The patch titled
Subject: lib: make a test module with set/clear bit
has been added to the -mm tree. Its filename is
lib-make-a-test-module-with-set-clear-bit.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lib-make-a-test-module-with-set-clear-bit.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lib-make-a-test-module-with-set-clear-bit.patch
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------------------------------------------------------
From: Jesse Brandeburg <jesse.brandeburg@xxxxxxxxx>
Subject: lib: make a test module with set/clear bit
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
insmod lib/test_bitops.ko
rmmod lib/test_bitops.ko
<check dmesg>, there should be no compiler/sparse warnings and no
error messages in log.
Link: http://lkml.kernel.org/r/20200310221747.2848474-2-jesse.brandeburg@xxxxxxxxx
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@xxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CcL Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Wei Yang <richard.weiyang@xxxxxxxxx>
Cc: Christian Brauner <christian.brauner@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/Kconfig.debug | 13 +++++
lib/Makefile | 2
lib/test_bitops.c | 60 +++++++++++++++++++++++++++
tools/testing/selftests/lib/config | 1
4 files changed, 76 insertions(+)
--- a/lib/Kconfig.debug~lib-make-a-test-module-with-set-clear-bit
+++ a/lib/Kconfig.debug
@@ -2035,6 +2035,19 @@ 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
--- a/lib/Makefile~lib-make-a-test-module-with-set-clear-bit
+++ a/lib/Makefile
@@ -76,6 +76,8 @@ obj-$(CONFIG_TEST_SORT) += test_sort.o
obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
+obj-$(CONFIG_TEST_BITOPS) += test_bitops.o
+CFLAGS_test_bitops.o += -Werror
obj-$(CONFIG_TEST_PRINTF) += test_printf.o
obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
obj-$(CONFIG_TEST_STRSCPY) += test_strscpy.o
--- /dev/null
+++ a/lib/test_bitops.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Intel Corporation
+ */
+
+#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 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_LENGTH = 256
+};
+
+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@xxxxxxxxx>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Bit testing module");
--- a/tools/testing/selftests/lib/config~lib-make-a-test-module-with-set-clear-bit
+++ a/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
_
Patches currently in -mm which might be from jesse.brandeburg@xxxxxxxxx are
lib-make-a-test-module-with-set-clear-bit.patch
