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arm64: move kernel image to base of vmalloc area

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This moves the module area to right before the vmalloc area, and moves
the kernel image to the base of the vmalloc area. This is an intermediate
step towards implementing KASLR, which allows the kernel image to be
located anywhere in the vmalloc area.

Since other subsystems such as hibernate may still need to refer to the
kernel text or data segments via their linears addresses, both are mapped
in the linear region as well. The linear alias of the text region is
mapped read-only/non-executable to prevent inadvertent modification or
execution.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Ard Biesheuvel
2016-02-16 13:52:40 +01:00
committed by Catalin Marinas
parent a0bf9776cd
commit f9040773b7
7 changed files with 137 additions and 68 deletions
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21
arch/arm64/include/asm/memory.h
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@@ -45,16 +45,15 @@
* VA_START - the first kernel virtual address.
* TASK_SIZE - the maximum size of a user space task.
* TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.
* The module space lives between the addresses given by TASK_SIZE
* and PAGE_OFFSET - it must be within 128MB of the kernel text.
*/
#define VA_BITS (CONFIG_ARM64_VA_BITS)
#define VA_START (UL(0xffffffffffffffff) << VA_BITS)
#define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1))
#define KIMAGE_VADDR (PAGE_OFFSET)
#define MODULES_END (KIMAGE_VADDR)
#define MODULES_VADDR (MODULES_END - SZ_64M)
#define PCI_IO_END (MODULES_VADDR - SZ_2M)
#define KIMAGE_VADDR (MODULES_END)
#define MODULES_END (MODULES_VADDR + MODULES_VSIZE)
#define MODULES_VADDR (VA_START + KASAN_SHADOW_SIZE)
#define MODULES_VSIZE (SZ_64M)
#define PCI_IO_END (PAGE_OFFSET - SZ_2M)
#define PCI_IO_START (PCI_IO_END - PCI_IO_SIZE)
#define FIXADDR_TOP (PCI_IO_START - SZ_2M)
#define TASK_SIZE_64 (UL(1) << VA_BITS)
@@ -71,6 +70,16 @@
#define TASK_UNMAPPED_BASE (PAGE_ALIGN(TASK_SIZE / 4))
/*
* The size of the KASAN shadow region. This should be 1/8th of the
* size of the entire kernel virtual address space.
*/
#ifdef CONFIG_KASAN
#define KASAN_SHADOW_SIZE (UL(1) << (VA_BITS - 3))
#else
#define KASAN_SHADOW_SIZE (0)
#endif
/*
* Physical vs virtual RAM address space conversion. These are
* private definitions which should NOT be used outside memory.h