arch/s390/mm/kasan_init.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #include <linux/kasan.h>
 #include <linux/sched/task.h>
 #include <linux/pgtable.h>
 #include <asm/pgalloc.h>
 #include <asm/kasan.h>
 #include <asm/mem_detect.h>
 #include <asm/processor.h>
 #include <asm/sclp.h>
 #include <asm/facility.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/uv.h>

 static unsigned long segment_pos __initdata;
 static unsigned long segment_low __initdata;
 static bool has_edat __initdata;
 static bool has_nx __initdata;

 #define __sha(x) ((unsigned long)kasan_mem_to_shadow((void *)x))

 static void __init kasan_early_panic(const char *reason)
 {
 	sclp_early_printk("The Linux kernel failed to boot with the KernelAddressSanitizer:\n");
 	sclp_early_printk(reason);
 	disabled_wait();
 }

 static void * __init kasan_early_alloc_segment(void)
 {
 	segment_pos -= _SEGMENT_SIZE;

 	if (segment_pos < segment_low)
 		kasan_early_panic("out of memory during initialisation\n");

 	return __va(segment_pos);
 }

 static void * __init kasan_early_alloc_pages(unsigned int order)
 {
 	pgalloc_pos -= (PAGE_SIZE << order);

 	if (pgalloc_pos < pgalloc_low)
 		kasan_early_panic("out of memory during initialisation\n");

 	return __va(pgalloc_pos);
 }

 static void * __init kasan_early_crst_alloc(unsigned long val)
 {
 	unsigned long *table;

 	table = kasan_early_alloc_pages(CRST_ALLOC_ORDER);
 	if (table)
 		crst_table_init(table, val);
 	return table;
 }

 static pte_t * __init kasan_early_pte_alloc(void)
 {
 	static void *pte_leftover;
 	pte_t *pte;

 	BUILD_BUG_ON(_PAGE_TABLE_SIZE * 2 != PAGE_SIZE);

 	if (!pte_leftover) {
 		pte_leftover = kasan_early_alloc_pages(0);
 		pte = pte_leftover + _PAGE_TABLE_SIZE;
 	} else {
 		pte = pte_leftover;
 		pte_leftover = NULL;
 	}
 	memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
 	return pte;
 }

 enum populate_mode {
 	POPULATE_MAP,
 	POPULATE_ZERO_SHADOW,
 	POPULATE_SHALLOW
 };

 static inline pgprot_t pgprot_clear_bit(pgprot_t pgprot, unsigned long bit)
 {
 	return __pgprot(pgprot_val(pgprot) & ~bit);
 }

 static void __init kasan_early_pgtable_populate(unsigned long address,
 						unsigned long end,
 						enum populate_mode mode)
 {
 	pgprot_t pgt_prot_zero = PAGE_KERNEL_RO;
 	pgprot_t pgt_prot = PAGE_KERNEL;
 	pgprot_t sgt_prot = SEGMENT_KERNEL;
 	pgd_t *pg_dir;
 	p4d_t *p4_dir;
 	pud_t *pu_dir;
 	pmd_t *pm_dir;
 	pte_t *pt_dir;
 	pmd_t pmd;
 	pte_t pte;

 	if (!has_nx) {
 		pgt_prot_zero = pgprot_clear_bit(pgt_prot_zero, _PAGE_NOEXEC);
 		pgt_prot = pgprot_clear_bit(pgt_prot, _PAGE_NOEXEC);
 		sgt_prot = pgprot_clear_bit(sgt_prot, _SEGMENT_ENTRY_NOEXEC);
 	}

 	while (address < end) {
 		pg_dir = pgd_offset_k(address);
 		if (pgd_none(*pg_dir)) {
 			if (mode == POPULATE_ZERO_SHADOW &&
 			    IS_ALIGNED(address, PGDIR_SIZE) &&
 			    end - address >= PGDIR_SIZE) {
 				pgd_populate(&init_mm, pg_dir,
 						kasan_early_shadow_p4d);
 				address = (address + PGDIR_SIZE) & PGDIR_MASK;
 				continue;
 			}
 			p4_dir = kasan_early_crst_alloc(_REGION2_ENTRY_EMPTY);
 			pgd_populate(&init_mm, pg_dir, p4_dir);
 		}

