Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/Documentation/dev-tools/coccinelle.rst b/Documentation/dev-tools/coccinelle.rst
index 94f41c2..00a3409 100644
--- a/Documentation/dev-tools/coccinelle.rst
+++ b/Documentation/dev-tools/coccinelle.rst
@@ -4,6 +4,8 @@
.. highlight:: none
+.. _devtools_coccinelle:
+
Coccinelle
==========
@@ -30,18 +32,29 @@
- NetBSD
- FreeBSD
-You can get the latest version released from the Coccinelle homepage at
+Some distribution packages are obsolete and it is recommended
+to use the latest version released from the Coccinelle homepage at
http://coccinelle.lip6.fr/
-Once you have it, run the following command::
+Or from Github at:
- ./configure
+https://github.com/coccinelle/coccinelle
+
+Once you have it, run the following commands::
+
+ ./autogen
+ ./configure
make
as a regular user, and install it with::
sudo make install
+More detailed installation instructions to build from source can be
+found at:
+
+https://github.com/coccinelle/coccinelle/blob/master/install.txt
+
Supplemental documentation
---------------------------
@@ -51,6 +64,10 @@
The wiki documentation always refers to the linux-next version of the script.
+For Semantic Patch Language(SmPL) grammar documentation refer to:
+
+http://coccinelle.lip6.fr/documentation.php
+
Using Coccinelle on the Linux kernel
------------------------------------
@@ -223,7 +240,7 @@
proper dir, as such the second rule above would be implied for picking up a
.cocciconfig when using ``make coccicheck``.
-``make coccicheck`` also supports using M= targets.If you do not supply
+``make coccicheck`` also supports using M= targets. If you do not supply
any M= target, it is assumed you want to target the entire kernel.
The kernel coccicheck script has::
diff --git a/Documentation/dev-tools/conf.py b/Documentation/dev-tools/conf.py
deleted file mode 100644
index 7faafa3..0000000
--- a/Documentation/dev-tools/conf.py
+++ /dev/null
@@ -1,10 +0,0 @@
-# -*- coding: utf-8; mode: python -*-
-
-project = "Development tools for the kernel"
-
-tags.add("subproject")
-
-latex_documents = [
- ('index', 'dev-tools.tex', project,
- 'The kernel development community', 'manual'),
-]
diff --git a/Documentation/dev-tools/gcov.rst b/Documentation/dev-tools/gcov.rst
index 69a7d90..46aae52 100644
--- a/Documentation/dev-tools/gcov.rst
+++ b/Documentation/dev-tools/gcov.rst
@@ -34,10 +34,6 @@
CONFIG_DEBUG_FS=y
CONFIG_GCOV_KERNEL=y
-select the gcc's gcov format, default is autodetect based on gcc version::
-
- CONFIG_GCOV_FORMAT_AUTODETECT=y
-
and to get coverage data for the entire kernel::
CONFIG_GCOV_PROFILE_ALL=y
@@ -169,6 +165,20 @@
[user@build] gcov -o /tmp/coverage/tmp/out/init main.c
+Note on compilers
+-----------------
+
+GCC and LLVM gcov tools are not necessarily compatible. Use gcov_ to work with
+GCC-generated .gcno and .gcda files, and use llvm-cov_ for Clang.
+
+.. _gcov: http://gcc.gnu.org/onlinedocs/gcc/Gcov.html
+.. _llvm-cov: https://llvm.org/docs/CommandGuide/llvm-cov.html
+
+Build differences between GCC and Clang gcov are handled by Kconfig. It
+automatically selects the appropriate gcov format depending on the detected
+toolchain.
+
+
Troubleshooting
---------------
diff --git a/Documentation/dev-tools/index.rst b/Documentation/dev-tools/index.rst
index e313925..b0522a4 100644
--- a/Documentation/dev-tools/index.rst
+++ b/Documentation/dev-tools/index.rst
@@ -3,8 +3,8 @@
================================
This document is a collection of documents about development tools that can
-be used to work on the kernel. For now, the documents have been pulled
-together without any significant effot to integrate them into a coherent
+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!
