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lib/bitmap: workaround const_eval test build failure

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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@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307171254.yFcH97ej-lkp@intel.com/
Fixes: dc34d50366 ("lib: test_bitmap: add compile-time optimization/evaluations assertions")
Co-developed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
This commit is contained in:
Yury Norov 2023-07-17 12:17:03 -07:00
parent dcb60f9c40
commit 2356d198d2
2 changed files with 10 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
lib/Makefile
View File

@ -82,7 +82,13 @@ 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-$(CONFIG_TEST_BITMAP) += test_bitmap.o
ifeq ($(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

8
lib/test_bitmap.c
View File

@ -1161,6 +1161,10 @@ 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);
@ -1186,11 +1190,7 @@ 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)` */