s390/kasan: move shadow mapping to decompressor

Since regular paging structs are initialized in decompressor already
move KASAN shadow mapping to decompressor as well. This helps to avoid
allocating KASAN required memory in 1 large chunk, de-duplicate paging
structs creation code and start the uncompressed kernel with KASAN
instrumentation right away. This also allows to avoid all pitfalls
accidentally calling KASAN instrumented code during KASAN initialization.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

3 files changed, 11 insertions, 301 deletions

diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile
index 57e4f3a24829..d90db06a8af5 100644
--- a/arch/s390/mm/Makefile
+++ b/arch/s390/mm/Makefile
@@ -10,6 +10,3 @@ obj-$(CONFIG_CMM)		+= cmm.o
 obj-$(CONFIG_HUGETLB_PAGE)	+= hugetlbpage.o
 obj-$(CONFIG_PTDUMP_CORE)	+= dump_pagetables.o
 obj-$(CONFIG_PGSTE)		+= gmap.o
-
-KASAN_SANITIZE_kasan_init.o	:= n
-obj-$(CONFIG_KASAN)		+= kasan_init.o
diff --git a/arch/s390/mm/kasan_init.c b/arch/s390/mm/kasan_init.c
deleted file mode 100644
index 2b20382f1bd8..000000000000
--- a/arch/s390/mm/kasan_init.c
+++ /dev/null
@@ -1,298 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <linux/memblock.h>
-#include <linux/pgtable.h>
-#include <linux/kasan.h>
-#include <asm/physmem_info.h>
-#include <asm/processor.h>
-#include <asm/facility.h>
-#include <asm/pgalloc.h>
-#include <asm/sclp.h>
-
-static unsigned long pgalloc_pos __initdata;
-static unsigned long segment_pos __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)
-{
-	unsigned long addr = segment_pos;
-
-	segment_pos += _SEGMENT_SIZE;
-	if (segment_pos > pgalloc_pos)
-		kasan_early_panic("out of memory during initialisation\n");
-
-	return __va(addr);
-}
-
-static void * __init kasan_early_alloc_pages(unsigned int order)
-{
-	pgalloc_pos -= (PAGE_SIZE << order);
-
-	if (segment_pos > pgalloc_pos)
-		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 pgalloc_pos_initial, segment_pos_initial;
-	unsigned long untracked_end = MODULES_VADDR;
-	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);
-
-	/* segment allocations go bottom up -> <- pgalloc go top down */
-	segment_pos_initial = physmem_info.reserved[RR_KASAN].start;
-	segment_pos = segment_pos_initial;
-	pgalloc_pos_initial = physmem_info.reserved[RR_KASAN].end;
-	pgalloc_pos = pgalloc_pos_initial;
-	/*
-	 * 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_physmem_usable_range(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");
-	memblock_reserve(segment_pos_initial, segment_pos - segment_pos_initial);
-	memblock_reserve(pgalloc_pos, pgalloc_pos_initial - pgalloc_pos);
-}
diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
index 4113a7ffa149..242f95aa9801 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -5,6 +5,7 @@
 
 #include <linux/memory_hotplug.h>
 #include <linux/memblock.h>
+#include <linux/kasan.h>
 #include <linux/pfn.h>
 #include <linux/mm.h>
 #include <linux/init.h>
@@ -664,6 +665,9 @@ static void __init memblock_region_swap(void *a, void *b, int size)
 	swap(*(struct memblock_region *)a, *(struct memblock_region *)b);
 }
 
+#ifdef CONFIG_KASAN
+#define __sha(x)	((unsigned long)kasan_mem_to_shadow((void *)x))
+#endif
 /*
  * map whole physical memory to virtual memory (identity mapping)
  * we reserve enough space in the vmalloc area for vmemmap to hotplug
@@ -733,6 +737,13 @@ void __init vmem_map_init(void)
 			     SET_MEMORY_RW | SET_MEMORY_NX);
 	}
 
+#ifdef CONFIG_KASAN
+	for_each_mem_range(i, &base, &end)
+		__set_memory(__sha(base),
+			     (__sha(end) - __sha(base)) >> PAGE_SHIFT,
+			     SET_MEMORY_RW | SET_MEMORY_NX);
+#endif
+
 	__set_memory((unsigned long)_stext,
 		     (unsigned long)(_etext - _stext) >> PAGE_SHIFT,
 		     SET_MEMORY_RO | SET_MEMORY_X);