diff options
Diffstat (limited to 'Documentation/dev-tools')
| -rw-r--r-- | Documentation/dev-tools/checkpatch.rst | 509 | ||||
| -rw-r--r-- | Documentation/dev-tools/kasan.rst | 22 | ||||
| -rw-r--r-- | Documentation/dev-tools/kcsan.rst | 105 | ||||
| -rw-r--r-- | Documentation/dev-tools/kfence.rst | 98 | ||||
| -rw-r--r-- | Documentation/dev-tools/kunit/api/index.rst | 8 | ||||
| -rw-r--r-- | Documentation/dev-tools/kunit/faq.rst | 2 | ||||
| -rw-r--r-- | Documentation/dev-tools/kunit/index.rst | 15 | ||||
| -rw-r--r-- | Documentation/dev-tools/kunit/kunit-tool.rst | 191 | ||||
| -rw-r--r-- | Documentation/dev-tools/kunit/running_tips.rst | 257 | ||||
| -rw-r--r-- | Documentation/dev-tools/kunit/start.rst | 8 | ||||
| -rw-r--r-- | Documentation/dev-tools/kunit/tips.rst | 5 | ||||
| -rw-r--r-- | Documentation/dev-tools/kunit/usage.rst | 65 | ||||
| -rw-r--r-- | Documentation/dev-tools/testing-overview.rst | 18 |
13 files changed, 1094 insertions, 209 deletions
diff --git a/Documentation/dev-tools/checkpatch.rst b/Documentation/dev-tools/checkpatch.rst index 51fed1bd72ec..f0956e9ea2d8 100644 --- a/Documentation/dev-tools/checkpatch.rst +++ b/Documentation/dev-tools/checkpatch.rst @@ -246,6 +246,7 @@ Allocation style 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** @@ -264,6 +265,7 @@ Allocation style **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 @@ -284,6 +286,7 @@ API usage 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** @@ -292,12 +295,161 @@ API usage 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 + **CONSTANT_CONVERSION** + Use of __constant_<foo> form is discouraged for the following functions:: + + __constant_cpu_to_be[x] + __constant_cpu_to_le[x] + __constant_be[x]_to_cpu + __constant_le[x]_to_cpu + __constant_htons + __constant_ntohs + + Using any of these outside of include/uapi/ is not preferred as using the + function without __constant_ is identical when the argument is a + constant. + + In big endian systems, the macros like __constant_cpu_to_be32(x) and + cpu_to_be32(x) expand to the same expression:: + + #define __constant_cpu_to_be32(x) ((__force __be32)(__u32)(x)) + #define __cpu_to_be32(x) ((__force __be32)(__u32)(x)) + + In little endian systems, the macros __constant_cpu_to_be32(x) and + cpu_to_be32(x) expand to __constant_swab32 and __swab32. __swab32 + has a __builtin_constant_p check:: + + #define __swab32(x) \ + (__builtin_constant_p((__u32)(x)) ? \ + ___constant_swab32(x) : \ + __fswab32(x)) + + So ultimately they have a special case for constants. + Similar is the case with all of the macros in the list. Thus + using the __constant_... forms are unnecessarily verbose and + not preferred outside of include/uapi. + + See: https://lore.kernel.org/lkml/1400106425.12666.6.camel@joe-AO725/ + + **DEPRECATED_API** + Usage of a deprecated RCU API is detected. It is recommended to replace + old flavourful RCU APIs by their new vanilla-RCU counterparts. + + The full list of available RCU APIs can be viewed from the kernel docs. + + See: https://www.kernel.org/doc/html/latest/RCU/whatisRCU.html#full-list-of-rcu-apis + + **DEPRECATED_VARIABLE** + EXTRA_{A,C,CPP,LD}FLAGS are deprecated and should be replaced by the new + flags added via commit f77bf01425b1 ("kbuild: introduce ccflags-y, + asflags-y and ldflags-y"). + + The following conversion scheme maybe used:: + + EXTRA_AFLAGS -> asflags-y + EXTRA_CFLAGS -> ccflags-y + EXTRA_CPPFLAGS -> cppflags-y + EXTRA_LDFLAGS -> ldflags-y + + See: + + 1. https://lore.kernel.org/lkml/20070930191054.GA15876@uranus.ravnborg.org/ + 2. https://lore.kernel.org/lkml/1313384834-24433-12-git-send-email-lacombar@gmail.com/ + 3. https://www.kernel.org/doc/html/latest/kbuild/makefiles.html#compilation-flags + + **DEVICE_ATTR_FUNCTIONS** + The function names used in DEVICE_ATTR is unusual. + Typically, the store and show functions are used with <attr>_store and + <attr>_show, where <attr> is a named attribute variable of the device. + + Consider the following examples:: + + static DEVICE_ATTR(type, 0444, type_show, NULL); + static DEVICE_ATTR(power, 0644, power_show, power_store); + + The function names should preferably follow the above pattern. + + See: https://www.kernel.org/doc/html/latest/driver-api/driver-model/device.html#attributes + + **DEVICE_ATTR_RO** + The DEVICE_ATTR_RO(name) helper macro can be used instead of + DEVICE_ATTR(name, 0444, name_show, NULL); + + Note that the macro automatically appends _show to the named + attribute variable of the device for the show method. + + See: https://www.kernel.org/doc/html/latest/driver-api/driver-model/device.html#attributes + + **DEVICE_ATTR_RW** + The DEVICE_ATTR_RW(name) helper macro can be used instead of + DEVICE_ATTR(name, 0644, name_show, name_store); + + Note that the macro automatically appends _show and _store to the + named attribute variable of the device for the show and store methods. + + See: https://www.kernel.org/doc/html/latest/driver-api/driver-model/device.html#attributes + + **DEVICE_ATTR_WO** + The DEVICE_AATR_WO(name) helper macro can be used instead of + DEVICE_ATTR(name, 0200, NULL, name_store); + + Note that the macro automatically appends _store to the + named attribute variable of the device for the store method. + + See: https://www.kernel.org/doc/html/latest/driver-api/driver-model/device.html#attributes + + **DUPLICATED_SYSCTL_CONST** + Commit d91bff3011cf ("proc/sysctl: add shared variables for range + check") added some shared const variables to be used instead of a local + copy in each source file. + + Consider replacing the sysctl range checking value with the shared + one in include/linux/sysctl.h. The following conversion scheme may + be used:: + + &zero -> SYSCTL_ZERO + &one -> SYSCTL_ONE + &int_max -> SYSCTL_INT_MAX + + See: + + 1. https://lore.kernel.org/lkml/20190430180111.10688-1-mcroce@redhat.com/ + 2. https://lore.kernel.org/lkml/20190531131422.14970-1-mcroce@redhat.com/ + + **ENOSYS** + ENOSYS means that a nonexistent system call was called. + Earlier, it was wrongly used for things like invalid operations on + otherwise valid syscalls. This should be avoided in new code. + + See: https://lore.kernel.org/lkml/5eb299021dec23c1a48fa7d9f2c8b794e967766d.1408730669.git.luto@amacapital.net/ + + **ENOTSUPP** + ENOTSUPP is not a standard error code and should be avoided in new patches. + EOPNOTSUPP should be used instead. + + See: https://lore.kernel.org/netdev/20200510182252.GA411829@lunn.ch/ + + **EXPORT_SYMBOL** + EXPORT_SYMBOL should immediately follow the symbol to be exported. + + **IN_ATOMIC** + in_atomic() is not for driver use so any such use is reported as an ERROR. + Also in_atomic() is often used to determine if sleeping is permitted, + but it is not reliable in this use model. Therefore its use is + strongly discouraged. + + However, in_atomic() is ok for core kernel use. + + See: https://lore.kernel.org/lkml/20080320201723.b87b3732.akpm@linux-foundation.org/ + **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** @@ -308,14 +460,21 @@ API usage **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. + **USLEEP_RANGE** + usleep_range() should be preferred over udelay(). The proper way of + using usleep_range() is mentioned in the kernel docs. -Comment style -------------- + See: https://www.kernel.org/doc/html/latest/timers/timers-howto.html#delays-information-on-the-various-kernel-delay-sleep-mechanisms + + +Comments +-------- **BLOCK_COMMENT_STYLE** The comment style is incorrect. The preferred style for multi- @@ -338,8 +497,24 @@ Comment style **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 + **DATA_RACE** + Applications of data_race() should have a comment so as to document the + reasoning behind why it was deemed safe. + + See: https://lore.kernel.org/lkml/20200401101714.44781-1-elver@google.com/ + + **FSF_MAILING_ADDRESS** + Kernel maintainers reject new instances of the GPL boilerplate paragraph + directing people to write to the FSF for a copy of the GPL, since the + FSF has moved in the past and may do so again. + So do not write paragraphs about writing to the Free Software Foundation's + mailing address. + + See: https://lore.kernel.org/lkml/20131006222342.GT19510@leaf/ + Commit message -------------- @@ -347,6 +522,7 @@ 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** @@ -368,12 +544,33 @@ Commit message **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 + + **EMAIL_SUBJECT** + Naming the tool that found the issue is not very useful in the + subject line. A good subject line summarizes the change that + the patch brings. + See: https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes + **FROM_SIGN_OFF_MISMATCH** + The author's email does not match with that in the Signed-off-by: + line(s). This can be sometimes caused due to an improperly configured + email client. + + This message is emitted due to any of the following reasons:: + + - The email names do not match. + - The email addresses do not match. + - The email subaddresses do not match. + - The email comments do not match. + **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** @@ -382,6 +579,7 @@ Commit message 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** @@ -389,6 +587,7 @@ 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** @@ -431,6 +630,7 @@ Comparison style **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** @@ -442,6 +642,87 @@ Comparison style side of the test should be avoided. +Indentation and Line Breaks +--------------------------- + + **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 + + **DEEP_INDENTATION** + Indentation with 6 or more tabs usually indicate overly indented + code. + + It is suggested to refactor excessive indentation of + if/else/for/do/while/switch statements. + + See: https://lore.kernel.org/lkml/1328311239.21255.24.camel@joe2Laptop/ + + **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; + fallthrough; + default: + break; + } + + See: https://www.kernel.org/doc/html/latest/process/coding-style.html#indentation + + **LONG_LINE** + The line has exceeded the specified maximum length. + To use a different maximum line length, the --max-line-length=n option + may be added while invoking checkpatch. + + Earlier, the default line length was 80 columns. Commit bdc48fa11e46 + ("checkpatch/coding-style: deprecate 80-column warning") increased the + limit to 100 columns. This is not a hard limit either and it's + preferable to stay within 80 columns whenever possible. + + See: https://www.kernel.org/doc/html/latest/process/coding-style.html#breaking-long-lines-and-strings + + **LONG_LINE_STRING** + A string starts before but extends beyond the maximum line length. + To use a different maximum line length, the --max-line-length=n option + may be added while invoking checkpatch. + + See: https://www.kernel.org/doc/html/latest/process/coding-style.html#breaking-long-lines-and-strings + + **LONG_LINE_COMMENT** + A comment starts before but extends beyond the maximum line length. + To use a different maximum line length, the --max-line-length=n option + may be added while invoking checkpatch. + + See: https://www.kernel.org/doc/html/latest/process/coding-style.html#breaking-long-lines-and-strings + + **TRAILING_STATEMENTS** + Trailing statements (for example after any conditional) should be + on the next line. + Statements, such as:: + + if (x == y) break; + + should be:: + + if (x == y) + break; + + Macros, Attributes and Symbols ------------------------------ @@ -472,7 +753,7 @@ Macros, Attributes and Symbols **BIT_MACRO** Defines like: 1 << <digit> could be BIT(digit). - The BIT() macro is defined in include/linux/bitops.h:: + The BIT() macro is defined via include/linux/bits.h:: #define BIT(nr) (1UL << (nr)) @@ -492,6 +773,7 @@ Macros, Attributes and Symbols 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** @@ -502,8 +784,12 @@ Macros, Attributes and Symbols 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/ + **DO_WHILE_MACRO_WITH_TRAILING_SEMICOLON** + do {} while(0) macros should not have a trailing semicolon. + **INIT_ATTRIBUTE** Const init definitions should use __initconst instead of __initdata. @@ -528,6 +814,20 @@ Macros, Attributes and Symbols ... } + **MISPLACED_INIT** + It is possible to use section markers on variables in a way + which gcc doesn't understand (or at least not the way the + developer intended):: + + static struct __initdata samsung_pll_clock exynos4_plls[nr_plls] = { + + does not put exynos4_plls in the .initdata section. The __initdata + marker can be virtually anywhere on the line, except right after + "struct". The preferred location is before the "=" sign if there is + one, or before the trailing ";" otherwise. + + See: https://lore.kernel.org/lkml/1377655732.3619.19.camel@joe-AO722/ + **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 @@ -541,6 +841,10 @@ Macros, Attributes and Symbols See: https://www.kernel.org/doc/html/latest/process/coding-style.html#macros-enums-and-rtl + **PREFER_FALLTHROUGH** + Use the `fallthrough;` pseudo keyword instead of + `/* fallthrough */` like comments. + **WEAK_DECLARATION** Using weak declarations like __attribute__((weak)) or __weak can have unintended link defects. Avoid using them. @@ -551,8 +855,51 @@ Functions and Variables **CAMELCASE** Avoid CamelCase Identifiers. + See: https://www.kernel.org/doc/html/latest/process/coding-style.html#naming + **CONST_CONST** + Using `const <type> const *` is generally meant to be + written `const <type> * const`. + + **CONST_STRUCT** + Using const is generally a good idea. Checkpatch reads + a list of frequently used structs that are always or + almost always constant. + + The existing structs list can be viewed from + `scripts/const_structs.checkpatch`. + + See: https://lore.kernel.org/lkml/alpine.DEB.2.10.1608281509480.3321@hadrien/ + + **EMBEDDED_FUNCTION_NAME** + Embedded function names are less appropriate to use as + refactoring can cause function renaming. Prefer the use of + "%s", __func__ to embedded function names. + + Note that this does not work with -f (--file) checkpatch option + as it depends on patch context providing the function name. + + **FUNCTION_ARGUMENTS** + This warning is emitted due to any of the following reasons: + + 1. Arguments for the function declaration do not follow + the identifier name. Example:: + + void foo + (int bar, int baz) + + This should be corrected to:: + + void foo(int bar, int baz) + + 2. Some arguments for the function definition do not + have an identifier name. Example:: + + void foo(int) + + All arguments should have identifier names. + **FUNCTION_WITHOUT_ARGS** Function declarations without arguments like:: @@ -583,6 +930,34 @@ Functions and Variables return bar; +Permissions +----------- + + **DEVICE_ATTR_PERMS** + The permissions used in DEVICE_ATTR are unusual. + Typically only three permissions are used - 0644 (RW), 0444 (RO) + and 0200 (WO). + + See: https://www.kernel.org/doc/html/latest/filesystems/sysfs.html#attributes + + **EXECUTE_PERMISSIONS** + There is no reason for source files to be executable. The executable + bit can be removed safely. + + **EXPORTED_WORLD_WRITABLE** + Exporting world writable sysfs/debugfs files is usually a bad thing. + When done arbitrarily they can introduce serious security bugs. + In the past, some of the debugfs vulnerabilities would seemingly allow + any local user to write arbitrary values into device registers - a + situation from which little good can be expected to emerge. + + See: https://lore.kernel.org/linux-arm-kernel/cover.1296818921.git.segoon@openwall.com/ + + **NON_OCTAL_PERMISSIONS** + Permission bits should use 4 digit octal permissions (like 0700 or 0444). + Avoid using any other base like decimal. + + Spacing and Brackets -------------------- @@ -616,7 +991,7 @@ Spacing and Brackets 1. With a type on the left:: - ;int [] a; + int [] a; 2. At the beginning of a line for slice initialisers:: @@ -626,12 +1001,6 @@ Spacing and Brackets = { [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:: @@ -644,17 +1013,20 @@ Spacing and Brackets **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** @@ -671,37 +1043,47 @@ Spacing and Brackets **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 + See: https://www.kernel.org/doc/html/latest/process/coding-style.html#spaces **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 + **UNNECESSARY_PARENTHESES** + Parentheses are not required in the following cases: + + 1. Function pointer uses:: + + (foo->bar)(); + + could be:: + + foo->bar(); + + 2. Comparisons in if:: + + if ((foo->bar) && (foo->baz)) + if ((foo == bar)) + + could be:: + + if (foo->bar && foo->baz) + if (foo == bar) + + 3. addressof/dereference single Lvalues:: + + &(foo->bar) + *(foo->bar) + + could be:: + + &foo->bar + *foo->bar + **WHILE_AFTER_BRACE** while should follow the closing bracket on the same line:: @@ -723,17 +1105,50 @@ Others The patch seems to be corrupted or lines are wrapped. Please regenerate the patch file before sending it to the maintainer. + **CVS_KEYWORD** + Since linux moved to git, the CVS markers are no longer used. + So, CVS style keywords ($Id$, $Revision$, $Log$) should not be + added. + + **DEFAULT_NO_BREAK** + switch default case is sometimes written as "default:;". This can + cause new cases added below default to be defective. + + A "break;" should be added after empty default statement to avoid + unwanted fallthrough. + **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. + **DT_SCHEMA_BINDING_PATCH** + DT bindings moved to a json-schema based format instead of + freeform text. - **NON_OCTAL_PERMISSIONS** - Permission bits should use 4 digit octal permissions (like 0700 or 0444). - Avoid using any other base like decimal. + See: https://www.kernel.org/doc/html/latest/devicetree/bindings/writing-schema.html + + **DT_SPLIT_BINDING_PATCH** + Devicetree bindings should be their own patch. This is because + bindings are logically independent from a driver implementation, + they have a different maintainer (even though they often + are applied via the same tree), and it makes for a cleaner history in the + DT only tree created with git-filter-branch. + + See: https://www.kernel.org/doc/html/latest/devicetree/bindings/submitting-patches.html#i-for-patch-submitters + + **EMBEDDED_FILENAME** + Embedding the complete filename path inside the file isn't particularly + useful as often the path is moved around and becomes incorrect. + + **FILE_PATH_CHANGES** + Whenever files are added, moved, or deleted, the MAINTAINERS file + patterns can be out of sync or outdated. + + So MAINTAINERS might need updating in these cases. + + **MEMSET** + The memset use appears to be incorrect. This may be caused due to + badly ordered parameters. Please recheck the usage. **NOT_UNIFIED_DIFF** The patch file does not appear to be in unified-diff format. Please @@ -742,14 +1157,12 @@ Others **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; + **SPDX_LICENSE_TAG** + The source file is missing or has an improper SPDX identifier tag. + The Linux kernel requires the precise SPDX identifier in all source files, + and it is thoroughly documented in the kernel docs. - should be:: + See: https://www.kernel.org/doc/html/latest/process/license-rules.html - if (x == y) - break; + **TYPO_SPELLING** + Some words may have been misspelled. Consider reviewing them. diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst index d3f335ffc751..21dc03bc10a4 100644 --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -181,9 +181,16 @@ By default, KASAN prints a bug report only for the first invalid memory access. With ``kasan_multi_shot``, KASAN prints a report on every invalid access. This effectively disables ``panic_on_warn`` for KASAN reports. +Alternatively, independent of ``panic_on_warn`` the ``kasan.fault=`` boot +parameter can be used to control panic and reporting behaviour: + +- ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN + report or also panic the kernel (default: ``report``). The panic happens even + if ``kasan_multi_shot`` is enabled. + Hardware tag-based KASAN mode (see the section about various modes below) is intended for use in production as a security mitigation. Therefore, it supports -boot parameters that allow disabling KASAN or controlling its features. +additional boot parameters that allow disabling KASAN or controlling features: - ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``). @@ -199,10 +206,6 @@ boot parameters that allow disabling KASAN or controlling its features. - ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack traces collection (default: ``on``). -- ``kasan.fault=report`` or ``=panic`` controls whether to only print a KASAN - report or also panic the kernel (default: ``report``). The panic happens even - if ``kasan_multi_shot`` is enabled. - Implementation details ---------------------- @@ -447,11 +450,10 @@ When a test fails due to a failed ``kmalloc``:: When a test fails due to a missing KASAN report:: - # kmalloc_double_kzfree: EXPECTATION FAILED at lib/test_kasan.c:629 - Expected kasan_data->report_expected == kasan_data->report_found, but - kasan_data->report_expected == 1 - kasan_data->report_found == 0 - not ok 28 - kmalloc_double_kzfree + # kmalloc_double_kzfree: EXPECTATION FAILED at lib/test_kasan.c:974 + KASAN failure expected in "kfree_sensitive(ptr)", but none occurred + not ok 44 - kmalloc_double_kzfree + At the end the cumulative status of all KASAN tests is printed. On success:: diff --git a/Documentation/dev-tools/kcsan.rst b/Documentation/dev-tools/kcsan.rst index d85ce238ace7..7db43c7c09b8 100644 --- a/Documentation/dev-tools/kcsan.rst +++ b/Documentation/dev-tools/kcsan.rst @@ -27,75 +27,57 @@ Error reports A typical data race report looks like this:: ================================================================== - BUG: KCSAN: data-race in generic_permission / kernfs_refresh_inode - - write to 0xffff8fee4c40700c of 4 bytes by task 175 on cpu 4: - kernfs_refresh_inode+0x70/0x170 - kernfs_iop_permission+0x4f/0x90 - inode_permission+0x190/0x200 - link_path_walk.part.0+0x503/0x8e0 - path_lookupat.isra.0+0x69/0x4d0 - filename_lookup+0x136/0x280 - user_path_at_empty+0x47/0x60 - vfs_statx+0x9b/0x130 - __do_sys_newlstat+0x50/0xb0 - __x64_sys_newlstat+0x37/0x50 - do_syscall_64+0x85/0x260 - entry_SYSCALL_64_after_hwframe+0x44/0xa9 - - read to 0xffff8fee4c40700c of 4 bytes by task 166 on cpu 6: - generic_permission+0x5b/0x2a0 - kernfs_iop_permission+0x66/0x90 - inode_permission+0x190/0x200 - link_path_walk.part.0+0x503/0x8e0 - path_lookupat.isra.0+0x69/0x4d0 - filename_lookup+0x136/0x280 - user_path_at_empty+0x47/0x60 - do_faccessat+0x11a/0x390 - __x64_sys_access+0x3c/0x50 - do_syscall_64+0x85/0x260 - entry_SYSCALL_64_after_hwframe+0x44/0xa9 + BUG: KCSAN: data-race in test_kernel_read / test_kernel_write + + write to 0xffffffffc009a628 of 8 bytes by task 487 on cpu 0: + test_kernel_write+0x1d/0x30 + access_thread+0x89/0xd0 + kthread+0x23e/0x260 + ret_from_fork+0x22/0x30 + + read to 0xffffffffc009a628 of 8 bytes by task 488 on cpu 6: + test_kernel_read+0x10/0x20 + access_thread+0x89/0xd0 + kthread+0x23e/0x260 + ret_from_fork+0x22/0x30 + + value changed: 0x00000000000009a6 -> 0x00000000000009b2 Reported by Kernel Concurrency Sanitizer on: - CPU: 6 PID: 166 Comm: systemd-journal Not tainted 5.3.0-rc7+ #1 - Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 + CPU: 6 PID: 488 Comm: access_thread Not tainted 5.12.0-rc2+ #1 + Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 ================================================================== The header of the report provides a short summary of the functions involved in the race. It is followed by the access types and stack traces of the 2 threads -involved in the data race. +involved in the data race. If KCSAN also observed a value change, the observed +old value and new value are shown on the "value changed" line respectively. The other less common type of data race report looks like this:: ================================================================== - BUG: KCSAN: data-race in e1000_clean_rx_irq+0x551/0xb10 - - race at unknown origin, with read to 0xffff933db8a2ae6c of 1 bytes by interrupt on cpu 0: - e1000_clean_rx_irq+0x551/0xb10 - e1000_clean+0x533/0xda0 - net_rx_action+0x329/0x900 - __do_softirq+0xdb/0x2db - irq_exit+0x9b/0xa0 - do_IRQ+0x9c/0xf0 - ret_from_intr+0x0/0x18 - default_idle+0x3f/0x220 - arch_cpu_idle+0x21/0x30 - do_idle+0x1df/0x230 - cpu_startup_entry+0x14/0x20 - rest_init+0xc5/0xcb - arch_call_rest_init+0x13/0x2b - start_kernel+0x6db/0x700 + BUG: KCSAN: data-race in test_kernel_rmw_array+0x71/0xd0 + + race at unknown origin, with read to 0xffffffffc009bdb0 of 8 bytes by task 515 on cpu 2: + test_kernel_rmw_array+0x71/0xd0 + access_thread+0x89/0xd0 + kthread+0x23e/0x260 + ret_from_fork+0x22/0x30 + + value changed: 0x0000000000002328 -> 0x0000000000002329 Reported by Kernel Concurrency Sanitizer on: - CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.3.0-rc7+ #2 - Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 + CPU: 2 PID: 515 Comm: access_thread Not tainted 5.12.0-rc2+ #1 + Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 ================================================================== This report is generated where it was not possible to determine the other racing thread, but a race was inferred due to the data value of the watched -memory location having changed. These can occur either due to missing -instrumentation or e.g. DMA accesses. These reports will only be generated if -``CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN=y`` (selected by default). +memory location having changed. These reports always show a "value changed" +line. A common reason for reports of this type are missing instrumentation in +the racing thread, but could also occur due to e.g. DMA accesses. Such reports +are shown only if ``CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN=y``, which is +enabled by default. Selective analysis ~~~~~~~~~~~~~~~~~~ @@ -106,7 +88,8 @@ the below options are available: * KCSAN understands the ``data_race(expr)`` annotation, which tells KCSAN that any data races due to accesses in ``expr`` should be ignored and resulting - behaviour when encountering a data race is deemed safe. + behaviour when encountering a data race is deemed safe. Please see + `"Marking Shared-Memory Accesses" in the LKMM`_ for more information. * Disabling data race detection for entire functions can be accomplished by using the function attribute ``__no_kcsan``:: @@ -128,6 +111,8 @@ the below options are available: KCSAN_SANITIZE := n +.. _"Marking Shared-Memory Accesses" in the LKMM: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/memory-model/Documentation/access-marking.txt + Furthermore, it is possible to tell KCSAN to show or hide entire classes of data races, depending on preferences. These can be changed via the following Kconfig options: @@ -142,6 +127,18 @@ Kconfig options: causes KCSAN to not report data races due to conflicts where the only plain accesses are aligned writes up to word size. +* ``CONFIG_KCSAN_PERMISSIVE``: Enable additional permissive rules to ignore + certain classes of common data races. Unlike the above, the rules are more + complex involving value-change patterns, access type, and address. This + option depends on ``CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY=y``. For details + please see the ``kernel/kcsan/permissive.h``. Testers and maintainers that + only focus on reports from specific subsystems and not the whole kernel are + recommended to disable this option. + +To use the strictest possible rules, select ``CONFIG_KCSAN_STRICT=y``, which +configures KCSAN to follow the Linux-kernel memory consistency model (LKMM) as +closely as possible. + DebugFS interface ~~~~~~~~~~~~~~~~~ diff --git a/Documentation/dev-tools/kfence.rst b/Documentation/dev-tools/kfence.rst index fdf04e741ea5..0fbe3308bf37 100644 --- a/Documentation/dev-tools/kfence.rst +++ b/Documentation/dev-tools/kfence.rst @@ -65,25 +65,27 @@ Error reports A typical out-of-bounds access looks like this:: ================================================================== - BUG: KFENCE: out-of-bounds read in test_out_of_bounds_read+0xa3/0x22b + BUG: KFENCE: out-of-bounds read in test_out_of_bounds_read+0xa6/0x234 - Out-of-bounds read at 0xffffffffb672efff (1B left of kfence-#17): - test_out_of_bounds_read+0xa3/0x22b - kunit_try_run_case+0x51/0x85 + Out-of-bounds read at 0xffff8c3f2e291fff (1B left of kfence-#72): + test_out_of_bounds_read+0xa6/0x234 + kunit_try_run_case+0x61/0xa0 kunit_generic_run_threadfn_adapter+0x16/0x30 - kthread+0x137/0x160 + kthread+0x176/0x1b0 ret_from_fork+0x22/0x30 - kfence-#17 [0xffffffffb672f000-0xffffffffb672f01f, size=32, cache=kmalloc-32] allocated by task 507: - test_alloc+0xf3/0x25b - test_out_of_bounds_read+0x98/0x22b - kunit_try_run_case+0x51/0x85 + kfence-#72: 0xffff8c3f2e292000-0xffff8c3f2e29201f, size=32, cache=kmalloc-32 + + allocated by task 484 on cpu 0 at 32.919330s: + test_alloc+0xfe/0x738 + test_out_of_bounds_read+0x9b/0x234 + kunit_try_run_case+0x61/0xa0 kunit_generic_run_threadfn_adapter+0x16/0x30 - kthread+0x137/0x160 + kthread+0x176/0x1b0 ret_from_fork+0x22/0x30 - CPU: 4 PID: 107 Comm: kunit_try_catch Not tainted 5.8.0-rc6+ #7 - Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014 + CPU: 0 PID: 484 Comm: kunit_try_catch Not tainted 5.13.0-rc3+ #7 + Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 ================================================================== The header of the report provides a short summary of the function involved in @@ -96,30 +98,32 @@ Use-after-free accesses are reported as:: ================================================================== BUG: KFENCE: use-after-free read in test_use_after_free_read+0xb3/0x143 - Use-after-free read at 0xffffffffb673dfe0 (in kfence-#24): + Use-after-free read at 0xffff8c3f2e2a0000 (in kfence-#79): test_use_after_free_read+0xb3/0x143 - kunit_try_run_case+0x51/0x85 + kunit_try_run_case+0x61/0xa0 kunit_generic_run_threadfn_adapter+0x16/0x30 - kthread+0x137/0x160 + kthread+0x176/0x1b0 ret_from_fork+0x22/0x30 - kfence-#24 [0xffffffffb673dfe0-0xffffffffb673dfff, size=32, cache=kmalloc-32] allocated by task 507: - test_alloc+0xf3/0x25b + kfence-#79: 0xffff8c3f2e2a0000-0xffff8c3f2e2a001f, size=32, cache=kmalloc-32 + + allocated by task 488 on cpu 2 at 33.871326s: + test_alloc+0xfe/0x738 test_use_after_free_read+0x76/0x143 - kunit_try_run_case+0x51/0x85 + kunit_try_run_case+0x61/0xa0 kunit_generic_run_threadfn_adapter+0x16/0x30 - kthread+0x137/0x160 + kthread+0x176/0x1b0 ret_from_fork+0x22/0x30 - freed by task 507: + freed by task 488 on cpu 2 at 33.871358s: test_use_after_free_read+0xa8/0x143 - kunit_try_run_case+0x51/0x85 + kunit_try_run_case+0x61/0xa0 kunit_generic_run_threadfn_adapter+0x16/0x30 - kthread+0x137/0x160 + kthread+0x176/0x1b0 ret_from_fork+0x22/0x30 - CPU: 4 PID: 109 Comm: kunit_try_catch Tainted: G W 5.8.0-rc6+ #7 - Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014 + CPU: 2 PID: 488 Comm: kunit_try_catch Tainted: G B 5.13.0-rc3+ #7 + Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 ================================================================== KFENCE also reports on invalid frees, such as double-frees:: @@ -127,30 +131,32 @@ KFENCE also reports on invalid frees, such as double-frees:: ================================================================== BUG: KFENCE: invalid free in test_double_free+0xdc/0x171 - Invalid free of 0xffffffffb6741000: + Invalid free of 0xffff8c3f2e2a4000 (in kfence-#81): test_double_free+0xdc/0x171 - kunit_try_run_case+0x51/0x85 + kunit_try_run_case+0x61/0xa0 kunit_generic_run_threadfn_adapter+0x16/0x30 - kthread+0x137/0x160 + kthread+0x176/0x1b0 ret_from_fork+0x22/0x30 - kfence-#26 [0xffffffffb6741000-0xffffffffb674101f, size=32, cache=kmalloc-32] allocated by task 507: - test_alloc+0xf3/0x25b + kfence-#81: 0xffff8c3f2e2a4000-0xffff8c3f2e2a401f, size=32, cache=kmalloc-32 + + allocated by task 490 on cpu 1 at 34.175321s: + test_alloc+0xfe/0x738 test_double_free+0x76/0x171 - kunit_try_run_case+0x51/0x85 + kunit_try_run_case+0x61/0xa0 kunit_generic_run_threadfn_adapter+0x16/0x30 - kthread+0x137/0x160 + kthread+0x176/0x1b0 ret_from_fork+0x22/0x30 - freed by task 507: + freed by task 490 on cpu 1 at 34.175348s: test_double_free+0xa8/0x171 - kunit_try_run_case+0x51/0x85 + kunit_try_run_case+0x61/0xa0 kunit_generic_run_threadfn_adapter+0x16/0x30 - kthread+0x137/0x160 + kthread+0x176/0x1b0 ret_from_fork+0x22/0x30 - CPU: 4 PID: 111 Comm: kunit_try_catch Tainted: G W 5.8.0-rc6+ #7 - Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014 + CPU: 1 PID: 490 Comm: kunit_try_catch Tainted: G B 5.13.0-rc3+ #7 + Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 ================================================================== KFENCE also uses pattern-based redzones on the other side of an object's guard @@ -160,23 +166,25 @@ These are reported on frees:: ================================================================== BUG: KFENCE: memory corruption in test_kmalloc_aligned_oob_write+0xef/0x184 - Corrupted memory at 0xffffffffb6797ff9 [ 0xac . . . . . . ] (in kfence-#69): + Corrupted memory at 0xffff8c3f2e33aff9 [ 0xac . . . . . . ] (in kfence-#156): test_kmalloc_aligned_oob_write+0xef/0x184 - kunit_try_run_case+0x51/0x85 + kunit_try_run_case+0x61/0xa0 kunit_generic_run_threadfn_adapter+0x16/0x30 - kthread+0x137/0x160 + kthread+0x176/0x1b0 ret_from_fork+0x22/0x30 - kfence-#69 [0xffffffffb6797fb0-0xffffffffb6797ff8, size=73, cache=kmalloc-96] allocated by task 507: - test_alloc+0xf3/0x25b + kfence-#156: 0xffff8c3f2e33afb0-0xffff8c3f2e33aff8, size=73, cache=kmalloc-96 + + allocated by task 502 on cpu 7 at 42.159302s: + test_alloc+0xfe/0x738 test_kmalloc_aligned_oob_write+0x57/0x184 - kunit_try_run_case+0x51/0x85 + kunit_try_run_case+0x61/0xa0 kunit_generic_run_threadfn_adapter+0x16/0x30 - kthread+0x137/0x160 + kthread+0x176/0x1b0 ret_from_fork+0x22/0x30 - CPU: 4 PID: 120 Comm: kunit_try_catch Tainted: G W 5.8.0-rc6+ #7 - Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014 + CPU: 7 PID: 502 Comm: kunit_try_catch Tainted: G B 5.13.0-rc3+ #7 + Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 ================================================================== For such errors, the address where the corruption occurred as well as the diff --git a/Documentation/dev-tools/kunit/api/index.rst b/Documentation/dev-tools/kunit/api/index.rst index 9b9bffe5d41a..b33ad72bcf0b 100644 --- a/Documentation/dev-tools/kunit/api/index.rst +++ b/Documentation/dev-tools/kunit/api/index.rst @@ -10,7 +10,7 @@ API Reference This section documents the KUnit kernel testing API. It is divided into the following sections: -================================= ============================================== -:doc:`test` documents all of the standard testing API - excluding mocking or mocking related features. -================================= ============================================== +Documentation/dev-tools/kunit/api/test.rst + + - documents all of the standard testing API excluding mocking + or mocking related features. diff --git a/Documentation/dev-tools/kunit/faq.rst b/Documentation/dev-tools/kunit/faq.rst index 8d5029ad210a..5c6555d020f3 100644 --- a/Documentation/dev-tools/kunit/faq.rst +++ b/Documentation/dev-tools/kunit/faq.rst @@ -97,7 +97,7 @@ things to try. modules will automatically execute associated tests when loaded. Test results can be collected from ``/sys/kernel/debug/kunit/<test suite>/results``, and can be parsed with ``kunit.py parse``. For more details, see "KUnit on - non-UML architectures" in :doc:`usage`. + non-UML architectures" in Documentation/dev-tools/kunit/usage.rst. If none of the above tricks help, you are always welcome to email any issues to kunit-dev@googlegroups.com. diff --git a/Documentation/dev-tools/kunit/index.rst b/Documentation/dev-tools/kunit/index.rst index 848478838347..cacb35ec658d 100644 --- a/Documentation/dev-tools/kunit/index.rst +++ b/Documentation/dev-tools/kunit/index.rst @@ -14,6 +14,7 @@ KUnit - Unit Testing for the Linux Kernel style faq tips + running_tips What is KUnit? ============== @@ -36,7 +37,7 @@ To make running these tests (and reading the results) easier, KUnit offers results. This provides a quick way of running KUnit tests during development, without requiring a virtual machine or separate hardware. -Get started now: :doc:`start` +Get started now: Documentation/dev-tools/kunit/start.rst Why KUnit? ========== @@ -88,9 +89,9 @@ it takes to read their test log? How do I use it? ================ -* :doc:`start` - for new users of KUnit -* :doc:`tips` - for short examples of best practices -* :doc:`usage` - for a more detailed explanation of KUnit features -* :doc:`api/index` - for the list of KUnit APIs used for testing -* :doc:`kunit-tool` - for more information on the kunit_tool helper script -* :doc:`faq` - for answers to some common questions about KUnit +* Documentation/dev-tools/kunit/start.rst - for new users of KUnit +* Documentation/dev-tools/kunit/tips.rst - for short examples of best practices +* Documentation/dev-tools/kunit/usage.rst - for a more detailed explanation of KUnit features +* Documentation/dev-tools/kunit/api/index.rst - for the list of KUnit APIs used for testing +* Documentation/dev-tools/kunit/kunit-tool.rst - for more information on the kunit_tool helper script +* Documentation/dev-tools/kunit/faq.rst - for answers to some common questions about KUnit diff --git a/Documentation/dev-tools/kunit/kunit-tool.rst b/Documentation/dev-tools/kunit/kunit-tool.rst index 29ae2fee8123..ae52e0f489f9 100644 --- a/Documentation/dev-tools/kunit/kunit-tool.rst +++ b/Documentation/dev-tools/kunit/kunit-tool.rst @@ -22,14 +22,19 @@ not require any virtualization support: it is just a regular program. What is a .kunitconfig? ======================= -It's just a defconfig that kunit_tool looks for in the base directory. -kunit_tool uses it to generate a .config as you might expect. In addition, it -verifies that the generated .config contains the CONFIG options in the -.kunitconfig; the reason it does this is so that it is easy to be sure that a -CONFIG that enables a test actually ends up in the .config. +It's just a defconfig that kunit_tool looks for in the build directory +(``.kunit`` by default). kunit_tool uses it to generate a .config as you might +expect. In addition, it verifies that the generated .config contains the CONFIG +options in the .kunitconfig; the reason it does this is so that it is easy to +be sure that a CONFIG that enables a test actually ends up in the .config. -How do I use kunit_tool? -======================== +It's also possible to pass a separate .kunitconfig fragment to kunit_tool, +which is useful if you have several different groups of tests you wish +to run independently, or if you want to use pre-defined test configs for +certain subsystems. + +Getting Started