A 5-level paging capable machine can have memory above 46-bit in the physical address space. This memory is only addressable in the 5-level paging mode: we don't have enough virtual address space to create direct mapping for such memory in the 4-level paging mode
Teach KASLR to avoid memory regions above MAXMEM or truncate the region if the end is above MAXMEM.
Signed-off-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Reviewed-by: Dave Hansen dave.hansen@intel.com Cc: stable@vger.kernel.org # v4.14 --- arch/x86/boot/compressed/kaslr.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index d7408af55738..99db18eeb40e 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -695,7 +695,18 @@ static bool process_mem_region(struct mem_vector *region, unsigned long long minimum, unsigned long long image_size) { + unsigned long long end; int i; + + /* Cannot access memory region above MAXMEM: skip it. */ + if (region->start >= MAXMEM) + return 0; + + /* Truncate the region if the end is above MAXMEM */ + end = region->start + region->size; + end = min_t(unsigned long long, end, MAXMEM - 1); + region->size = end - region->start; + /* * If no immovable memory found, or MEMORY_HOTREMOVE disabled, * use @region directly.