 		if (mode == POPULATE_SHALLOW) {
 			address = (address + P4D_SIZE) & P4D_MASK;
 			continue;
 		}

 		p4_dir = p4d_offset(pg_dir, address);
 		if (p4d_none(*p4_dir)) {
 			if (mode == POPULATE_ZERO_SHADOW &&
 			    IS_ALIGNED(address, P4D_SIZE) &&
 			    end - address >= P4D_SIZE) {
 				p4d_populate(&init_mm, p4_dir,
 						kasan_early_shadow_pud);
 				address = (address + P4D_SIZE) & P4D_MASK;
 				continue;
 			}
 			pu_dir = kasan_early_crst_alloc(_REGION3_ENTRY_EMPTY);
 			p4d_populate(&init_mm, p4_dir, pu_dir);
 		}

 		pu_dir = pud_offset(p4_dir, address);
 		if (pud_none(*pu_dir)) {
 			if (mode == POPULATE_ZERO_SHADOW &&
 			    IS_ALIGNED(address, PUD_SIZE) &&
 			    end - address >= PUD_SIZE) {
 				pud_populate(&init_mm, pu_dir,
 						kasan_early_shadow_pmd);
 				address = (address + PUD_SIZE) & PUD_MASK;
 				continue;
 			}
 			pm_dir = kasan_early_crst_alloc(_SEGMENT_ENTRY_EMPTY);
 			pud_populate(&init_mm, pu_dir, pm_dir);
 		}

 		pm_dir = pmd_offset(pu_dir, address);
 		if (pmd_none(*pm_dir)) {
 			if (IS_ALIGNED(address, PMD_SIZE) &&
 			    end - address >= PMD_SIZE) {
 				if (mode == POPULATE_ZERO_SHADOW) {
 					pmd_populate(&init_mm, pm_dir, kasan_early_shadow_pte);
 					address = (address + PMD_SIZE) & PMD_MASK;
 					continue;
 				} else if (has_edat) {
 					void *page = kasan_early_alloc_segment();

 					memset(page, 0, _SEGMENT_SIZE);
 					pmd = __pmd(__pa(page));
 					pmd = set_pmd_bit(pmd, sgt_prot);
 					set_pmd(pm_dir, pmd);
 					address = (address + PMD_SIZE) & PMD_MASK;
 					continue;
 				}
 			}
 			pt_dir = kasan_early_pte_alloc();
 			pmd_populate(&init_mm, pm_dir, pt_dir);
 		} else if (pmd_large(*pm_dir)) {
 			address = (address + PMD_SIZE) & PMD_MASK;
 			continue;
 		}

 		pt_dir = pte_offset_kernel(pm_dir, address);
 		if (pte_none(*pt_dir)) {
 			void *page;

 			switch (mode) {
 			case POPULATE_MAP:
 				page = kasan_early_alloc_pages(0);
 				memset(page, 0, PAGE_SIZE);
 				pte = __pte(__pa(page));
 				pte = set_pte_bit(pte, pgt_prot);
 				set_pte(pt_dir, pte);
 				break;
 			case POPULATE_ZERO_SHADOW:
 				page = kasan_early_shadow_page;
 				pte = __pte(__pa(page));
 				pte = set_pte_bit(pte, pgt_prot_zero);
 				set_pte(pt_dir, pte);
 				break;
 			case POPULATE_SHALLOW:
 				/* should never happen */
 				break;
 			}
 		}
 		address += PAGE_SIZE;
 	}
 }

 static void __init kasan_early_detect_facilities(void)
 {
 	if (test_facility(8)) {
 		has_edat = true;
 		__ctl_set_bit(0, 23);
 	}
 	if (!noexec_disabled && test_facility(130)) {
 		has_nx = true;
 		__ctl_set_bit(0, 20);
 	}
 }

