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Commit be8a0705 authored by Andrey Ryabinin's avatar Andrey Ryabinin Committed by Alex Shi
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x86/kasan, mm: Introduce generic kasan_populate_zero_shadow() 



Introduce generic kasan_populate_zero_shadow(shadow_start,
shadow_end). This function maps kasan_zero_page to the
[shadow_start, shadow_end] addresses.

This replaces x86_64 specific populate_zero_shadow() and will
be used for ARM64 in follow on patches.

The main changes from original version are:

 * Use p?d_populate*() instead of set_p?d()
 * Use memblock allocator directly instead of vmemmap_alloc_block()
 * __pa() instead of __pa_nodebug(). __pa() causes troubles
   iff we use it before kasan_early_init(). kasan_populate_zero_shadow()
   will be used later, so we ok with __pa() here.

Signed-off-by: default avatarAndrey Ryabinin <ryabinin.a.a@gmail.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alexey Klimov <klimov.linux@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Keitel <dkeitel@codeaurora.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yury <yury.norov@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/1439444244-26057-3-git-send-email-ryabinin.a.a@gmail.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
(cherry picked from commit 69786cdb379bbc6eab14cf2393c1abd879316e85)
Signed-off-by: default avatarAlex Shi <alex.shi@linaro.org>

Conflicts:
	don't care arch/x86/mm/kasan_init_64.c
parent 157612eb

arch/x86/mm/kasan_init_64.c

+5 −4
Original line number Diff line number Diff line
@@ -179,7 +179,7 @@ void __init kasan_init(void) 


	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);



	populate_zero_shadow((void *)KASAN_SHADOW_START,

	kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,

			kasan_mem_to_shadow((void *)PAGE_OFFSET));



	for (i = 0; i < E820_X_MAX; i++) {
@@ -189,14 +189,15 @@ void __init kasan_init(void) 
		if (map_range(&pfn_mapped[i]))

			panic("kasan: unable to allocate shadow!");

	}

	populate_zero_shadow(kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),

	kasan_populate_zero_shadow(

		kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),

		kasan_mem_to_shadow((void *)__START_KERNEL_map));



	vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext),

			(unsigned long)kasan_mem_to_shadow(_end),

			NUMA_NO_NODE);



	populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),

	kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),

			(void *)KASAN_SHADOW_END);



	memset(kasan_zero_page, 0, PAGE_SIZE);

include/linux/kasan.h

+9 −0
Original line number Diff line number Diff line
@@ -12,8 +12,17 @@ struct vm_struct; 
#define KASAN_SHADOW_SCALE_SHIFT 3



#include <asm/kasan.h>

#include <asm/pgtable.h>

#include <linux/sched.h>



extern unsigned char kasan_zero_page[PAGE_SIZE];

extern pte_t kasan_zero_pte[PTRS_PER_PTE];

extern pmd_t kasan_zero_pmd[PTRS_PER_PMD];

extern pud_t kasan_zero_pud[PTRS_PER_PUD];



void kasan_populate_zero_shadow(const void *shadow_start,

				const void *shadow_end);



static inline void *kasan_mem_to_shadow(const void *addr)

{

	return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)

mm/kasan/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -5,4 +5,4 @@ CFLAGS_REMOVE_kasan.o = -pg 
# see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533

CFLAGS_kasan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)



obj-y := kasan.o report.o
 
obj-y := kasan.o report.o kasan_init.o

mm/kasan/kasan_init.c

0 → 100644
+152 −0
Original line number Diff line number Diff line 
/*

 * This file contains some kasan initialization code.

 *

 * Copyright (c) 2015 Samsung Electronics Co., Ltd.

 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 */



#include <linux/bootmem.h>

#include <linux/init.h>

#include <linux/kasan.h>

#include <linux/kernel.h>

#include <linux/memblock.h>

#include <linux/pfn.h>



#include <asm/page.h>

#include <asm/pgalloc.h>



/*

 * This page serves two purposes:

 *   - It used as early shadow memory. The entire shadow region populated

 *     with this page, before we will be able to setup normal shadow memory.

