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| author | Steve Capper <steve.capper@arm.com> | 2019-08-07 17:55:14 +0200 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2019-08-09 12:16:51 +0200 |
| commit | 14c127c957c1c6070647c171e72f06e0db275ebf (patch) | |
| tree | 6f5e57a4dd8c8cbe895b01513c2bd6a1cb3ddcff /arch/arm64/mm/init.c | |
| parent | arm64: mm: Remove bit-masking optimisations for PAGE_OFFSET and VMEMMAP_START (diff) | |
| download | linux-14c127c957c1c6070647c171e72f06e0db275ebf.tar.xz linux-14c127c957c1c6070647c171e72f06e0db275ebf.zip | |
arm64: mm: Flip kernel VA space
In order to allow for a KASAN shadow that changes size at boot time, one
must fix the KASAN_SHADOW_END for both 48 & 52-bit VAs and "grow" the
start address. Also, it is highly desirable to maintain the same
function addresses in the kernel .text between VA sizes. Both of these
requirements necessitate us to flip the kernel address space halves s.t.
the direct linear map occupies the lower addresses.
This patch puts the direct linear map in the lower addresses of the
kernel VA range and everything else in the higher ranges.
We need to adjust:
*) KASAN shadow region placement logic,
*) KASAN_SHADOW_OFFSET computation logic,
*) virt_to_phys, phys_to_virt checks,
*) page table dumper.
These are all small changes, that need to take place atomically, so they
are bundled into this commit.
As part of the re-arrangement, a guard region of 2MB (to preserve
alignment for fixed map) is added after the vmemmap. Otherwise the
vmemmap could intersect with IS_ERR pointers.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steve Capper <steve.capper@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/mm/init.c')
| -rw-r--r-- | arch/arm64/mm/init.c | 9 |
1 files changed, 1 insertions, 8 deletions
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index f3c795278def..62927ed02229 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -301,7 +301,7 @@ static void __init fdt_enforce_memory_region(void) void __init arm64_memblock_init(void) { - const s64 linear_region_size = -(s64)PAGE_OFFSET; + const s64 linear_region_size = BIT(VA_BITS - 1); /* Handle linux,usable-memory-range property */ fdt_enforce_memory_region(); @@ -310,13 +310,6 @@ void __init arm64_memblock_init(void) memblock_remove(1ULL << PHYS_MASK_SHIFT, ULLONG_MAX); /* - * 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(), |