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authorJesse Brandeburg <jesse.brandeburg@intel.com>2020-06-04 16:50:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-04 19:06:25 -0700
commitc348c16305280fe3e6c1186378f96c8634c149f9 (patch)
treeaa53fa861170b36756d7d1aa14c1ce4c00089da5 /lib/test_bitops.c
parent63d7f8167fe65891617d5eca6314eca46029955c (diff)
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@intel.com Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> CcL Ingo Molnar <mingo@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wei Yang <richard.weiyang@gmail.com> Cc: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/test_bitops.c')
-rw-r--r--lib/test_bitops.c60
1 files changed, 60 insertions, 0 deletions
diff --git a/lib/test_bitops.c b/lib/test_bitops.c
new file mode 100644
index 000000000000..fd50b3ae4a14
--- /dev/null
+++ b/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@intel.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Bit testing module");