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-rw-r--r--Documentation/dev-tools/checkpatch.rst755
-rw-r--r--Documentation/dev-tools/gcov.rst8
-rw-r--r--Documentation/dev-tools/index.rst5
-rw-r--r--Documentation/dev-tools/kasan.rst9
-rw-r--r--Documentation/dev-tools/kselftest.rst4
-rw-r--r--Documentation/dev-tools/testing-overview.rst117
6 files changed, 894 insertions, 4 deletions
diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst
new file mode 100644
index 000000000000..51fed1bd72ec
--- /dev/null
+++ b/Documentation/dev-tools/checkpatch.rst
@@ -0,0 +1,755 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+==========
+Checkpatch
+==========
+
+Checkpatch (scripts/checkpatch.pl) is a perl script which checks for trivial
+style violations in patches and optionally corrects them. Checkpatch can
+also be run on file contexts and without the kernel tree.
+
+Checkpatch is not always right. Your judgement takes precedence over checkpatch
+messages. If your code looks better with the violations, then its probably
+best left alone.
+
+
+Options
+=======
+
+This section will describe the options checkpatch can be run with.
+
+Usage::
+
+ ./scripts/checkpatch.pl [OPTION]... [FILE]...
+
+Available options:
+
+ - -q, --quiet
+
+ Enable quiet mode.
+
+ - -v, --verbose
+ Enable verbose mode. Additional verbose test descriptions are output
+ so as to provide information on why that particular message is shown.
+
+ - --no-tree
+
+ Run checkpatch without the kernel tree.
+
+ - --no-signoff
+
+ Disable the 'Signed-off-by' line check. The sign-off is a simple line at
+ the end of the explanation for the patch, which certifies that you wrote it
+ or otherwise have the right to pass it on as an open-source patch.
+
+ Example::
+
+ Signed-off-by: Random J Developer <random@developer.example.org>
+
+ Setting this flag effectively stops a message for a missing signed-off-by
+ line in a patch context.
+
+ - --patch
+
+ Treat FILE as a patch. This is the default option and need not be
+ explicitly specified.
+
+ - --emacs
+
+ Set output to emacs compile window format. This allows emacs users to jump
+ from the error in the compile window directly to the offending line in the
+ patch.
+
+ - --terse
+
+ Output only one line per report.
+
+ - --showfile
+
+ Show the diffed file position instead of the input file position.
+
+ - -g, --git
+
+ Treat FILE as a single commit or a git revision range.
+
+ Single commit with:
+
+ - <rev>
+ - <rev>^
+ - <rev>~n
+
+ Multiple commits with:
+
+ - <rev1>..<rev2>
+ - <rev1>...<rev2>
+ - <rev>-<count>
+
+ - -f, --file
+
+ Treat FILE as a regular source file. This option must be used when running
+ checkpatch on source files in the kernel.
+
+ - --subjective, --strict
+
+ Enable stricter tests in checkpatch. By default the tests emitted as CHECK
+ do not activate by default. Use this flag to activate the CHECK tests.
+
+ - --list-types
+
+ Every message emitted by checkpatch has an associated TYPE. Add this flag
+ to display all the types in checkpatch.
+
+ Note that when this flag is active, checkpatch does not read the input FILE,
+ and no message is emitted. Only a list of types in checkpatch is output.
+
+ - --types TYPE(,TYPE2...)
+
+ Only display messages with the given types.
+
+ Example::
+
+ ./scripts/checkpatch.pl mypatch.patch --types EMAIL_SUBJECT,BRACES
+
+ - --ignore TYPE(,TYPE2...)
+
+ Checkpatch will not emit messages for the specified types.
+
+ Example::
+
+ ./scripts/checkpatch.pl mypatch.patch --ignore EMAIL_SUBJECT,BRACES
+
+ - --show-types
+
+ By default checkpatch doesn't display the type associated with the messages.
+ Set this flag to show the message type in the output.
