12 Nov, 2021
1 commit
-
commit 4f612ed3f748962cbef1316ff3d323e2b9055b6e upstream.
We have observed that on very large machines with newer CPUs, the static
key/branch switching delay is on the order of milliseconds. This is due
to the required broadcast IPIs, which simply does not scale well to
hundreds of CPUs (cores). If done too frequently, this can adversely
affect tail latencies of various workloads.One workaround is to increase the sample interval to several seconds,
while decreasing sampled allocation coverage, but the problem still
exists and could still increase tail latencies.As already noted in the Kconfig help text, there are trade-offs: at
lower sample intervals the dynamic branch results in better performance;
however, at very large sample intervals, the static keys mode can result
in better performance -- careful benchmarking is recommended.Our initial benchmarking showed that with large enough sample intervals
and workloads stressing the allocator, the static keys mode was slightly
better. Evaluating and observing the possible system-wide side-effects
of the static-key-switching induced broadcast IPIs, however, was a blind
spot (in particular on large machines with 100s of cores).Therefore, a major downside of the static keys mode is, unfortunately,
that it is hard to predict performance on new system architectures and
topologies, but also making conclusions about performance of new
workloads based on a limited set of benchmarks.Most distributions will simply select the defaults, while targeting a
large variety of different workloads and system architectures. As such,
the better default is CONFIG_KFENCE_STATIC_KEYS=n, and re-enabling it is
only recommended after careful evaluation.For reference, on x86-64 the condition in kfence_alloc() generates
exactly
2 instructions in the kmem_cache_alloc() fast-path:| ...
| cmpl $0x0,0x1a8021c(%rip) # ffffffff82d560d0
| je ffffffff812d6003
| ...which, given kfence_allocation_gate is infrequently modified, should be
well predicted by most CPUs.Link: https://lkml.kernel.org/r/20211019102524.2807208-2-elver@google.com
Signed-off-by: Marco Elver
Cc: Alexander Potapenko
Cc: Dmitry Vyukov
Cc: Jann Horn
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
Signed-off-by: Greg Kroah-Hartman
09 Sep, 2021
2 commits
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Merge more updates from Andrew Morton:
"147 patches, based on 7d2a07b769330c34b4deabeed939325c77a7ec2f.Subsystems affected by this patch series: mm (memory-hotplug, rmap,
ioremap, highmem, cleanups, secretmem, kfence, damon, and vmscan),
alpha, percpu, procfs, misc, core-kernel, MAINTAINERS, lib,
checkpatch, epoll, init, nilfs2, coredump, fork, pids, criu, kconfig,
selftests, ipc, and scripts"* emailed patches from Andrew Morton : (94 commits)
scripts: check_extable: fix typo in user error message
mm/workingset: correct kernel-doc notations
ipc: replace costly bailout check in sysvipc_find_ipc()
selftests/memfd: remove unused variable
Kconfig.debug: drop selecting non-existing HARDLOCKUP_DETECTOR_ARCH
configs: remove the obsolete CONFIG_INPUT_POLLDEV
prctl: allow to setup brk for et_dyn executables
pid: cleanup the stale comment mentioning pidmap_init().
