diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-03-02 09:47:13 +0100 |
|---|---|---|
| committer | Alex Shi <alex.shi@linaro.org> | 2016-05-12 08:41:11 +0800 |
| commit | 3d3fe7cf1fbc97ea285fd1ee3ed55b7527e4d1ae (patch) | |
| tree | a9e615efb0bd038d8fcfa8a08b3e7f9165d9ec5c /arch | |
| parent | 9ca29910090bc04686fbed05306131093da667f1 (diff) | |
arm64: mm: check at build time that PAGE_OFFSET divides the VA space evenly
Commit 8439e62a1561 ("arm64: mm: use bit ops rather than arithmetic in
pa/va translations") changed the boundary check against PAGE_OFFSET from
an arithmetic comparison to a bit test. This means we now silently assume
that PAGE_OFFSET is a power of 2 that divides the kernel virtual address
space into two equal halves. So make that assumption explicit.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 6d2aa549de1fc998581d216de3853aa131aa4446)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/mm/init.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 58a6d3f7525c..19ccdb73c680 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -171,6 +171,13 @@ void __init arm64_memblock_init(void) const s64 linear_region_size = -(s64)PAGE_OFFSET; /* + * Ensure that the linear region takes up exactly half of the kernel + * virtual address space. This way, we can distinguish a linear address + * from a kernel/module/vmalloc address by testing a single bit. + */ + BUILD_BUG_ON(linear_region_size != BIT(VA_BITS - 1)); + + /* * Select a suitable value for the base of physical memory. */ memstart_addr = round_down(memblock_start_of_DRAM(), |