+
+ - --max-line-length=n
+
+ Set the max line length (default 100). If a line exceeds the specified
+ length, a LONG_LINE message is emitted.
+
+
+ The message level is different for patch and file contexts. For patches,
+ a WARNING is emitted. While a milder CHECK is emitted for files. So for
+ file contexts, the --strict flag must also be enabled.
+
+ - --min-conf-desc-length=n
+
+ Set the Kconfig entry minimum description length, if shorter, warn.
+
+ - --tab-size=n
+
+ Set the number of spaces for tab (default 8).
+
+ - --root=PATH
+
+ PATH to the kernel tree root.
+
+ This option must be specified when invoking checkpatch from outside
+ the kernel root.
+
+ - --no-summary
+
+ Suppress the per file summary.
+
+ - --mailback
+
+ Only produce a report in case of Warnings or Errors. Milder Checks are
+ excluded from this.
+
+ - --summary-file
+
+ Include the filename in summary.
+
+ - --debug KEY=[0|1]
+
+ Turn on/off debugging of KEY, where KEY is one of 'values', 'possible',
+ 'type', and 'attr' (default is all off).
+
+ - --fix
+
+ This is an EXPERIMENTAL feature. If correctable errors exists, a file
+ <inputfile>.EXPERIMENTAL-checkpatch-fixes is created which has the
+ automatically fixable errors corrected.
+
+ - --fix-inplace
+
+ EXPERIMENTAL - Similar to --fix but input file is overwritten with fixes.
+
+ DO NOT USE this flag unless you are absolutely sure and you have a backup
+ in place.
+
+ - --ignore-perl-version
+
+ Override checking of perl version. Runtime errors maybe encountered after
+ enabling this flag if the perl version does not meet the minimum specified.
+
+ - --codespell
+
+ Use the codespell dictionary for checking spelling errors.
+
+ - --codespellfile
+
+ Use the specified codespell file.
+ Default is '/usr/share/codespell/dictionary.txt'.
+
+ - --typedefsfile
+
+ Read additional types from this file.
+
+ - --color[=WHEN]
+
+ Use colors 'always', 'never', or only when output is a terminal ('auto').
+ Default is 'auto'.
+
+ - --kconfig-prefix=WORD
+
+ Use WORD as a prefix for Kconfig symbols (default is `CONFIG_`).
+
+ - -h, --help, --version
+
+ Display the help text.
+
+Message Levels
+==============
+
+Messages in checkpatch are divided into three levels. The levels of messages
+in checkpatch denote the severity of the error. They are:
+
+ - ERROR
+
+ This is the most strict level. Messages of type ERROR must be taken
+ seriously as they denote things that are very likely to be wrong.
+
+ - WARNING
+
+ This is the next stricter level. Messages of type WARNING requires a
+ more careful review. But it is milder than an ERROR.
+
+ - CHECK
+
+ This is the mildest level. These are things which may require some thought.
+
+Type Descriptions
+=================
+
+This section contains a description of all the message types in checkpatch.
+
+.. Types in this section are also parsed by checkpatch.
+.. The types are grouped into subsections based on use.
+
+
+Allocation style
+----------------
+
+ **ALLOC_ARRAY_ARGS**
+ The first argument for kcalloc or kmalloc_array should be the
+ number of elements. sizeof() as the first argument is generally
+ wrong.
+ See: https://www.kernel.org/doc/html/latest/core-api/memory-allocation.html
+
+ **ALLOC_SIZEOF_STRUCT**
+ The allocation style is bad. In general for family of
+ allocation functions using sizeof() to get memory size,
+ constructs like::
+
+ p = alloc(sizeof(struct foo), ...)
+
+ should be::
+
+ p = alloc(sizeof(*p), ...)
+
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#allocating-memory
+
+ **ALLOC_WITH_MULTIPLY**
+ Prefer kmalloc_array/kcalloc over kmalloc/kzalloc with a
+ sizeof multiply.
