Commit 751c263b authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Will Deacon

arm64: remove TEXT_OFFSET randomization

TEXT_OFFSET was recently changed to 0x0, in preparation for its removal
at a later stage, and a warning is emitted into the kernel log when the
bootloader appears to have failed to take the TEXT_OFFSET image header
value into account.

Ironically, this warning itself fails to take TEXT_OFFSET into account,
and compares the kernel image's alignment modulo 2M against a hardcoded
value of 0x0, and so the warning will trigger spuriously when TEXT_OFFSET
randomization is enabled.

Given the intent to get rid of TEXT_OFFSET entirely, let's fix this
oversight by just removing support for TEXT_OFFSET randomization.
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20200615101939.634391-1-ardb@kernel.orgSigned-off-by: default avatarWill Deacon <will@kernel.org>
parent b3a9e3b9
...@@ -8,21 +8,6 @@ config PID_IN_CONTEXTIDR ...@@ -8,21 +8,6 @@ config PID_IN_CONTEXTIDR
instructions during context switch. Say Y here only if you are instructions during context switch. Say Y here only if you are
planning to use hardware trace tools with this kernel. planning to use hardware trace tools with this kernel.
config ARM64_RANDOMIZE_TEXT_OFFSET
bool "Randomize TEXT_OFFSET at build time"
help
Say Y here if you want the image load offset (AKA TEXT_OFFSET)
of the kernel to be randomized at build-time. When selected,
this option will cause TEXT_OFFSET to be randomized upon any
build of the kernel, and the offset will be reflected in the
text_offset field of the resulting Image. This can be used to
fuzz-test bootloaders which respect text_offset.
This option is intended for bootloader and/or kernel testing
only. Bootloaders must make no assumptions regarding the value
of TEXT_OFFSET and platforms must not require a specific
value.
config DEBUG_EFI config DEBUG_EFI
depends on EFI && DEBUG_INFO depends on EFI && DEBUG_INFO
bool "UEFI debugging" bool "UEFI debugging"
......
...@@ -121,13 +121,7 @@ endif ...@@ -121,13 +121,7 @@ endif
head-y := arch/arm64/kernel/head.o head-y := arch/arm64/kernel/head.o
# The byte offset of the kernel image in RAM from the start of RAM. # The byte offset of the kernel image in RAM from the start of RAM.
ifeq ($(CONFIG_ARM64_RANDOMIZE_TEXT_OFFSET), y)
TEXT_OFFSET := $(shell awk "BEGIN {srand(); printf \"0x%06x\n\", \
int(2 * 1024 * 1024 / (2 ^ $(CONFIG_ARM64_PAGE_SHIFT)) * \
rand()) * (2 ^ $(CONFIG_ARM64_PAGE_SHIFT))}")
else
TEXT_OFFSET := 0x0 TEXT_OFFSET := 0x0
endif
ifeq ($(CONFIG_KASAN_SW_TAGS), y) ifeq ($(CONFIG_KASAN_SW_TAGS), y)
KASAN_SHADOW_SCALE_SHIFT := 4 KASAN_SHADOW_SCALE_SHIFT := 4
......
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