 void __init kasan_early_init(void)
 {
 	pte_t pte_z = __pte(__pa(kasan_early_shadow_page) | pgprot_val(PAGE_KERNEL_RO));
 	pmd_t pmd_z = __pmd(__pa(kasan_early_shadow_pte) | _SEGMENT_ENTRY);
 	pud_t pud_z = __pud(__pa(kasan_early_shadow_pmd) | _REGION3_ENTRY);
 	p4d_t p4d_z = __p4d(__pa(kasan_early_shadow_pud) | _REGION2_ENTRY);
 	unsigned long untracked_end = MODULES_VADDR;
 	unsigned long shadow_alloc_size;
 	unsigned long start, end;
 	int i;

 	kasan_early_detect_facilities();
 	if (!has_nx)
 		pte_z = clear_pte_bit(pte_z, __pgprot(_PAGE_NOEXEC));

 	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE));
 	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE));

 	/* init kasan zero shadow */
 	crst_table_init((unsigned long *)kasan_early_shadow_p4d, p4d_val(p4d_z));
 	crst_table_init((unsigned long *)kasan_early_shadow_pud, pud_val(pud_z));
 	crst_table_init((unsigned long *)kasan_early_shadow_pmd, pmd_val(pmd_z));
 	memset64((u64 *)kasan_early_shadow_pte, pte_val(pte_z), PTRS_PER_PTE);

 	if (has_edat) {
 		shadow_alloc_size = get_mem_detect_usable_total() >> KASAN_SHADOW_SCALE_SHIFT;
 		segment_pos = round_down(pgalloc_pos, _SEGMENT_SIZE);
 		segment_low = segment_pos - shadow_alloc_size;
 		segment_low = round_down(segment_low, _SEGMENT_SIZE);
 		pgalloc_pos = segment_low;
 	}
 	/*
 	 * Current memory layout:
 	 * +- 0 -------------+	       +- shadow start -+
 	 * |1:1 ident mapping|	      /|1/8 of ident map|
 	 * |		     |	     / |		|
 	 * +-end of ident map+	    /  +----------------+
 	 * | ... gap ...     |	   /   |    kasan	|
 	 * |		     |	  /    |  zero page	|
 	 * +- vmalloc area  -+	 /     |   mapping	|
 	 * | vmalloc_size    |	/      | (untracked)	|
 	 * +- modules vaddr -+ /       +----------------+
 	 * | 2Gb	     |/        |    unmapped	| allocated per module
 	 * +- shadow start  -+	       +----------------+
 	 * | 1/8 addr space  |	       | zero pg mapping| (untracked)
 	 * +- shadow end ----+---------+- shadow end ---+
 	 *
 	 * Current memory layout (KASAN_VMALLOC):
 	 * +- 0 -------------+	       +- shadow start -+
 	 * |1:1 ident mapping|	      /|1/8 of ident map|
 	 * |		     |	     / |		|
 	 * +-end of ident map+	    /  +----------------+
 	 * | ... gap ...     |	   /   | kasan zero page| (untracked)
 	 * |		     |	  /    | mapping	|
 	 * +- vmalloc area  -+	 /     +----------------+
 	 * | vmalloc_size    |	/      |shallow populate|
 	 * +- modules vaddr -+ /       +----------------+
 	 * | 2Gb	     |/        |shallow populate|
 	 * +- shadow start  -+	       +----------------+
 	 * | 1/8 addr space  |	       | zero pg mapping| (untracked)
 	 * +- shadow end ----+---------+- shadow end ---+
 	 */
 	/* populate kasan shadow (for identity mapping and zero page mapping) */
 	for_each_mem_detect_usable_block(i, &start, &end)
 		kasan_early_pgtable_populate(__sha(start), __sha(end), POPULATE_MAP);
 	if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
 		untracked_end = VMALLOC_START;
 		/* shallowly populate kasan shadow for vmalloc and modules */
 		kasan_early_pgtable_populate(__sha(VMALLOC_START), __sha(MODULES_END),
 					     POPULATE_SHALLOW);
 	}
 	/* populate kasan shadow for untracked memory */
 	kasan_early_pgtable_populate(__sha(ident_map_size), __sha(untracked_end),
 				     POPULATE_ZERO_SHADOW);
 	kasan_early_pgtable_populate(__sha(MODULES_END), __sha(_REGION1_SIZE),
 				     POPULATE_ZERO_SHADOW);
 	/* enable kasan */
 	init_task.kasan_depth = 0;
 	sclp_early_printk("KernelAddressSanitizer initialized\n");
 }
	// SPDX-License-Identifier: GPL-2.0
	#include <linux/kasan.h>
	#include <linux/sched/task.h>
	#include <linux/pgtable.h>
	#include <asm/pgalloc.h>
	#include <asm/kasan.h>
	#include <asm/mem_detect.h>
	#include <asm/processor.h>
	#include <asm/sclp.h>
	#include <asm/facility.h>
	#include <asm/sections.h>
	#include <asm/setup.h>
	#include <asm/uv.h>

