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Commit 8624c1f6 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Ingo Molnar
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x86/mm: Add support for 5-level paging for KASLR 



With 5-level paging randomization happens on P4D level instead of PUD.

Maximum amount of physical memory also bumped to 52-bits for 5-level
paging.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170606113133.22974-13-kirill.shutemov@linux.intel.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 7e82ea94

arch/x86/mm/kaslr.c

+62 −19
Original line number Original line Diff line number Diff line
@@ -6,12 +6,12 @@ 
 *

 *

 * Entropy is generated using the KASLR early boot functions now shared in

 * Entropy is generated using the KASLR early boot functions now shared in

 * the lib directory (originally written by Kees Cook). Randomization is

 * the lib directory (originally written by Kees Cook). Randomization is

 * done on PGD & PUD page table levels to increase possible addresses. The

 * done on PGD & P4D/PUD page table levels to increase possible addresses.

 * physical memory mapping code was adapted to support PUD level virtual

 * The physical memory mapping code was adapted to support P4D/PUD level

 * addresses. This implementation on the best configuration provides 30,000

 * virtual addresses. This implementation on the best configuration provides

 * possible virtual addresses in average for each memory region. An additional

 * 30,000 possible virtual addresses in average for each memory region.

 * low memory page is used to ensure each CPU can start with a PGD aligned

 * An additional low memory page is used to ensure each CPU can start with

 * virtual address (for realmode).

 * a PGD aligned virtual address (for realmode).

 *

 *

 * The order of each memory region is not changed. The feature looks at

 * The order of each memory region is not changed. The feature looks at

 * the available space for the regions based on different configuration

 * the available space for the regions based on different configuration
@@ -70,7 +70,7 @@ static __initdata struct kaslr_memory_region { 
	unsigned long *base;

	unsigned long *base;

	unsigned long size_tb;

	unsigned long size_tb;

} kaslr_regions[] = {

} kaslr_regions[] = {

	{ &page_offset_base, 64/* Maximum */ },

	{ &page_offset_base, 1 << (__PHYSICAL_MASK_SHIFT - TB_SHIFT) /* Maximum */ },

	{ &vmalloc_base, VMALLOC_SIZE_TB },

	{ &vmalloc_base, VMALLOC_SIZE_TB },

	{ &vmemmap_base, 1 },

	{ &vmemmap_base, 1 },

};

};
@@ -142,6 +142,9 @@ void __init kernel_randomize_memory(void) 
		 */

		 */

		entropy = remain_entropy / (ARRAY_SIZE(kaslr_regions) - i);

		entropy = remain_entropy / (ARRAY_SIZE(kaslr_regions) - i);

		prandom_bytes_state(&rand_state, &rand, sizeof(rand));

		prandom_bytes_state(&rand_state, &rand, sizeof(rand));

		if (IS_ENABLED(CONFIG_X86_5LEVEL))

			entropy = (rand % (entropy + 1)) & P4D_MASK;

		else

			entropy = (rand % (entropy + 1)) & PUD_MASK;

			entropy = (rand % (entropy + 1)) & PUD_MASK;

		vaddr += entropy;

		vaddr += entropy;

		*kaslr_regions[i].base = vaddr;

		*kaslr_regions[i].base = vaddr;
@@ -151,27 +154,21 @@ void __init kernel_randomize_memory(void) 
		 * randomization alignment.

		 * randomization alignment.

		 */

		 */

		vaddr += get_padding(&kaslr_regions[i]);

		vaddr += get_padding(&kaslr_regions[i]);

		if (IS_ENABLED(CONFIG_X86_5LEVEL))

			vaddr = round_up(vaddr + 1, P4D_SIZE);

		else

			vaddr = round_up(vaddr + 1, PUD_SIZE);

			vaddr = round_up(vaddr + 1, PUD_SIZE);

		remain_entropy -= entropy;

		remain_entropy -= entropy;

	}

	}

}

}





/*

static void __meminit init_trampoline_pud(void)

 * Create PGD aligned trampoline table to allow real mode initialization

 * of additional CPUs. Consume only 1 low memory page.

 */

void __meminit init_trampoline(void)

{

{

	unsigned long paddr, paddr_next;

	unsigned long paddr, paddr_next;

	pgd_t *pgd;

	pgd_t *pgd;

	pud_t *pud_page, *pud_page_tramp;

	pud_t *pud_page, *pud_page_tramp;

	int i;

	int i;





	if (!kaslr_memory_enabled()) {

		init_trampoline_default();

		return;

	}



	pud_page_tramp = alloc_low_page();

	pud_page_tramp = alloc_low_page();





	paddr = 0;

	paddr = 0;
@@ -192,3 +189,49 @@ void __meminit init_trampoline(void) 
	set_pgd(&trampoline_pgd_entry,

	set_pgd(&trampoline_pgd_entry,

		__pgd(_KERNPG_TABLE | __pa(pud_page_tramp)));

		__pgd(_KERNPG_TABLE | __pa(pud_page_tramp)));

}

}



static void __meminit init_trampoline_p4d(void)

{

	unsigned long paddr, paddr_next;

	pgd_t *pgd;

	p4d_t *p4d_page, *p4d_page_tramp;

	int i;



	p4d_page_tramp = alloc_low_page();



	paddr = 0;

	pgd = pgd_offset_k((unsigned long)__va(paddr));

	p4d_page = (p4d_t *) pgd_page_vaddr(*pgd);



	for (i = p4d_index(paddr); i < PTRS_PER_P4D; i++, paddr = paddr_next) {

		p4d_t *p4d, *p4d_tramp;

		unsigned long vaddr = (unsigned long)__va(paddr);



		p4d_tramp = p4d_page_tramp + p4d_index(paddr);

		p4d = p4d_page + p4d_index(vaddr);

		paddr_next = (paddr & P4D_MASK) + P4D_SIZE;



		*p4d_tramp = *p4d;

	}



	set_pgd(&trampoline_pgd_entry,

		__pgd(_KERNPG_TABLE | __pa(p4d_page_tramp)));

}



/*

 * Create PGD aligned trampoline table to allow real mode initialization

 * of additional CPUs. Consume only 1 low memory page.

 */

void __meminit init_trampoline(void)

{



	if (!kaslr_memory_enabled()) {

		init_trampoline_default();

		return;

	}



	if (IS_ENABLED(CONFIG_X86_5LEVEL))

		init_trampoline_p4d();

	else

		init_trampoline_pud();

}