+ See: https://www.kernel.org/doc/html/latest/core-api/memory-allocation.html
+
+
+API usage
+---------
+
+ **ARCH_DEFINES**
+ Architecture specific defines should be avoided wherever
+ possible.
+
+ **ARCH_INCLUDE_LINUX**
+ Whenever asm/file.h is included and linux/file.h exists, a
+ conversion can be made when linux/file.h includes asm/file.h.
+ However this is not always the case (See signal.h).
+ This message type is emitted only for includes from arch/.
+
+ **AVOID_BUG**
+ BUG() or BUG_ON() should be avoided totally.
+ Use WARN() and WARN_ON() instead, and handle the "impossible"
+ error condition as gracefully as possible.
+ See: https://www.kernel.org/doc/html/latest/process/deprecated.html#bug-and-bug-on
+
+ **CONSIDER_KSTRTO**
+ The simple_strtol(), simple_strtoll(), simple_strtoul(), and
+ simple_strtoull() functions explicitly ignore overflows, which
+ may lead to unexpected results in callers. The respective kstrtol(),
+ kstrtoll(), kstrtoul(), and kstrtoull() functions tend to be the
+ correct replacements.
+ See: https://www.kernel.org/doc/html/latest/process/deprecated.html#simple-strtol-simple-strtoll-simple-strtoul-simple-strtoull
+
+ **LOCKDEP**
+ The lockdep_no_validate class was added as a temporary measure to
+ prevent warnings on conversion of device->sem to device->mutex.
+ It should not be used for any other purpose.
+ See: https://lore.kernel.org/lkml/1268959062.9440.467.camel@laptop/
+
+ **MALFORMED_INCLUDE**
+ The #include statement has a malformed path. This has happened
+ because the author has included a double slash "//" in the pathname
+ accidentally.
+
+ **USE_LOCKDEP**
+ lockdep_assert_held() annotations should be preferred over
+ assertions based on spin_is_locked()
+ See: https://www.kernel.org/doc/html/latest/locking/lockdep-design.html#annotations
+
+ **UAPI_INCLUDE**
+ No #include statements in include/uapi should use a uapi/ path.
+
+
+Comment style
+-------------
+
+ **BLOCK_COMMENT_STYLE**
+ The comment style is incorrect. The preferred style for multi-
+ line comments is::
+
+ /*
+ * This is the preferred style
+ * for multi line comments.
+ */
+
+ The networking comment style is a bit different, with the first line
+ not empty like the former::
+
+ /* This is the preferred comment style
+ * for files in net/ and drivers/net/
+ */
+
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#commenting
+
+ **C99_COMMENTS**
+ C99 style single line comments (//) should not be used.
+ Prefer the block comment style instead.
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#commenting
+
+
+Commit message
+--------------
+
+ **BAD_SIGN_OFF**
+ The signed-off-by line does not fall in line with the standards
+ specified by the community.
+ See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#developer-s-certificate-of-origin-1-1
+
+ **BAD_STABLE_ADDRESS_STYLE**
+ The email format for stable is incorrect.
+ Some valid options for stable address are::
+
+ 1. stable@vger.kernel.org
+ 2. stable@kernel.org
+
+ For adding version info, the following comment style should be used::
+
+ stable@vger.kernel.org # version info
+
+ **COMMIT_COMMENT_SYMBOL**
+ Commit log lines starting with a '#' are ignored by git as
+ comments. To solve this problem addition of a single space
+ infront of the log line is enough.
+
+ **COMMIT_MESSAGE**
+ The patch is missing a commit description. A brief
+ description of the changes made by the patch should be added.
+ See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes
+
+ **MISSING_SIGN_OFF**
+ The patch is missing a Signed-off-by line. A signed-off-by
+ line should be added according to Developer's certificate of
+ Origin.