.. class:: toc-title
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index aabc873..5252961 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -4,15 +4,25 @@
Overview
--------
-KernelAddressSANitizer (KASAN) is a dynamic memory error detector. It provides
-a fast and comprehensive solution for finding use-after-free and out-of-bounds
-bugs.
+KernelAddressSANitizer (KASAN) is a dynamic memory error detector designed to
+find out-of-bound and use-after-free bugs. KASAN has two modes: generic KASAN
+(similar to userspace ASan) and software tag-based KASAN (similar to userspace
+HWASan).
-KASAN uses compile-time instrumentation for checking every memory access,
-therefore you will need a GCC version 4.9.2 or later. GCC 5.0 or later is
-required for detection of out-of-bounds accesses to stack or global variables.
+KASAN uses compile-time instrumentation to insert validity checks before every
+memory access, and therefore requires a compiler version that supports that.
-Currently KASAN is supported only for the x86_64 and arm64 architectures.
+Generic KASAN is supported in both GCC and Clang. With GCC it requires version
+4.9.2 or later for basic support and version 5.0 or later for detection of
+out-of-bounds accesses for stack and global variables and for inline
+instrumentation mode (see the Usage section). With Clang it requires version
+7.0.0 or later and it doesn't support detection of out-of-bounds accesses for
+global variables yet.
+
+Tag-based KASAN is only supported in Clang and requires version 7.0.0 or later.
+
+Currently generic KASAN is supported for the x86_64, arm64, xtensa and s390
+architectures, and tag-based KASAN is supported only for arm64.
Usage
-----
@@ -21,14 +31,19 @@
CONFIG_KASAN = y
-and choose between CONFIG_KASAN_OUTLINE and CONFIG_KASAN_INLINE. Outline and
-inline are compiler instrumentation types. The former produces smaller binary
-the latter is 1.1 - 2 times faster. Inline instrumentation requires a GCC
-version 5.0 or later.
+and choose between CONFIG_KASAN_GENERIC (to enable generic KASAN) and
+CONFIG_KASAN_SW_TAGS (to enable software tag-based KASAN).
-KASAN works with both SLUB and SLAB memory allocators.
+You also need to choose between CONFIG_KASAN_OUTLINE and CONFIG_KASAN_INLINE.
+Outline and inline are compiler instrumentation types. The former produces
+smaller binary while the latter is 1.1 - 2 times faster.
+
+Both KASAN modes work with both SLUB and SLAB memory allocators.
For better bug detection and nicer reporting, enable CONFIG_STACKTRACE.
+To augment reports with last allocation and freeing stack of the physical page,
+it is recommended to enable also CONFIG_PAGE_OWNER and boot with page_owner=on.
+
To disable instrumentation for specific files or directories, add a line
similar to the following to the respective kernel Makefile:
@@ -43,85 +58,85 @@
Error reports
~~~~~~~~~~~~~
-A typical out of bounds access report looks like this::
+A typical out-of-bounds access generic KASAN report looks like this::
==================================================================
- BUG: AddressSanitizer: out of bounds access in kmalloc_oob_right+0x65/0x75 [test_kasan] at addr ffff8800693bc5d3
- Write of size 1 by task modprobe/1689
- =============================================================================
- BUG kmalloc-128 (Not tainted): kasan error
- -----------------------------------------------------------------------------
+ BUG: KASAN: slab-out-of-bounds in kmalloc_oob_right+0xa8/0xbc [test_kasan]
+ Write of size 1 at addr ffff8801f44ec37b by task insmod/2760
- Disabling lock debugging due to kernel taint
- INFO: Allocated in kmalloc_oob_right+0x3d/0x75 [test_kasan] age=0 cpu=0 pid=1689
- __slab_alloc+0x4b4/0x4f0
- kmem_cache_alloc_trace+0x10b/0x190
- kmalloc_oob_right+0x3d/0x75 [test_kasan]
- init_module+0x9/0x47 [test_kasan]
- do_one_initcall+0x99/0x200
- load_module+0x2cb3/0x3b20
- SyS_finit_module+0x76/0x80
- system_call_fastpath+0x12/0x17
- INFO: Slab 0xffffea0001a4ef00 objects=17 used=7 fp=0xffff8800693bd728 flags=0x100000000004080
- INFO: Object 0xffff8800693bc558 @offset=1368 fp=0xffff8800693bc720
-
- Bytes b4 ffff8800693bc548: 00 00 00 00 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ
- Object ffff8800693bc558: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
- Object ffff8800693bc568: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
- Object ffff8800693bc578: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
- Object ffff8800693bc588: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
- Object ffff8800693bc598: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
- Object ffff8800693bc5a8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
- Object ffff8800693bc5b8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
- Object ffff8800693bc5c8: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkkkkkk.
