x86/insn: Rename insn_decode() to insn_decode_from_regs()

Rename insn_decode() to insn_decode_from_regs() to denote that it
receives regs as param and uses registers from there during decoding.
Free the former name for a more generic version of the function.

No functional changes.
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210304174237.31945-2-bp@alien8.de

arch/x86/include/asm/insn-eval.h

@@ -25,7 +25,7 @@ int insn_fetch_from_user(struct pt_regs *regs,
 			 unsigned char buf[MAX_INSN_SIZE]);
 int insn_fetch_from_user_inatomic(struct pt_regs *regs,
 				  unsigned char buf[MAX_INSN_SIZE]);
-bool insn_decode(struct insn *insn, struct pt_regs *regs,
-		 unsigned char buf[MAX_INSN_SIZE], int buf_size);
+bool insn_decode_from_regs(struct insn *insn, struct pt_regs *regs,
+			   unsigned char buf[MAX_INSN_SIZE], int buf_size);
 
 #endif /* _ASM_X86_INSN_EVAL_H */

arch/x86/kernel/sev-es.c

@@ -266,7 +266,7 @@ static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt)
 			return ES_EXCEPTION;
 		}
 
-		if (!insn_decode(&ctxt->insn, ctxt->regs, buffer, res))
+		if (!insn_decode_from_regs(&ctxt->insn, ctxt->regs, buffer, res))
 			return ES_DECODE_FAILED;
 	} else {
 		res = vc_fetch_insn_kernel(ctxt, buffer);

arch/x86/kernel/umip.c

@@ -356,7 +356,7 @@ bool fixup_umip_exception(struct pt_regs *regs)
 	if (!nr_copied)
 		return false;
 
-	if (!insn_decode(&insn, regs, buf, nr_copied))
+	if (!insn_decode_from_regs(&insn, regs, buf, nr_copied))
 		return false;
 
 	umip_inst = identify_insn(&insn);

arch/x86/lib/insn-eval.c

@@ -1488,7 +1488,7 @@ int insn_fetch_from_user_inatomic(struct pt_regs *regs, unsigned char buf[MAX_IN
 }
 
 /**
- * insn_decode() - Decode an instruction
+ * insn_decode_from_regs() - Decode an instruction
  * @insn:	Structure to store decoded instruction
  * @regs:	Structure with register values as seen when entering kernel mode
  * @buf:	Buffer containing the instruction bytes
@@ -1501,8 +1501,8 @@ int insn_fetch_from_user_inatomic(struct pt_regs *regs, unsigned char buf[MAX_IN
  *
  * True if instruction was decoded, False otherwise.
  */
-bool insn_decode(struct insn *insn, struct pt_regs *regs,
-		 unsigned char buf[MAX_INSN_SIZE], int buf_size)
+bool insn_decode_from_regs(struct insn *insn, struct pt_regs *regs,
+			   unsigned char buf[MAX_INSN_SIZE], int buf_size)
 {
 	int seg_defs;