+ See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin
+
+ **NO_AUTHOR_SIGN_OFF**
+ The author of the patch has not signed off the patch. It is
+ required that a simple sign off line should be present at the
+ end of explanation of the patch to denote that the author has
+ written it or otherwise has the rights to pass it on as an open
+ source patch.
+ See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#sign-your-work-the-developer-s-certificate-of-origin
+
+ **DIFF_IN_COMMIT_MSG**
+ Avoid having diff content in commit message.
+ This causes problems when one tries to apply a file containing both
+ the changelog and the diff because patch(1) tries to apply the diff
+ which it found in the changelog.
+ See: https://lore.kernel.org/lkml/20150611134006.9df79a893e3636019ad2759e@linux-foundation.org/
+
+ **GERRIT_CHANGE_ID**
+ To be picked up by gerrit, the footer of the commit message might
+ have a Change-Id like::
+
+ Change-Id: Ic8aaa0728a43936cd4c6e1ed590e01ba8f0fbf5b
+ Signed-off-by: A. U. Thor <author@example.com>
+
+ The Change-Id line must be removed before submitting.
+
+ **GIT_COMMIT_ID**
+ The proper way to reference a commit id is:
+ commit <12+ chars of sha1> ("<title line>")
+
+ An example may be::
+
+ Commit e21d2170f36602ae2708 ("video: remove unnecessary
+ platform_set_drvdata()") removed the unnecessary
+ platform_set_drvdata(), but left the variable "dev" unused,
+ delete it.
+
+ See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes
+
+
+Comparison style
+----------------
+
+ **ASSIGN_IN_IF**
+ Do not use assignments in if condition.
+ Example::
+
+ if ((foo = bar(...)) < BAZ) {
+
+ should be written as::
+
+ foo = bar(...);
+ if (foo < BAZ) {
+
+ **BOOL_COMPARISON**
+ Comparisons of A to true and false are better written
+ as A and !A.
+ See: https://lore.kernel.org/lkml/1365563834.27174.12.camel@joe-AO722/
+
+ **COMPARISON_TO_NULL**
+ Comparisons to NULL in the form (foo == NULL) or (foo != NULL)
+ are better written as (!foo) and (foo).
+
+ **CONSTANT_COMPARISON**
+ Comparisons with a constant or upper case identifier on the left
+ side of the test should be avoided.
+
+
+Macros, Attributes and Symbols
+------------------------------
+
+ **ARRAY_SIZE**
+ The ARRAY_SIZE(foo) macro should be preferred over
+ sizeof(foo)/sizeof(foo[0]) for finding number of elements in an
+ array.
+
+ The macro is defined in include/linux/kernel.h::
+
+ #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+ **AVOID_EXTERNS**
+ Function prototypes don't need to be declared extern in .h
+ files. It's assumed by the compiler and is unnecessary.
+
+ **AVOID_L_PREFIX**
+ Local symbol names that are prefixed with `.L` should be avoided,
+ as this has special meaning for the assembler; a symbol entry will
+ not be emitted into the symbol table. This can prevent `objtool`
+ from generating correct unwind info.
+
+ Symbols with STB_LOCAL binding may still be used, and `.L` prefixed
+ local symbol names are still generally usable within a function,
+ but `.L` prefixed local symbol names should not be used to denote
+ the beginning or end of code regions via
+ `SYM_CODE_START_LOCAL`/`SYM_CODE_END`
+
+ **BIT_MACRO**
+ Defines like: 1 << <digit> could be BIT(digit).
+ The BIT() macro is defined in include/linux/bitops.h::
+
+ #define BIT(nr) (1UL << (nr))
+
+ **CONST_READ_MOSTLY**
+ When a variable is tagged with the __read_mostly annotation, it is a
+ signal to the compiler that accesses to the variable will be mostly
+ reads and rarely(but NOT never) a write.
+
+ const __read_mostly does not make any sense as const data is already
+ read-only. The __read_mostly annotation thus should be removed.
+
+ **DATE_TIME**
+ It is generally desirable that building the same source code with
+ the same set of tools is reproducible, i.e. the output is always
+ exactly the same.