- Redzone ffff8800693bc5d8: cc cc cc cc cc cc cc cc ........
- Padding ffff8800693bc718: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ
- CPU: 0 PID: 1689 Comm: modprobe Tainted: G B 3.18.0-rc1-mm1+ #98
- Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5-0-ge51488c-20140602_164612-nilsson.home.kraxel.org 04/01/2014
- ffff8800693bc000 0000000000000000 ffff8800693bc558 ffff88006923bb78
- ffffffff81cc68ae 00000000000000f3 ffff88006d407600 ffff88006923bba8
- ffffffff811fd848 ffff88006d407600 ffffea0001a4ef00 ffff8800693bc558
+ CPU: 1 PID: 2760 Comm: insmod Not tainted 4.19.0-rc3+ #698
+ Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
Call Trace:
- [<ffffffff81cc68ae>] dump_stack+0x46/0x58
- [<ffffffff811fd848>] print_trailer+0xf8/0x160
- [<ffffffffa00026a7>] ? kmem_cache_oob+0xc3/0xc3 [test_kasan]
- [<ffffffff811ff0f5>] object_err+0x35/0x40
- [<ffffffffa0002065>] ? kmalloc_oob_right+0x65/0x75 [test_kasan]
- [<ffffffff8120b9fa>] kasan_report_error+0x38a/0x3f0
- [<ffffffff8120a79f>] ? kasan_poison_shadow+0x2f/0x40
- [<ffffffff8120b344>] ? kasan_unpoison_shadow+0x14/0x40
- [<ffffffff8120a79f>] ? kasan_poison_shadow+0x2f/0x40
- [<ffffffffa00026a7>] ? kmem_cache_oob+0xc3/0xc3 [test_kasan]
- [<ffffffff8120a995>] __asan_store1+0x75/0xb0
- [<ffffffffa0002601>] ? kmem_cache_oob+0x1d/0xc3 [test_kasan]
- [<ffffffffa0002065>] ? kmalloc_oob_right+0x65/0x75 [test_kasan]
- [<ffffffffa0002065>] kmalloc_oob_right+0x65/0x75 [test_kasan]
- [<ffffffffa00026b0>] init_module+0x9/0x47 [test_kasan]
- [<ffffffff810002d9>] do_one_initcall+0x99/0x200
- [<ffffffff811e4e5c>] ? __vunmap+0xec/0x160
- [<ffffffff81114f63>] load_module+0x2cb3/0x3b20
- [<ffffffff8110fd70>] ? m_show+0x240/0x240
- [<ffffffff81115f06>] SyS_finit_module+0x76/0x80
- [<ffffffff81cd3129>] system_call_fastpath+0x12/0x17
+ dump_stack+0x94/0xd8
+ print_address_description+0x73/0x280
+ kasan_report+0x144/0x187
+ __asan_report_store1_noabort+0x17/0x20
+ kmalloc_oob_right+0xa8/0xbc [test_kasan]
+ kmalloc_tests_init+0x16/0x700 [test_kasan]
+ do_one_initcall+0xa5/0x3ae
+ do_init_module+0x1b6/0x547
+ load_module+0x75df/0x8070
+ __do_sys_init_module+0x1c6/0x200
+ __x64_sys_init_module+0x6e/0xb0
+ do_syscall_64+0x9f/0x2c0
+ entry_SYSCALL_64_after_hwframe+0x44/0xa9
+ RIP: 0033:0x7f96443109da
+ RSP: 002b:00007ffcf0b51b08 EFLAGS: 00000202 ORIG_RAX: 00000000000000af
+ RAX: ffffffffffffffda RBX: 000055dc3ee521a0 RCX: 00007f96443109da
+ RDX: 00007f96445cff88 RSI: 0000000000057a50 RDI: 00007f9644992000
+ RBP: 000055dc3ee510b0 R08: 0000000000000003 R09: 0000000000000000
+ R10: 00007f964430cd0a R11: 0000000000000202 R12: 00007f96445cff88
+ R13: 000055dc3ee51090 R14: 0000000000000000 R15: 0000000000000000
+
+ Allocated by task 2760:
+ save_stack+0x43/0xd0
+ kasan_kmalloc+0xa7/0xd0
+ kmem_cache_alloc_trace+0xe1/0x1b0
+ kmalloc_oob_right+0x56/0xbc [test_kasan]
+ kmalloc_tests_init+0x16/0x700 [test_kasan]
+ do_one_initcall+0xa5/0x3ae
+ do_init_module+0x1b6/0x547