with kunit_tool +=============================== If a kunitconfig is present at the root directory, all you have to do is: @@ -48,10 +53,180 @@ However, you most likely want to use it with the following options: .. note:: This command will work even without a .kunitconfig file: if no - .kunitconfig is present, a default one will be used instead. + .kunitconfig is present, a default one will be used instead. + +If you wish to use a different .kunitconfig file (such as one provided for +testing a particular subsystem), you can pass it as an option. + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py run --kunitconfig=fs/ext4/.kunitconfig For a list of all the flags supported by kunit_tool, you can run: .. code-block:: bash ./tools/testing/kunit/kunit.py run --help + +Configuring, Building, and Running Tests +======================================== + +It's also possible to run just parts of the KUnit build process independently, +which is useful if you want to make manual changes to part of the process. + +A .config can be generated from a .kunitconfig by using the ``config`` argument +when running kunit_tool: + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py config + +Similarly, if you just want to build a KUnit kernel from the current .config, +you can use the ``build`` argument: + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py build + +And, if you already have a built UML kernel with built-in KUnit tests, you can +run the kernel and display the test results with the ``exec`` argument: + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py exec + +The ``run`` command which is discussed above is equivalent to running all three +of these in sequence. + +All of these commands accept a number of optional command-line arguments. The +``--help`` flag will give a complete list of these, or keep reading this page +for a guide to some of the more useful ones. + +Parsing Test Results +==================== + +KUnit tests output their results in TAP (Test Anything Protocol) format. +kunit_tool will, when running tests, parse this output and print a summary +which is much more pleasant to read. If you wish to look at the raw test +results in TAP format, you can pass the ``--raw_output`` argument. + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py run --raw_output + +The raw output from test runs may contain other, non-KUnit kernel log +lines. You can see just KUnit output with ``--raw_output=kunit``: + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py run --raw_output=kunit + +If you have KUnit results in their raw TAP format, you can parse them and print +the human-readable summary with the ``parse`` command for kunit_tool. This +accepts a filename for an argument, or will read from standard input. + +.. code-block:: bash + + # Reading from a file + ./tools/testing/kunit/kunit.py parse /var/log/dmesg + # Reading from stdin + dmesg | ./tools/testing/kunit/kunit.py parse + +This is very useful if you wish to run tests in a configuration not supported +by kunit_tool (such as on real hardware, or an unsupported architecture). + +Filtering Tests +=============== + +It's possible to run only a subset of the tests built into a kernel by passing +a filter to the ``exec`` or ``run`` commands. For example, if you only wanted +to run KUnit resource tests, you could use: + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py run 'kunit-resource*' + +This uses the standard glob format for wildcards. + +Running Tests on QEMU +===================== + +kunit_tool supports running tests on QEMU as well as via UML (as mentioned +elsewhere). The default way of running tests on QEMU requires two flags: + +``--arch`` + Selects a collection of configs (Kconfig as well as QEMU configs + options, etc) that allow KUnit tests to be run on the specified + architecture in a minimal way; this is usually not much slower than + using UML. The architecture argument is the same as the name of the + option passed to the ``ARCH`` variable used by Kbuild. Not all + architectures are currently supported by this flag, but can be handled + by the ``--qemu_config`` discussed later. If ``um`` is passed (or this + this flag is ignored) the tests will run via UML. Non-UML architectures, + e.g. i386, x86_64, arm, um, etc. Non-UML run on QEMU. + +``--cross_compile`` + Specifies the use of a toolchain by Kbuild. The argument passed here is + the same passed to the ``CROSS_COMPILE`` variable used by Kbuild. As a + reminder this will be the prefix for the toolchain binaries such as gcc + for example ``sparc64-linux-gnu-`` if you have the sparc toolchain + installed on your system, or + ``$HOME/toolchains/microblaze/gcc-9.2.0-nolibc/microblaze-linux/bin/microblaze-linux-`` + if you have downloaded the microblaze toolchain from the 0-day website + to a directory in your home directory called ``toolchains``. + +In many cases it is likely that you may want to run an architecture which is +not supported by the ``--arch`` flag, or you may want to just run KUnit tests +on QEMU using a non-default configuration. For this use case, you can write +your own QemuConfig. These QemuConfigs are written in Python. They must have an +import line ``from ..qemu_config import QemuArchParams`` at the top of the file +and the file must contain a variable called ``QEMU_ARCH`` that has an instance +of ``QemuArchParams`` assigned to it. An example can be seen in +``tools/testing/kunit/qemu_configs/x86_64.py``. + +Once you have a QemuConfig you can pass it into kunit_tool using the +``--qemu_config`` flag; when used this flag replaces the ``--arch`` flag. If we +were to do this with the ``x86_64.py`` example from above, the invocation would +look something like this: + +.. code-block:: bash + + ./tools/testing/kunit/kunit.py run \ + --timeout=60 \ + --jobs=12 \ + --qemu_config=./tools/testing/kunit/qemu_configs/x86_64.py + +Other Useful Options +==================== + +kunit_tool has a number of other command-line arguments which can be useful +when adapting it to fit your environment or needs. + +Some of the more useful ones are: + +``--help`` + Lists all of the available options. Note that different commands + (``config``, ``build``, ``run``, etc) will have different supported + options. Place ``--help`` before the command to list common options, + and after the command for options specific to that command. + +``--build_dir`` + Specifies the build directory that kunit_tool will use. This is where + the .kunitconfig file is located, as well as where the .config and + compiled kernel will be placed. Defaults to ``.kunit``. + +``--make_options`` + Specifies additional options to pass to ``make`` when compiling a + kernel (with the ``build`` or ``run`` commands). For example, to enable + compiler warnings, you can pass ``--make_options W=1``. + +``--alltests`` + Builds a UML kernel with all config options enabled using ``make + allyesconfig``. This allows you to run as many tests as is possible, + but is very slow and prone to breakage as new options are added or + modified. In most cases, enabling all tests which have satisfied + dependencies by adding ``CONFIG_KUNIT_ALL_TESTS=1`` to your + .kunitconfig is preferable. + +There are several other options (and new ones are often added), so do check +``--help`` if you're looking for something not mentioned here. diff --git a/Documentation/dev-tools/kunit/running_tips.rst b/Documentation/dev-tools/kunit/running_tips.rst new file mode 100644 index 000000000000..30d2147eb5b5 --- /dev/null +++ b/Documentation/dev-tools/kunit/running_tips.rst @@ -0,0 +1,257 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================ +Tips For Running KUnit Tests +============================ + +Using ``kunit.py run`` ("kunit tool") +===================================== + +Running