lib: Add ASan support to ramstage on x86 arch

This patch adds address sanitizer module to the library and reserves
a linker section representing the shadow region for ramstage. Also,
it adds an instruction to initialize shadow region on x86
architecture when ramstage is loaded.

Change-Id: Ica06bd2be78fcfc79fa888721ed920d4e8248f3b
Signed-off-by: Harshit Sharma <harshitsharmajs@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/42496
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Werner Zeh <werner.zeh@siemens.com>

2 files changed, 400 insertions, 19 deletions

diff --git a/src/lib/asan.c b/src/lib/asan.c
index e4a1012e13..0c186d62a3 100644
--- a/src/lib/asan.c
+++ b/src/lib/asan.c
@@ -1,16 +1,337 @@
-#include <stddef.h>
+/* SPDX-License-Identifier: GPL-2.0 */
 
-#pragma GCC diagnostic ignored "-Wmissing-prototypes"
+/*
+ * Address sanitizer support.
+ *
+ * Parts of this file are based on mm/kasan
+ * from the Linux kernel 4.19.137.
+ *
+ */
 
-#define DEFINE_ASAN_LOAD_STORE(size)                        \
-	void __asan_load##size(unsigned long addr)              \
-	{}                                                      \
-	void __asan_load##size##_noabort(unsigned long addr)    \
-	{}                                                      \
-	void __asan_store##size(unsigned long addr)             \
-	{}                                                      \
-	void __asan_store##size##_noabort(unsigned long addr)   \
-	{}
+#include <symbols.h>
+#include <assert.h>
+#include <asan.h>
+
+static inline void *asan_mem_to_shadow(const void *addr)
+{
+	return (void *)((uintptr_t)&_asan_shadow + (((uintptr_t)addr -
+		(uintptr_t)&_data) >> ASAN_SHADOW_SCALE_SHIFT));
+}
+
+static inline const void *asan_shadow_to_mem(const void *shadow_addr)
+{
+	return (void *)((uintptr_t)&_data + (((uintptr_t)shadow_addr -
+		(uintptr_t)&_asan_shadow) << ASAN_SHADOW_SCALE_SHIFT));
+}
+
+static void asan_poison_shadow(const void *address, size_t size, u8 value)
+{
+	void *shadow_start, *shadow_end;
+
+	shadow_start = asan_mem_to_shadow(address);
+	shadow_end = asan_mem_to_shadow(address + size);
+
+	__builtin_memset(shadow_start, value, shadow_end - shadow_start);
+}
+
+void asan_unpoison_shadow(const void *address, size_t size)
+{
+	asan_poison_shadow(address, size, 0);
+
+	if (size & ASAN_SHADOW_MASK) {
+		u8 *shadow = (u8 *)asan_mem_to_shadow(address + size);
+		*shadow = size & ASAN_SHADOW_MASK;
+	}
+}
+
+static __always_inline bool memory_is_poisoned_1(unsigned long addr)
+{
+	s8 shadow_value = *(s8 *)asan_mem_to_shadow((void *)addr);
+
+	if (unlikely(shadow_value)) {
+		s8 last_accessible_byte = addr & ASAN_SHADOW_MASK;
+		return unlikely(last_accessible_byte >= shadow_value);
+	}
+
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
+						unsigned long size)
+{
+	u8 *shadow_addr = (u8 *)asan_mem_to_shadow((void *)addr);
+
+	if (unlikely(((addr + size - 1) & ASAN_SHADOW_MASK) < size - 1))
+		return *shadow_addr || memory_is_poisoned_1(addr + size - 1);
+
+	return memory_is_poisoned_1(addr + size - 1);
+}
+
+static __always_inline bool memory_is_poisoned_16(unsigned long addr)
+{
+	u16 *shadow_addr = (u16 *)asan_mem_to_shadow((void *)addr);
+
