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Commit ab72a27d authored by Matt Fleming's avatar Matt Fleming
Browse files

x86/efi: Consolidate region mapping logic 



EFI regions are currently mapped in two separate places. The bulk of
the work is done in efi_map_regions() but when CONFIG_EFI_MIXED is
enabled the additional regions that are required when operating in
mixed mode are mapping in efi_setup_page_tables().

Pull everything into efi_map_regions() and refactor the test for
which regions should be mapped into a should_map_region() function.
Generously sprinkle comments to clarify the different cases.

Acked-by: default avatarBorislav Petkov <bp@suse.de>
Tested-by: Dave Young <dyoung@redhat.com> [kexec/kdump]
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> [arm]
Acked-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarMatt Fleming <matt@codeblueprint.co.uk>
parent 4971531a

arch/x86/platform/efi/efi.c

+43 −7
Original line number Diff line number Diff line
@@ -745,6 +745,46 @@ static void *efi_map_next_entry(void *entry) 
	return entry;

}



static bool should_map_region(efi_memory_desc_t *md)

{

	/*

	 * Runtime regions always require runtime mappings (obviously).

	 */

	if (md->attribute & EFI_MEMORY_RUNTIME)

		return true;



	/*

	 * 32-bit EFI doesn't suffer from the bug that requires us to

	 * reserve boot services regions, and mixed mode support

	 * doesn't exist for 32-bit kernels.

	 */

	if (IS_ENABLED(CONFIG_X86_32))

		return false;



	/*

	 * Map all of RAM so that we can access arguments in the 1:1

	 * mapping when making EFI runtime calls.

	 */

	if (IS_ENABLED(CONFIG_EFI_MIXED) && !efi_is_native()) {

		if (md->type == EFI_CONVENTIONAL_MEMORY ||

		    md->type == EFI_LOADER_DATA ||

		    md->type == EFI_LOADER_CODE)

			return true;

	}



	/*

	 * Map boot services regions as a workaround for buggy

	 * firmware that accesses them even when they shouldn't.

	 *

	 * See efi_{reserve,free}_boot_services().

	 */

	if (md->type == EFI_BOOT_SERVICES_CODE ||

	    md->type == EFI_BOOT_SERVICES_DATA)

		return true;



	return false;

}



/*

 * Map the efi memory ranges of the runtime services and update new_mmap with

 * virtual addresses.
@@ -761,13 +801,9 @@ static void * __init efi_map_regions(int *count, int *pg_shift) 
	p = NULL;

	while ((p = efi_map_next_entry(p))) {

		md = p;

		if (!(md->attribute & EFI_MEMORY_RUNTIME)) {

#ifdef CONFIG_X86_64

			if (md->type != EFI_BOOT_SERVICES_CODE &&

			    md->type != EFI_BOOT_SERVICES_DATA)

#endif



		if (!should_map_region(md))

			continue;

		}



		efi_map_region(md);

		get_systab_virt_addr(md);

arch/x86/platform/efi/efi_64.c

+0 −20
Original line number Diff line number Diff line
@@ -214,7 +214,6 @@ void efi_sync_low_kernel_mappings(void) 
int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)

{

	unsigned long pfn, text;

	efi_memory_desc_t *md;

	struct page *page;

	unsigned npages;

	pgd_t *pgd;
@@ -248,25 +247,6 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) 
	if (!IS_ENABLED(CONFIG_EFI_MIXED))

		return 0;



	/*

	 * Map all of RAM so that we can access arguments in the 1:1

	 * mapping when making EFI runtime calls.

	 */

	for_each_efi_memory_desc(md) {

		if (md->type != EFI_CONVENTIONAL_MEMORY &&

		    md->type != EFI_LOADER_DATA &&

		    md->type != EFI_LOADER_CODE)

			continue;



		pfn = md->phys_addr >> PAGE_SHIFT;

		npages = md->num_pages;



		if (kernel_map_pages_in_pgd(pgd, pfn, md->phys_addr, npages, _PAGE_RW)) {

			pr_err("Failed to map 1:1 memory\n");

			return 1;

		}

	}



	page = alloc_page(GFP_KERNEL|__GFP_DMA32);

	if (!page)

		panic("Unable to allocate EFI runtime stack < 4GB\n");