+ load_module+0x75df/0x8070
+ __do_sys_init_module+0x1c6/0x200
+ __x64_sys_init_module+0x6e/0xb0
+ do_syscall_64+0x9f/0x2c0
+ entry_SYSCALL_64_after_hwframe+0x44/0xa9
+
+ Freed by task 815:
+ save_stack+0x43/0xd0
+ __kasan_slab_free+0x135/0x190
+ kasan_slab_free+0xe/0x10
+ kfree+0x93/0x1a0
+ umh_complete+0x6a/0xa0
+ call_usermodehelper_exec_async+0x4c3/0x640
+ ret_from_fork+0x35/0x40
+
+ The buggy address belongs to the object at ffff8801f44ec300
+ which belongs to the cache kmalloc-128 of size 128
+ The buggy address is located 123 bytes inside of
+ 128-byte region [ffff8801f44ec300, ffff8801f44ec380)
+ The buggy address belongs to the page:
+ page:ffffea0007d13b00 count:1 mapcount:0 mapping:ffff8801f7001640 index:0x0
+ flags: 0x200000000000100(slab)
+ raw: 0200000000000100 ffffea0007d11dc0 0000001a0000001a ffff8801f7001640
+ raw: 0000000000000000 0000000080150015 00000001ffffffff 0000000000000000
+ page dumped because: kasan: bad access detected
+
Memory state around the buggy address:
- ffff8800693bc300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
- ffff8800693bc380: fc fc 00 00 00 00 00 00 00 00 00 00 00 00 00 fc
- ffff8800693bc400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
- ffff8800693bc480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
- ffff8800693bc500: fc fc fc fc fc fc fc fc fc fc fc 00 00 00 00 00
- >ffff8800693bc580: 00 00 00 00 00 00 00 00 00 00 03 fc fc fc fc fc
- ^
- ffff8800693bc600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
- ffff8800693bc680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
- ffff8800693bc700: fc fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb
- ffff8800693bc780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
- ffff8800693bc800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
+ ffff8801f44ec200: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
+ ffff8801f44ec280: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
+ >ffff8801f44ec300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03
+ ^
+ ffff8801f44ec380: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
+ ffff8801f44ec400: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================
-The header of the report discribe what kind of bug happened and what kind of
-access caused it. It's followed by the description of the accessed slub object
-(see 'SLUB Debug output' section in Documentation/vm/slub.rst for details) and
-the description of the accessed memory page.
+The header of the report provides a short summary of what kind of bug happened
+and what kind of access caused it. It's followed by a stack trace of the bad
+access, a stack trace of where the accessed memory was allocated (in case bad
+access happens on a slab object), and a stack trace of where the object was
+freed (in case of a use-after-free bug report). Next comes a description of
+the accessed slab object and information about the accessed memory page.