kernel/fork.c: unexport get_{mm,task}_exe_file
coredump: fix memleak in dump_vma_snapshot()
fs/coredump.c: log if a core dump is aborted due to changed file permissions
nilfs2: use refcount_dec_and_lock() to fix potential UAF
nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group
nilfs2: fix memory leak in nilfs_sysfs_create_snapshot_group
nilfs2: fix memory leak in nilfs_sysfs_delete_##name##_group
nilfs2: fix memory leak in nilfs_sysfs_create_##name##_group
nilfs2: fix NULL pointer in nilfs_##name##_attr_release
nilfs2: fix memory leak in nilfs_sysfs_create_device_group
trap: cleanup trap_init()
init: move usermodehelper_enable() to populate_rootfs()
... -
Record cpu and timestamp on allocations and frees, and show them in
reports. Upon an error, this can help correlate earlier messages in the
kernel log via allocation and free timestamps.Link: https://lkml.kernel.org/r/20210714175312.2947941-1-elver@google.com
Suggested-by: Joern Engel
Signed-off-by: Marco Elver
Acked-by: Alexander Potapenko
Acked-by: Joern Engel
Cc: Yuanyuan Zhong
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
04 Sep, 2021
2 commits
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Merge misc updates from Andrew Morton:
"173 patches.Subsystems affected by this series: ia64, ocfs2, block, and mm (debug,
pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap,
bootmem, sparsemem, vmalloc, kasan, pagealloc, memory-failure,
hugetlb, userfaultfd, vmscan, compaction, mempolicy, memblock,
oom-kill, migration, ksm, percpu, vmstat, and madvise)"* emailed patches from Andrew Morton : (173 commits)
mm/madvise: add MADV_WILLNEED to process_madvise()
mm/vmstat: remove unneeded return value
mm/vmstat: simplify the array size calculation
mm/vmstat: correct some wrong comments
mm/percpu,c: remove obsolete comments of pcpu_chunk_populated()
selftests: vm: add COW time test for KSM pages
selftests: vm: add KSM merging time test
mm: KSM: fix data type
selftests: vm: add KSM merging across nodes test
selftests: vm: add KSM zero page merging test
selftests: vm: add KSM unmerge test
selftests: vm: add KSM merge test
mm/migrate: correct kernel-doc notation
mm: wire up syscall process_mrelease
mm: introduce process_mrelease system call
memblock: make memblock_find_in_range method private
mm/mempolicy.c: use in_task() in mempolicy_slab_node()
mm/mempolicy: unify the create() func for bind/interleave/prefer-many policies
mm/mempolicy: advertise new MPOL_PREFERRED_MANY
mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY
... -
Move the boot parameter 'kasan.fault' from hw_tags.c to report.c, so it
can support all KASAN modes - generic, and both tag-based.Link: https://lkml.kernel.org/r/20210713010536.3161822-1-woodylin@google.com
Signed-off-by: Woody Lin
Reviewed-by: Marco Elver
Reviewed-by: Andrey Konovalov
Cc: Andrey Ryabinin
Cc: Dmitry Vyukov
Cc: Alexander Potapenko
Cc: Jonathan Corbet
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
03 Sep, 2021
1 commit
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Pull memory model updates from Ingo Molnar:
"LKMM updates:- Update documentation and code example
KCSAN updates:
- Introduce CONFIG_KCSAN_STRICT (which RCU uses)
- Optimize use of get_ctx() by kcsan_found_watchpoint()
- Rework atomic.h into permissive.h
- Add the ability to ignore writes that change only one bit of a
given data-racy variable.- Improve comments"
* tag 'locking-debug-2021-09-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
tools/memory-model: Document data_race(READ_ONCE())
tools/memory-model: Heuristics using data_race() must handle all values
tools/memory-model: Add example for heuristic lockless reads
tools/memory-model: Make read_foo_diagnostic() more clearly diagnostic
kcsan: Make strict mode imply interruptible watchers
kcsan: permissive: Ignore data-racy 1-bit value changes
kcsan: Print if strict or non-strict during init
kcsan: Rework atomic.h into permissive.h
kcsan: Reduce get_ctx() uses in kcsan_found_watchpoint()
kcsan: Introduce CONFIG_KCSAN_STRICT
kcsan: Remove CONFIG_KCSAN_DEBUG
kcsan: Improve some Kconfig comments
14 Aug, 2021
2 commits
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--raw_output is nice, but it would be nicer if could show only output
after KUnit tests have started.So change the flag to allow specifying a string ('kunit').
Make it so `--raw_output` alone will default to `--raw_output=all` and
have the same original behavior.Drop the small kunit_parser.raw_output() function since it feels wrong
to put it in "kunit_parser.py" when the point of it is to not parse
anything.E.g.
$ ./tools/testing/kunit/kunit.py run --raw_output=kunit
...
[15:24:07] Starting KUnit Kernel ...
TAP version 14
1..1
# Subtest: example
1..3
# example_simple_test: initializing
ok 1 - example_simple_test
# example_skip_test: initializing
# example_skip_test: You should not see a line below.
ok 2 - example_skip_test # SKIP this test should be skipped
# example_mark_skipped_test: initializing
# example_mark_skipped_test: You should see a line below.
# example_mark_skipped_test: You should see this line.
ok 3 - example_mark_skipped_test # SKIP this test should be skipped
ok 1 - example
[15:24:10] Elapsed time: 6.487s total, 0.001s configuring, 3.510s building, 0.000s runningSigned-off-by: Daniel Latypov
Reviewed-by: David Gow
Signed-off-by: Shuah Khan -
kunit.py currently does not make it possible for users to specify module
parameters (/kernel arguments more generally) unless one directly tweaks
the kunit.py code itself.This hasn't mattered much so far, but this would make it easier to port
existing tests that expose module parameters over to KUnit and/or let
current KUnit tests take advantage of them.Tested using an kunit internal parameter:
$ ./tools/testing/kunit/kunit.py run --kunitconfig=lib/kunit \
--kernel_args=kunit.filter_glob=kunit_status
...
