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author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2014-08-13 18:53:03 +0100 |
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committer | Will Deacon <will.deacon@arm.com> | 2014-08-19 19:26:09 +0100 |
commit | 4190312beb2acfb7bfb1bb971e24a759aa96b0e8 (patch) | |
tree | 8de244a8483bf476270dfea7b49585fd86494cdd /arch/arm64/Makefile | |
parent | 503e6636b6f96056210062be703356f4253b6db9 (diff) | |
download | op-kernel-dev-4190312beb2acfb7bfb1bb971e24a759aa96b0e8.zip op-kernel-dev-4190312beb2acfb7bfb1bb971e24a759aa96b0e8.tar.gz |
arm64: align randomized TEXT_OFFSET on 4 kB boundary
When booting via UEFI, the kernel Image is loaded at a 4 kB boundary and
the embedded EFI stub is executed in place. The EFI stub relocates the
Image to reside TEXT_OFFSET bytes above a 2 MB boundary, and jumps into
the kernel proper.
In AArch64, PC relative symbol references are emitted using adrp/add or
adrp/ldr pairs, where the offset into a 4 kB page is resolved using a
separate :lo12: relocation. This implicitly assumes that the code will
always be executed at the same relative offset with respect to a 4 kB
boundary, or the references will point to the wrong address.
This means we should link the kernel at a 4 kB aligned base address in
order to remain compatible with the base address the UEFI loader uses
when doing the initial load of Image. So update the code that generates
TEXT_OFFSET to choose a multiple of 4 kB.
At the same time, update the code so it chooses from the interval [0..2MB)
as the author originally intended.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/Makefile')
-rw-r--r-- | arch/arm64/Makefile | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 5783354..2df5e5d 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -39,7 +39,7 @@ head-y := arch/arm64/kernel/head.o # 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%04x0\n", int(65535 * rand())}') +TEXT_OFFSET := $(shell awk 'BEGIN {srand(); printf "0x%03x000\n", int(512 * rand())}') else TEXT_OFFSET := 0x00080000 endif |