In the last section the report shows memory state around the accessed address.
Reading this part requires some understanding of how KASAN works.
@@ -138,18 +153,24 @@
In the report above the arrows point to the shadow byte 03, which means that
the accessed address is partially accessible.
+For tag-based KASAN this last report section shows the memory tags around the
+accessed address (see Implementation details section).
+
Implementation details
----------------------
+Generic KASAN
+~~~~~~~~~~~~~
+
From a high level, our approach to memory error detection is similar to that
of kmemcheck: use shadow memory to record whether each byte of memory is safe
-to access, and use compile-time instrumentation to check shadow memory on each
-memory access.
+to access, and use compile-time instrumentation to insert checks of shadow
+memory on each memory access.
-AddressSanitizer dedicates 1/8 of kernel memory to its shadow memory
-(e.g. 16TB to cover 128TB on x86_64) and uses direct mapping with a scale and
-offset to translate a memory address to its corresponding shadow address.
+Generic KASAN dedicates 1/8th of kernel memory to its shadow memory (e.g. 16TB
+to cover 128TB on x86_64) and uses direct mapping with a scale and offset to
+translate a memory address to its corresponding shadow address.
Here is the function which translates an address to its corresponding shadow
address::
@@ -162,12 +183,38 @@
where ``KASAN_SHADOW_SCALE_SHIFT = 3``.
-Compile-time instrumentation used for checking memory accesses. Compiler inserts
-function calls (__asan_load*(addr), __asan_store*(addr)) before each memory
-access of size 1, 2, 4, 8 or 16. These functions check whether memory access is
-valid or not by checking corresponding shadow memory.
+Compile-time instrumentation is used to insert memory access checks. Compiler
+inserts function calls (__asan_load*(addr), __asan_store*(addr)) before each
+memory access of size 1, 2, 4, 8 or 16. These functions check whether memory
+access is valid or not by checking corresponding shadow memory.
GCC 5.0 has possibility to perform inline instrumentation. Instead of making
function calls GCC directly inserts the code to check the shadow memory.
This option significantly enlarges kernel but it gives x1.1-x2 performance
boost over outline instrumented kernel.
+
+Software tag-based KASAN
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Tag-based KASAN uses the Top Byte Ignore (TBI) feature of modern arm64 CPUs to
+store a pointer tag in the top byte of kernel pointers. Like generic KASAN it
+uses shadow memory to store memory tags associated with each 16-byte memory
+cell (therefore it dedicates 1/16th of the kernel memory for shadow memory).
+
+On each memory allocation tag-based KASAN generates a random tag, tags the
+allocated memory with this tag, and embeds this tag into the returned pointer.
+Software tag-based KASAN uses compile-time instrumentation to insert checks
+before each memory access. These checks make sure that tag of the memory that
+is being accessed is equal to tag of the pointer that is used to access this
+memory. In case of a tag mismatch tag-based KASAN prints a bug report.
+
+Software tag-based KASAN also has two instrumentation modes (outline, that
+emits callbacks to check memory accesses; and inline, that performs the shadow
+memory checks inline). With outline instrumentation mode, a bug report is
+simply printed from the function that performs the access check. With inline
+instrumentation a brk instruction is emitted by the compiler, and a dedicated
+brk handler is used to print bug reports.
+
+A potential expansion of this mode is a hardware tag-based mode, which would
+use hardware memory tagging support instead of compiler instrumentation and
+manual shadow memory manipulation.
diff --git a/Documentation/dev-tools/kcov.rst b/Documentation/dev-tools/kcov.rst
index c2f6452..42b6126 100644
--- a/Documentation/dev-tools/kcov.rst
+++ b/Documentation/dev-tools/kcov.rst
@@ -22,7 +22,7 @@
CONFIG_KCOV=y
-CONFIG_KCOV requires gcc built on revision 231296 or later.
+CONFIG_KCOV requires gcc 6.1.0 or later.
