arm-trusted-firmware/lib/romlib/init.s
Soby Mathew f1722b693d PIE: Use PC relative adrp/adr for symbol reference
This patch fixes up the AArch64 assembly code to use
adrp/adr instructions instead of ldr instruction for
reference to symbols. This allows these assembly
sequences to be Position Independant. Note that the
the reference to sizes have been replaced with
calculation of size at runtime. This is because size
is a constant value and does not depend on execution
address and using PC relative instructions for loading
them makes them relative to execution address. Also
we cannot use `ldr` instruction to load size as it
generates a dynamic relocation entry which must *not*
be fixed up and it is difficult for a dynamic loader
to differentiate which entries need to be skipped.

Change-Id: I8bf4ed5c58a9703629e5498a27624500ef40a836
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
2018-10-29 09:54:31 +00:00

36 lines
698 B
ArmAsm

/*
* Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
.globl rom_lib_init
.extern __DATA_RAM_START__, __DATA_ROM_START__, __DATA_RAM_END__
.extern memset, memcpy
rom_lib_init:
cmp w0, #1
mov w0, #0
b.le 1f
ret
1: stp x29, x30, [sp, #-16]!
adrp x0, __DATA_RAM_START__
adrp x1, __DATA_ROM_START__
add x1, x1, :lo12:__DATA_ROM_START__
adrp x2, __DATA_RAM_END__
add x2, x2, :lo12:__DATA_RAM_END__
sub x2, x2, x0
bl memcpy
adrp x0,__BSS_START__
add x0, x0, :lo12:__BSS_START__
mov x1, #0
adrp x2, __BSS_END__
add x2, x2, :lo12:__BSS_END__
sub x2, x2, x0
bl memset
ldp x29, x30, [sp], #16
mov w0, #1
ret