tracing/probes: Integrate duplicate set_print_fmt()

The set_print_fmt() functions are implemented almost same for
[ku]probes.  Move it to a common place and get rid of the duplication.

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

1 files changed, 62 insertions, 0 deletions

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 430505b08a6f..d8347b01ce89 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -837,3 +837,65 @@ out:
 
         return ret;
 }
+
+static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
+                           bool is_return)
+{
+        int i;
+        int pos = 0;
+
+        const char *fmt, *arg;
+
+        if (!is_return) {
+                fmt = "(%lx)";
+                arg = "REC->" FIELD_STRING_IP;
+        } else {
+                fmt = "(%lx <- %lx)";
+                arg = "REC->" FIELD_STRING_FUNC ", REC->" FIELD_STRING_RETIP;
+        }
+
+        /* When len=0, we just calculate the needed length */
+#define LEN_OR_ZERO (len ? len - pos : 0)
+
+        pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
+
+        for (i = 0; i < tp->nr_args; i++) {
+                pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
+                                tp->args[i].name, tp->args[i].type->fmt);
+        }
+
+        pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
+
+        for (i = 0; i < tp->nr_args; i++) {
+                if (strcmp(tp->args[i].type->name, "string") == 0)
+                        pos += snprintf(buf + pos, LEN_OR_ZERO,
+                                        ", __get_str(%s)",
+                                        tp->args[i].name);
+                else
+                        pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
+                                        tp->args[i].name);
+        }
+
+#undef LEN_OR_ZERO
+
+        /* return the length of print_fmt */
+        return pos;
+}
+
+int set_print_fmt(struct trace_probe *tp, bool is_return)
+{
+        int len;
+        char *print_fmt;
+
+        /* First: called with 0 length to calculate the needed length */
+        len = __set_print_fmt(tp, NULL, 0, is_return);
+        print_fmt = kmalloc(len + 1, GFP_KERNEL);
+        if (!print_fmt)
+                return -ENOMEM;
+
+        /* Second: actually write the @print_fmt */
+        __set_print_fmt(tp, print_fmt, len + 1, is_return);
+        tp->call.print_fmt = print_fmt;
+
+        return 0;
+}