Commit e2d68a95 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Ingo Molnar
Browse files

efi/x86: Don't panic or BUG() on non-critical error conditions 



The logic in __efi_enter_virtual_mode() does a number of steps in
sequence, all of which may fail in one way or the other. In most
cases, we simply print an error and disable EFI runtime services
support, but in some cases, we BUG() or panic() and bring down the
system when encountering conditions that we could easily handle in
the same way.

While at it, replace a pointless page-to-virt-phys conversion with
one that goes straight from struct page to physical.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Matthew Garrett <mjg59@google.com>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20200103113953.9571-14-ardb@kernel.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 5b279a26

arch/x86/platform/efi/efi.c

+14 −14
Original line number Diff line number Diff line
@@ -889,16 +889,14 @@ static void __init __efi_enter_virtual_mode(void) 


	if (efi_alloc_page_tables()) {

		pr_err("Failed to allocate EFI page tables\n");

		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);

		return;

		goto err;

	}



	efi_merge_regions();

	new_memmap = efi_map_regions(&count, &pg_shift);

	if (!new_memmap) {

		pr_err("Error reallocating memory, EFI runtime non-functional!\n");

		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);

		return;

		goto err;

	}



	pa = __pa(new_memmap);
@@ -912,8 +910,7 @@ static void __init __efi_enter_virtual_mode(void) 


	if (efi_memmap_init_late(pa, efi.memmap.desc_size * count)) {

		pr_err("Failed to remap late EFI memory map\n");

		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);

		return;

		goto err;

	}



	if (efi_enabled(EFI_DBG)) {
@@ -921,12 +918,11 @@ static void __init __efi_enter_virtual_mode(void) 
		efi_print_memmap();

	}



	BUG_ON(!efi.systab);

	if (WARN_ON(!efi.systab))

		goto err;



	if (efi_setup_page_tables(pa, 1 << pg_shift)) {

		clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);

		return;

	}

	if (efi_setup_page_tables(pa, 1 << pg_shift))

		goto err;



	efi_sync_low_kernel_mappings();
@@ -935,9 +931,9 @@ static void __init __efi_enter_virtual_mode(void) 
					     efi.memmap.desc_version,

					     (efi_memory_desc_t *)pa);

	if (status != EFI_SUCCESS) {

		pr_alert("Unable to switch EFI into virtual mode (status=%lx)!\n",

		pr_err("Unable to switch EFI into virtual mode (status=%lx)!\n",

		       status);

		panic("EFI call to SetVirtualAddressMap() failed!");

		goto err;

	}



	efi_free_boot_services();
@@ -964,6 +960,10 @@ static void __init __efi_enter_virtual_mode(void) 


	/* clean DUMMY object */

	efi_delete_dummy_variable();

	return;



err:

	clear_bit(EFI_RUNTIME_SERVICES, &efi.flags);

}



void __init efi_enter_virtual_mode(void)

arch/x86/platform/efi/efi_64.c

+5 −4
Original line number Diff line number Diff line
@@ -384,11 +384,12 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) 
		return 0;



	page = alloc_page(GFP_KERNEL|__GFP_DMA32);

	if (!page)

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

	if (!page) {

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

		return 1;

	}



	efi_scratch.phys_stack = virt_to_phys(page_address(page));

	efi_scratch.phys_stack += PAGE_SIZE; /* stack grows down */

	efi_scratch.phys_stack = page_to_phys(page + 1); /* stack grows down */



	npages = (_etext - _text) >> PAGE_SHIFT;

	text = __pa(_text);

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