+
+ The kernel does *not* use the ``__DATE__`` and ``__TIME__`` macros,
+ and enables warnings if they are used as they can lead to
+ non-deterministic builds.
+ See: https://www.kernel.org/doc/html/latest/kbuild/reproducible-builds.html#timestamps
+
+ **DEFINE_ARCH_HAS**
+ The ARCH_HAS_xyz and ARCH_HAVE_xyz patterns are wrong.
+
+ For big conceptual features use Kconfig symbols instead. And for
+ smaller things where we have compatibility fallback functions but
+ want architectures able to override them with optimized ones, we
+ should either use weak functions (appropriate for some cases), or
+ the symbol that protects them should be the same symbol we use.
+ See: https://lore.kernel.org/lkml/CA+55aFycQ9XJvEOsiM3txHL5bjUc8CeKWJNR_H+MiicaddB42Q@mail.gmail.com/
+
+ **INIT_ATTRIBUTE**
+ Const init definitions should use __initconst instead of
+ __initdata.
+
+ Similarly init definitions without const require a separate
+ use of const.
+
+ **INLINE_LOCATION**
+ The inline keyword should sit between storage class and type.
+
+ For example, the following segment::
+
+ inline static int example_function(void)
+ {
+ ...
+ }
+
+ should be::
+
+ static inline int example_function(void)
+ {
+ ...
+ }
+
+ **MULTISTATEMENT_MACRO_USE_DO_WHILE**
+ Macros with multiple statements should be enclosed in a
+ do - while block. Same should also be the case for macros
+ starting with `if` to avoid logic defects::
+
+ #define macrofun(a, b, c) \
+ do { \
+ if (a == 5) \
+ do_this(b, c); \
+ } while (0)
+
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#macros-enums-and-rtl
+
+ **WEAK_DECLARATION**
+ Using weak declarations like __attribute__((weak)) or __weak
+ can have unintended link defects. Avoid using them.
+
+
+Functions and Variables
+-----------------------
+
+ **CAMELCASE**
+ Avoid CamelCase Identifiers.
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#naming
+
+ **FUNCTION_WITHOUT_ARGS**
+ Function declarations without arguments like::
+
+ int foo()
+
+ should be::
+
+ int foo(void)
+
+ **GLOBAL_INITIALISERS**
+ Global variables should not be initialized explicitly to
+ 0 (or NULL, false, etc.). Your compiler (or rather your
+ loader, which is responsible for zeroing out the relevant
+ sections) automatically does it for you.
+
+ **INITIALISED_STATIC**
+ Static variables should not be initialized explicitly to zero.
+ Your compiler (or rather your loader) automatically does
+ it for you.
+
+ **RETURN_PARENTHESES**
+ return is not a function and as such doesn't need parentheses::
+
+ return (bar);
+
+ can simply be::
+
+ return bar;
+
+
+Spacing and Brackets
+--------------------
+
+ **ASSIGNMENT_CONTINUATIONS**
+ Assignment operators should not be written at the start of a
+ line but should follow the operand at the previous line.
+
+ **BRACES**
+ The placement of braces is stylistically incorrect.
+ The preferred way is to put the opening brace last on the line,
+ and put the closing brace first::
+
+ if (x is true) {
+ we do y
+ }
+
+ This applies for all non-functional blocks.
+ However, there is one special case, namely functions: they have the
+ opening brace at the beginning of the next line, thus::
+
+ int function(int x)
+ {
+ body of function
+ }
+
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
+
+ **BRACKET_SPACE**
+ Whitespace before opening bracket '[' is prohibited.
+ There are some exceptions:
+
+ 1. With a type on the left::
+
+ ;int [] a;
+
+ 2. At the beginning of a line for slice initialisers::
+
+ [0...10] = 5,
+
+ 3. Inside a curly brace::
+
+ = { [0...10] = 5 }
+
+ **CODE_INDENT**
+ Code indent should use tabs instead of spaces.