Testing complete. 2 tests run. 0 failed. 0 crashed. 0 skipped.Signed-off-by: Daniel Latypov
Reviewed-by: David Gow
Reviewed-by: Brendan Higgins
Signed-off-by: Shuah Khan
21 Jul, 2021
2 commits
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Rework atomic.h into permissive.h to better reflect its purpose, and
introduce kcsan_ignore_address() and kcsan_ignore_data_race().Introduce CONFIG_KCSAN_PERMISSIVE and update the stub functions in
preparation for subsequent changes.As before, developers who choose to use KCSAN in "strict" mode will see
all data races and are not affected. Furthermore, by relying on the
value-change filter logic for kcsan_ignore_data_race(), even if the
permissive rules are enabled, the opt-outs in report.c:skip_report()
override them (such as for RCU-related functions by default).The option CONFIG_KCSAN_PERMISSIVE is disabled by default, so that the
documented default behaviour of KCSAN does not change. Instead, like
CONFIG_KCSAN_IGNORE_ATOMICS, the option needs to be explicitly opted in.Signed-off-by: Marco Elver
Acked-by: Mark Rutland
Signed-off-by: Paul E. McKenney -
Add a simpler Kconfig variable to configure KCSAN's "strict" mode. This
makes it simpler in documentation or messages to suggest just a single
configuration option to select the strictest checking mode (vs.
currently having to list several options).Signed-off-by: Marco Elver
Acked-by: Mark Rutland
Signed-off-by: Paul E. McKenney
13 Jul, 2021
1 commit
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Commit b6d5799b0b58 ("kunit: Add 'kunit_shutdown' option") changes KUnit
to call kernel_halt() by default when done testing.This fixes the issue with not having .gcda files due to not calling
atexit() handlers, and therefore we can stop recommending people
manually tweak UML code.The need to use older versions of GCC (
Reviewed-by: David Gow
Reviewed-by: Brendan Higgins
Signed-off-by: Shuah Khan
05 Jul, 2021
1 commit
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Pull KCSAN updates from Paul McKenney.
* 'kcsan.2021.05.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
kcsan: Use URL link for pointing access-marking.txt
kcsan: Document "value changed" line
kcsan: Report observed value changes
kcsan: Remove kcsan_report_type
kcsan: Remove reporting indirection
kcsan: Refactor access_info initialization
kcsan: Fold panic() call into print_report()
kcsan: Refactor passing watchpoint/other_info
kcsan: Distinguish kcsan_report() calls
kcsan: Simplify value change detection
kcsan: Add pointer to access-marking.txt to data_race() bullet
03 Jul, 2021
1 commit
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…/linux/kernel/git/shuah/linux-kselftest
Pull KUnit update from Shuah Khan:
"Fixes and features:- add support for skipped tests
- introduce kunit_kmalloc_array/kunit_kcalloc() helpers
- add gnu_printf specifiers
- add kunit_shutdown
- add unit test for filtering suites by names
- convert lib/test_list_sort.c to use KUnit
- code organization moving default config to tools/testing/kunit
- refactor of internal parser input handling
- cleanups and updates to documentation
- code cleanup related to casts"
* tag 'linux-kselftest-kunit-fixes-5.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (29 commits)
kunit: add unit test for filtering suites by names
kasan: test: make use of kunit_skip()
kunit: test: Add example tests which are always skipped
kunit: tool: Support skipped tests in kunit_tool
kunit: Support skipped tests
thunderbolt: test: Reinstate a few casts of bitfields
kunit: tool: internal refactor of parser input handling
lib/test: convert lib/test_list_sort.c to use KUnit
kunit: introduce kunit_kmalloc_array/kunit_kcalloc() helpers
kunit: Remove the unused all_tests.config
kunit: Move default config from arch/um -> tools/testing/kunit
kunit: arch/um/configs: Enable KUNIT_ALL_TESTS by default
kunit: Add gnu_printf specifiers
lib/cmdline_kunit: Remove a cast which are no-longer required
kernel/sysctl-test: Remove some casts which are no-longer required
thunderbolt: test: Remove some casts which are no longer required
mmc: sdhci-of-aspeed: Remove some unnecessary casts from KUnit tests
iio: Remove a cast in iio-test-format which is no longer required
device property: Remove some casts in property-entry-test
Documentation: kunit: Clean up some string casts in examples
...