	static unsigned long segment_pos __initdata;
	static unsigned long segment_low __initdata;
	static bool has_edat __initdata;
	static bool has_nx __initdata;

	#define __sha(x) ((unsigned long)kasan_mem_to_shadow((void *)x))

	static void __init kasan_early_panic(const char *reason)
	{
	sclp_early_printk("The Linux kernel failed to boot with the KernelAddressSanitizer:\n");
	sclp_early_printk(reason);
	disabled_wait();
	}

	static void * __init kasan_early_alloc_segment(void)
	{
	segment_pos -= _SEGMENT_SIZE;

	if (segment_pos < segment_low)
	kasan_early_panic("out of memory during initialisation\n");

	return __va(segment_pos);
	}

	static void * __init kasan_early_alloc_pages(unsigned int order)
	{
	pgalloc_pos -= (PAGE_SIZE << order);

	if (pgalloc_pos < pgalloc_low)
	kasan_early_panic("out of memory during initialisation\n");

	return __va(pgalloc_pos);
	}

	static void * __init kasan_early_crst_alloc(unsigned long val)
	{
	unsigned long *table;

	table = kasan_early_alloc_pages(CRST_ALLOC_ORDER);
	if (table)
	crst_table_init(table, val);
	return table;
	}

	static pte_t * __init kasan_early_pte_alloc(void)
	{
	static void *pte_leftover;
	pte_t *pte;

	BUILD_BUG_ON(_PAGE_TABLE_SIZE * 2 != PAGE_SIZE);

	if (!pte_leftover) {
	pte_leftover = kasan_early_alloc_pages(0);
	pte = pte_leftover + _PAGE_TABLE_SIZE;
	} else {
	pte = pte_leftover;
	pte_leftover = NULL;
	}
	memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
	return pte;
	}

	enum populate_mode {
	POPULATE_MAP,
	POPULATE_ZERO_SHADOW,
	POPULATE_SHALLOW
	};

	static inline pgprot_t pgprot_clear_bit(pgprot_t pgprot, unsigned long bit)
	{
	return __pgprot(pgprot_val(pgprot) & ~bit);
	}

	static void __init kasan_early_pgtable_populate(unsigned long address,
	unsigned long end,
	enum populate_mode mode)
	{
	pgprot_t pgt_prot_zero = PAGE_KERNEL_RO;
	pgprot_t pgt_prot = PAGE_KERNEL;
	pgprot_t sgt_prot = SEGMENT_KERNEL;
	pgd_t *pg_dir;
	p4d_t *p4_dir;
	pud_t *pu_dir;
	pmd_t *pm_dir;
	pte_t *pt_dir;
	pmd_t pmd;
	pte_t pte;

	if (!has_nx) {
	pgt_prot_zero = pgprot_clear_bit(pgt_prot_zero, _PAGE_NOEXEC);
	pgt_prot = pgprot_clear_bit(pgt_prot, _PAGE_NOEXEC);
	sgt_prot = pgprot_clear_bit(sgt_prot, _SEGMENT_ENTRY_NOEXEC);
	}

