forked from Minki/linux
arm64: kaslr: randomize the linear region
When KASLR is enabled (CONFIG_RANDOMIZE_BASE=y), and entropy has been provided by the bootloader, randomize the placement of RAM inside the linear region if sufficient space is available. For instance, on a 4KB granule/3 levels kernel, the linear region is 256 GB in size, and we can choose any 1 GB aligned offset that is far enough from the top of the address space to fit the distance between the start of the lowest memblock and the top of the highest memblock. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
parent
f80fb3a3d5
commit
c031a4213c
@ -21,6 +21,7 @@
|
||||
#include <asm/sections.h>
|
||||
|
||||
u64 __read_mostly module_alloc_base;
|
||||
u16 __initdata memstart_offset_seed;
|
||||
|
||||
static __init u64 get_kaslr_seed(void *fdt)
|
||||
{
|
||||
@ -123,6 +124,9 @@ u64 __init kaslr_early_init(u64 dt_phys)
|
||||
mask = ((1UL << (VA_BITS - 2)) - 1) & ~(SZ_2M - 1);
|
||||
offset = seed & mask;
|
||||
|
||||
/* use the top 16 bits to randomize the linear region */
|
||||
memstart_offset_seed = seed >> 48;
|
||||
|
||||
/*
|
||||
* The kernel Image should not extend across a 1GB/32MB/512MB alignment
|
||||
* boundary (for 4KB/16KB/64KB granule kernels, respectively). If this
|
||||
|
@ -196,6 +196,23 @@ void __init arm64_memblock_init(void)
|
||||
memblock_add(__pa(_text), (u64)(_end - _text));
|
||||
}
|
||||
|
||||
if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
|
||||
extern u16 memstart_offset_seed;
|
||||
u64 range = linear_region_size -
|
||||
(memblock_end_of_DRAM() - memblock_start_of_DRAM());
|
||||
|
||||
/*
|
||||
* If the size of the linear region exceeds, by a sufficient
|
||||
* margin, the size of the region that the available physical
|
||||
* memory spans, randomize the linear region as well.
|
||||
*/
|
||||
if (memstart_offset_seed > 0 && range >= ARM64_MEMSTART_ALIGN) {
|
||||
range = range / ARM64_MEMSTART_ALIGN + 1;
|
||||
memstart_addr -= ARM64_MEMSTART_ALIGN *
|
||||
((range * memstart_offset_seed) >> 16);
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Register the kernel text, kernel data, initrd, and initial
|
||||
* pagetables with memblock.
|
||||
@ -365,12 +382,13 @@ void __init mem_init(void)
|
||||
#ifdef CONFIG_SPARSEMEM_VMEMMAP
|
||||
MLG((unsigned long)vmemmap,
|
||||
(unsigned long)vmemmap + VMEMMAP_SIZE),
|
||||
MLM((unsigned long)virt_to_page(PAGE_OFFSET),
|
||||
MLM((unsigned long)phys_to_page(memblock_start_of_DRAM()),
|
||||
(unsigned long)virt_to_page(high_memory)),
|
||||
#endif
|
||||
MLK(FIXADDR_START, FIXADDR_TOP),
|
||||
MLM(PCI_IO_START, PCI_IO_END),
|
||||
MLM(PAGE_OFFSET, (unsigned long)high_memory));
|
||||
MLM(__phys_to_virt(memblock_start_of_DRAM()),
|
||||
(unsigned long)high_memory));
|
||||
|
||||
#undef MLK
|
||||
#undef MLM
|
||||
|
Loading…
Reference in New Issue
Block a user