+ Outside of comments, documentation and Kconfig,
+ spaces are never used for indentation.
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#indentation
+
+ **CONCATENATED_STRING**
+ Concatenated elements should have a space in between.
+ Example::
+
+ printk(KERN_INFO"bar");
+
+ should be::
+
+ printk(KERN_INFO "bar");
+
+ **ELSE_AFTER_BRACE**
+ `else {` should follow the closing block `}` on the same line.
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
+
+ **LINE_SPACING**
+ Vertical space is wasted given the limited number of lines an
+ editor window can display when multiple blank lines are used.
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
+
+ **OPEN_BRACE**
+ The opening brace should be following the function definitions on the
+ next line. For any non-functional block it should be on the same line
+ as the last construct.
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
+
+ **POINTER_LOCATION**
+ When using pointer data or a function that returns a pointer type,
+ the preferred use of * is adjacent to the data name or function name
+ and not adjacent to the type name.
+ Examples::
+
+ char *linux_banner;
+ unsigned long long memparse(char *ptr, char **retptr);
+ char *match_strdup(substring_t *s);
+
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
+
+ **SPACING**
+ Whitespace style used in the kernel sources is described in kernel docs.
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
+
+ **SWITCH_CASE_INDENT_LEVEL**
+ switch should be at the same indent as case.
+ Example::
+
+ switch (suffix) {
+ case 'G':
+ case 'g':
+ mem <<= 30;
+ break;
+ case 'M':
+ case 'm':
+ mem <<= 20;
+ break;
+ case 'K':
+ case 'k':
+ mem <<= 10;
+ /* fall through */
+ default:
+ break;
+ }
+
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#indentation
+
+ **TRAILING_WHITESPACE**
+ Trailing whitespace should always be removed.
+ Some editors highlight the trailing whitespace and cause visual
+ distractions when editing files.
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces
+
+ **WHILE_AFTER_BRACE**
+ while should follow the closing bracket on the same line::
+
+ do {
+ ...
+ } while(something);
+
+ See: https://www.kernel.org/doc/html/latest/process/coding-style.html#placing-braces-and-spaces
+
+
+Others
+------
+
+ **CONFIG_DESCRIPTION**
+ Kconfig symbols should have a help text which fully describes
+ it.
+
+ **CORRUPTED_PATCH**
+ The patch seems to be corrupted or lines are wrapped.
+ Please regenerate the patch file before sending it to the maintainer.
+
+ **DOS_LINE_ENDINGS**
+ For DOS-formatted patches, there are extra ^M symbols at the end of
+ the line. These should be removed.
+
+ **EXECUTE_PERMISSIONS**
+ There is no reason for source files to be executable. The executable
+ bit can be removed safely.
+
+ **NON_OCTAL_PERMISSIONS**
+ Permission bits should use 4 digit octal permissions (like 0700 or 0444).
+ Avoid using any other base like decimal.
+
+ **NOT_UNIFIED_DIFF**
+ The patch file does not appear to be in unified-diff format. Please
+ regenerate the patch file before sending it to the maintainer.
+
+ **PRINTF_0XDECIMAL**
+ Prefixing 0x with decimal output is defective and should be corrected.
+
+ **TRAILING_STATEMENTS**
+ Trailing statements (for example after any conditional) should be
+ on the next line.
+ Like::
+
+ if (x == y) break;
+
+ should be::
+
+ if (x == y)
+ break;
diff --git a/Documentation/dev-tools/gcov.rst b/Documentation/dev-tools/gcov.rst
index 9e989baae154..5fce2b06f229 100644
--- a/Documentation/dev-tools/gcov.rst
+++ b/Documentation/dev-tools/gcov.rst
@@ -124,6 +124,8 @@ box for setups where kernels are built and run on the same machine. In
cases where the kernel runs on a separate machine, special preparations
must be made, depending on where the gcov tool is used:
+.. _gcov-test:
+
a) gcov is run on the TEST machine
The gcov tool version on the test machine must be compatible with the
@@ -143,6 +145,8 @@ a) gcov is run on the TEST machine
machine. If any of the path components is symbolic link, the actual
directory needs to be used instead (due to make's CURDIR handling).