	while (address < end) {
	pg_dir = pgd_offset_k(address);
	if (pgd_none(*pg_dir)) {
	if (mode == POPULATE_ZERO_SHADOW &&
	IS_ALIGNED(address, PGDIR_SIZE) &&
	end - address >= PGDIR_SIZE) {
	pgd_populate(&init_mm, pg_dir,
	kasan_early_shadow_p4d);
	address = (address + PGDIR_SIZE) & PGDIR_MASK;
	continue;
	}
	p4_dir = kasan_early_crst_alloc(_REGION2_ENTRY_EMPTY);
	pgd_populate(&init_mm, pg_dir, p4_dir);
	}

	if (mode == POPULATE_SHALLOW) {
	address = (address + P4D_SIZE) & P4D_MASK;
	continue;
	}

	p4_dir = p4d_offset(pg_dir, address);
	if (p4d_none(*p4_dir)) {
	if (mode == POPULATE_ZERO_SHADOW &&
	IS_ALIGNED(address, P4D_SIZE) &&
	end - address >= P4D_SIZE) {
	p4d_populate(&init_mm, p4_dir,
	kasan_early_shadow_pud);
	address = (address + P4D_SIZE) & P4D_MASK;
	continue;
	}
	pu_dir = kasan_early_crst_alloc(_REGION3_ENTRY_EMPTY);
	p4d_populate(&init_mm, p4_dir, pu_dir);
	}

	pu_dir = pud_offset(p4_dir, address);
	if (pud_none(*pu_dir)) {
	if (mode == POPULATE_ZERO_SHADOW &&
	IS_ALIGNED(address, PUD_SIZE) &&
	end - address >= PUD_SIZE) {
	pud_populate(&init_mm, pu_dir,
	kasan_early_shadow_pmd);
	address = (address + PUD_SIZE) & PUD_MASK;
	continue;
	}
	pm_dir = kasan_early_crst_alloc(_SEGMENT_ENTRY_EMPTY);
	pud_populate(&init_mm, pu_dir, pm_dir);
	}

	pm_dir = pmd_offset(pu_dir, address);
	if (pmd_none(*pm_dir)) {
	if (IS_ALIGNED(address, PMD_SIZE) &&
	end - address >= PMD_SIZE) {
	if (mode == POPULATE_ZERO_SHADOW) {
	pmd_populate(&init_mm, pm_dir, kasan_early_shadow_pte);
	address = (address + PMD_SIZE) & PMD_MASK;
	continue;
	} else if (has_edat) {
	void *page = kasan_early_alloc_segment();

	memset(page, 0, _SEGMENT_SIZE);
	pmd = __pmd(__pa(page));
	pmd = set_pmd_bit(pmd, sgt_prot);
	set_pmd(pm_dir, pmd);
	address = (address + PMD_SIZE) & PMD_MASK;
	continue;
	}
	}
	pt_dir = kasan_early_pte_alloc();
	pmd_populate(&init_mm, pm_dir, pt_dir);
	} else if (pmd_large(*pm_dir)) {
	address = (address + PMD_SIZE) & PMD_MASK;
	continue;
	}

	pt_dir = pte_offset_kernel(pm_dir, address);
	if (pte_none(*pt_dir)) {
	void *page;

	switch (mode) {
	case POPULATE_MAP:
	page = kasan_early_alloc_pages(0);
	memset(page, 0, PAGE_SIZE);
	pte = __pte(__pa(page));
	pte = set_pte_bit(pte, pgt_prot);
	set_pte(pt_dir, pte);
	break;
	case POPULATE_ZERO_SHADOW:
	page = kasan_early_shadow_page;
	pte = __pte(__pa(page));
	pte = set_pte_bit(pte, pgt_prot_zero);
	set_pte(pt_dir, pte);
	break;
	case POPULATE_SHALLOW:
	/* should never happen */
	break;
	}
	}
	address += PAGE_SIZE;
	}
	}

	static void __init kasan_early_detect_facilities(void)
	{
	if (test_facility(8)) {
	has_edat = true;
	__ctl_set_bit(0, 23);
	}
	if (!noexec_disabled && test_facility(130)) {
	has_nx = true;
	__ctl_set_bit(0, 20);
	}
	}

