[release-branch.go1.16] runtime: set vdsoSP to caller's SP consistently

m.vdsoSP should be set to the SP of the caller of nanotime1,
instead of the SP of nanotime1 itself, which matches m.vdsoPC.
Otherwise the unmatched vdsoPC and vdsoSP would make the stack
trace look like recursive.

We already do it correctly on AMD64, 386, and RISCV64. This CL
fixes the rest.

Also incorporate CL 352509, skipping a flaky test.

Updates #47324, #50772.
Fixes #50780.

Change-Id: I98b6fcfbe9fc6bdd28b8fe2a1299b7c505371dd4
Reviewed-on: https://go-review.googlesource.com/c/go/+/337590
Trust: Cherry Mui <cherryyz@google.com>
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
(cherry picked from commit 217507eb035933bac6c990844f0d71d6000fd339)
Reviewed-on: https://go-review.googlesource.com/c/go/+/380716
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/src/runtime/pprof/pprof_test.go b/src/runtime/pprof/pprof_test.go
index 0e0cccbc6a..7bd28fc8bb 100644
--- a/src/runtime/pprof/pprof_test.go
+++ b/src/runtime/pprof/pprof_test.go
@@ -1458,3 +1458,38 @@ func TestTryAdd(t *testing.T) {
 		})
 	}
 }
+
+func TestTimeVDSO(t *testing.T) {
+	// Test that time functions have the right stack trace. In particular,
+	// it shouldn't be recursive.
+
+	if runtime.GOOS == "android" {
+		// Flaky on Android, issue 48655. VDSO may not be enabled.
+		testenv.SkipFlaky(t, 48655)
+	}
+
+	p := testCPUProfile(t, stackContains, []string{"time.now"}, avoidFunctions(), func(dur time.Duration) {
+		t0 := time.Now()
+		for {
+			t := time.Now()
+			if t.Sub(t0) >= dur {
+				return
+			}
+		}
+	})
+
+	// Check for recursive time.now sample.
+	for _, sample := range p.Sample {
+		var seenNow bool
+		for _, loc := range sample.Location {
+			for _, line := range loc.Line {
+				if line.Function.Name == "time.now" {
+					if seenNow {
+						t.Fatalf("unexpected recursive time.now")
+					}
+					seenNow = true
+				}
+			}
+		}
+	}
+}