livepatch: checks only if the replaced instruction is on the stack

hulk inclusion
category: feature
bugzilla: 119440 https://gitee.com/openeuler/kernel/issues/I4DDEL

--------------------------------

When the CONFIG_LIVEPATCH_STOP_MACHINE_CONSISTENCY macro is turned
on, the system checks whether the function to patch is on the stack
under the stop_machine. If the function is on the stack, the livepatch
cannot be patched and returns a busy signal.

Hotspot functions are easily on the stack under the stop_machine
condition. As a result, the livpatch success rate is low when the
patch includes a hot function.

For the repalced function, only the first seceral instructions are
rewritten, and the rest of the instructions are the same as the
original ones. Therefore, if the force flag is KLP_STACK_OPTIMIZE,
only need to check whether the replaced instructions are on the
stack.
Signed-off-by: NYe Weihua <yeweihua4@huawei.com>
Reviewed-by: NKuohai Xu <xukuohai@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm/kernel/livepatch.c

@@ -31,16 +31,19 @@
 #include <asm/insn.h>
 #include <asm/patch.h>
 
-#ifdef CONFIG_ARM_MODULE_PLTS
-#define LJMP_INSN_SIZE	3
-#endif
-
 #ifdef ARM_INSN_SIZE
 #error "ARM_INSN_SIZE have been redefined, please check"
 #else
 #define ARM_INSN_SIZE	4
 #endif
 
+#ifdef CONFIG_ARM_MODULE_PLTS
+#define LJMP_INSN_SIZE	3
+#define MAX_SIZE_TO_CHECK (LJMP_INSN_SIZE * ARM_INSN_SIZE)
+#else
+#define MAX_SIZE_TO_CHECK ARM_INSN_SIZE
+#endif
+
 struct klp_func_node {
 	struct list_head node;
 	struct list_head func_stack;
@@ -73,10 +76,20 @@ struct walk_stackframe_args {
 	int ret;
 };
 
+static inline unsigned long klp_size_to_check(unsigned long func_size,
+		int force)
+{
+	unsigned long size = func_size;
+
+	if (force == KLP_STACK_OPTIMIZE && size > MAX_SIZE_TO_CHECK)
+		size = MAX_SIZE_TO_CHECK;
+	return size;
+}
+
 static inline int klp_compare_address(unsigned long pc, unsigned long func_addr,
-				unsigned long func_size, const char *func_name)
+		const char *func_name, unsigned long check_size)
 {
-	if (pc >= func_addr && pc < func_addr + func_size) {
+	if (pc >= func_addr && pc < func_addr + check_size) {
 		pr_err("func %s is in use!\n", func_name);
 		return -EBUSY;
 	}
@@ -136,8 +149,8 @@ static int klp_check_activeness_func(struct stackframe *frame, void *data)
 				func_size = func->new_size;
 			}
 			func_name = func->old_name;
-			args->ret = klp_compare_address(frame->pc, func_addr,
-					func_size, func_name);
+			args->ret = klp_compare_address(frame->pc, func_addr, func_name,
+					klp_size_to_check(func_size, func->force));
 			if (args->ret)
 				return args->ret;
 		}

arch/arm64/kernel/livepatch.c

@@ -34,7 +34,11 @@
 #include <linux/sched/debug.h>
 #include <linux/kallsyms.h>
 
+#define LJMP_INSN_SIZE 4
+
 #ifdef CONFIG_ARM64_MODULE_PLTS
+#define MAX_SIZE_TO_CHECK (LJMP_INSN_SIZE * sizeof(u32))
+
 static inline bool offset_in_range(unsigned long pc, unsigned long addr,
 		long range)
 {
@@ -42,9 +46,10 @@ static inline bool offset_in_range(unsigned long pc, unsigned long addr,
 
 	return (offset >= -range && offset < range);
 }
-#endif
 
-#define LJMP_INSN_SIZE 4
+#else
+#define MAX_SIZE_TO_CHECK sizeof(u32)
+#endif
 
 struct klp_func_node {
 	struct list_head node;
@@ -78,10 +83,20 @@ struct walk_stackframe_args {
 	int ret;
 };
 
