Merge tag 'linux-kselftest-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

Pull Kselftest updates from Shuah Khan:

 - fixes to seccomp test, and kselftest framework

 - cleanups to remove duplicate header defines

 - fixes to efivarfs "make clean" target

 - cgroup cleanup path

 - Moving the IMA kexec_load selftest to selftests/kexec work from Mimi
   Johar and Petr Vorel

 - A framework to kselftest for writing kernel test modules addition
   from Tobin C. Harding

* tag 'linux-kselftest-5.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (29 commits)
  selftests: build and run gpio when output directory is the src dir
  selftests/ipc: Fix msgque compiler warnings
  selftests/efivarfs: clean up test files from test_create*()
  selftests: fix headers_install circular dependency
  selftests/kexec: update get_secureboot_mode
  selftests/kexec: make kexec_load test independent of IMA being enabled
  selftests/kexec: check kexec_load and kexec_file_load are enabled
  selftests/kexec: Add missing '=y' to config options
  selftests/kexec: kexec_file_load syscall test
  selftests/kexec: define "require_root_privileges"
  selftests/kexec: define common logging functions
  selftests/kexec: define a set of common functions
  selftests/kexec: cleanup the kexec selftest
  selftests/kexec: move the IMA kexec_load selftest to selftests/kexec
  selftests/harness: Add 30 second timeout per test
  selftests/seccomp: Handle namespace failures gracefully
  selftests: cgroup: fix cleanup path in test_memcg_subtree_control()
  selftests: efivarfs: remove the test_create_read file if it was exist
  rseq/selftests: Adapt number of threads to the number of detected cpus
  lib: Add test module for strscpy_pad
  ...

Author: torvalds

Documentation/dev-tools/kselftest.rst

@@ -14,6 +14,10 @@ in safe mode with a limited scope. In limited mode, cpu-hotplug test is
 run on a single cpu as opposed to all hotplug capable cpus, and memory
 hotplug test is run on 2% of hotplug capable memory instead of 10%.
 
+kselftest runs as a userspace process.  Tests that can be written/run in
+userspace may wish to use the `Test Harness`_.  Tests that need to be
+run in kernel space may wish to use a `Test Module`_.
+
 Running the selftests (hotplug tests are run in limited mode)
 =============================================================
 
@@ -161,11 +165,97 @@ Contributing new tests (details)
 
    e.g: tools/testing/selftests/android/config
 
+Test Module
+===========
+
+Kselftest tests the kernel from userspace.  Sometimes things need
+testing from within the kernel, one method of doing this is to create a
+test module.  We can tie the module into the kselftest framework by
+using a shell script test runner.  ``kselftest_module.sh`` is designed
+to facilitate this process.  There is also a header file provided to
+assist writing kernel modules that are for use with kselftest:
+
+- ``tools/testing/kselftest/kselftest_module.h``
+- ``tools/testing/kselftest/kselftest_module.sh``
+
+How to use
+----------
+
+Here we show the typical steps to create a test module and tie it into
+kselftest.  We use kselftests for lib/ as an example.
+
+1. Create the test module
+
+2. Create the test script that will run (load/unload) the module
+   e.g. ``tools/testing/selftests/lib/printf.sh``
+
+3. Add line to config file e.g. ``tools/testing/selftests/lib/config``
+
+4. Add test script to makefile  e.g. ``tools/testing/selftests/lib/Makefile``
+
+5. Verify it works:
+
+.. code-block:: sh
+
+   # Assumes you have booted a fresh build of this kernel tree
+   cd /path/to/linux/tree
+   make kselftest-merge
+   make modules
+   sudo make modules_install
+   make TARGETS=lib kselftest
+
+Example Module
+--------------
+
+A bare bones test module might look like this:
+
+.. code-block:: c
+
+   // SPDX-License-Identifier: GPL-2.0+
+
+   #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+   #include "../tools/testing/selftests/kselftest_module.h"
+
+   KSTM_MODULE_GLOBALS();
+
+   /*
+    * Kernel module for testing the foobinator
+    */
+
+   static int __init test_function()
+   {
+           ...
+   }
+
+   static void __init selftest(void)
+   {
+           KSTM_CHECK_ZERO(do_test_case("", 0));
+   }
+
+   KSTM_MODULE_LOADERS(test_foo);
+   MODULE_AUTHOR("John Developer <[email protected]>");
+   MODULE_LICENSE("GPL");
+
+Example test script
+-------------------
+
+.. code-block:: sh
+
+    #!/bin/bash
+    # SPDX-License-Identifier: GPL-2.0+
+    $(dirname $0)/../kselftest_module.sh "foo" test_foo
+
+
 Test Harness
 ============
 