+	if (unlikely(!IS_ALIGNED(addr, ASAN_SHADOW_SCALE_SIZE)))
+		return *shadow_addr || memory_is_poisoned_1(addr + 15);
+
+	return *shadow_addr;
+}
+
+static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
+					size_t size)
+{
+	while (size) {
+		if (unlikely(*start))
+			return (unsigned long)start;
+		start++;
+		size--;
+	}
+
+	return 0;
+}
+
+static __always_inline unsigned long memory_is_nonzero(const void *start,
+						const void *end)
+{
+	unsigned int words;
+	unsigned long ret;
+	unsigned int prefix = (unsigned long)start % 8;
+
+	if (end - start <= 16)
+		return bytes_is_nonzero(start, end - start);
+
+	if (prefix) {
+		prefix = 8 - prefix;
+		ret = bytes_is_nonzero(start, prefix);
+		if (unlikely(ret))
+			return ret;
+		start += prefix;
+	}
+
+	words = (end - start) / 8;
+	while (words) {
+		if (unlikely(*(u64 *)start))
+			return bytes_is_nonzero(start, 8);
+		start += 8;
+		words--;
+	}
+
+	return bytes_is_nonzero(start, (end - start) % 8);
+}
+
+static __always_inline bool memory_is_poisoned_n(unsigned long addr,
+						size_t size)
+{
+	unsigned long ret;
+
+	ret = memory_is_nonzero(asan_mem_to_shadow((void *)addr),
+			asan_mem_to_shadow((void *)addr + size - 1) + 1);
+
+	if (unlikely(ret)) {
+		unsigned long last_byte = addr + size - 1;
+		s8 *last_shadow = (s8 *)asan_mem_to_shadow((void *)last_byte);
+
+		if (unlikely(ret != (unsigned long)last_shadow ||
+			((long)(last_byte & ASAN_SHADOW_MASK) >= *last_shadow)))
+			return true;
+	}
+	return false;
+}
+
+static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
+{
+	if (__builtin_constant_p(size)) {
+		switch (size) {
+		case 1:
+			return memory_is_poisoned_1(addr);
+		case 2:
+		case 4:
+		case 8:
+			return memory_is_poisoned_2_4_8(addr, size);
+		case 16:
+			return memory_is_poisoned_16(addr);
+		default:
+			assert(0);
+		}
+	}
+
+	return memory_is_poisoned_n(addr, size);
+}
+
+static const void *find_first_bad_addr(const void *addr, size_t size)
+{
+	u8 shadow_val = *(u8 *)asan_mem_to_shadow(addr);
+	const void *first_bad_addr = addr;
+
+	while (!shadow_val && first_bad_addr < addr + size) {
+		first_bad_addr += ASAN_SHADOW_SCALE_SIZE;
+		shadow_val = *(u8 *)asan_mem_to_shadow(first_bad_addr);
+	}
+	return first_bad_addr;
+}
+
+static const char *get_shadow_bug_type(const void *addr, size_t size)
+{
+	const char *bug_type = "unknown-crash";
+	u8 *shadow_addr;
+	const void *first_bad_addr;
+
+	if (addr < asan_shadow_to_mem((void *) &_asan_shadow))
+		return bug_type;
+
+	first_bad_addr = find_first_bad_addr(addr, size);
+
+	shadow_addr = (u8 *)asan_mem_to_shadow(first_bad_addr);
+
+	if (*shadow_addr > 0 && *shadow_addr <= ASAN_SHADOW_SCALE_SIZE - 1)
+		shadow_addr++;
+
+	switch (*shadow_addr) {
+	case 0 ... ASAN_SHADOW_SCALE_SIZE - 1:
+		bug_type = "out-of-bounds";
+		break;
+	case ASAN_GLOBAL_REDZONE:
+		bug_type = "global-out-of-bounds";
+		break;
+	case ASAN_STACK_LEFT:
+	case ASAN_STACK_MID:
+	case ASAN_STACK_RIGHT:
+	case ASAN_STACK_PARTIAL:
+		bug_type = "stack-out-of-bounds";
+		break;
+	case ASAN_USE_AFTER_SCOPE:
+		bug_type = "use-after-scope";
+		break;
+	default:
+		bug_type = "unknown-crash";
+	}
+
+	return bug_type;
+}
+
+void asan_report(unsigned long addr, size_t size, bool is_write,
