s390/kasan: add KASAN_VMALLOC support

Add KASAN_VMALLOC support which now enables vmalloc memory area access
checks as well as enables usage of VMAP_STACK under kasan.

KASAN_VMALLOC changes the way vmalloc and modules areas shadow memory
is handled. With this new approach only top level page tables are
pre-populated and lower levels are filled dynamically upon memory
allocation.
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/Kconfig

@@ -124,6 +124,7 @@ config S390
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_JUMP_LABEL_RELATIVE
 	select HAVE_ARCH_KASAN
+	select HAVE_ARCH_KASAN_VMALLOC
 	select CPU_NO_EFFICIENT_FFS if !HAVE_MARCH_Z9_109_FEATURES
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_SOFT_DIRTY

arch/s390/mm/kasan_init.c

@@ -82,7 +82,8 @@ static pte_t * __init kasan_early_pte_alloc(void)
 enum populate_mode {
 	POPULATE_ONE2ONE,
 	POPULATE_MAP,
-	POPULATE_ZERO_SHADOW
+	POPULATE_ZERO_SHADOW,
+	POPULATE_SHALLOW
 };
 static void __init kasan_early_vmemmap_populate(unsigned long address,
 						unsigned long end,
@@ -116,6 +117,12 @@ static void __init kasan_early_vmemmap_populate(unsigned long address,
 			pgd_populate(&init_mm, pg_dir, p4_dir);
 		}
 
+		if (IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING) &&
+		    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 &&
@@ -130,6 +137,12 @@ static void __init kasan_early_vmemmap_populate(unsigned long address,
 			p4d_populate(&init_mm, p4_dir, pu_dir);
 		}
 
+		if (!IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING) &&
+		    mode == POPULATE_SHALLOW) {
+			address = (address + PUD_SIZE) & PUD_MASK;
+			continue;
+		}
+
 		pu_dir = pud_offset(p4_dir, address);
 		if (pud_none(*pu_dir)) {
 			if (mode == POPULATE_ZERO_SHADOW &&
@@ -195,6 +208,9 @@ static void __init kasan_early_vmemmap_populate(unsigned long address,
 				page = kasan_early_shadow_page;
 				pte_val(*pt_dir) = __pa(page) | pgt_prot_zero;
 				break;
+			case POPULATE_SHALLOW:
+				/* should never happen */
+				break;
 			}
 		}
 		address += PAGE_SIZE;
@@ -313,22 +329,50 @@ void __init kasan_early_init(void)
 	init_mm.pgd = early_pg_dir;
 	/*
 	 * Current memory layout:
-	 * +- 0 -------------+	 +- shadow start -+
-	 * | 1:1 ram mapping |	/| 1/8 ram	  |
-	 * +- end of ram ----+ / +----------------+
-	 * | ... gap ...     |/  |	kasan	  |
-	 * +- shadow start --+	 |	zero	  |
-	 * | 1/8 addr space  |	 |	page	  |
-	 * +- shadow end    -+	 |	mapping	  |
-	 * | ... gap ...     |\  |    (untracked) |
-	 * +- modules vaddr -+ \ +----------------+
-	 * | 2Gb	     |	\|	unmapped  | allocated per module
-	 * +-----------------+	 +- shadow end ---+
+	 * +- 0 -------------+	   +- shadow start -+
+	 * | 1:1 ram mapping |	  /| 1/8 ram	    |
+	 * |		     |	 / |		    |
+	 * +- end of ram ----+	/  +----------------+
+	 * | ... gap ...     | /   |		    |
+	 * |		     |/    |	kasan	    |
+	 * +- shadow start --+	   |	zero	    |
+	 * | 1/8 addr space  |	   |	page	    |
+	 * +- shadow end    -+	   |	mapping	    |
+	 * | ... gap ...     |\    |  (untracked)   |
+	 * +- vmalloc area  -+ \   |		    |
+	 * | vmalloc_size    |	\  |		    |
+	 * +- modules vaddr -+	 \ +----------------+
+	 * | 2Gb	     |	  \|	  unmapped  | allocated per module
+	 * +-----------------+	   +- shadow end ---+
+	 *
+	 * Current memory layout (KASAN_VMALLOC):
+	 * +- 0 -------------+	   +- shadow start -+
+	 * | 1:1 ram mapping |	  /| 1/8 ram	    |
+	 * |		     |	 / |		    |
+	 * +- end of ram ----+	/  +----------------+
+	 * | ... gap ...     | /   |	kasan	    |
+	 * |		     |/    |	zero	    |
+	 * +- shadow start --+	   |	page	    |
+	 * | 1/8 addr space  |	   |	mapping     |
+	 * +- shadow end    -+	   |  (untracked)   |
+	 * | ... gap ...     |\    |		    |
+	 * +- vmalloc area  -+ \   +- vmalloc area -+
+	 * | vmalloc_size    |	\  |shallow populate|
+	 * +- modules vaddr -+	 \ +- modules area -+
+	 * | 2Gb	     |	  \|shallow populate|
+	 * +-----------------+	   +- shadow end ---+
 	 */
 	/* populate kasan shadow (for identity mapping and zero page mapping) */
 	kasan_early_vmemmap_populate(__sha(0), __sha(memsize), POPULATE_MAP);
 	if (IS_ENABLED(CONFIG_MODULES))
 		untracked_mem_end = vmax - MODULES_LEN;
+	if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
+		untracked_mem_end = vmax - vmalloc_size - MODULES_LEN;
+		/* shallowly populate kasan shadow for vmalloc and modules */
+		kasan_early_vmemmap_populate(__sha(untracked_mem_end),
+					     __sha(vmax), POPULATE_SHALLOW);
+	}
+	/* populate kasan shadow for untracked memory */
 	kasan_early_vmemmap_populate(__sha(max_physmem_end),
 				     __sha(untracked_mem_end),
 				     POPULATE_ZERO_SHADOW);