1 files changed, 51 insertions, 11 deletions

diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index 67315fa3956a..1cc15528ce29 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -44,6 +44,8 @@ extern void text_poke_early(void *addr, const void *opcode, size_t len);
 extern void *text_poke(void *addr, const void *opcode, size_t len);
 extern void text_poke_sync(void);
 extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len);
+extern void *text_poke_copy(void *addr, const void *opcode, size_t len);
+extern void *text_poke_set(void *addr, int c, size_t len);
 extern int poke_int3_handler(struct pt_regs *regs);
 extern void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate);
 
@@ -53,6 +55,9 @@ extern void text_poke_finish(void);
 #define INT3_INSN_SIZE		1
 #define INT3_INSN_OPCODE	0xCC
 
+#define RET_INSN_SIZE		1
+#define RET_INSN_OPCODE		0xC3
+
 #define CALL_INSN_SIZE		5
 #define CALL_INSN_OPCODE	0xE8
 
@@ -64,7 +69,7 @@ extern void text_poke_finish(void);
 
 #define DISP32_SIZE		4
 
-static inline int text_opcode_size(u8 opcode)
+static __always_inline int text_opcode_size(u8 opcode)
 {
 	int size = 0;
 
@@ -73,6 +78,7 @@ static inline int text_opcode_size(u8 opcode)
 
 	switch(opcode) {
 	__CASE(INT3);
+	__CASE(RET);
 	__CASE(CALL);
 	__CASE(JMP32);
 	__CASE(JMP8);
@@ -92,24 +98,40 @@ union text_poke_insn {
 };
 
 static __always_inline
-void *text_gen_insn(u8 opcode, const void *addr, const void *dest)
+void __text_gen_insn(void *buf, u8 opcode, const void *addr, const void *dest, int size)
 {
-	static union text_poke_insn insn; /* per instance */
-	int size = text_opcode_size(opcode);
+	union text_poke_insn *insn = buf;
+
+	BUG_ON(size < text_opcode_size(opcode));
+
+	/*
+	 * Hide the addresses to avoid the compiler folding in constants when
+	 * referencing code, these can mess up annotations like
+	 * ANNOTATE_NOENDBR.
+	 */
+	OPTIMIZER_HIDE_VAR(insn);
+	OPTIMIZER_HIDE_VAR(addr);
+	OPTIMIZER_HIDE_VAR(dest);
 
-	insn.opcode = opcode;
+	insn->opcode = opcode;
 
 	if (size > 1) {
-		insn.disp = (long)dest - (long)(addr + size);
+		insn->disp = (long)dest - (long)(addr + size);
 		if (size == 2) {
 			/*
-			 * Ensure that for JMP9 the displacement
+			 * Ensure that for JMP8 the displacement
 			 * actually fits the signed byte.
 			 */
-			BUG_ON((insn.disp >> 31) != (insn.disp >> 7));
+			BUG_ON((insn->disp >> 31) != (insn->disp >> 7));
 		}
 	}
+}
 
+static __always_inline
+void *text_gen_insn(u8 opcode, const void *addr, const void *dest)
+{
+	static union text_poke_insn insn; /* per instance */
+	__text_gen_insn(&insn, opcode, addr, dest, text_opcode_size(opcode));
 	return &insn.text;
 }
 
@@ -118,12 +140,14 @@ extern __ro_after_init struct mm_struct *poking_mm;
 extern __ro_after_init unsigned long poking_addr;
 
 #ifndef CONFIG_UML_X86
-static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
+static __always_inline
+void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
 {
 	regs->ip = ip;
 }
 
-static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
+static __always_inline
+void int3_emulate_push(struct pt_regs *regs, unsigned long val)
 {
 	/*
 	 * The int3 handler in entry_64.S adds a gap between the
@@ -138,11 +162,27 @@ static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
 	*(unsigned long *)regs->sp = val;
 }
 
-static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func)
+static __always_inline
+unsigned long int3_emulate_pop(struct pt_regs *regs)
+{
+	unsigned long val = *(unsigned long *)regs->sp;
+	regs->sp += sizeof(unsigned long);
+	return val;
+}
+
+static __always_inline
+void int3_emulate_call(struct pt_regs *regs, unsigned long func)
 {
 	int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
 	int3_emulate_jmp(regs, func);
 }
+
+static __always_inline
+void int3_emulate_ret(struct pt_regs *regs)
+{
+	unsigned long ip = int3_emulate_pop(regs);
+	int3_emulate_jmp(regs, ip);
+}
 #endif /* !CONFIG_UML_X86 */
 
 #endif /* _ASM_X86_TEXT_PATCHING_H */