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authorMark Rutland <mark.rutland@arm.com>2014-06-24 16:51:37 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2014-07-10 12:36:58 +0100
commitda57a369d3bc5cd61db90f7e9555840381db9b09 (patch)
tree6e2e032c24d4b36e792e91984191752f527baf09 /arch/arm64/Makefile
parentarm64: Update the Image header (diff)
downloadlinux-dev-da57a369d3bc5cd61db90f7e9555840381db9b09.tar.xz
linux-dev-da57a369d3bc5cd61db90f7e9555840381db9b09.zip
arm64: Enable TEXT_OFFSET fuzzing
The arm64 Image header contains a text_offset field which bootloaders are supposed to read to determine the offset (from a 2MB aligned "start of memory" per booting.txt) at which to load the kernel. The offset is not well respected by bootloaders at present, and due to the lack of variation there is little incentive to support it. This is unfortunate for the sake of future kernels where we may wish to vary the text offset (even zeroing it). This patch adds options to arm64 to enable fuzz-testing of text_offset. CONFIG_ARM64_RANDOMIZE_TEXT_OFFSET forces the text offset to a random 16-byte aligned value value in the range [0..2MB) upon a build of the kernel. It is recommended that distribution kernels enable randomization to test bootloaders such that any compliance issues can be fixed early. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Tom Rini <trini@ti.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/Makefile')
-rw-r--r--arch/arm64/Makefile4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 8185a913c5ed..e8d025c1459e 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -38,7 +38,11 @@ CHECKFLAGS += -D__aarch64__
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())}')
+else
TEXT_OFFSET := 0x00080000
+endif
export TEXT_OFFSET GZFLAGS