diff options
| -rw-r--r-- | arch/arm64/Kconfig.debug | 15 | ||||
| -rw-r--r-- | arch/arm64/Makefile | 4 | ||||
| -rw-r--r-- | arch/arm64/kernel/head.S | 8 | ||||
| -rw-r--r-- | arch/arm64/kernel/vmlinux.lds.S | 5 |
4 files changed, 30 insertions, 2 deletions
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug index 1c1b756..4ee8e90 100644 --- a/arch/arm64/Kconfig.debug +++ b/arch/arm64/Kconfig.debug @@ -28,4 +28,19 @@ config PID_IN_CONTEXTIDR instructions during context switch. Say Y here only if you are 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. + endmenu diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 8185a91..e8d025c 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 diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 3ba0fc0..69dafe9 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 diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index a814768..97f0c04 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -125,3 +125,8 @@ SECTIONS */ ASSERT(((__hyp_idmap_text_start + PAGE_SIZE) > __hyp_idmap_text_end), "HYP init code too big") + +/* + * If padding is applied before .head.text, virt<->phys conversions will fail. + */ +ASSERT(_text == (PAGE_OFFSET + TEXT_OFFSET), "HEAD is misaligned") |