If the comparison operands need to be collected, set::
diff --git a/Documentation/dev-tools/kmemleak.rst b/Documentation/dev-tools/kmemleak.rst
index e6f5126..3621cd5 100644
--- a/Documentation/dev-tools/kmemleak.rst
+++ b/Documentation/dev-tools/kmemleak.rst
@@ -2,8 +2,8 @@
===========================
Kmemleak provides a way of detecting possible kernel memory leaks in a
-way similar to a tracing garbage collector
-(https://en.wikipedia.org/wiki/Garbage_collection_%28computer_science%29#Tracing_garbage_collectors),
+way similar to a `tracing garbage collector
+<https://en.wikipedia.org/wiki/Tracing_garbage_collection>`_,
with the difference that the orphan objects are not freed but only
reported via /sys/kernel/debug/kmemleak. A similar method is used by the
Valgrind tool (``memcheck --leak-check``) to detect the memory leaks in
@@ -15,10 +15,13 @@
CONFIG_DEBUG_KMEMLEAK in "Kernel hacking" has to be enabled. A kernel
thread scans the memory every 10 minutes (by default) and prints the
-number of new unreferenced objects found. To display the details of all
-the possible memory leaks::
+number of new unreferenced objects found. If the ``debugfs`` isn't already
+mounted, mount with::
# mount -t debugfs nodev /sys/kernel/debug/
+
+To display the details of all the possible scanned memory leaks::
+
# cat /sys/kernel/debug/kmemleak
To trigger an intermediate memory scan::
@@ -72,6 +75,9 @@
disabled by default. Passing ``kmemleak=on`` on the kernel command
line enables the function.
+If you are getting errors like "Error while writing to stdout" or "write_loop:
+Invalid argument", make sure kmemleak is properly enabled.
+
Basic Algorithm
---------------
@@ -218,3 +224,37 @@
macro or the pointer is stored in a location not scanned by kmemleak.
Page allocations and ioremap are not tracked.
+
+Testing with kmemleak-test
+--------------------------
+
+To check if you have all set up to use kmemleak, you can use the kmemleak-test
+module, a module that deliberately leaks memory. Set CONFIG_DEBUG_KMEMLEAK_TEST
+as module (it can't be used as bult-in) and boot the kernel with kmemleak
+enabled. Load the module and perform a scan with::
+
+ # modprobe kmemleak-test
+ # echo scan > /sys/kernel/debug/kmemleak
+
+Note that the you may not get results instantly or on the first scanning. When
+kmemleak gets results, it'll log ``kmemleak: <count of leaks> new suspected
+memory leaks``. Then read the file to see then::
+
+ # cat /sys/kernel/debug/kmemleak
+ unreferenced object 0xffff89862ca702e8 (size 32):
+ comm "modprobe", pid 2088, jiffies 4294680594 (age 375.486s)
+ hex dump (first 32 bytes):
+ 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
+ 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkkkkkk.
+ backtrace:
+ [<00000000e0a73ec7>] 0xffffffffc01d2036
+ [<000000000c5d2a46>] do_one_initcall+0x41/0x1df
+ [<0000000046db7e0a>] do_init_module+0x55/0x200
+ [<00000000542b9814>] load_module+0x203c/0x2480
+ [<00000000c2850256>] __do_sys_finit_module+0xba/0xe0
+ [<000000006564e7ef>] do_syscall_64+0x43/0x110
+ [<000000007c873fa6>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
+ ...
+
+Removing the module with ``rmmod kmemleak_test`` should also trigger some
+kmemleak results.
diff --git a/Documentation/dev-tools/kselftest.rst b/Documentation/dev-tools/kselftest.rst
index 6f653ac..ecdfdc9 100644
--- a/Documentation/dev-tools/kselftest.rst
+++ b/Documentation/dev-tools/kselftest.rst
@@ -7,13 +7,22 @@
paths in the kernel. Tests are intended to be run after building, installing
and booting a kernel.