from any directory +-------------------------- + +It can be handy to create a bash function like: + +.. code-block:: bash + + function run_kunit() { + ( cd "$(git rev-parse --show-toplevel)" && ./tools/testing/kunit/kunit.py run $@ ) + } + +.. note:: + Early versions of ``kunit.py`` (before 5.6) didn't work unless run from + the kernel root, hence the use of a subshell and ``cd``. + +Running a subset of tests +------------------------- + +``kunit.py run`` accepts an optional glob argument to filter tests. Currently +this only matches against suite names, but this may change in the future. + +Say that we wanted to run the sysctl tests, we could do so via: + +.. code-block:: bash + + $ echo -e 'CONFIG_KUNIT=y\nCONFIG_KUNIT_ALL_TESTS=y' > .kunit/.kunitconfig + $ ./tools/testing/kunit/kunit.py run 'sysctl*' + +We're paying the cost of building more tests than we need this way, but it's +easier than fiddling with ``.kunitconfig`` files or commenting out +``kunit_suite``'s. + +However, if we wanted to define a set of tests in a less ad hoc way, the next +tip is useful. + +Defining a set of tests +----------------------- + +``kunit.py run`` (along with ``build``, and ``config``) supports a +``--kunitconfig`` flag. So if you have a set of tests that you want to run on a +regular basis (especially if they have other dependencies), you can create a +specific ``.kunitconfig`` for them. + +E.g. kunit has one for its tests: + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit/.kunitconfig + +Alternatively, if you're following the convention of naming your +file ``.kunitconfig``, you can just pass in the dir, e.g. + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit + +.. note:: + This is a relatively new feature (5.12+) so we don't have any + conventions yet about on what files should be checked in versus just + kept around locally. It's up to you and your maintainer to decide if a + config is useful enough to submit (and therefore have to maintain). + +.. note:: + Having ``.kunitconfig`` fragments in a parent and child directory is + iffy. There's discussion about adding an "import" statement in these + files to make it possible to have a top-level config run tests from all + child directories. But that would mean ``.kunitconfig`` files are no + longer just simple .config fragments. + + One alternative would be to have kunit tool recursively combine configs + automagically, but tests could theoretically depend on incompatible + options, so handling that would be tricky. + +Setting kernel commandline parameters +------------------------------------- + +You can use ``--kernel_args`` to pass arbitrary kernel arguments, e.g. + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --kernel_args=param=42 --kernel_args=param2=false + + +Generating code coverage reports under UML +------------------------------------------ + +.. note:: + TODO(brendanhiggins@google.com): There are various issues with UML and + versions of gcc 7 and up. You're likely to run into missing ``.gcda`` + files or compile errors. + +This is different from the "normal" way of getting coverage information that is +documented in Documentation/dev-tools/gcov.rst. + +Instead of enabling ``CONFIG_GCOV_KERNEL=y``, we can set these options: + +.. code-block:: none + + CONFIG_DEBUG_KERNEL=y + CONFIG_DEBUG_INFO=y + CONFIG_GCOV=y + + +Putting it together into a copy-pastable sequence of commands: + +.. code-block:: bash + + # Append coverage options to the current config + $ echo -e "CONFIG_DEBUG_KERNEL=y\nCONFIG_DEBUG_INFO=y\nCONFIG_GCOV=y" >> .kunit/.kunitconfig + $ ./tools/testing/kunit/kunit.py run + # Extract the coverage information from the build dir (.kunit/) + $ lcov -t "my_kunit_tests" -o coverage.info -c -d .kunit/ + + # From here on, it's the same process as with CONFIG_GCOV_KERNEL=y + # E.g. can generate an HTML report in a tmp dir like so: + $ genhtml -o /tmp/coverage_html coverage.info + + +If your installed version of gcc doesn't work, you can tweak the steps: + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py run --make_options=CC=/usr/bin/gcc-6 + $ lcov -t "my_kunit_tests" -o coverage.info -c -d .kunit/ --gcov-tool=/usr/bin/gcov-6 + + +Running tests manually +====================== + +Running tests without using ``kunit.py run`` is also an important use case. +Currently it's your only option if you want to test on architectures other than +UML. + +As running the tests under UML is fairly straightforward (configure and compile +the kernel, run the ``./linux`` binary), this section will focus on testing +non-UML architectures. + + +Running built-in tests +---------------------- + +When setting tests to ``=y``, the tests will run as part of boot and print +results to dmesg in TAP format. So you just need to add your tests to your +``.config``, build and boot your kernel as normal. + +So if we compiled our kernel with: + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=y + +Then we'd see output like this in dmesg signaling the test ran and passed: + +.. code-block:: none + + TAP version 14 + 1..1 + # Subtest: example + 1..1 + # example_simple_test: initializing + ok 1 - example_simple_test + ok 1 - example + +Running tests as modules +------------------------ + +Depending on the tests, you can build them as loadable modules. + +For example, we'd change the config options from before to + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=m + +Then after booting into our kernel, we can run the test via + +.. code-block:: none + + $ modprobe kunit-example-test + +This will then cause it to print TAP output to stdout. + +.. note:: + The ``modprobe`` will *not* have a non-zero exit code if any test + failed (as of 5.13). But ``kunit.py parse`` would, see below. + +.. note:: + You can set ``CONFIG_KUNIT=m`` as well, however, some features will not + work and thus some tests might break. Ideally tests would specify they + depend on ``KUNIT=y`` in their ``Kconfig``'s, but this is an edge case + most test authors won't think about. + As of 5.13, the only difference is that ``current->kunit_test`` will + not exist. + +Pretty-printing results +----------------------- + +You can use ``kunit.py parse`` to parse dmesg for test output and print out +results in the same familiar format that ``kunit.py run`` does. + +.. code-block:: bash + + $ ./tools/testing/kunit/kunit.py parse /var/log/dmesg + + +Retrieving per suite results +---------------------------- + +Regardless of how you're running your tests, you can enable +``CONFIG_KUNIT_DEBUGFS`` to expose per-suite TAP-formatted results: + +.. code-block:: none + + CONFIG_KUNIT=y + CONFIG_KUNIT_EXAMPLE_TEST=m + CONFIG_KUNIT_DEBUGFS=y + +The results for each suite will be exposed under +``/sys/kernel/debug/kunit/<suite>/results``. +So using our example config: + +.. code-block:: bash + + $ modprobe kunit-example-test > /dev/null + $ cat /sys/kernel/debug/kunit/example/results + ... <TAP output> ... + + # After removing the module, the corresponding files will go away + $ modprobe -r kunit-example-test + $ cat /sys/kernel/debug/kunit/example/results + /sys/kernel/debug/kunit/example/results: No such file or directory + +Generating code coverage reports +-------------------------------- + +See Documentation/dev-tools/gcov.rst for details on how to do this. + +The only vaguely KUnit-specific advice here is that you probably want to build +your tests as modules. That way you can isolate the coverage from tests from +other code executed during boot, e.g. + +.. code-block:: bash + + # Reset coverage counters before running the test. + $ echo 0 > /sys/kernel/debug/gcov/reset + $ modprobe kunit-example-test diff --git a/Documentation/dev-tools/kunit/start.rst b/Documentation/dev-tools/kunit/start.rst index 0e65cabe08eb..1e00f9226f74 100644 --- a/Documentation/dev-tools/kunit/start.rst +++ b/Documentation/dev-tools/kunit/start.rst @@ -21,7 +21,7 @@ The wrapper can be run with: ./tools/testing/kunit/kunit.py run For more information on this wrapper (also called kunit_tool) check out the -:doc:`kunit-tool` page. +Documentation/dev-tools/kunit/kunit-tool.rst page. Creating a .kunitconfig ----------------------- @@ -36,7 +36,7 @@ A good starting point for a ``.kunitconfig`` is the KUnit defconfig: .. code-block:: bash cd $PATH_TO_LINUX_REPO - cp arch/um/configs/kunit_defconfig .kunitconfig + cp tools/testing/kunit/configs/default.config .kunitconfig You can then add any other Kconfig options you wish, e.g.: @@ -234,7 +234,9 @@ Congrats! You just wrote your first KUnit test! Next Steps ========== -* Check out the :doc:`tips` page for tips on +* Check out the Documentation/dev-tools/kunit/tips.rst page for tips on writing idiomatic KUnit tests. +* Check out the :doc:`running_tips` page for tips on + how to make running KUnit tests easier. * Optional: see the :doc:`usage` page for a more in-depth explanation of KUnit. diff --git a/Documentation/dev-tools/kunit/tips.rst b/Documentation/dev-tools/kunit/tips.rst index 8d8c238f7f79..492d2ded2f5a 100644 --- a/Documentation/dev-tools/kunit/tips.rst +++ b/Documentation/dev-tools/kunit/tips.rst @@ -125,7 +125,8 @@ Here's a slightly in-depth example of how one could implement "mocking": Note: here we're able to get away with using ``test->priv``, but if you wanted -something more flexible you could use a named ``kunit_resource``, see :doc:`api/test`. +something more flexible you could use a named ``kunit_resource``, see +Documentation/dev-tools/kunit/api/test.rst. Failing the current test ------------------------ @@ -185,5 +186,5 @@ Alternatively, one can take full control over the error message by using ``KUNIT Next Steps ========== -* Optional: see the :doc:`usage` page for a more +* Optional: see the Documentation/dev-tools/kunit/usage.rst page for a more in-depth explanation of KUnit. diff --git a/Documentation/dev-tools/kunit/usage.rst b/Documentation/dev-tools/kunit/usage.rst index 650f99590df5..63f1bb89ebf5 100644 --- a/Documentation/dev-tools/kunit/usage.rst +++ b/Documentation/dev-tools/kunit/usage.rst @@ -10,7 +10,7 @@ understand it. This guide assumes a working knowledge of the Linux kernel and some basic knowledge of testing. For a high level introduction to KUnit, including setting up KUnit for your -project, see :doc:`start`. +project, see Documentation/dev-tools/kunit/start.rst. Organization of this document ============================= @@ -99,7 +99,8 @@ violated; however, the test will continue running, potentially trying other expectations until the test case ends or is otherwise terminated. This is as opposed to *assertions* which are discussed later. -To learn about more expectations supported by KUnit, see :doc:`api/test`. +To learn about more expectations supported by KUnit, see +Documentation/dev-tools/kunit/api/test.rst. .. note:: A single test case should be pretty short, pretty easy to understand, @@ -216,7 +217,8 @@ test suite in a special linker section so that it can be run by KUnit either after late_init, or when the test module is loaded (depending on whether the test was built in or not). -For more information on these types of things see the :doc:`api/test`. +For more information on these types of things see the +Documentation/dev-tools/kunit/api/test.rst. Common Patterns =============== @@ -465,10 +467,9 @@ fictitious example for ``sha1sum(1)`` .. code-block:: c - /* Note: the cast is to satisfy overly strict type-checking. */ #define TEST_SHA1(in, want) \ sha1sum(in, out); \ - KUNIT_EXPECT_STREQ_MSG(test, (char *)out, want, "sha1sum(%s)", in); + KUNIT_EXPECT_STREQ_MSG(test, out, want, "sha1sum(%s)", in); char out[40]; TEST_SHA1("hello world", "2aae6c35c94fcfb415dbe95f408b9ce91ee846ed"); @@ -507,7 +508,7 @@ In some cases, it can be helpful to write a *table-driven test* instead, e.g. }; for (i = 0; i < ARRAY_SIZE(cases); ++i) { sha1sum(cases[i].str, out); - KUNIT_EXPECT_STREQ_MSG(test, (char *)out, cases[i].sha1, + KUNIT_EXPECT_STREQ_MSG(test, out, cases[i].sha1, "sha1sum(%s)", cases[i].str); } @@ -568,7 +569,7 @@ Reusing the same ``cases`` array from above, we can write the test as a struct sha1_test_case *test_param = (struct sha1_test_case *)(test->param_value); sha1sum(test_param->str, out); - KUNIT_EXPECT_STREQ_MSG(test, (char *)out, test_param->sha1, + KUNIT_EXPECT_STREQ_MSG(test, out, test_param->sha1, "sha1sum(%s)", test_param->str); } @@ -609,17 +610,45 @@ non-UML architectures: None of these are reasons not to run your KUnit tests on real hardware; they are only things to be aware of when doing so. -The biggest impediment will likely be that certain KUnit features and -infrastructure may not support your target environment. For example, at this -time the KUnit Wrapper (``tools/testing/kunit/kunit.py``) does not work outside -of UML. Unfortunately, there is no way around this. Using UML (or even just a -particular architecture) allows us to make a lot of assumptions that make it -possible to do things which might otherwise be impossible. - -Nevertheless, all core KUnit framework features are fully supported on all -architectures, and using them is straightforward: all you need to do is to take -your kunitconfig, your Kconfig options for the tests you would like to run, and -merge them into whatever config your are using for your platform. That's it! +Currently, the KUnit Wrapper (``tools/testing/kunit/kunit.py``) (aka +kunit_tool) only fully supports running tests inside of UML and QEMU; however, +this is only due to our own time limitations as humans working on KUnit. It is +entirely possible to support other emulators and even actual hardware, but for +now QEMU and UML is what is fully supported within the KUnit Wrapper. Again, to +be clear, this is just the Wrapper. The actualy KUnit tests and the KUnit +library they are written in is fully architecture agnostic and can be used in +virtually any setup, you just won't have the benefit of typing a single command +out of the box and having everything magically work perfectly. + +Again, all core KUnit framework features are fully supported on all +architectures, and using them is straightforward: Most popular architectures +are supported directly in the KUnit Wrapper via QEMU. Currently, supported +architectures on QEMU include: + +* i386 +* x86_64 +* arm +* arm64 +* alpha +* powerpc +* riscv +* s390 +* sparc + +In order to run KUnit tests on one of these architectures via QEMU with the +KUnit wrapper, all you need to do is specify the flags ``--arch`` and +``--cross_compile`` when invoking the KUnit Wrapper. For example, we could run +the default KUnit tests on ARM in the following manner (assuming we have an ARM +toolchain installed): + +.. code-block:: bash + + tools/testing/kunit/kunit.py run --timeout=60 --jobs=12 --arch=arm --cross_compile=arm-linux-gnueabihf- + +Alternatively, if you want to run your tests on real hardware or in some other +emulation environment, all you need to do is to take your kunitconfig, your +Kconfig options for the tests you would like to run, and merge them into +whatever config your are using for your platform. That's it! For example, let's say you have the following kunitconfig: diff --git a/Documentation/dev-tools/testing-overview.rst b/Documentation/dev-tools/testing-overview.rst index b5b46709969c..65feb81edb14 100644 --- a/Documentation/dev-tools/testing-overview.rst +++ b/Documentation/dev-tools/testing-overview.rst @@ -71,15 +71,15 @@ 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. +Documentation/dev-tools/gcov.rst 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. + +Documentation/dev-tools/kcov.rst 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 |