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efistub/x86: Remap inittext read-execute when needed

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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: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250828102202.1849035-44-ardb+git@google.com
This commit is contained in:
Ard Biesheuvel 2025-08-28 12:22:23 +02:00 • committed by Borislav Petkov (AMD)
parent 7b38dec3c5
commit e7b88bc005
5 changed files with 10 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

2
arch/x86/boot/compressed/Makefile
View file

@ -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) > $@

2
arch/x86/boot/compressed/misc.c
View file

@ -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);

2
arch/x86/include/asm/boot.h
View file

@ -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,

2
arch/x86/kernel/vmlinux.lds.S
View file

@ -227,6 +227,8 @@ SECTIONS
*/
.altinstr_aux : AT(ADDR(.altinstr_aux) - LOAD_OFFSET) {
*(.altinstr_aux)
. = ALIGN(PAGE_SIZE);
__inittext_end = .;
}
INIT_DATA_SECTION(16)

4
drivers/firmware/efi/libstub/x86-stub.c
View file

@ -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,