+.. _gcov-build:
+
b) gcov is run on the BUILD machine
The following files need to be copied after each test case from test
@@ -211,7 +215,7 @@ Appendix A: gather_on_build.sh
------------------------------
Sample script to gather coverage meta files on the build machine
-(see 6a):
+(see :ref:`Separated build and test machines a. <gcov-test>`):
.. code-block:: sh
@@ -244,7 +248,7 @@ Appendix B: gather_on_test.sh
-----------------------------
Sample script to gather coverage data files on the test machine
-(see 6b):
+(see :ref:`Separated build and test machines b. <gcov-build>`):
.. code-block:: sh
diff --git a/Documentation/dev-tools/index.rst b/Documentation/dev-tools/index.rst
index 1b1cf4f5c9d9..010a2af1e7d9 100644
--- a/Documentation/dev-tools/index.rst
+++ b/Documentation/dev-tools/index.rst
@@ -7,6 +7,9 @@ be used to work on the kernel. For now, the documents have been pulled
together without any significant effort to integrate them into a coherent
whole; patches welcome!
+A brief overview of testing-specific tools can be found in
+Documentation/dev-tools/testing-overview.rst
+
.. class:: toc-title
Table of contents
@@ -14,6 +17,8 @@ whole; patches welcome!
.. toctree::
:maxdepth: 2
+ testing-overview
+ checkpatch
coccinelle
sparse
kcov
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index ddf4239a5890..6f6ab3ed7b79 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -161,6 +161,15 @@ particular KASAN features.
- ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``).
+- ``kasan.mode=sync`` or ``=async`` controls whether KASAN is configured in
+ synchronous or asynchronous mode of execution (default: ``sync``).
+ Synchronous mode: a bad access is detected immediately when a tag
+ check fault occurs.
+ Asynchronous mode: a bad access detection is delayed. When a tag check
+ fault occurs, the information is stored in hardware (in the TFSR_EL1
+ register for arm64). The kernel periodically checks the hardware and
+ only reports tag faults during these checks.
+
- ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack
traces collection (default: ``on``).
diff --git a/Documentation/dev-tools/kselftest.rst b/Documentation/dev-tools/kselftest.rst
index a901def730d9..dcefee707ccd 100644
--- a/Documentation/dev-tools/kselftest.rst
+++ b/Documentation/dev-tools/kselftest.rst
@@ -239,8 +239,8 @@ 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``
+- ``tools/testing/selftests/kselftest_module.h``
+- ``tools/testing/selftests/kselftest/module.sh``
How to use
----------
diff --git a/Documentation/dev-tools/testing-overview.rst b/Documentation/dev-tools/testing-overview.rst
new file mode 100644
index 000000000000..b5b46709969c
--- /dev/null
+++ b/Documentation/dev-tools/testing-overview.rst
@@ -0,0 +1,117 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====================
+Kernel Testing Guide
+====================
+
+
+There are a number of different tools for testing the Linux kernel, so knowing
+when to use each of them can be a challenge. This document provides a rough
+overview of their differences, and how they fit together.
+
+
+Writing and Running Tests
+=========================
+
+The bulk of kernel tests are written using either the kselftest or KUnit
+frameworks. These both provide infrastructure to help make running tests and
+groups of tests easier, as well as providing helpers to aid in writing new
+tests.
+
+If you're looking to verify the behaviour of the Kernel — particularly specific
+parts of the kernel — then you'll want to use KUnit or kselftest.
