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| author | Mark Rutland <mark.rutland@arm.com> | 2016-05-31 15:58:00 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2016-06-03 10:57:18 +0100 |
| commit | aed7eb8367939244ba19445292ffdfc398e0d66a (patch) | |
| tree | ef1dd844179bf42f5c068b4db58488ecf9f65cc3 /arch/arm64/Makefile | |
| parent | 030c4d24447cbf2bd612baea5695952e5f62c042 (diff) | |
| download | lwn-aed7eb8367939244ba19445292ffdfc398e0d66a.tar.gz lwn-aed7eb8367939244ba19445292ffdfc398e0d66a.zip | |
arm64: fix alignment when RANDOMIZE_TEXT_OFFSET is enabled
With ARM64_64K_PAGES and RANDOMIZE_TEXT_OFFSET enabled, we hit the
following issue on the boot:
kernel BUG at arch/arm64/mm/mmu.c:480!
Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 4.6.0 #310
Hardware name: ARM Juno development board (r2) (DT)
task: ffff000008d58a80 ti: ffff000008d30000 task.ti: ffff000008d30000
PC is at map_kernel_segment+0x44/0xb0
LR is at paging_init+0x84/0x5b0
pc : [<ffff000008c450b4>] lr : [<ffff000008c451a4>] pstate: 600002c5
Call trace:
[<ffff000008c450b4>] map_kernel_segment+0x44/0xb0
[<ffff000008c451a4>] paging_init+0x84/0x5b0
[<ffff000008c42728>] setup_arch+0x198/0x534
[<ffff000008c40848>] start_kernel+0x70/0x388
[<ffff000008c401bc>] __primary_switched+0x30/0x74
Commit 7eb90f2ff7e3 ("arm64: cover the .head.text section in the .text
segment mapping") removed the alignment between the .head.text and .text
sections, and used the _text rather than the _stext interval for mapping
the .text segment.
Prior to this commit _stext was always section aligned and didn't cause
any issue even when RANDOMIZE_TEXT_OFFSET was enabled. Since that
alignment has been removed and _text is used to map the .text segment,
we need ensure _text is always page aligned when RANDOMIZE_TEXT_OFFSET
is enabled.
This patch adds logic to TEXT_OFFSET fuzzing to ensure that the offset
is always aligned to the kernel page size. To ensure this, we rely on
the PAGE_SHIFT being available via Kconfig.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reported-by: Sudeep Holla <sudeep.holla@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Fixes: 7eb90f2ff7e3 ("arm64: cover the .head.text section in the .text segment mapping")
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/Makefile')
| -rw-r--r-- | arch/arm64/Makefile | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 354d75402ace..7085e322dc42 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -60,7 +60,9 @@ 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%03x000\n", int(512 * rand())}') +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 := 0x00080000 endif |