kernel/trace: extract common part in process_fetch_insn

Each probe has an instance of process_fetch_insn respectively,
but they have something in common.

This patch aims to extract the common part into
process_common_fetch_insn which can be shared by each probe,
and they only need to focus on their special cases.

Signed-off-by: Song Chen <[email protected]>
Suggested-by: Masami Hiramatsu <[email protected]>
Acked-by: Masami Hiramatsu <[email protected]>
Signed-off-by: Masami Hiramatsu <[email protected]>

Author: Song Chen

kernel/trace/trace_eprobe.c

@@ -396,20 +396,12 @@ static int get_eprobe_size(struct trace_probe *tp, void *rec)
 			case FETCH_OP_TP_ARG:
 				val = get_event_field(code, rec);
 				break;
-			case FETCH_OP_IMM:
-				val = code->immediate;
-				break;
-			case FETCH_OP_COMM:
-				val = (unsigned long)current->comm;
-				break;
-			case FETCH_OP_DATA:
-				val = (unsigned long)code->data;
-				break;
 			case FETCH_NOP_SYMBOL:	/* Ignore a place holder */
 				code++;
 				goto retry;
 			default:
-				continue;
+				if (process_common_fetch_insn(code, &val) < 0)
+					continue;
 			}
 			code++;
 			len = process_fetch_insn_bottom(code, val, NULL, NULL);
@@ -429,26 +421,20 @@ process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
 		   void *base)
 {
 	unsigned long val;
+	int ret;
 
  retry:
 	switch (code->op) {
 	case FETCH_OP_TP_ARG:
 		val = get_event_field(code, rec);
 		break;
-	case FETCH_OP_IMM:
-		val = code->immediate;
-		break;
-	case FETCH_OP_COMM:
-		val = (unsigned long)current->comm;
-		break;
-	case FETCH_OP_DATA:
-		val = (unsigned long)code->data;
-		break;
 	case FETCH_NOP_SYMBOL:	/* Ignore a place holder */
 		code++;
 		goto retry;
 	default:
-		return -EILSEQ;
+		ret = process_common_fetch_insn(code, &val);
+		if (ret < 0)
+			return ret;
 	}
 	code++;
 	return process_fetch_insn_bottom(code, val, dest, base);

kernel/trace/trace_kprobe.c

@@ -1225,6 +1225,7 @@ process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
 {
 	struct pt_regs *regs = rec;
 	unsigned long val;
+	int ret;
 
 retry:
 	/* 1st stage: get value from context */
@@ -1241,15 +1242,6 @@ process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
 	case FETCH_OP_RETVAL:
 		val = regs_return_value(regs);
 		break;
-	case FETCH_OP_IMM:
-		val = code->immediate;
-		break;
-	case FETCH_OP_COMM:
-		val = (unsigned long)current->comm;
-		break;
-	case FETCH_OP_DATA:
-		val = (unsigned long)code->data;
-		break;
 #ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
 	case FETCH_OP_ARG:
 		val = regs_get_kernel_argument(regs, code->param);
@@ -1259,7 +1251,9 @@ process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
 		code++;
 		goto retry;
 	default:
-		return -EILSEQ;
+		ret = process_common_fetch_insn(code, &val);
+		if (ret < 0)
+			return ret;
 	}
 	code++;
 

kernel/trace/trace_probe_tmpl.h

@@ -98,6 +98,26 @@ fetch_store_symstring(unsigned long addr, void *dest, void *base)
 	return sprint_symbol(__dest, addr);
 }
 
+/* common part of process_fetch_insn*/
+static nokprobe_inline int
+process_common_fetch_insn(struct fetch_insn *code, unsigned long *val)
+{
+	switch (code->op) {
+	case FETCH_OP_IMM:
+		*val = code->immediate;
+		break;
+	case FETCH_OP_COMM:
+		*val = (unsigned long)current->comm;
+		break;
+	case FETCH_OP_DATA:
+		*val = (unsigned long)code->data;
+		break;
+	default:
+		return -EILSEQ;
+	}
+	return 0;
+}
+
 /* From the 2nd stage, routine is same */
 static nokprobe_inline int
 process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,

kernel/trace/trace_uprobe.c

@@ -220,6 +220,7 @@ process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
 {
 	struct pt_regs *regs = rec;
 	unsigned long val;
+	int ret;
 
 	/* 1st stage: get value from context */
 	switch (code->op) {
@@ -235,20 +236,16 @@ process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
 	case FETCH_OP_RETVAL:
 		val = regs_return_value(regs);
 		break;
-	case FETCH_OP_IMM:
-		val = code->immediate;
-		break;
 	case FETCH_OP_COMM:
 		val = FETCH_TOKEN_COMM;
 		break;
-	case FETCH_OP_DATA:
-		val = (unsigned long)code->data;
-		break;
 	case FETCH_OP_FOFFS:
 		val = translate_user_vaddr(code->immediate);
 		break;
 	default:
-		return -EILSEQ;
+		ret = process_common_fetch_insn(code, &val);
+		if (ret < 0)
+			return ret;
 	}
 	code++;