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| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-03-02 08:47:13 (GMT) |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-03-02 09:45:52 (GMT) |
| commit | 6d2aa549de1fc998581d216de3853aa131aa4446 (patch) | |
| tree | 76ecfc517079dfe3118bc96e0f523252a5618a82 /arch/arm64/mm/init.c | |
| parent | 22b39ca3f22ac46a42731447aadc0a5109078241 (diff) | |
| download | linux-6d2aa549de1fc998581d216de3853aa131aa4446.tar.xz | |
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>
Diffstat (limited to 'arch/arm64/mm/init.c')
| -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 22c6758..8c3d7dd 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(), |