2 files changed, 132 insertions, 0 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index 6762529ad9e4..40b114a11d7c 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -575,4 +575,7 @@ config PARMAN
 config PRIME_NUMBERS
         tristate
 
+config STRING_SELFTEST
+        bool "Test string functions"
+
 endmenu
diff --git a/lib/string.c b/lib/string.c
index 198148bb61fd..abf6499e3915 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -1051,3 +1051,132 @@ void fortify_panic(const char *name)
         BUG();
 }
 EXPORT_SYMBOL(fortify_panic);
+
+#ifdef CONFIG_STRING_SELFTEST
+#include <linux/slab.h>
+#include <linux/module.h>
+
+static __init int memset16_selftest(void)
+{
+        unsigned i, j, k;
+        u16 v, *p = kmalloc(256 * 2 * 2, GFP_KERNEL);
+
+        for (i = 0; i < 256; i++) {
+                for (j = 0; j < 256; j++) {
+                        memset(p, 0xa1, 256 * 2 * sizeof(v));
+                        memset16(p + i, 0xb1b2, j);
+                        for (k = 0; k < 512; k++) {
+                                v = p[k];
+                                if (k < i) {
+                                        if (v != 0xa1a1)
+                                                goto fail;
+                                } else if (k < i + j) {
+                                        if (v != 0xb1b2)
+                                                goto fail;
+                                } else {
+                                        if (v != 0xa1a1)
+                                                goto fail;
+                                }
+                        }
+                }
+        }
+
+fail:
+        kfree(p);
+        if (i < 256)
+                return (i << 24) | (j << 16) | k;
+        return 0;
+}
+
+static __init int memset32_selftest(void)
+{
+        unsigned i, j, k;
+        u32 v, *p = kmalloc(256 * 2 * 4, GFP_KERNEL);
+
+        for (i = 0; i < 256; i++) {
+                for (j = 0; j < 256; j++) {
+                        memset(p, 0xa1, 256 * 2 * sizeof(v));
+                        memset32(p + i, 0xb1b2b3b4, j);
+                        for (k = 0; k < 512; k++) {
+                                v = p[k];
+                                if (k < i) {
+                                        if (v != 0xa1a1a1a1)
+                                                goto fail;
+                                } else if (k < i + j) {
+                                        if (v != 0xb1b2b3b4)
+                                                goto fail;
+                                } else {
+                                        if (v != 0xa1a1a1a1)
+                                                goto fail;
+                                }
+                        }
+                }
+        }
+
+fail:
+        kfree(p);
+        if (i < 256)
+                return (i << 24) | (j << 16) | k;
+        return 0;
+}
+
+static __init int memset64_selftest(void)
+{
+        unsigned i, j, k;
+        u64 v, *p = kmalloc(256 * 2 * 8, GFP_KERNEL);
+
+        for (i = 0; i < 256; i++) {
+                for (j = 0; j < 256; j++) {
+                        memset(p, 0xa1, 256 * 2 * sizeof(v));
+                        memset64(p + i, 0xb1b2b3b4b5b6b7b8ULL, j);
+                        for (k = 0; k < 512; k++) {
+                                v = p[k];
+                                if (k < i) {
+                                        if (v != 0xa1a1a1a1a1a1a1a1ULL)
+                                                goto fail;
+                                } else if (k < i + j) {
+                                        if (v != 0xb1b2b3b4b5b6b7b8ULL)
+                                                goto fail;
+                                } else {
+                                        if (v != 0xa1a1a1a1a1a1a1a1ULL)
+                                                goto fail;
+                                }
+                        }
+                }
+        }
+
+fail:
+        kfree(p);
+        if (i < 256)
+                return (i << 24) | (j << 16) | k;
+        return 0;
+}
+
+static __init int string_selftest_init(void)
+{
+        int test, subtest;
+
+        test = 1;
+        subtest = memset16_selftest();
+        if (subtest)
+                goto fail;
+
+        test = 2;
+        subtest = memset32_selftest();
+        if (subtest)
+                goto fail;
+
+        test = 3;
+        subtest = memset64_selftest();
+        if (subtest)
+                goto fail;
+
+        pr_info("String selftests succeeded\n");
+        return 0;
+fail:
+        pr_crit("String selftest failure %d.%08x\n", test, subtest);
+        return 0;
+}
+
+module_init(string_selftest_init);
+#endif  /* CONFIG_STRING_SELFTEST */