+	unsigned long ip)
+{
+	const char *bug_type = get_shadow_bug_type((void *) addr, size);
+	printk(BIOS_ERR, "\n");
+	printk(BIOS_ERR, "ASan: %s in %p\n", bug_type, (void *) ip);
+	printk(BIOS_ERR, "%s of %zu byte%s at addr %p\n",
+		is_write ? "Write" : "Read", size, (size > 1 ? "s" : ""),
+		(void *) addr);
+	printk(BIOS_ERR, "\n");
+}
+
+static __always_inline void check_memory_region_inline(unsigned long addr,
+						size_t size, bool write,
+						unsigned long ret_ip)
+{
+	if (((uintptr_t)addr < (uintptr_t)&_data) ||
+			((uintptr_t)addr > (uintptr_t)&_eheap))
+		return;
+
+	if (unlikely(size == 0))
+		return;
+
+	if (unlikely((void *)addr <
+		asan_shadow_to_mem((void *) &_asan_shadow))) {
+		asan_report(addr, size, write, ret_ip);
+		return;
+	}
+
+	if (likely(!memory_is_poisoned(addr, size)))
+		return;
+
+	asan_report(addr, size, write, ret_ip);
+}
+
+static void check_memory_region(unsigned long addr, size_t size, bool write,
+				unsigned long ret_ip)
+{
+	check_memory_region_inline(addr, size, write, ret_ip);
+}
+
+uintptr_t __asan_shadow_offset(uintptr_t addr)
+{
+	return (uintptr_t)&_asan_shadow - (((uintptr_t)&_data) >>
+		ASAN_SHADOW_SCALE_SHIFT);
+}
+
+static void register_global(struct asan_global *global)
+{
+	size_t aligned_size = ALIGN_UP(global->size, ASAN_SHADOW_SCALE_SIZE);
+
+	asan_unpoison_shadow(global->beg, global->size);
+
+	asan_poison_shadow(global->beg + aligned_size,
+		global->size_with_redzone - aligned_size,
+		ASAN_GLOBAL_REDZONE);
+}
+
+void __asan_register_globals(struct asan_global *globals, size_t size)
+{
+	int i;
+
+	for (i = 0; i < size; i++)
+		register_global(&globals[i]);
+}
+
+void __asan_unregister_globals(struct asan_global *globals, size_t size)
+{
+}
+
+/*
+ * GCC adds constructors invoking __asan_register_globals() and passes
+ * information about global variable (address, size, size with redzone ...)
+ * to it so we could poison variable's redzone.
+ * This function calls those constructors.
+ */
+static void asan_ctors(void)
+{
+	extern long __CTOR_LIST__;
+	typedef void (*func_ptr)(void);
+	func_ptr *ctor = (func_ptr *) &__CTOR_LIST__;
+	if (ctor == NULL)
+		return;
+
+	for (; *ctor != (func_ptr) 0; ctor++)
+		(*ctor)();
+}
+
+void asan_init(void)
+{
+	size_t size = (size_t)&_eheap - (size_t)&_data;
+	asan_unpoison_shadow((void *)&_data, size);
+	asan_ctors();
+}
+
+void __asan_poison_stack_memory(const void *addr, size_t size)
+{
+	asan_poison_shadow(addr, ALIGN_UP(size, ASAN_SHADOW_SCALE_SIZE),
+			    ASAN_USE_AFTER_SCOPE);
+}
+
+void __asan_unpoison_stack_memory(const void *addr, size_t size)
+{
+	asan_unpoison_shadow(addr, size);
+}
+
+#define DEFINE_ASAN_LOAD_STORE(size)	\
+	void __asan_load##size(unsigned long addr)	\
+	{	\
+		check_memory_region_inline(addr, size, false, _RET_IP_);\
+	}	\
+	void __asan_load##size##_noabort(unsigned long addr)	\
+	{	\
+		check_memory_region_inline(addr, size, false, _RET_IP_);\
+	}	\
+	void __asan_store##size(unsigned long addr)	\
+	{	\
+		check_memory_region_inline(addr, size, true, _RET_IP_);	\
+	}	\
+	void __asan_store##size##_noabort(unsigned long addr)	\
+	{	\
+		check_memory_region_inline(addr, size, true, _RET_IP_);	\
+	}
 