-The kselftest_harness.h file contains useful helpers to build tests.  The tests
-from tools/testing/selftests/seccomp/seccomp_bpf.c can be used as example.
+The kselftest_harness.h file contains useful helpers to build tests.  The
+test harness is for userspace testing, for kernel space testing see `Test
+Module`_ above.
+
+The tests from tools/testing/selftests/seccomp/seccomp_bpf.c can be used as
+example.
 
 Example
 -------

include/linux/string.h

@@ -31,6 +31,10 @@ size_t strlcpy(char *, const char *, size_t);
 #ifndef __HAVE_ARCH_STRSCPY
 ssize_t strscpy(char *, const char *, size_t);
 #endif
+
+/* Wraps calls to strscpy()/memset(), no arch specific code required */
+ssize_t strscpy_pad(char *dest, const char *src, size_t count);
+
 #ifndef __HAVE_ARCH_STRCAT
 extern char * strcat(char *, const char *);
 #endif

lib/Kconfig.debug

@@ -1769,6 +1769,9 @@ config TEST_HEXDUMP
 config TEST_STRING_HELPERS
 	tristate "Test functions located in the string_helpers module at runtime"
 
+config TEST_STRSCPY
+	tristate "Test strscpy*() family of functions at runtime"
+
 config TEST_KSTRTOX
 	tristate "Test kstrto*() family of functions at runtime"
 

lib/Makefile

@@ -81,6 +81,7 @@ obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_keys.o
 obj-$(CONFIG_TEST_STATIC_KEYS) += test_static_key_base.o
 obj-$(CONFIG_TEST_PRINTF) += test_printf.o
 obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
+obj-$(CONFIG_TEST_STRSCPY) += test_strscpy.o
 obj-$(CONFIG_TEST_BITFIELD) += test_bitfield.o
 obj-$(CONFIG_TEST_UUID) += test_uuid.o
 obj-$(CONFIG_TEST_XARRAY) += test_xarray.o

lib/string.c

@@ -159,11 +159,9 @@ EXPORT_SYMBOL(strlcpy);
  * @src: Where to copy the string from
  * @count: Size of destination buffer
  *
- * Copy the string, or as much of it as fits, into the dest buffer.
- * The routine returns the number of characters copied (not including
- * the trailing NUL) or -E2BIG if the destination buffer wasn't big enough.
- * The behavior is undefined if the string buffers overlap.
- * The destination buffer is always NUL terminated, unless it's zero-sized.
+ * Copy the string, or as much of it as fits, into the dest buffer.  The
+ * behavior is undefined if the string buffers overlap.  The destination
+ * buffer is always NUL terminated, unless it's zero-sized.
  *
  * Preferred to strlcpy() since the API doesn't require reading memory
  * from the src string beyond the specified "count" bytes, and since
@@ -173,8 +171,10 @@ EXPORT_SYMBOL(strlcpy);
  *
  * Preferred to strncpy() since it always returns a valid string, and
  * doesn't unnecessarily force the tail of the destination buffer to be
- * zeroed.  If the zeroing is desired, it's likely cleaner to use strscpy()
- * with an overflow test, then just memset() the tail of the dest buffer.
+ * zeroed.  If zeroing is desired please use strscpy_pad().
+ *
+ * Return: The number of characters copied (not including the trailing
+ *         %NUL) or -E2BIG if the destination buffer wasn't big enough.
  */
 ssize_t strscpy(char *dest, const char *src, size_t count)
 {
@@ -237,6 +237,39 @@ ssize_t strscpy(char *dest, const char *src, size_t count)
 EXPORT_SYMBOL(strscpy);
 #endif
 
