tracing: infrastructure for supporting binary record

Impact: save on memory for tracing

Current tracers are typically using a struct(like struct ftrace_entry,
struct ctx_switch_entry, struct special_entr etc...)to record a binary
event. These structs can only record a their own kind of events.
A new kind of tracer need a new struct and a lot of code too handle it.

So we need a generic binary record for events. This infrastructure
is for this purpose.

[fweisbec@gmail.com: rebase against latest -tip, make it safe while sched
tracing as reported by Steven Rostedt]

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 75 insertions, 0 deletions

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 306fef84c503..4ab71201862e 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -53,6 +53,26 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
         return len;
 }
 
+static int
+trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
+{
+        int len = (PAGE_SIZE - 1) - s->len;
+        int ret;
+
+        if (!len)
+                return 0;
+
+        ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+
+        /* If we can't write it all, don't bother writing anything */
+        if (ret >= len)
+                return 0;
+
+        s->len += ret;
+
+        return len;
+}
+
 /**
  * trace_seq_puts - trace sequence printing of simple string
  * @s: trace sequence descriptor
@@ -855,6 +875,60 @@ static struct trace_event trace_print_event = {
         .raw            = trace_print_raw,
 };
 
+/* TRACE_BPRINTK */
+static enum print_line_t
+trace_bprintk_print(struct trace_iterator *iter, int flags)
+{
+        struct trace_entry *entry = iter->ent;
+        struct trace_seq *s = &iter->seq;
+        struct bprintk_entry *field;
+
+        trace_assign_type(field, entry);
+
+        if (!seq_print_ip_sym(s, field->ip, flags))
+                goto partial;
+
+        if (!trace_seq_puts(s, ": "))
+                goto partial;
+
+        if (!trace_seq_bprintf(s, field->fmt, field->buf))
+                goto partial;
+
+        return TRACE_TYPE_HANDLED;
+
+ partial:
+        return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static enum print_line_t
+trace_bprintk_raw(struct trace_iterator *iter, int flags)
+{
+        struct trace_entry *entry = iter->ent;
+        struct trace_seq *s = &iter->seq;
+        struct bprintk_entry *field;
+
+        trace_assign_type(field, entry);
+
+        if (!trace_seq_printf(s, ": %lx : ", field->ip))
+                goto partial;
+
+        if (!trace_seq_bprintf(s, field->fmt, field->buf))
+                goto partial;
+
+        return TRACE_TYPE_HANDLED;
+
+ partial:
+        return TRACE_TYPE_PARTIAL_LINE;
+}
+
+static struct trace_event trace_bprintk_event = {
+        .type           = TRACE_BPRINTK,
+        .trace          = trace_bprintk_print,
+        .raw            = trace_bprintk_raw,
+        .hex            = trace_nop_print,
+        .binary         = trace_nop_print,
+};
+
 static struct trace_event *events[] __initdata = {
         &trace_fn_event,
         &trace_ctx_event,
@@ -863,6 +937,7 @@ static struct trace_event *events[] __initdata = {
         &trace_stack_event,
         &trace_user_stack_event,
         &trace_print_event,
+        &trace_bprintk_event,
         NULL
 };