 DEFINE_ASAN_LOAD_STORE(1);
 DEFINE_ASAN_LOAD_STORE(2);
@@ -19,16 +340,71 @@ DEFINE_ASAN_LOAD_STORE(8);
 DEFINE_ASAN_LOAD_STORE(16);
 
 void __asan_loadN(unsigned long addr, size_t size)
-{}
-
-void __asan_loadN_noabort(unsigned long addr, size_t size)
-{}
+{
+	check_memory_region(addr, size, false, _RET_IP_);
+}
 
 void __asan_storeN(unsigned long addr, size_t size)
-{}
+{
+	check_memory_region(addr, size, true, _RET_IP_);
+}
+
+void __asan_loadN_noabort(unsigned long addr, size_t size)
+{
+	check_memory_region(addr, size, false, _RET_IP_);
+}
 
 void __asan_storeN_noabort(unsigned long addr, size_t size)
-{}
+{
+	check_memory_region(addr, size, true, _RET_IP_);
+}
 
 void __asan_handle_no_return(void)
-{}
+{
+}
+
+#define DEFINE_ASAN_SET_SHADOW(byte)	\
+	void __asan_set_shadow_##byte(const void *addr, size_t size)	\
+	{	\
+		__builtin_memset((void *)addr, 0x##byte, size);	\
+	}
+
+DEFINE_ASAN_SET_SHADOW(00);
+DEFINE_ASAN_SET_SHADOW(f1);
+DEFINE_ASAN_SET_SHADOW(f2);
+DEFINE_ASAN_SET_SHADOW(f3);
+DEFINE_ASAN_SET_SHADOW(f5);
+DEFINE_ASAN_SET_SHADOW(f8);
+
+#define DEFINE_ASAN_REPORT_LOAD(size)	\
+void __asan_report_load##size##_noabort(unsigned long addr)	\
+{	\
+	asan_report(addr, size, false, _RET_IP_);	\
+}
+
+#define DEFINE_ASAN_REPORT_STORE(size)	\
+void __asan_report_store##size##_noabort(unsigned long addr)	\
+{	\
+	asan_report(addr, size, true, _RET_IP_);	\
+}
+
+DEFINE_ASAN_REPORT_LOAD(1);
+DEFINE_ASAN_REPORT_LOAD(2);
+DEFINE_ASAN_REPORT_LOAD(4);
+DEFINE_ASAN_REPORT_LOAD(8);
+DEFINE_ASAN_REPORT_LOAD(16);
+DEFINE_ASAN_REPORT_STORE(1);
+DEFINE_ASAN_REPORT_STORE(2);
+DEFINE_ASAN_REPORT_STORE(4);
+DEFINE_ASAN_REPORT_STORE(8);
+DEFINE_ASAN_REPORT_STORE(16);
+
+void __asan_report_load_n_noabort(unsigned long addr, size_t size)
+{
+	asan_report(addr, size, false, _RET_IP_);
+}
+
+void __asan_report_store_n_noabort(unsigned long addr, size_t size)
+{
+	asan_report(addr, size, true, _RET_IP_);
+}
diff --git a/src/lib/program.ld b/src/lib/program.ld
index 88a3126038..3b6aa2ecba 100644
--- a/src/lib/program.ld
+++ b/src/lib/program.ld
@@ -51,7 +51,7 @@
 	_etext = .;
 } : to_load
 
-#if ENV_RAMSTAGE && CONFIG(COVERAGE)
+#if ENV_RAMSTAGE && (CONFIG(COVERAGE) || CONFIG(ASAN_IN_RAMSTAGE))
 .ctors . : {
 	. = ALIGN(0x100);
 	__CTOR_LIST__ = .;
@@ -126,6 +126,11 @@
 }
 #endif
 
+#if ENV_RAMSTAGE && CONFIG(ASAN_IN_RAMSTAGE)
+	_shadow_size = (_eheap - _data) >> 3;
+	REGION(asan_shadow, ., _shadow_size, ARCH_POINTER_ALIGN_SIZE)
+#endif
+
 _eprogram = .;
 
 /* Discard the sections we don't need/want */