Messages in this thread | | | Date | Fri, 21 Feb 2020 12:25:18 +0200 | From | Andy Shevchenko <> | Subject | Re: [PATCH v3 2/2] lib: make a test module with set/clear bit |
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On Thu, Feb 20, 2020 at 03:21:55PM -0800, Jesse Brandeburg wrote: > Test some bit clears/sets to make sure assembly doesn't change, and > that the set_bit and clear_bit functions work and don't cause sparse > warnings. > > Instruct Kbuild to build this file with extra warning level -Wextra, > to catch new issues, and also doesn't hurt to build with C=1. > > This was used to test changes to arch/x86/include/asm/bitops.h. > > In particular, sparse (C=1) was very concerned when the last bit > before a natural boundary, like 7, or 31, was being tested, as this > causes sign extension (0xffffff7f) for instance when clearing bit 7. > > Recommended usage: > make defconfig > scripts/config -m CONFIG_TEST_BITOPS > make modules_prepare > make C=1 W=1 lib/test_bitops.ko > objdump -S -d lib/test_bitops.ko
Thanks! One comments below, after addressing: Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
> Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com> > > --- > v3: update the test to fail if bits aren't cleared, and make the > test reproduce the original issue without patch 1/2, showing that > the issue is fixed in patch 1/2. Thanks PeterZ! > v2: correct CC: list > --- > lib/Kconfig.debug | 13 +++++++ > lib/Makefile | 2 ++ > lib/test_bitops.c | 55 ++++++++++++++++++++++++++++++ > tools/testing/selftests/lib/config | 1 + > 4 files changed, 71 insertions(+) > create mode 100644 lib/test_bitops.c > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 69def4a9df00..61a5d00ea064 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1947,6 +1947,19 @@ config TEST_LKM > > If unsure, say N. > > +config TEST_BITOPS > + tristate "Test module for compilation of clear_bit/set_bit operations" > + depends on m > + help > + This builds the "test_bitops" module that is much like the > + TEST_LKM module except that it does a basic exercise of the > + clear_bit and set_bit macros to make sure there are no compiler > + warnings from C=1 sparse checker or -Wextra compilations. It has > + no dependencies and doesn't run or load unless explicitly requested > + by name. for example: modprobe test_bitops. > + > + If unsure, say N. > + > config TEST_VMALLOC > tristate "Test module for stress/performance analysis of vmalloc allocator" > default n > diff --git a/lib/Makefile b/lib/Makefile > index 611872c06926..b18db565b355 100644 > --- a/lib/Makefile > +++ b/lib/Makefile > @@ -89,6 +89,8 @@ obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o > obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o > obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o > obj-$(CONFIG_TEST_MEMINIT) += test_meminit.o > +obj-$(CONFIG_TEST_BITOPS) += test_bitops.o > +CFLAGS_test_bitops.o += -Werror > > obj-$(CONFIG_TEST_LIVEPATCH) += livepatch/ > > diff --git a/lib/test_bitops.c b/lib/test_bitops.c > new file mode 100644 > index 000000000000..97339d6455b0 > --- /dev/null > +++ b/lib/test_bitops.c > @@ -0,0 +1,55 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > + > +#include <linux/init.h> > +#include <linux/module.h> > +#include <linux/printk.h> > + > +/* a tiny module only meant to compile-test set/clear_bit */ > + > +/* use an enum because thats the most common BITMAP usage */ > +enum bitops_fun { > + BITOPS_4 = 4, > + BITOPS_7 = 7, > + BITOPS_11 = 11, > + BITOPS_31 = 31, > + BITOPS_88 = 88, > + BITOPS_LAST = 255
BITOPS_LAST = 255, BITOPS_LENGTH = 256
and...
> +}; > + > +static DECLARE_BITMAP(g_bitmap, BITOPS_LAST);
static DECLARE_BITMAP(g_bitmap, BITOPS_LENGTH);
> + > +static int __init test_bitops_startup(void) > +{ > + pr_warn("Loaded test module\n"); > + set_bit(BITOPS_4, g_bitmap); > + set_bit(BITOPS_7, g_bitmap); > + set_bit(BITOPS_11, g_bitmap); > + set_bit(BITOPS_31, g_bitmap); > + set_bit(BITOPS_88, g_bitmap); > + return 0; > +} > + > +static void __exit test_bitops_unstartup(void) > +{ > + int bit_set; > + > + clear_bit(BITOPS_4, g_bitmap); > + clear_bit(BITOPS_7, g_bitmap); > + clear_bit(BITOPS_11, g_bitmap); > + clear_bit(BITOPS_31, g_bitmap); > + clear_bit(BITOPS_88, g_bitmap); > + > + bit_set = find_first_bit(g_bitmap, BITOPS_LAST); > + if (bit_set != BITOPS_LAST) > + pr_err("ERROR: FOUND SET BIT %d\n", bit_set); > + > + pr_warn("Unloaded test module\n"); > +} > + > +module_init(test_bitops_startup); > +module_exit(test_bitops_unstartup); > + > +MODULE_AUTHOR("Jesse Brandeburg <jesse.brandeburg@intel.com>"); > +MODULE_LICENSE("GPL"); > +MODULE_DESCRIPTION("Bit testing module"); > diff --git a/tools/testing/selftests/lib/config b/tools/testing/selftests/lib/config > index 14a77ea4a8da..b80ee3f6e265 100644 > --- a/tools/testing/selftests/lib/config > +++ b/tools/testing/selftests/lib/config > @@ -2,3 +2,4 @@ CONFIG_TEST_PRINTF=m > CONFIG_TEST_BITMAP=m > CONFIG_PRIME_NUMBERS=m > CONFIG_TEST_STRSCPY=m > +CONFIG_TEST_BITOPS=m > -- > 2.24.1 >
-- With Best Regards, Andy Shevchenko
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