30 Jun, 2021
2 commits
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Merge misc updates from Andrew Morton:
"191 patches.Subsystems affected by this patch series: kthread, ia64, scripts,
ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab,
slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap,
mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization,
pagealloc, and memory-failure)"* emailed patches from Andrew Morton : (191 commits)
mm,hwpoison: make get_hwpoison_page() call get_any_page()
mm,hwpoison: send SIGBUS with error virutal address
mm/page_alloc: split pcp->high across all online CPUs for cpuless nodes
mm/page_alloc: allow high-order pages to be stored on the per-cpu lists
mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA
docs: remove description of DISCONTIGMEM
arch, mm: remove stale mentions of DISCONIGMEM
mm: remove CONFIG_DISCONTIGMEM
m68k: remove support for DISCONTIGMEM
arc: remove support for DISCONTIGMEM
arc: update comment about HIGHMEM implementation
alpha: remove DISCONTIGMEM and NUMA
mm/page_alloc: move free_the_page
mm/page_alloc: fix counting of managed_pages
mm/page_alloc: improve memmap_pages dbg msg
mm: drop SECTION_SHIFT in code comments
mm/page_alloc: introduce vm.percpu_pagelist_high_fraction
mm/page_alloc: limit the number of pages on PCP lists when reclaim is active
mm/page_alloc: scale the number of pages that are batch freed
... -
The KUNIT_EXPECT_KASAN_FAIL() macro currently uses KUNIT_EXPECT_EQ() to
compare fail_data.report_expected and fail_data.report_found. This always
gave a somewhat useless error message on failure, but the addition of
extra compile-time checking with READ_ONCE() has caused it to get much
longer, and be truncated before anything useful is displayed.Instead, just check fail_data.report_found by hand (we've just set
report_expected to 'true'), and print a better failure message with
KUNIT_FAIL(). Because of this, report_expected is no longer used
anywhere, and can be removed.Beforehand, a failure in:
KUNIT_EXPECT_KASAN_FAIL(test, ((volatile char *)area)[3100]);
would have looked like:
[22:00:34] [FAILED] vmalloc_oob
[22:00:34] # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:991
[22:00:34] Expected ({ do { extern void __compiletime_assert_705(void) __attribute__((__error__("Unsupported access size for {READ,WRITE}_ONCE()."))); if (!((sizeof(fail_data.report_expected) == sizeof(char) || sizeof(fail_data.repp
[22:00:34] not ok 45 - vmalloc_oobWith this change, it instead looks like:
[22:04:04] [FAILED] vmalloc_oob
[22:04:04] # vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:993
[22:04:04] KASAN failure expected in "((volatile char *)area)[3100]", but none occurred
[22:04:04] not ok 45 - vmalloc_oobAlso update the example failure in the documentation to reflect this.
Link: https://lkml.kernel.org/r/20210606005531.165954-1-davidgow@google.com
Signed-off-by: David Gow
Reviewed-by: Andrey Konovalov
Reviewed-by: Marco Elver
Acked-by: Brendan Higgins
Cc: Andrey Ryabinin
Cc: Dmitry Vyukov
Cc: Daniel Axtens
Cc: David Gow
Cc: Jonathan Corbet
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
24 Jun, 2021
3 commits
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The default .kunitconfig file is currently kept in
arch/um/configs/kunit_defconfig, but -- with the impending QEMU patch
-- will no-longer be exclusively used for UML-based kernels.Move it alongside the other KUnit configs in
tools/testing/kunit/configs, and give it a name which matches the
existing all_tests.config and broken_on_uml.config files.Also update the Getting Started documentation to point to the new file.
Signed-off-by: David Gow
Reviewed-by: Brendan Higgins
Signed-off-by: Shuah Khan -
As the type checking is no longer excessively strict, get rid of the
unsightly (char*) casts -- and comment discussing them -- from the KUnit
usage page.Signed-off-by: David Gow
Reviewed-by: Daniel Latypov
Acked-by: Brendan Higgins
Signed-off-by: Shuah Khan -
We'll be replacing :doc:`foo` references to
Documentation/foo.rst. Yet, here it happens inside a table.
