From da57a369d3bc5cd61db90f7e9555840381db9b09 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Tue, 24 Jun 2014 16:51:37 +0100 Subject: 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 Acked-by: Tom Rini Acked-by: Will Deacon Signed-off-by: Catalin Marinas --- arch/arm64/kernel/head.S | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'arch/arm64/kernel/head.S') diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 3ba0fc02c0de..69dafe9621fd 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -37,8 +37,12 @@ #define KERNEL_RAM_VADDR (PAGE_OFFSET + TEXT_OFFSET) -#if (KERNEL_RAM_VADDR & 0xfffff) != 0x80000 -#error KERNEL_RAM_VADDR must start at 0xXXX80000 +#if (TEXT_OFFSET & 0xf) != 0 +#error TEXT_OFFSET must be at least 16B aligned +#elif (PAGE_OFFSET & 0xfffff) != 0 +#error PAGE_OFFSET must be at least 2MB aligned +#elif TEXT_OFFSET > 0xfffff +#error TEXT_OFFSET must be less than 2MB #endif .macro pgtbl, ttb0, ttb1, virt_to_phys -- cgit v1.2.1