[merged mm-stable] kmsan-fix-memcpy-tests.patch removed from -mm tree

[merged mm-stable] kmsan-fix-memcpy-tests.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: kmsan: fix memcpy tests
has been removed from the -mm tree.  Its filename was
     kmsan-fix-memcpy-tests.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Alexander Potapenko <glider@google.com>
Subject: kmsan: fix memcpy tests
Date: Mon, 5 Dec 2022 15:57:40 +0100

Recent Clang changes may cause it to delete calls of memcpy(), if the
source is an uninitialized volatile local.  This happens because passing a
pointer to a volatile local into memcpy() discards the volatile qualifier,
giving the compiler a free hand to optimize the memcpy() call away.

Use OPTIMIZER_HIDE_VAR() to hide the uninitialized var from the too-smart
compiler.

Link: https://lkml.kernel.org/r/20221205145740.694038-1-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/kmsan/kmsan_test.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/mm/kmsan/kmsan_test.c~kmsan-fix-memcpy-tests
+++ a/mm/kmsan/kmsan_test.c
@@ -419,6 +419,7 @@ static void test_memcpy_aligned_to_align
 	kunit_info(
 		test,
 		"memcpy()ing aligned uninit src to aligned dst (UMR report)\n");
+	OPTIMIZER_HIDE_VAR(uninit_src);
 	memcpy((void *)&dst, (void *)&uninit_src, sizeof(uninit_src));
 	kmsan_check_memory((void *)&dst, sizeof(dst));
 	KUNIT_EXPECT_TRUE(test, report_matches(&expect));
@@ -441,6 +442,7 @@ static void test_memcpy_aligned_to_unali
 	kunit_info(
 		test,
 		"memcpy()ing aligned uninit src to unaligned dst (UMR report)\n");
+	OPTIMIZER_HIDE_VAR(uninit_src);
 	memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src));
 	kmsan_check_memory((void *)dst, 4);
 	KUNIT_EXPECT_TRUE(test, report_matches(&expect));
@@ -464,6 +466,7 @@ static void test_memcpy_aligned_to_unali
 	kunit_info(
 		test,
 		"memcpy()ing aligned uninit src to unaligned dst - part 2 (UMR report)\n");
+	OPTIMIZER_HIDE_VAR(uninit_src);
 	memcpy((void *)&dst[1], (void *)&uninit_src, sizeof(uninit_src));
 	kmsan_check_memory((void *)&dst[4], sizeof(uninit_src));
 	KUNIT_EXPECT_TRUE(test, report_matches(&expect));
_

Patches currently in -mm which might be from glider@google.com are