Commit 4fc8e738 authored by Ard Biesheuvel's avatar Ard Biesheuvel
Browse files

efi: libstub: remove DT dependency from generic stub 



Refactor the generic EFI stub entry code so that all the dependencies on
device tree are abstracted and hidden behind a generic efi_boot_kernel()
routine that can also be implemented in other ways. This allows users of
the generic stub to avoid using FDT for passing information to the core
kernel.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
parent f4dc7fff

drivers/firmware/efi/libstub/efi-stub.c

+1 −52
Original line number Diff line number Diff line
@@ -10,7 +10,6 @@ 
 */



#include <linux/efi.h>

#include <linux/libfdt.h>

#include <asm/efi.h>



#include "efistub.h"
@@ -132,14 +131,11 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, 
	unsigned long image_addr;

	unsigned long image_size = 0;

	/* addr/point and size pairs for memory management*/

	unsigned long fdt_addr = 0;  /* Original DTB */

	unsigned long fdt_size = 0;

	char *cmdline_ptr = NULL;

	int cmdline_size = 0;

	efi_guid_t loaded_image_proto = LOADED_IMAGE_PROTOCOL_GUID;

	unsigned long reserve_addr = 0;

	unsigned long reserve_size = 0;

	enum efi_secureboot_mode secure_boot;

	struct screen_info *si;

	efi_properties_table_t *prop_tbl;
@@ -215,38 +211,6 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, 
	/* Ask the firmware to clear memory on unclean shutdown */

	efi_enable_reset_attack_mitigation();



	secure_boot = efi_get_secureboot();



	/*

	 * Unauthenticated device tree data is a security hazard, so ignore

	 * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure

	 * boot is enabled if we can't determine its state.

	 */

	if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||

	     secure_boot != efi_secureboot_mode_disabled) {

		if (strstr(cmdline_ptr, "dtb="))

			efi_err("Ignoring DTB from command line.\n");

	} else {

		status = efi_load_dtb(image, &fdt_addr, &fdt_size);



		if (status != EFI_SUCCESS && status != EFI_NOT_READY) {

			efi_err("Failed to load device tree!\n");

			goto fail_free_image;

		}

	}



	if (fdt_addr) {

		efi_info("Using DTB from command line\n");

	} else {

		/* Look for a device tree configuration table entry. */

		fdt_addr = (uintptr_t)get_fdt(&fdt_size);

		if (fdt_addr)

			efi_info("Using DTB from configuration table\n");

	}



	if (!fdt_addr)

		efi_info("Generating empty DTB\n");



	efi_load_initrd(image, ULONG_MAX, efi_get_max_initrd_addr(image_addr),

			NULL);
@@ -290,23 +254,8 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, 


	install_memreserve_table();



	status = allocate_new_fdt_and_exit_boot(handle, &fdt_addr, cmdline_ptr,

						fdt_addr, fdt_size);

	if (status != EFI_SUCCESS)

		goto fail_free_fdt;



	if (IS_ENABLED(CONFIG_ARM))

		efi_handle_post_ebs_state();



	efi_enter_kernel(image_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));

	/* not reached */



fail_free_fdt:

	efi_err("Failed to update FDT and exit boot services\n");



	efi_free(fdt_size, fdt_addr);

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



fail_free_image:

	efi_free(image_size, image_addr);

	efi_free(reserve_size, reserve_addr);

fail_free_screeninfo:

drivers/firmware/efi/libstub/efistub.h

+2 −5
Original line number Diff line number Diff line
@@ -844,11 +844,8 @@ typedef efi_status_t (*efi_exit_boot_map_processing)( 
efi_status_t efi_exit_boot_services(void *handle, void *priv,

				    efi_exit_boot_map_processing priv_func);



efi_status_t allocate_new_fdt_and_exit_boot(void *handle,

					    unsigned long *new_fdt_addr,

					    char *cmdline_ptr,

					    unsigned long fdt_addr,

					    unsigned long fdt_size);

efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,

			     unsigned long kernel_addr, char *cmdline_ptr);



void *get_fdt(unsigned long *fdt_size);

drivers/firmware/efi/libstub/fdt.c

+57 −4
Original line number Diff line number Diff line
@@ -219,17 +219,18 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map, void *priv) 
 * exit_boot_services() call, so the exiting of boot services is very tightly

 * tied to the creation of the FDT with the final memory map in it.

 */



static

efi_status_t allocate_new_fdt_and_exit_boot(void *handle,

					    efi_loaded_image_t *image,

					    unsigned long *new_fdt_addr,

					    char *cmdline_ptr,

					    unsigned long fdt_addr,

					    unsigned long fdt_size)

					    char *cmdline_ptr)

{

	unsigned long desc_size;

	u32 desc_ver;

	efi_status_t status;

	struct exit_boot_struct priv;

	unsigned long fdt_addr = 0;

	unsigned long fdt_size = 0;



	if (!efi_novamap) {

		status = efi_alloc_virtmap(&priv.runtime_map, &desc_size,
@@ -240,6 +241,36 @@ efi_status_t allocate_new_fdt_and_exit_boot(void *handle, 
		}

	}



	/*

	 * Unauthenticated device tree data is a security hazard, so ignore

	 * 'dtb=' unless UEFI Secure Boot is disabled.  We assume that secure

	 * boot is enabled if we can't determine its state.

	 */

	if (!IS_ENABLED(CONFIG_EFI_ARMSTUB_DTB_LOADER) ||

	    efi_get_secureboot() != efi_secureboot_mode_disabled) {

		if (strstr(cmdline_ptr, "dtb="))

			efi_err("Ignoring DTB from command line.\n");

	} else {

		status = efi_load_dtb(image, &fdt_addr, &fdt_size);



		if (status != EFI_SUCCESS && status != EFI_NOT_READY) {

			efi_err("Failed to load device tree!\n");

			goto fail;

		}

	}



	if (fdt_addr) {

		efi_info("Using DTB from command line\n");

	} else {

		/* Look for a device tree configuration table entry. */

		fdt_addr = (uintptr_t)get_fdt(&fdt_size);

		if (fdt_addr)

			efi_info("Using DTB from configuration table\n");

	}



	if (!fdt_addr)

		efi_info("Generating empty DTB\n");



	efi_info("Exiting boot services...\n");



	status = efi_allocate_pages(MAX_FDT_SIZE, new_fdt_addr, ULONG_MAX);
@@ -303,11 +334,33 @@ efi_status_t allocate_new_fdt_and_exit_boot(void *handle, 
	efi_free(MAX_FDT_SIZE, *new_fdt_addr);



fail:

	efi_free(fdt_size, fdt_addr);



	efi_bs_call(free_pool, priv.runtime_map);



	return EFI_LOAD_ERROR;

}



efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,

			     unsigned long kernel_addr, char *cmdline_ptr)

{

	unsigned long fdt_addr;

	efi_status_t status;



	status = allocate_new_fdt_and_exit_boot(handle, image, &fdt_addr,

						cmdline_ptr);

	if (status != EFI_SUCCESS) {

		efi_err("Failed to update FDT and exit boot services\n");

		return status;

	}



	if (IS_ENABLED(CONFIG_ARM))

		efi_handle_post_ebs_state();



	efi_enter_kernel(kernel_addr, fdt_addr, fdt_totalsize((void *)fdt_addr));

	/* not reached */

}



void *get_fdt(unsigned long *fdt_size)

{

	void *fdt;