perf: split perf_trace_buf_prepare into alloc and update parts

split allows to move expensive update of 'struct trace_entry' to later phase.
Repurpose unused 1st argument of perf_tp_event() to indicate event type.

While splitting use temp variable 'rctx' instead of '*rctx' to avoid
unnecessary loads done by the compiler due to -fno-strict-aliasing

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 7915142c89e4..c53485441c88 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -1131,7 +1131,7 @@ static void __uprobe_perf_func(struct trace_uprobe *tu,
 	if (hlist_empty(head))
 		goto out;
 
-	entry = perf_trace_buf_prepare(size, call->event.type, NULL, &rctx);
+	entry = perf_trace_buf_alloc(size, NULL, &rctx);
 	if (!entry)
 		goto out;
 
@@ -1152,7 +1152,8 @@ static void __uprobe_perf_func(struct trace_uprobe *tu,
 		memset(data + len, 0, size - esize - len);
 	}
 
-	perf_trace_buf_submit(entry, size, rctx, 0, 1, regs, head, NULL);
+	perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
+			      head, NULL);
  out:
 	preempt_enable();
 }