 *   - Latter it reused it as zero shadow to cover large ranges of memory

 *     that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).

 */

unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;



#if CONFIG_PGTABLE_LEVELS > 3

pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;

#endif

#if CONFIG_PGTABLE_LEVELS > 2

pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;

#endif

pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;



static __init void *early_alloc(size_t size, int node)

{

	return memblock_virt_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),

					BOOTMEM_ALLOC_ACCESSIBLE, node);

}



static void __init zero_pte_populate(pmd_t *pmd, unsigned long addr,

				unsigned long end)

{

	pte_t *pte = pte_offset_kernel(pmd, addr);

	pte_t zero_pte;



	zero_pte = pfn_pte(PFN_DOWN(__pa(kasan_zero_page)), PAGE_KERNEL);

	zero_pte = pte_wrprotect(zero_pte);



	while (addr + PAGE_SIZE <= end) {

		set_pte_at(&init_mm, addr, pte, zero_pte);

		addr += PAGE_SIZE;

		pte = pte_offset_kernel(pmd, addr);

	}

}



static void __init zero_pmd_populate(pud_t *pud, unsigned long addr,

				unsigned long end)

{

	pmd_t *pmd = pmd_offset(pud, addr);

	unsigned long next;



	do {

		next = pmd_addr_end(addr, end);



		if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {

			pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);

			continue;

		}



		if (pmd_none(*pmd)) {

			pmd_populate_kernel(&init_mm, pmd,

					early_alloc(PAGE_SIZE, NUMA_NO_NODE));

		}

		zero_pte_populate(pmd, addr, next);

	} while (pmd++, addr = next, addr != end);

}



static void __init zero_pud_populate(pgd_t *pgd, unsigned long addr,

				unsigned long end)

{

	pud_t *pud = pud_offset(pgd, addr);

	unsigned long next;



	do {

		next = pud_addr_end(addr, end);

		if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {

			pmd_t *pmd;



			pud_populate(&init_mm, pud, kasan_zero_pmd);

			pmd = pmd_offset(pud, addr);

			pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);

			continue;

		}



		if (pud_none(*pud)) {

			pud_populate(&init_mm, pud,

				early_alloc(PAGE_SIZE, NUMA_NO_NODE));

		}

		zero_pmd_populate(pud, addr, next);

	} while (pud++, addr = next, addr != end);

}



/**

 * kasan_populate_zero_shadow - populate shadow memory region with

 *                               kasan_zero_page

 * @shadow_start - start of the memory range to populate

 * @shadow_end   - end of the memory range to populate

 */

void __init kasan_populate_zero_shadow(const void *shadow_start,

				const void *shadow_end)

{

	unsigned long addr = (unsigned long)shadow_start;

	unsigned long end = (unsigned long)shadow_end;

	pgd_t *pgd = pgd_offset_k(addr);

	unsigned long next;



	do {

		next = pgd_addr_end(addr, end);



		if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {

			pud_t *pud;

			pmd_t *pmd;



			/*

			 * kasan_zero_pud should be populated with pmds

			 * at this moment.

			 * [pud,pmd]_populate*() below needed only for

			 * 3,2 - level page tables where we don't have

			 * puds,pmds, so pgd_populate(), pud_populate()

			 * is noops.

			 */

			pgd_populate(&init_mm, pgd, kasan_zero_pud);

			pud = pud_offset(pgd, addr);

			pud_populate(&init_mm, pud, kasan_zero_pmd);

			pmd = pmd_offset(pud, addr);

			pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);

			continue;

		}



		if (pgd_none(*pgd)) {

			pgd_populate(&init_mm, pgd,

				early_alloc(PAGE_SIZE, NUMA_NO_NODE));

		}

		zero_pud_populate(pgd, addr, next);

	} while (pgd++, addr = next, addr != end);

}