This is a note to let you know that I've just added the patch titled
lib/bitmap: workaround const_eval test build failure
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
lib-bitmap-workaround-const_eval-test-build-failure.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4b3871264abb0a1444618dd7d57b6bcc58e9b206
Author: Yury Norov <yury.norov@xxxxxxxxx>
Date: Mon Jul 17 12:17:03 2023 -0700
lib/bitmap: workaround const_eval test build failure
[ Upstream commit 2356d198d2b4ddec24efea98271cb3be230bc787 ]
When building with Clang, and when KASAN and GCOV_PROFILE_ALL are both
enabled, the test fails to build [1]:
>> lib/test_bitmap.c:920:2: error: call to '__compiletime_assert_239' declared with 'error' attribute: BUILD_BUG_ON failed: !__builtin_constant_p(res)
BUILD_BUG_ON(!__builtin_constant_p(res));
^
include/linux/build_bug.h:50:2: note: expanded from macro 'BUILD_BUG_ON'
BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
^
include/linux/build_bug.h:39:37: note: expanded from macro 'BUILD_BUG_ON_MSG'
#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
^
include/linux/compiler_types.h:352:2: note: expanded from macro 'compiletime_assert'
_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
^
include/linux/compiler_types.h:340:2: note: expanded from macro '_compiletime_assert'
__compiletime_assert(condition, msg, prefix, suffix)
^
include/linux/compiler_types.h:333:4: note: expanded from macro '__compiletime_assert'
prefix ## suffix(); \
^
<scratch space>:185:1: note: expanded from here
__compiletime_assert_239
Originally it was attributed to s390, which now looks seemingly wrong. The
issue is not related to bitmap code itself, but it breaks build for a given
configuration.
Disabling the const_eval test under that config may potentially hide other
bugs. Instead, workaround it by disabling GCOV for the test_bitmap unless
the compiler will get fixed.
[1] https://github.com/ClangBuiltLinux/linux/issues/1874
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202307171254.yFcH97ej-lkp@xxxxxxxxx/
Fixes: dc34d5036692 ("lib: test_bitmap: add compile-time optimization/evaluations assertions")
Co-developed-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/lib/Makefile b/lib/Makefile
index 59bd7c2f793a7..5ffe72ec99797 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -81,8 +81,14 @@ obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
obj-$(CONFIG_TEST_DYNAMIC_DEBUG) += test_dynamic_debug.o
obj-$(CONFIG_TEST_PRINTF) += test_printf.o
obj-$(CONFIG_TEST_SCANF) += test_scanf.o
+
obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
obj-$(CONFIG_TEST_STRSCPY) += test_strscpy.o
+ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_KASAN),yy)
+# FIXME: Clang breaks test_bitmap_const_eval when KASAN and GCOV are enabled
+GCOV_PROFILE_test_bitmap.o := n
+endif
+
obj-$(CONFIG_TEST_UUID) += test_uuid.o
obj-$(CONFIG_TEST_XARRAY) += test_xarray.o
obj-$(CONFIG_TEST_MAPLE_TREE) += test_maple_tree.o
diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index a8005ad3bd589..37a9108c4f588 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -1149,6 +1149,10 @@ static void __init test_bitmap_print_buf(void)
}
}
+/*
+ * FIXME: Clang breaks compile-time evaluations when KASAN and GCOV are enabled.
+ * To workaround it, GCOV is force-disabled in Makefile for this configuration.
+ */
static void __init test_bitmap_const_eval(void)
{
DECLARE_BITMAP(bitmap, BITS_PER_LONG);
@@ -1174,11 +1178,7 @@ static void __init test_bitmap_const_eval(void)
* the compiler is fixed.
*/
bitmap_clear(bitmap, 0, BITS_PER_LONG);
-#if defined(__s390__) && defined(__clang__)
- if (!const_test_bit(7, bitmap))
-#else
if (!test_bit(7, bitmap))
-#endif
bitmap_set(bitmap, 5, 2);
/* Equals to `unsigned long bitopvar = BIT(20)` */