+static inline unsigned long klp_size_to_check(unsigned long func_size,
+		int force)
+{
+	unsigned long size = func_size;
+
+	if (force == KLP_STACK_OPTIMIZE && size > MAX_SIZE_TO_CHECK)
+		size = MAX_SIZE_TO_CHECK;
+	return size;
+}
+
 static inline int klp_compare_address(unsigned long pc, unsigned long func_addr,
-				unsigned long func_size, const char *func_name)
+		const char *func_name, unsigned long check_size)
 {
-	if (pc >= func_addr && pc < func_addr + func_size) {
+	if (pc >= func_addr && pc < func_addr + check_size) {
 		pr_err("func %s is in use!\n", func_name);
 		return -EBUSY;
 	}
@@ -137,8 +152,8 @@ static bool klp_check_activeness_func(void *data, unsigned long pc)
 				func_size = func->new_size;
 			}
 			func_name = func->old_name;
-			args->ret = klp_compare_address(pc, func_addr,
-					func_size, func_name);
+			args->ret = klp_compare_address(pc, func_addr, func_name,
+					klp_size_to_check(func_size, func->force));
 			if (args->ret)
 				return false;
 		}

arch/powerpc/kernel/livepatch_32.c

@@ -32,6 +32,7 @@
 #if defined (CONFIG_LIVEPATCH_STOP_MACHINE_CONSISTENCY) || \
     defined (CONFIG_LIVEPATCH_WO_FTRACE)
 #define LJMP_INSN_SIZE	4
+#define MAX_SIZE_TO_CHECK (LJMP_INSN_SIZE * sizeof(u32))
 
 struct klp_func_node {
 	struct list_head node;
@@ -67,10 +68,20 @@ struct walk_stackframe_args {
 	int ret;
 };
 
+static inline unsigned long klp_size_to_check(unsigned long func_size,
+		int force)
+{
+	unsigned long size = func_size;
+
+	if (force == KLP_STACK_OPTIMIZE && size > MAX_SIZE_TO_CHECK)
+		size = MAX_SIZE_TO_CHECK;
+	return size;
+}
+
 static inline int klp_compare_address(unsigned long pc, unsigned long func_addr,
-				unsigned long func_size, const char *func_name)
+		const char *func_name, unsigned long check_size)
 {
-	if (pc >= func_addr && pc < func_addr + func_size) {
+	if (pc >= func_addr && pc < func_addr + check_size) {
 		pr_err("func %s is in use!\n", func_name);
 		return -EBUSY;
 	}
@@ -130,8 +141,8 @@ static int klp_check_activeness_func(struct stackframe *frame, void *data)
 				func_size = func->new_size;
 			}
 			func_name = func->old_name;
-			args->ret = klp_compare_address(frame->pc, func_addr,
-					func_size, func_name);
+			args->ret = klp_compare_address(frame->pc, func_addr, func_name,
+					klp_size_to_check(func_size, func->force));
 			if (args->ret)
 				return args->ret;
 		}

arch/powerpc/kernel/livepatch_64.c

@@ -36,6 +36,8 @@
 
 #if defined(CONFIG_LIVEPATCH_STOP_MACHINE_CONSISTENCY) || \
     defined(CONFIG_LIVEPATCH_WO_FTRACE)
+#define MAX_SIZE_TO_CHECK (LJMP_INSN_SIZE * sizeof(u32))
+
 struct klp_func_node {
 	struct list_head node;
 	struct list_head func_stack;
@@ -76,12 +78,20 @@ struct walk_stackframe_args {
 	int ret;
 };
 