+
+
+The Difference Between KUnit and kselftest
+------------------------------------------
+
+KUnit (Documentation/dev-tools/kunit/index.rst) is an entirely in-kernel system
+for "white box" testing: because test code is part of the kernel, it can access
+internal structures and functions which aren't exposed to userspace.
+
+KUnit tests therefore are best written against small, self-contained parts
+of the kernel, which can be tested in isolation. This aligns well with the
+concept of 'unit' testing.
+
+For example, a KUnit test might test an individual kernel function (or even a
+single codepath through a function, such as an error handling case), rather
+than a feature as a whole.
+
+This also makes KUnit tests very fast to build and run, allowing them to be
+run frequently as part of the development process.
+
+There is a KUnit test style guide which may give further pointers in
+Documentation/dev-tools/kunit/style.rst
+
+
+kselftest (Documentation/dev-tools/kselftest.rst), on the other hand, is
+largely implemented in userspace, and tests are normal userspace scripts or
+programs.
+
+This makes it easier to write more complicated tests, or tests which need to
+manipulate the overall system state more (e.g., spawning processes, etc.).
+However, it's not possible to call kernel functions directly from kselftest.
+This means that only kernel functionality which is exposed to userspace somehow
+(e.g. by a syscall, device, filesystem, etc.) can be tested with kselftest. To
+work around this, some tests include a companion kernel module which exposes
+more information or functionality. If a test runs mostly or entirely within the
+kernel, however, KUnit may be the more appropriate tool.
+
+kselftest is therefore suited well to tests of whole features, as these will
+expose an interface to userspace, which can be tested, but not implementation
+details. This aligns well with 'system' or 'end-to-end' testing.
+
+For example, all new system calls should be accompanied by kselftest tests.
+
+Code Coverage Tools
+===================
+
+The Linux Kernel supports two different code coverage measurement tools. These
+can be used to verify that a test is executing particular functions or lines
+of code. This is useful for determining how much of the kernel is being tested,
+and for finding corner-cases which are not covered by the appropriate test.
+
+:doc:`gcov` is GCC's coverage testing tool, which can be used with the kernel
+to get global or per-module coverage. Unlike KCOV, it does not record per-task
+coverage. Coverage data can be read from debugfs, and interpreted using the
+usual gcov tooling.
+
+:doc:`kcov` is a feature which can be built in to the kernel to allow
+capturing coverage on a per-task level. It's therefore useful for fuzzing and
+other situations where information about code executed during, for example, a
+single syscall is useful.
+
+
+Dynamic Analysis Tools
+======================
+
+The kernel also supports a number of dynamic analysis tools, which attempt to
+detect classes of issues when they occur in a running kernel. These typically
+each look for a different class of bugs, such as invalid memory accesses,
+concurrency issues such as data races, or other undefined behaviour like
+integer overflows.
+
+Some of these tools are listed below:
+
+* kmemleak detects possible memory leaks. See
+ Documentation/dev-tools/kmemleak.rst
+* KASAN detects invalid memory accesses such as out-of-bounds and
+ use-after-free errors. See Documentation/dev-tools/kasan.rst
+* UBSAN detects behaviour that is undefined by the C standard, like integer
+ overflows. See Documentation/dev-tools/ubsan.rst
+* KCSAN detects data races. See Documentation/dev-tools/kcsan.rst
+* KFENCE is a low-overhead detector of memory issues, which is much faster than
+ KASAN and can be used in production. See Documentation/dev-tools/kfence.rst
+* lockdep is a locking correctness validator. See
+ Documentation/locking/lockdep-design.rst
+* There are several other pieces of debug instrumentation in the kernel, many
+ of which can be found in lib/Kconfig.debug
+
+These tools tend to test the kernel as a whole, and do not "pass" like
+kselftest or KUnit tests. They can be combined with KUnit or kselftest by
+running tests on a kernel with these tools enabled: you can then be sure
+that none of these errors are occurring during the test.
+
+Some of these tools integrate with KUnit or kselftest and will
+automatically fail tests if an issue is detected.
+