Doing a search-and-replace would break it.Yet, as there's no good reason to use a table there,
let's just convert it into a list.Reviewed-by: David Gow
Acked-by: Brendan Higgins
Signed-off-by: Mauro Carvalho Chehab
Signed-off-by: Shuah Khan
18 Jun, 2021
3 commits
-
The :doc:`foo` tag is auto-generated via automarkup.py.
So, use the filename at the sources, instead of :doc:`foo`.Reviewed-by: David Gow
Acked-by: Brendan Higgins
Signed-off-by: Mauro Carvalho Chehab
Link: https://lore.kernel.org/r/6fde409079959a95b62b9b2692503608d7ff0dbd.1623824363.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet -
The :doc:`foo` tag is auto-generated via automarkup.py.
So, use the filename at the sources, instead of :doc:`foo`.Signed-off-by: Mauro Carvalho Chehab
Link: https://lore.kernel.org/r/6bbecd4170ee08f36f8060b0719a46c64a21aefc.1623824363.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet -
We'll be replacing :doc:`foo` references to
Documentation/foo.rst. Yet, here it happens inside a table.
Doing a search-and-replace would break it.Yet, as there's no good reason to use a table there,
let's just convert it into a list.Reviewed-by: David Gow
Acked-by: Brendan Higgins
Signed-off-by: Mauro Carvalho Chehab
Link: https://lore.kernel.org/r/07d3a8ccafbb6345d6e78fb090290859e84361a1.1623824363.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet
15 Jun, 2021
1 commit
-
Add and document more checkpatch message types. About 50% of all
message types are documented now.In addition to this:
- Create a new subsection 'Indentation and Line Breaks'.
- Rename subsection 'Comment style' to simply 'Comments'.
- Refactor some of the existing types to appropriate subsections.Reviewed-by: Lukas Bulwahn
Tested-by: Lukas Bulwahn
Signed-off-by: Dwaipayan Ray
Link: https://lore.kernel.org/r/20210614141132.6881-1-dwaipayanray1@gmail.com
Signed-off-by: Jonathan Corbet
12 Jun, 2021
1 commit
-
Document QEMU support, what it does, and how to use it in kunit_tool.
Signed-off-by: Brendan Higgins
Reviewed-by: David Gow
Signed-off-by: Shuah Khan
22 May, 2021
2 commits
-
The kunit_tool documentation page was pretty minimal, and a bit
outdated. Update it and flesh it out a bit.In particular,
- Mention that .kunitconfig is now in the build directory
- Describe the use of --kunitconfig to specify a different config
framgent
- Mention the split functionality (i.e., commands other than 'run')
- Describe --raw_output and kunit.py parse
- Mention the globbing support
- Provide a quick overview of other options, including --build_dir and
--alltestsNote that this does overlap a little with the new running_tips page. I
don't think it's a problem having both: this page is supposed to be a
bit more of a reference, rather than a list of useful tips, so the fact
that they both describe the same features isn't a problem.Signed-off-by: David Gow
Reviewed-by: Daniel Latypov
Signed-off-by: Shuah Khan -
This is long overdue.
There are several things that aren't nailed down (in-tree
.kunitconfig's), or partially broken (GCOV on UML), but having them
documented, warts and all, is better than having nothing.This covers a bunch of the more recent features
* kunit_filter_glob
* kunit.py run --kunitconfig
* slightly more detail on building tests as modules
* CONFIG_KUNIT_DEBUGFSBy my count, the only headline features now not mentioned are the KASAN
integration and KernelCI json output support (kunit.py run --json).And then it also discusses how to get code coverage reports under UML
and non-UML since this is a question people have repeatedly asked.Non-UML coverage collection is no different from normal, but we should
probably explicitly call this out.As for UML, I was able to get it working again with two small hacks.*
E.g. with CONFIG_KUNIT=y && CONFIG_KUNIT_ALL_TESTS=y
Overall coverage rate:
lines......: 15.1% (18294 of 120776 lines)
functions..: 16.8% (1860 of 11050 functions)Note: this doesn't document --alltests since this is not stable yet.
