[src/trunk]: src Add KCOV_LOAD() and KCOV_STORE() - new helper macros

[kamil <kamil%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/cc23cca166ff
branches:  trunk
changeset: 839544:cc23cca166ff
user:      kamil <kamil%NetBSD.org@localhost>
date:      Sun Feb 24 21:14:43 2019 +0000

description:
Add KCOV_LOAD() and KCOV_STORE() - new helper macros

New macros prefer 64-bit atomic operations whenever accessible.

As a fallback they use volatile move operations that are not known
to have negative effect in KCOV even if interrupted in the middle of
operation.

Enable kcov_basic and kcov_thread tests on targets without
__HAVE_ATOMIC64_OPS.

diffstat:

 sys/sys/kcov.h         |  21 ++++++++++++++++++++-
 tests/modules/t_kcov.c |  10 ++++------
 2 files changed, 24 insertions(+), 7 deletions(-)

diffs (78 lines):

diff -r 8752d341afe4 -r cc23cca166ff sys/sys/kcov.h
--- a/sys/sys/kcov.h    Sun Feb 24 21:07:59 2019 +0000
+++ b/sys/sys/kcov.h    Sun Feb 24 21:14:43 2019 +0000
@@ -1,4 +1,4 @@
-/*      $NetBSD: kcov.h,v 1.1 2019/02/23 03:10:06 kamil Exp $        */
+/*      $NetBSD: kcov.h,v 1.2 2019/02/24 21:14:43 kamil Exp $        */
 
 /*
  * Copyright (c) 2019 The NetBSD Foundation, Inc.
@@ -32,6 +32,10 @@
 #ifndef _SYS_KCOV_H_
 #define _SYS_KCOV_H_
 
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/atomic.h>
+
 #define KCOV_IOC_SETBUFSIZE    _IOW('K', 1, uint64_t)
 #define KCOV_IOC_ENABLE                _IO('K', 2)
 #define KCOV_IOC_DISABLE       _IO('K', 3)
@@ -39,4 +43,19 @@
 typedef volatile uint64_t kcov_int_t;
 #define KCOV_ENTRY_SIZE sizeof(kcov_int_t)
 
+/*
+ * Always prefer 64-bit atomic operations whenever accessible.
+ *
+ * As a fallback keep regular volatile move operation that it's not known
+ * to have negative effect in KCOV even if interrupted in the middle of
+ * operation.
+ */
+#ifdef __HAVE_ATOMIC64_OPS
+#define KCOV_STORE(x,v)        __atomic_store_n(&(x), (v), __ATOMIC_RELAXED)
+#define KCOV_LOAD(x)   __atomic_load_n(&(x), __ATOMIC_RELAXED)
+#else
+#define KCOV_STORE(x,v)        (x) = (y)
+#define KCOV_LOAD(x)   (x)
+#endif
+
 #endif /* !_SYS_KCOV_H_ */
diff -r 8752d341afe4 -r cc23cca166ff tests/modules/t_kcov.c
--- a/tests/modules/t_kcov.c    Sun Feb 24 21:07:59 2019 +0000
+++ b/tests/modules/t_kcov.c    Sun Feb 24 21:14:43 2019 +0000
@@ -254,10 +254,10 @@
        ATF_REQUIRE_MSG(ioctl(fd, KCOV_IOC_ENABLE) == 0,
            "Unable to enable kcov ");
 
-       __atomic_store_n(&buf[0], 0 , __ATOMIC_RELAXED);
+       KCOV_STORE(&buf[0], 0);
 
        sleep(0);
-       ATF_REQUIRE_MSG(__atomic_load_n(&buf[0], __ATOMIC_RELAXED) != 0, "No records found");
+       ATF_REQUIRE_MSG(KCOV_LOAD(&buf[0]) != 0, "No records found");
 
        ATF_REQUIRE_MSG(ioctl(fd, KCOV_IOC_DISABLE) == 0,
            "Unable to disable kcov");
@@ -270,9 +270,9 @@
 {
        kcov_int_t *buf = ptr;
 
-       __atomic_store_n(&buf[0], 0, __ATOMIC_RELAXED);
+       KCOV_STORE(&buf[0], 0);
        sleep(0);
-       ATF_REQUIRE_MSG(__atomic_load_n(&buf[0], __ATOMIC_RELAXED) == 0,
+       ATF_REQUIRE_MSG(KCOV_LOAD(&buf[0]) == 0,
            "Records changed in blocked thread");
 
        return NULL;
@@ -311,9 +311,7 @@
        ATF_TP_ADD_TC(tp, kcov_enable_no_disable);
        ATF_TP_ADD_TC(tp, kcov_enable_no_disable_no_close);
        ATF_TP_ADD_TC(tp, kcov_mmap_enable_thread_close);
-#ifdef __HAVE_ATOMIC64_OPS
        ATF_TP_ADD_TC(tp, kcov_basic);
        ATF_TP_ADD_TC(tp, kcov_thread);
-#endif
        return atf_no_error();
 }