tracing: probeevent: Add array type support

Add array type support for probe events.
This allows user to get arraied types from memory address.
The array type syntax is

	TYPE[N]

Where TYPE is one of types (u8/16/32/64,s8/16/32/64,
x8/16/32/64, symbol, string) and N is a fixed value less
than 64.

The string array type is a bit different from other types. For
other base types, <base-type>[1] is equal to <base-type>
(e.g. +0(%di):x32[1] is same as +0(%di):x32.) But string[1] is not
equal to string. The string type itself represents "char array",
but string array type represents "char * array". So, for example,
+0(%di):string[1] is equal to +0(+0(%di)):string.

Link: http://lkml.kernel.org/r/152465891533.26224.6150658225601339931.stgit@devbox

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 55 insertions, 8 deletions

diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
index b4075f3e3a29..5c56afc17cf8 100644
--- a/kernel/trace/trace_probe_tmpl.h
+++ b/kernel/trace/trace_probe_tmpl.h
@@ -67,10 +67,15 @@ static nokprobe_inline int
 process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
 			   void *dest, void *base)
 {
-	int ret = 0;
+	struct fetch_insn *s3 = NULL;
+	int total = 0, ret = 0, i = 0;
+	u32 loc = 0;
+	unsigned long lval = val;
 
+stage2:
 	/* 2nd stage: dereference memory if needed */
 	while (code->op == FETCH_OP_DEREF) {
+		lval = val;
 		ret = probe_mem_read(&val, (void *)val + code->offset,
 					sizeof(val));
 		if (ret)
@@ -78,11 +83,15 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
 		code++;
 	}
 
+	s3 = code;
+stage3:
 	/* 3rd stage: store value to buffer */
 	if (unlikely(!dest)) {
-		if (code->op == FETCH_OP_ST_STRING)
-			return fetch_store_strlen(val + code->offset);
-		else
+		if (code->op == FETCH_OP_ST_STRING) {
+			ret += fetch_store_strlen(val + code->offset);
+			code++;
+			goto array;
+		} else
 			return -EILSEQ;
 	}
 
@@ -94,6 +103,7 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
 		probe_mem_read(dest, (void *)val + code->offset, code->size);
 		break;
 	case FETCH_OP_ST_STRING:
+		loc = *(u32 *)dest;
 		ret = fetch_store_string(val + code->offset, dest, base);
 		break;
 	default:
@@ -107,6 +117,29 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
 		code++;
 	}
 
+array:
+	/* the last stage: Loop on array */
+	if (code->op == FETCH_OP_LP_ARRAY) {
+		total += ret;
+		if (++i < code->param) {
+			code = s3;
+			if (s3->op != FETCH_OP_ST_STRING) {
+				dest += s3->size;
+				val += s3->size;
+				goto stage3;
+			}
+			code--;
+			val = lval + sizeof(char *);
+			if (dest) {
+				dest += sizeof(u32);
+				*(u32 *)dest = update_data_loc(loc, ret);
+			}
+			goto stage2;
+		}
+		code++;
+		ret = total;
+	}
+
 	return code->op == FETCH_OP_END ? ret : -EILSEQ;
 }
 
@@ -158,12 +191,26 @@ static inline int
 print_probe_args(struct trace_seq *s, struct probe_arg *args, int nr_args,
 		 u8 *data, void *field)
 {
-	int i;
+	void *p;
+	int i, j;
 
 	for (i = 0; i < nr_args; i++) {
-		trace_seq_printf(s, " %s=", args[i].name);
-		if (!args[i].type->print(s, data + args[i].offset, field))
-			return -ENOMEM;
+		struct probe_arg *a = args + i;
+
+		trace_seq_printf(s, " %s=", a->name);
+		if (likely(!a->count)) {
+			if (!a->type->print(s, data + a->offset, field))
+				return -ENOMEM;
+			continue;
+		}
+		trace_seq_putc(s, '{');
+		p = data + a->offset;
+		for (j = 0; j < a->count; j++) {
+			if (!a->type->print(s, p, field))
+				return -ENOMEM;
+			trace_seq_putc(s, j == a->count - 1 ? '}' : ',');
+			p += a->type->size;
+		}
 	}
 	return 0;
 }