Hopefully being run more frequently as part of KernelCI will help...*Using gcc/gcov-6 and not using uml_abort() in os_dump_core().
I've documented these hacks in "Notes" but left TODOs for
brendanhiggins@google.com who tracked down the runtime issue in GCC.
To be clear: these are not issues specific to KUnit, but rather to UML.Signed-off-by: Daniel Latypov
Reviewed-by: David Gow
Reviewed-by: Brendan Higgins
Signed-off-by: Shuah Khan
21 May, 2021
2 commits
-
While include/linux/bitops.h brings in the BIT() macro, it was moved to
include/linux/bits.h in commit 8bd9cb51daac ("locking/atomics, asm-generic:
Move some macros from to a new file").Since that commit BIT() has moved again into include/vdso/bits.h via
commit 3945ff37d2f4 ("linux/bits.h: Extract common header for vDSO").I think the move to the vDSO header can be considered an implementation
detail, so for now update the checkpatch documentation to recommend use
of include/linux/bits.h.Signed-off-by: Andrew Jeffery
Acked-by: Jiri Slaby
Acked-by: Lukas Bulwahn
Acked-by: Dwaipayan Ray
Cc: Jiri Slaby
Link: https://lore.kernel.org/r/20210520093949.511471-1-andrew@aj.id.au
Signed-off-by: Jonathan Corbet -
- Document a couple of more checkpatch message types.
- Add a blank line before all `See:` lines to improve the
rst output.
- Create a new subsection `Permissions` and move a few types
to it.Signed-off-by: Dwaipayan Ray
Acked-by: Lukas Bulwahn
Link: https://lore.kernel.org/r/20210515132348.19082-1-dwaipayanray1@gmail.com
Signed-off-by: Jonathan Corbet
19 May, 2021
3 commits
-
For consistency within kcsan.rst, use a URL link as the same as in
section "Data Races".Acked-by: Marco Elver
Signed-off-by: Akira Yokosawa
Signed-off-by: Paul E. McKenney -
Update the example reports based on the latest reports generated by
kcsan_test module, which now include the "value changed" line. Add a
brief description of the "value changed" line.Signed-off-by: Marco Elver
Signed-off-by: Paul E. McKenney -
This commit references tools/memory-model/Documentation/access-marking.txt
in the bullet introducing data_race(). The access-marking.txt file
gives advice on when data_race() should and should not be used.Suggested-by: Akira Yokosawa
Signed-off-by: Paul E. McKenney
07 May, 2021
2 commits
-
arm64 uses SP_EL0 to save the current task_struct address. While running
in EL0, SP_EL0 is clobbered by userspace. So if the upper bit is not 1
(not TTBR1), the current address is invalid. This patch checks the upper
bit of SP_EL0, if the upper bit is 1, lx_current() of arm64 will return
the derefrence of current task. Otherwise, lx_current() will tell users
they are running in userspace(EL0).While arm64 is running in EL0, it is actually pointless to print current
task as the memory of kernel space is not accessible in EL0.Link: https://lkml.kernel.org/r/20210314203444.15188-3-song.bao.hua@hisilicon.com
Signed-off-by: Barry Song
Cc: Jan Kiszka
Cc: Jonathan Corbet
Cc: Kieran Bingham
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Patch series "scripts/gdb: clarify the platforms supporting lx_current and add arm64 support", v2.
lx_current depends on per_cpu current_task variable which exists on x86
only. so it actually works on x86 only. the 1st patch documents this
clearly; the 2nd patch adds support for arm64.This patch (of 2):
x86 is the only architecture which has per_cpu current_task:
arch$ git grep current_task | grep -i per_cpu
x86/include/asm/current.h:DECLARE_PER_CPU(struct task_struct *, current_task);
x86/kernel/cpu/common.c:DEFINE_PER_CPU(struct task_struct *, current_task) ____cacheline_aligned =
x86/kernel/cpu/common.c:EXPORT_PER_CPU_SYMBOL(current_task);
x86/kernel/cpu/common.c:DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
x86/kernel/cpu/common.c:EXPORT_PER_CPU_SYMBOL(current_task);
x86/kernel/smpboot.c: per_cpu(current_task, cpu) = idle;On other architectures, lx_current() will lead to a python exception:
(gdb) p $lx_current().pid
Python Exception No symbol "current_task" in current context.:
Error occurred in Python: No symbol "current_task" in current context.To avoid more people struggling and wasting time in other architectures,
document it.Link: https://lkml.kernel.org/r/20210314203444.15188-1-song.bao.hua@hisilicon.com
Link: https://lkml.kernel.org/r/20210314203444.15188-2-song.bao.hua@hisilicon.com
Signed-off-by: Barry Song
Cc: Jan Kiszka
Cc: Kieran Bingham
Cc: Jonathan Corbet
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 May, 2021
8 commits
-
Update the "Tests" section in KASAN documentation:
- Add an introductory sentence.