-static inline int klp_compare_address(unsigned long pc,
-				      unsigned long func_addr,
-				      unsigned long func_size,
-				      const char *func_name)
+static inline unsigned long klp_size_to_check(unsigned long func_size,
+		int force)
+{
+	unsigned long size = func_size;
+
+	if (force == KLP_STACK_OPTIMIZE && size > MAX_SIZE_TO_CHECK)
+		size = MAX_SIZE_TO_CHECK;
+	return size;
+}
+
+static inline int klp_compare_address(unsigned long pc, unsigned long func_addr,
+		const char *func_name, unsigned long check_size)
 {
-	if (pc >= func_addr && pc < func_addr + func_size) {
+	if (pc >= func_addr && pc < func_addr + check_size) {
 		pr_err("func %s is in use!\n", func_name);
 		return -EBUSY;
 	}
@@ -92,20 +102,21 @@ static inline int klp_check_activeness_func_addr(
 		struct stackframe *frame,
 		unsigned long func_addr,
 		unsigned long func_size,
-		const char *func_name)
+		const char *func_name,
+		int force)
 {
 	int ret;
 
 	/* Check PC first */
-	ret = klp_compare_address(frame->pc, func_addr,
-			func_size, func_name);
+	ret = klp_compare_address(frame->pc, func_addr, func_name,
+			klp_size_to_check(func_size, force));
 	if (ret)
 		return ret;
 
 	/* Check NIP when the exception stack switching */
 	if (frame->nip != 0) {
-		ret = klp_compare_address(frame->nip, func_addr,
-				func_size, func_name);
+		ret = klp_compare_address(frame->nip, func_addr, func_name,
+			klp_size_to_check(func_size, force));
 		if (ret)
 			return ret;
 	}
@@ -171,7 +182,8 @@ static int klp_check_activeness_func(struct stackframe *frame, void *data)
 			}
 			func_name = func->old_name;
 			args->ret = klp_check_activeness_func_addr(frame,
-					func_addr, func_size, func_name);
+					func_addr, func_size, func_name,
+					func->force);
 			if (args->ret)
 				return args->ret;
 
@@ -188,7 +200,7 @@ static int klp_check_activeness_func(struct stackframe *frame, void *data)
 				func_addr = (unsigned long)func->old_func;
 				func_size = func->old_size;
 				args->ret = klp_check_activeness_func_addr(frame,
-					func_addr, func_size, "OLD_FUNC");
+					func_addr, func_size, "OLD_FUNC", func->force);
 				if (args->ret)
 					return args->ret;
 
@@ -199,7 +211,8 @@ static int klp_check_activeness_func(struct stackframe *frame, void *data)
 				func_addr = (unsigned long)&func_node->trampoline;
 				func_size = sizeof(struct ppc64_klp_btramp_entry);
 				args->ret = klp_check_activeness_func_addr(frame,
-						func_addr, func_size, "trampoline");
+						func_addr, func_size, "trampoline",
+						func->force);
 				if (args->ret)
 					return args->ret;
 			}

arch/x86/kernel/livepatch.c

@@ -57,11 +57,21 @@ static struct klp_func_node *klp_find_func_node(void *old_func)
 #endif
 
 #ifdef CONFIG_LIVEPATCH_STOP_MACHINE_CONSISTENCY
+static inline unsigned long klp_size_to_check(unsigned long func_size,
+		int force)
+{
+	unsigned long size = func_size;
+
+	if (force == KLP_STACK_OPTIMIZE && size > JMP_E9_INSN_SIZE)
+		size = JMP_E9_INSN_SIZE;
+	return size;
+}
+
 static inline int klp_compare_address(unsigned long stack_addr,
-		unsigned long func_addr, unsigned long func_size,
-		const char *func_name)
+		unsigned long func_addr, const char *func_name,
+		unsigned long check_size)
 {
-	if (stack_addr >= func_addr && stack_addr < func_addr + func_size) {
+	if (stack_addr >= func_addr && stack_addr < func_addr + check_size) {
 		pr_err("func %s is in use!\n", func_name);
 		return -EBUSY;
 	}
@@ -124,8 +134,8 @@ static int klp_check_stack_func(struct klp_func *func,
 		}
 		func_name = func->old_name;
 
-		if (klp_compare_address(address, func_addr,
-				func_size, func_name))
+		if (klp_compare_address(address, func_addr, func_name,
+				klp_size_to_check(func_size, func->force)))
 			return -EAGAIN;
 	}