return efi_bs_call(allocate_pool, EFI_LOADER_DATA, size,
	(void **)virtmap);
	}

	/*
	* efi_get_virtmap() - create a virtual mapping for the EFI memory map
	*
	* This function populates the virt_addr fields of all memory region descriptors
	* in @memory_map whose EFI_MEMORY_RUNTIME attribute is set. Those descriptors
	* are also copied to @runtime_map, and their total count is returned in @count.
	*/
	void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size,
	unsigned long desc_size, efi_memory_desc_t *runtime_map,
	int *count)
	{
	u64 efi_virt_base = virtmap_base;
	efi_memory_desc_t in, out = runtime_map;
	int l;

	*count = 0;

	for (l = 0; l < map_size; l += desc_size) {
	u64 paddr, size;

	in = (void *)memory_map + l;
	if (!(in->attribute & EFI_MEMORY_RUNTIME))
	continue;

	paddr = in->phys_addr;
	size = in->num_pages * EFI_PAGE_SIZE;

	in->virt_addr = in->phys_addr + EFI_RT_VIRTUAL_OFFSET;
	if (efi_novamap) {
	continue;
	}

	/*
	* Make the mapping compatible with 64k pages: this allows
	* a 4k page size kernel to kexec a 64k page size kernel and
	* vice versa.
	*/
	if (!flat_va_mapping) {

	paddr = round_down(in->phys_addr, SZ_64K);
	size += in->phys_addr - paddr;

	/*
	* Avoid wasting memory on PTEs by choosing a virtual
	* base that is compatible with section mappings if this
	* region has the appropriate size and physical
	* alignment. (Sections are 2 MB on 4k granule kernels)
	*/
	if (IS_ALIGNED(in->phys_addr, SZ_2M) && size >= SZ_2M)
	efi_virt_base = round_up(efi_virt_base, SZ_2M);
	else
	efi_virt_base = round_up(efi_virt_base, SZ_64K);

	in->virt_addr += efi_virt_base - paddr;
	efi_virt_base += size;
	}

	memcpy(out, in, desc_size);
	out = (void *)out + desc_size;
	++*count;
	}
	}