+You can find additional information on Kselftest framework, how to
+write new tests using the framework on Kselftest wiki:
+
+https://kselftest.wiki.kernel.org/
+
On some systems, hot-plug tests could hang forever waiting for cpu and
memory to be ready to be offlined. A special hot-plug target is created
-to run full range of hot-plug tests. In default mode, hot-plug tests run
+to run the full range of hot-plug tests. In default mode, hot-plug tests run
in safe mode with a limited scope. In limited mode, cpu-hotplug test is
run on a single cpu as opposed to all hotplug capable cpus, and memory
hotplug test is run on 2% of hotplug capable memory instead of 10%.
+kselftest runs as a userspace process. Tests that can be written/run in
+userspace may wish to use the `Test Harness`_. Tests that need to be
+run in kernel space may wish to use a `Test Module`_.
+
Running the selftests (hotplug tests are run in limited mode)
=============================================================
@@ -31,17 +40,32 @@
Note that some tests will require root privileges.
-Build and run from user specific object directory (make O=dir)::
+Kselftest supports saving output files in a separate directory and then
+running tests. To locate output files in a separate directory two syntaxes
+are supported. In both cases the working directory must be the root of the
+kernel src. This is applicable to "Running a subset of selftests" section
+below.
+
+To build, save output files in a separate directory with O= ::
$ make O=/tmp/kselftest kselftest
-Build and run KBUILD_OUTPUT directory (make KBUILD_OUTPUT=)::
+To build, save output files in a separate directory with KBUILD_OUTPUT ::
- $ make KBUILD_OUTPUT=/tmp/kselftest kselftest
+ $ export KBUILD_OUTPUT=/tmp/kselftest; make kselftest
-The above commands run the tests and print pass/fail summary to make it
-easier to understand the test results. Please find the detailed individual
-test results for each test in /tmp/testname file(s).
+The O= assignment takes precedence over the KBUILD_OUTPUT environment
+variable.
+
+The above commands by default run the tests and print full pass/fail report.
+Kselftest supports "summary" option to make it easier to understand the test
+results. Please find the detailed individual test results for each test in
+/tmp/testname file(s) when summary option is specified. This is applicable
+to "Running a subset of selftests" section below.
+
+To run kselftest with summary option enabled ::
+
+ $ make summary=1 kselftest
Running a subset of selftests
=============================
@@ -57,17 +81,29 @@
$ make TARGETS="size timers" kselftest
-Build and run from user specific object directory (make O=dir)::
+To build, save output files in a separate directory with O= ::
$ make O=/tmp/kselftest TARGETS="size timers" kselftest
-Build and run KBUILD_OUTPUT directory (make KBUILD_OUTPUT=)::
+To build, save output files in a separate directory with KBUILD_OUTPUT ::
- $ make KBUILD_OUTPUT=/tmp/kselftest TARGETS="size timers" kselftest
+ $ export KBUILD_OUTPUT=/tmp/kselftest; make TARGETS="size timers" kselftest
-The above commands run the tests and print pass/fail summary to make it
-easier to understand the test results. Please find the detailed individual
-test results for each test in /tmp/testname file(s).
+Additionally you can use the "SKIP_TARGETS" variable on the make command
+line to specify one or more targets to exclude from the TARGETS list.
+
+To run all tests but a single subsystem::
+
+ $ make -C tools/testing/selftests SKIP_TARGETS=ptrace run_tests
+
+You can specify multiple tests to skip::
+
+ $ make SKIP_TARGETS="size timers" kselftest
+
+You can also specify a restricted list of tests to run together with a
+dedicated skiplist::
+
+ $ make TARGETS="bpf breakpoints size timers" SKIP_TARGETS=bpf kselftest
See the top-level tools/testing/selftests/Makefile for the list of all
possible targets.
@@ -89,9 +125,9 @@
Install selftests
=================
-You can use kselftest_install.sh tool installs selftests in default
-location which is tools/testing/selftests/kselftest or a user specified
-location.
+You can use the kselftest_install.sh tool to install selftests in the
+default location, which is tools/testing/selftests/kselftest, or in a
+user specified location.
To install selftests in default location::
@@ -109,7 +145,7 @@
Kselftest install as well as the Kselftest tarball provide a script
named "run_kselftest.sh" to run the tests.