- Add proper indentation for the list of ways to run KUnit tests.
- Punctuation, readability, and other minor clean-ups.
Link: https://lkml.kernel.org/r/fb08845e25c8847ffda271fa19cda2621c04a65b.1615559068.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov
Reviewed-by: Marco Elver
Cc: Alexander Potapenko
Cc: Andrey Ryabinin
Cc: Dmitry Vyukov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Update the "Ignoring accesses" section in KASAN documentation:
- Mention __no_sanitize_address/noinstr.
- Mention kasan_disable/enable_current().
- Mention kasan_reset_tag()/page_kasan_tag_reset().
- Readability and punctuation clean-ups.
Link: https://lkml.kernel.org/r/4531ba5f3eca61f6aade863c136778cc8c807a64.1615559068.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov
Reviewed-by: Marco Elver
Cc: Alexander Potapenko
Cc: Andrey Ryabinin
Cc: Dmitry Vyukov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Update the "Shadow memory" section in KASAN documentation:
- Rearrange the introduction paragraph do it doesn't give a
"KASAN has an issue" impression.- Update the list of architectures with vmalloc support.
- Punctuation, readability, and other minor clean-ups.
Link: https://lkml.kernel.org/r/00f8c38b0fd5290a3f4dced04eaba41383e67e14.1615559068.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov
Reviewed-by: Marco Elver
Cc: Alexander Potapenko
Cc: Andrey Ryabinin
Cc: Dmitry Vyukov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Update the "Implementation details" section for HW_TAGS KASAN:
- Punctuation, readability, and other minor clean-ups.
Link: https://lkml.kernel.org/r/ee2caf4c138cc1fd239822c2abefd5af6c057744.1615559068.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov
Reviewed-by: Marco Elver
Cc: Alexander Potapenko
Cc: Andrey Ryabinin
Cc: Dmitry Vyukov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Update the "Implementation details" section for SW_TAGS KASAN:
- Clarify the introduction sentence.
- Punctuation, readability, and other minor clean-ups.
Link: https://lkml.kernel.org/r/69b9b2e49d8cf789358fa24558be3fc0ce4ee32c.1615559068.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov
Reviewed-by: Marco Elver
Cc: Alexander Potapenko
Cc: Andrey Ryabinin
Cc: Dmitry Vyukov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Update the "Implementation details" section for generic KASAN:
- Don't mention kmemcheck, it's not present in the kernel anymore.
- Don't mention GCC as the only supported compiler.
- Update kasan_mem_to_shadow() definition to match actual code.
- Punctuation, readability, and other minor clean-ups.
Link: https://lkml.kernel.org/r/f2f35fdab701f8c709f63d328f98aec2982c8acc.1615559068.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov
Reviewed-by: Marco Elver
Cc: Alexander Potapenko
Cc: Andrey Ryabinin
Cc: Dmitry Vyukov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Update the "Boot parameters" section in KASAN documentation:
- Mention panic_on_warn.
- Mention kasan_multi_shot and its interaction with panic_on_warn.
- Clarify kasan.fault=panic interaction with panic_on_warn.
- A readability clean-up.
Link: https://lkml.kernel.org/r/01364952f15789948f0627d6733b5cdf5209f83a.1615559068.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov
Reviewed-by: Marco Elver
Cc: Alexander Potapenko
Cc: Andrey Ryabinin
Cc: Dmitry Vyukov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Update the "Error reports" section in KASAN documentation:
- Mention that bug titles are best-effort.
- Move and reword the part about auxiliary stacks from "Implementation
details".- Punctuation, readability, and other minor clean-ups.
Link: https://lkml.kernel.org/r/3531e8fe6972cf39d1954e3643237b19eb21227e.1615559068.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov
Reviewed-by: Marco Elver
Cc: Alexander Potapenko
Cc: Andrey Ryabinin
Cc: Dmitry Vyukov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
