x86: Add insn_decode_kernel()

Add a helper to decode kernel instructions; there's no point in
endlessly repeating those last two arguments.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210326151259.379242587@infradead.org

Author: Peter Zijlstra

arch/x86/include/asm/insn.h

@@ -150,6 +150,8 @@ enum insn_mode {
 
 extern int insn_decode(struct insn *insn, const void *kaddr, int buf_len, enum insn_mode m);
 
+#define insn_decode_kernel(_insn, _ptr) insn_decode((_insn), (_ptr), MAX_INSN_SIZE, INSN_MODE_KERN)
+
 /* Attribute will be determined after getting ModRM (for opcode groups) */
 static inline void insn_get_attribute(struct insn *insn)
 {

arch/x86/kernel/alternative.c

@@ -1280,7 +1280,7 @@ static void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
 	if (!emulate)
 		emulate = opcode;
 
-	ret = insn_decode(&insn, emulate, MAX_INSN_SIZE, INSN_MODE_KERN);
+	ret = insn_decode_kernel(&insn, emulate);
 
 	BUG_ON(ret < 0);
 	BUG_ON(len != insn.length);

arch/x86/kernel/cpu/mce/severity.c

@@ -225,7 +225,7 @@ static bool is_copy_from_user(struct pt_regs *regs)
 	if (copy_from_kernel_nofault(insn_buf, (void *)regs->ip, MAX_INSN_SIZE))
 		return false;
 
-	ret = insn_decode(&insn, insn_buf, MAX_INSN_SIZE, INSN_MODE_KERN);
+	ret = insn_decode_kernel(&insn, insn_buf);
 	if (ret < 0)
 		return false;
 

arch/x86/kernel/kprobes/core.c

@@ -285,7 +285,7 @@ static int can_probe(unsigned long paddr)
 		if (!__addr)
 			return 0;
 
-		ret = insn_decode(&insn, (void *)__addr, MAX_INSN_SIZE, INSN_MODE_KERN);
+		ret = insn_decode_kernel(&insn, (void *)__addr);
 		if (ret < 0)
 			return 0;
 
@@ -322,7 +322,7 @@ int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
 			MAX_INSN_SIZE))
 		return 0;
 
-	ret = insn_decode(insn, dest, MAX_INSN_SIZE, INSN_MODE_KERN);
+	ret = insn_decode_kernel(insn, dest);
 	if (ret < 0)
 		return 0;
 

arch/x86/kernel/kprobes/opt.c

@@ -324,7 +324,7 @@ static int can_optimize(unsigned long paddr)
 		if (!recovered_insn)
 			return 0;
 
-		ret = insn_decode(&insn, (void *)recovered_insn, MAX_INSN_SIZE, INSN_MODE_KERN);
+		ret = insn_decode_kernel(&insn, (void *)recovered_insn);
 		if (ret < 0)
 			return 0;
 

arch/x86/kernel/traps.c

@@ -504,7 +504,7 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
 			MAX_INSN_SIZE))
 		return GP_NO_HINT;
 
-	ret = insn_decode(&insn, insn_buf, MAX_INSN_SIZE, INSN_MODE_KERN);
+	ret = insn_decode_kernel(&insn, insn_buf);
 	if (ret < 0)
 		return GP_NO_HINT;
 

tools/arch/x86/include/asm/insn.h

@@ -150,6 +150,8 @@ enum insn_mode {
 
 extern int insn_decode(struct insn *insn, const void *kaddr, int buf_len, enum insn_mode m);
 
+#define insn_decode_kernel(_insn, _ptr) insn_decode((_insn), (_ptr), MAX_INSN_SIZE, INSN_MODE_KERN)
+
 /* Attribute will be determined after getting ModRM (for opcode groups) */
 static inline void insn_get_attribute(struct insn *insn)
 {