On Mon, Jun 08, 2020 at 03:54:24PM +0300, Kirill A. Shutemov wrote:

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

Reviewed-by: Mike Rapoport rppt@linux.ibm.com

---

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.

-- 2.26.2