Commit e7b88bc0 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Borislav Petkov (AMD)
Browse files

efistub/x86: Remap inittext read-execute when needed 



Recent EFI x86 systems are more strict when it comes to mapping boot
images, and require that mappings are either read-write or read-execute.

Now that the boot code is being cleaned up and refactored, most of it is
being moved into .init.text [where it arguably belongs] but that implies
that when booting on such strict EFI firmware, we need to take care to
map .init.text (and the .altinstr_aux section that follows it)
read-execute as well.

Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250828102202.1849035-44-ardb+git@google.com
parent 7b38dec3

arch/x86/boot/compressed/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -73,7 +73,7 @@ LDFLAGS_vmlinux += -T 
hostprogs	:= mkpiggy

HOST_EXTRACFLAGS += -I$(srctree)/tools/include



sed-voffset := -e 's/^\([0-9a-fA-F]*\) [ABbCDGRSTtVW] \(_text\|__start_rodata\|__bss_start\|_end\)$$/\#define VO_\2 _AC(0x\1,UL)/p'

sed-voffset := -e 's/^\([0-9a-fA-F]*\) [ABbCDGRSTtVW] \(_text\|__start_rodata\|_sinittext\|__inittext_end\|__bss_start\|_end\)$$/\#define VO_\2 _AC(0x\1,UL)/p'



quiet_cmd_voffset = VOFFSET $@

      cmd_voffset = $(NM) $< | sed -n $(sed-voffset) > $@

arch/x86/boot/compressed/misc.c

+2 −0
Original line number Diff line number Diff line
@@ -332,6 +332,8 @@ static size_t parse_elf(void *output) 
}



const unsigned long kernel_text_size = VO___start_rodata - VO__text;

const unsigned long kernel_inittext_offset = VO__sinittext - VO__text;

const unsigned long kernel_inittext_size = VO___inittext_end - VO__sinittext;

const unsigned long kernel_total_size = VO__end - VO__text;



static u8 boot_heap[BOOT_HEAP_SIZE] __aligned(4);

arch/x86/include/asm/boot.h

+2 −0
Original line number Diff line number Diff line
@@ -82,6 +82,8 @@ 
#ifndef __ASSEMBLER__

extern unsigned int output_len;

extern const unsigned long kernel_text_size;

extern const unsigned long kernel_inittext_offset;

extern const unsigned long kernel_inittext_size;

extern const unsigned long kernel_total_size;



unsigned long decompress_kernel(unsigned char *outbuf, unsigned long virt_addr,

arch/x86/kernel/vmlinux.lds.S

+2 −0
Original line number Diff line number Diff line
@@ -227,6 +227,8 @@ SECTIONS 
	 */

	.altinstr_aux : AT(ADDR(.altinstr_aux) - LOAD_OFFSET) {

		*(.altinstr_aux)

		. = ALIGN(PAGE_SIZE);

		__inittext_end = .;

	}



	INIT_DATA_SECTION(16)

drivers/firmware/efi/libstub/x86-stub.c

+3 −1
Original line number Diff line number Diff line
@@ -788,7 +788,9 @@ static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry, 


	*kernel_entry = addr + entry;



	return efi_adjust_memory_range_protection(addr, kernel_text_size);

	return efi_adjust_memory_range_protection(addr, kernel_text_size) ?:

	       efi_adjust_memory_range_protection(addr + kernel_inittext_offset,

						  kernel_inittext_size);

}



static void __noreturn enter_kernel(unsigned long kernel_addr,