-You can simply do the following to run the installed Kselftests. Please
+You can simply do the following to run the installed Kselftests. Please
note some tests will require root privileges::
$ cd kselftest
@@ -139,7 +175,7 @@
default.
TEST_CUSTOM_PROGS should be used by tests that require custom build
- rule and prevent common build rule use.
+ rules and prevent common build rule use.
TEST_PROGS are for test shell scripts. Please ensure shell script has
its exec bit set. Otherwise, lib.mk run_tests will generate a warning.
@@ -159,13 +195,99 @@
* If a test needs specific kernel config options enabled, add a config file in
the test directory to enable them.
- e.g: tools/testing/selftests/android/ion/config
+ e.g: tools/testing/selftests/android/config
+
+Test Module
+===========
+
+Kselftest tests the kernel from userspace. Sometimes things need
+testing from within the kernel, one method of doing this is to create a
+test module. We can tie the module into the kselftest framework by
+using a shell script test runner. ``kselftest_module.sh`` is designed
+to facilitate this process. There is also a header file provided to
+assist writing kernel modules that are for use with kselftest:
+
+- ``tools/testing/kselftest/kselftest_module.h``
+- ``tools/testing/kselftest/kselftest_module.sh``
+
+How to use
+----------
+
+Here we show the typical steps to create a test module and tie it into
+kselftest. We use kselftests for lib/ as an example.
+
+1. Create the test module
+
+2. Create the test script that will run (load/unload) the module
+ e.g. ``tools/testing/selftests/lib/printf.sh``
+
+3. Add line to config file e.g. ``tools/testing/selftests/lib/config``
+
+4. Add test script to makefile e.g. ``tools/testing/selftests/lib/Makefile``
+
+5. Verify it works:
+
+.. code-block:: sh
+
+ # Assumes you have booted a fresh build of this kernel tree
+ cd /path/to/linux/tree
+ make kselftest-merge
+ make modules
+ sudo make modules_install
+ make TARGETS=lib kselftest
+
+Example Module
+--------------
+
+A bare bones test module might look like this:
+
+.. code-block:: c
+
+ // SPDX-License-Identifier: GPL-2.0+
+
+ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+ #include "../tools/testing/selftests/kselftest_module.h"
+
+ KSTM_MODULE_GLOBALS();
+
+ /*
+ * Kernel module for testing the foobinator
+ */
+
+ static int __init test_function()
+ {
+ ...
+ }
+
+ static void __init selftest(void)
+ {
+ KSTM_CHECK_ZERO(do_test_case("", 0));
+ }
+
+ KSTM_MODULE_LOADERS(test_foo);
+ MODULE_AUTHOR("John Developer <jd@fooman.org>");
+ MODULE_LICENSE("GPL");
+
+Example test script
+-------------------
+
+.. code-block:: sh
+
+ #!/bin/bash
+ # SPDX-License-Identifier: GPL-2.0+
+ $(dirname $0)/../kselftest_module.sh "foo" test_foo
+
Test Harness
============
-The kselftest_harness.h file contains useful helpers to build tests. The tests
-from tools/testing/selftests/seccomp/seccomp_bpf.c can be used as example.
+The kselftest_harness.h file contains useful helpers to build tests. The
+test harness is for userspace testing, for kernel space testing see `Test
+Module`_ above.
+
+The tests from tools/testing/selftests/seccomp/seccomp_bpf.c can be used as
+example.
Example
-------
diff --git a/Documentation/dev-tools/sparse.rst b/Documentation/dev-tools/sparse.rst
index c401c95..6f48705 100644
--- a/Documentation/dev-tools/sparse.rst
+++ b/Documentation/dev-tools/sparse.rst
@@ -81,11 +81,6 @@
git://git.kernel.org/pub/scm/devel/sparse/sparse.git
-DaveJ has hourly generated tarballs of the git tree available at::
-
- http://www.codemonkey.org.uk/projects/git-snapshots/sparse/
-
-
Once you have it, just do::
make