e4bae4d0b5
To prevent unintended modifications to the kernel text (malicious or otherwise) while running the EFI stub, describe the kernel image as two separate sections: a .text section with read-execute permissions, covering .text, .rodata, .piggytext and the GOT sections (which the stub does not care about anyway), and a .data section with read-write permissions, covering .data and .bss. This relies on the firmware to actually take the section permission flags into account, but this is something that is currently being implemented in EDK2, which means we will likely start seeing it in the wild between one and two years from now. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20170818194947.19347-12-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
111 lines
2.5 KiB
ArmAsm
111 lines
2.5 KiB
ArmAsm
/*
|
|
* Copyright (C) 2000 Russell King
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
#ifdef CONFIG_CPU_ENDIAN_BE8
|
|
#define ZIMAGE_MAGIC(x) ( (((x) >> 24) & 0x000000ff) | \
|
|
(((x) >> 8) & 0x0000ff00) | \
|
|
(((x) << 8) & 0x00ff0000) | \
|
|
(((x) << 24) & 0xff000000) )
|
|
#else
|
|
#define ZIMAGE_MAGIC(x) (x)
|
|
#endif
|
|
|
|
OUTPUT_ARCH(arm)
|
|
ENTRY(_start)
|
|
SECTIONS
|
|
{
|
|
/DISCARD/ : {
|
|
*(.ARM.exidx*)
|
|
*(.ARM.extab*)
|
|
/*
|
|
* Discard any r/w data - this produces a link error if we have any,
|
|
* which is required for PIC decompression. Local data generates
|
|
* GOTOFF relocations, which prevents it being relocated independently
|
|
* of the text/got segments.
|
|
*/
|
|
*(.data)
|
|
}
|
|
|
|
. = TEXT_START;
|
|
_text = .;
|
|
|
|
.text : {
|
|
_start = .;
|
|
*(.start)
|
|
*(.text)
|
|
*(.text.*)
|
|
*(.fixup)
|
|
*(.gnu.warning)
|
|
*(.glue_7t)
|
|
*(.glue_7)
|
|
}
|
|
.rodata : {
|
|
*(.rodata)
|
|
*(.rodata.*)
|
|
}
|
|
.piggydata : {
|
|
*(.piggydata)
|
|
}
|
|
|
|
. = ALIGN(4);
|
|
_etext = .;
|
|
|
|
.got.plt : { *(.got.plt) }
|
|
_got_start = .;
|
|
.got : { *(.got) }
|
|
_got_end = .;
|
|
|
|
/* ensure the zImage file size is always a multiple of 64 bits */
|
|
/* (without a dummy byte, ld just ignores the empty section) */
|
|
.pad : { BYTE(0); . = ALIGN(8); }
|
|
|
|
#ifdef CONFIG_EFI_STUB
|
|
.data : ALIGN(4096) {
|
|
__pecoff_data_start = .;
|
|
/*
|
|
* The EFI stub always executes from RAM, and runs strictly before the
|
|
* decompressor, so we can make an exception for its r/w data, and keep it
|
|
*/
|
|
*(.data.efistub)
|
|
__pecoff_data_end = .;
|
|
|
|
/*
|
|
* PE/COFF mandates a file size which is a multiple of 512 bytes if the
|
|
* section size equals or exceeds 4 KB
|
|
*/
|
|
. = ALIGN(512);
|
|
}
|
|
__pecoff_data_rawsize = . - ADDR(.data);
|
|
#endif
|
|
|
|
_edata = .;
|
|
|
|
_magic_sig = ZIMAGE_MAGIC(0x016f2818);
|
|
_magic_start = ZIMAGE_MAGIC(_start);
|
|
_magic_end = ZIMAGE_MAGIC(_edata);
|
|
|
|
. = BSS_START;
|
|
__bss_start = .;
|
|
.bss : { *(.bss) }
|
|
_end = .;
|
|
|
|
. = ALIGN(8); /* the stack must be 64-bit aligned */
|
|
.stack : { *(.stack) }
|
|
|
|
PROVIDE(__pecoff_data_size = ALIGN(512) - ADDR(.data));
|
|
PROVIDE(__pecoff_end = ALIGN(512));
|
|
|
|
.stab 0 : { *(.stab) }
|
|
.stabstr 0 : { *(.stabstr) }
|
|
.stab.excl 0 : { *(.stab.excl) }
|
|
.stab.exclstr 0 : { *(.stab.exclstr) }
|
|
.stab.index 0 : { *(.stab.index) }
|
|
.stab.indexstr 0 : { *(.stab.indexstr) }
|
|
.comment 0 : { *(.comment) }
|
|
}
|