	void __init kasan_early_init(void)
	{
	pte_t pte_z = __pte(__pa(kasan_early_shadow_page) \| pgprot_val(PAGE_KERNEL_RO));
	pmd_t pmd_z = __pmd(__pa(kasan_early_shadow_pte) \| _SEGMENT_ENTRY);
	pud_t pud_z = __pud(__pa(kasan_early_shadow_pmd) \| _REGION3_ENTRY);
	p4d_t p4d_z = __p4d(__pa(kasan_early_shadow_pud) \| _REGION2_ENTRY);
	unsigned long untracked_end = MODULES_VADDR;
	unsigned long shadow_alloc_size;
	unsigned long start, end;
	int i;

	kasan_early_detect_facilities();
	if (!has_nx)
	pte_z = clear_pte_bit(pte_z, __pgprot(_PAGE_NOEXEC));

	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE));
	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE));

	/* init kasan zero shadow */
	crst_table_init((unsigned long *)kasan_early_shadow_p4d, p4d_val(p4d_z));
	crst_table_init((unsigned long *)kasan_early_shadow_pud, pud_val(pud_z));
	crst_table_init((unsigned long *)kasan_early_shadow_pmd, pmd_val(pmd_z));
	memset64((u64 *)kasan_early_shadow_pte, pte_val(pte_z), PTRS_PER_PTE);

	if (has_edat) {
	shadow_alloc_size = get_mem_detect_usable_total() >> KASAN_SHADOW_SCALE_SHIFT;
	segment_pos = round_down(pgalloc_pos, _SEGMENT_SIZE);
	segment_low = segment_pos - shadow_alloc_size;
	segment_low = round_down(segment_low, _SEGMENT_SIZE);
	pgalloc_pos = segment_low;
	}
	/*
	* Current memory layout:
	* +- 0 -------------+ +- shadow start -+
	* \|1:1 ident mapping\| /\|1/8 of ident map\|
	* \| \| / \| \|
	* +-end of ident map+ / +----------------+
	* \| ... gap ... \| / \| kasan \|
	* \| \| / \| zero page \|
	* +- vmalloc area -+ / \| mapping \|
	* \| vmalloc_size \| / \| (untracked) \|
	* +- modules vaddr -+ / +----------------+
	* \| 2Gb \|/ \| unmapped \| allocated per module
	* +- shadow start -+ +----------------+
	* \| 1/8 addr space \| \| zero pg mapping\| (untracked)
	* +- shadow end ----+---------+- shadow end ---+
	*
	* Current memory layout (KASAN_VMALLOC):
	* +- 0 -------------+ +- shadow start -+
	* \|1:1 ident mapping\| /\|1/8 of ident map\|
	* \| \| / \| \|
	* +-end of ident map+ / +----------------+
	* \| ... gap ... \| / \| kasan zero page\| (untracked)
	* \| \| / \| mapping \|
	* +- vmalloc area -+ / +----------------+
	* \| vmalloc_size \| / \|shallow populate\|
	* +- modules vaddr -+ / +----------------+
	* \| 2Gb \|/ \|shallow populate\|
	* +- shadow start -+ +----------------+
	* \| 1/8 addr space \| \| zero pg mapping\| (untracked)
	* +- shadow end ----+---------+- shadow end ---+
	*/
	/* populate kasan shadow (for identity mapping and zero page mapping) */
	for_each_mem_detect_usable_block(i, &start, &end)
	kasan_early_pgtable_populate(__sha(start), __sha(end), POPULATE_MAP);
	if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
	untracked_end = VMALLOC_START;
	/* shallowly populate kasan shadow for vmalloc and modules */
	kasan_early_pgtable_populate(__sha(VMALLOC_START), __sha(MODULES_END),
	POPULATE_SHALLOW);
	}
	/* populate kasan shadow for untracked memory */
	kasan_early_pgtable_populate(__sha(ident_map_size), __sha(untracked_end),
	POPULATE_ZERO_SHADOW);
	kasan_early_pgtable_populate(__sha(MODULES_END), __sha(_REGION1_SIZE),
	POPULATE_ZERO_SHADOW);
	/* enable kasan */
	init_task.kasan_depth = 0;
	sclp_early_printk("KernelAddressSanitizer initialized\n");
	}