+/**
+ * strscpy_pad() - Copy a C-string into a sized buffer
+ * @dest: Where to copy the string to
+ * @src: Where to copy the string from
+ * @count: Size of destination buffer
+ *
+ * Copy the string, or as much of it as fits, into the dest buffer.  The
+ * behavior is undefined if the string buffers overlap.  The destination
+ * buffer is always %NUL terminated, unless it's zero-sized.
+ *
+ * If the source string is shorter than the destination buffer, zeros
+ * the tail of the destination buffer.
+ *
+ * For full explanation of why you may want to consider using the
+ * 'strscpy' functions please see the function docstring for strscpy().
+ *
+ * Return: The number of characters copied (not including the trailing
+ *         %NUL) or -E2BIG if the destination buffer wasn't big enough.
+ */
+ssize_t strscpy_pad(char *dest, const char *src, size_t count)
+{
+	ssize_t written;
+
+	written = strscpy(dest, src, count);
+	if (written < 0 || written == count - 1)
+		return written;
+
+	memset(dest + written + 1, 0, count - written - 1);
+
+	return written;
+}
+EXPORT_SYMBOL(strscpy_pad);
+
 #ifndef __HAVE_ARCH_STRCAT
 /**
  * strcat - Append one %NUL-terminated string to another

lib/test_bitmap.c

@@ -12,6 +12,8 @@
 #include <linux/slab.h>
 #include <linux/string.h>
 
+#include "../tools/testing/selftests/kselftest_module.h"
+
 static unsigned total_tests __initdata;
 static unsigned failed_tests __initdata;
 
@@ -361,30 +363,16 @@ static void noinline __init test_mem_optimisations(void)
 	}
 }
 
-static int __init test_bitmap_init(void)
+static void __init selftest(void)
 {
 	test_zero_clear();
 	test_fill_set();
 	test_copy();
 	test_bitmap_arr32();
 	test_bitmap_parselist();
 	test_mem_optimisations();
-
-	if (failed_tests == 0)
-		pr_info("all %u tests passed\n", total_tests);
-	else
-		pr_warn("failed %u out of %u tests\n",
-			failed_tests, total_tests);
-
-	return failed_tests ? -EINVAL : 0;
 }
 
-static void __exit test_bitmap_cleanup(void)
-{
-}
-
-module_init(test_bitmap_init);
-module_exit(test_bitmap_cleanup);
-
+KSTM_MODULE_LOADERS(test_bitmap);
 MODULE_AUTHOR("david decotigny <[email protected]>");
 MODULE_LICENSE("GPL");

lib/test_printf.c

@@ -21,6 +21,8 @@
 #include <linux/gfp.h>
 #include <linux/mm.h>
 
+#include "../tools/testing/selftests/kselftest_module.h"
+
 #define BUF_SIZE 256
 #define PAD_SIZE 16
 #define FILL_CHAR '$'
@@ -590,12 +592,11 @@ test_pointer(void)
 	flags();
 }
 
-static int __init
-test_printf_init(void)
+static void __init selftest(void)
 {
 	alloced_buffer = kmalloc(BUF_SIZE + 2*PAD_SIZE, GFP_KERNEL);
 	if (!alloced_buffer)
-		return -ENOMEM;
+		return;
 	test_buffer = alloced_buffer + PAD_SIZE;
 
 	test_basic();
@@ -604,16 +605,8 @@ test_printf_init(void)
 	test_pointer();
 
 	kfree(alloced_buffer);
-
-	if (failed_tests == 0)
-		pr_info("all %u tests passed\n", total_tests);
-	else
-		pr_warn("failed %u out of %u tests\n", failed_tests, total_tests);
-
-	return failed_tests ? -EINVAL : 0;
 }
 
-module_init(test_printf_init);
-
+KSTM_MODULE_LOADERS(test_printf);
 MODULE_AUTHOR("Rasmus Villemoes <[email protected]>");
 MODULE_LICENSE("GPL");