diff options
| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-03-02 09:47:13 +0100 |
|---|---|---|
| committer | Jeff Vander Stoep <jeffv@google.com> | 2016-09-22 13:38:22 -0700 |
| commit | f41890295d6496ed50bbe8606d23fb10661a844f (patch) | |
| tree | 442fdb58f71907db685e0b0451943e38d0bbd0c6 /arch/arm64/mm/init.c | |
| parent | 1c4143d40cec48cac343bf1e8a426746ac240f92 (diff) | |
UPSTREAM: 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>
Bug: 30369029
Patchset: kaslr-arm64-4.4
(cherry picked from commit 6d2aa549de1fc998581d216de3853aa131aa4446)
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: I8c3bc8cdb7d7f7dea092fd1a208b04583a141054
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 8e3cf19e4f00..2c38be3df4c8 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -173,6 +173,13 @@ 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(), |