user/sven/linux.git/kernel/kcsan, branch v5.19.8

Merge tag 'linux-kselftest-kunit-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest

2022-05-25T18:32:53Z

Pull KUnit updates from Shuah Khan: "Several fixes, cleanups, and enhancements to tests and framework: - introduce _NULL and _NOT_NULL macros to pointer error checks - rework kunit_resource allocation policy to fix memory leaks when caller doesn't specify free() function to be used when allocating memory using kunit_add_resource() and kunit_alloc_resource() funcs. - add ability to specify suite-level init and exit functions" * tag 'linux-kselftest-kunit-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (41 commits) kunit: tool: Use qemu-system-i386 for i386 runs kunit: fix executor OOM error handling logic on non-UML kunit: tool: update riscv QEMU config with new serial dependency kcsan: test: use new suite_{init,exit} support kunit: tool: Add list of all valid test configs on UML kunit: take `kunit_assert` as `const` kunit: tool: misc cleanups kunit: tool: minor cosmetic cleanups in kunit_parser.py kunit: tool: make parser stop overwriting status of suites w/ no_tests kunit: tool: remove dead parse_crash_in_log() logic kunit: tool: print clearer error message when there's no TAP output kunit: tool: stop using a shell to run kernel under QEMU kunit: tool: update test counts summary line format kunit: bail out of test filtering logic quicker if OOM lib/Kconfig.debug: change KUnit tests to default to KUNIT_ALL_TESTS kunit: Rework kunit_resource allocation policy kunit: fix debugfs code to use enum kunit_status, not bool kfence: test: use new suite_{init/exit} support, add .kunitconfig kunit: add ability to specify suite-level init and exit functions kunit: rename print_subtest_{start,end} for clarity (s/subtest/suite) ...

kcsan: test: use new suite_{init,exit} support

2022-05-16T19:23:49Z

Use the newly added suite_{init,exit} support for suite-wide init and cleanup. This avoids the unsupported method by which the test used to do suite-wide init and cleanup (avoiding issues such as missing TAP headers, and possible future conflicts). Signed-off-by: Marco Elver Signed-off-by: Shuah Khan

kcsan: Use preemption model accessors

2022-04-05T08:24:42Z

Per PREEMPT_DYNAMIC, checking CONFIG_PREEMPT doesn't tell you the actual preemption model of the live kernel. Use the newly-introduced accessors instead. Signed-off-by: Valentin Schneider Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Marco Elver Acked-by: Frederic Weisbecker Link: https://lore.kernel.org/r/20211112185203.280040-4-valentin.schneider@arm.com

Merge tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

2022-01-11T17:51:26Z

Pull KCSAN updates from Paul McKenney: "This provides KCSAN fixes and also the ability to take memory barriers into account for weakly-ordered systems. This last can increase the probability of detecting certain types of data races" * tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (29 commits) kcsan: Only test clear_bit_unlock_is_negative_byte if arch defines it kcsan: Avoid nested contexts reading inconsistent reorder_access kcsan: Turn barrier instrumentation into macros kcsan: Make barrier tests compatible with lockdep kcsan: Support WEAK_MEMORY with Clang where no objtool support exists compiler_attributes.h: Add __disable_sanitizer_instrumentation objtool, kcsan: Remove memory barrier instrumentation from noinstr objtool, kcsan: Add memory barrier instrumentation to whitelist sched, kcsan: Enable memory barrier instrumentation mm, kcsan: Enable barrier instrumentation x86/qspinlock, kcsan: Instrument barrier of pv_queued_spin_unlock() x86/barriers, kcsan: Use generic instrumentation for non-smp barriers asm-generic/bitops, kcsan: Add instrumentation for barriers locking/atomics, kcsan: Add instrumentation for barriers locking/barriers, kcsan: Support generic instrumentation locking/barriers, kcsan: Add instrumentation for barriers kcsan: selftest: Add test case to check memory barrier instrumentation kcsan: Ignore GCC 11+ warnings about TSan runtime support kcsan: test: Add test cases for memory barrier instrumentation kcsan: test: Match reordered or normal accesses ...

arm64: Enable KCSAN

2021-12-14T18:54:34Z

This patch enables KCSAN for arm64, with updates to build rules to not use KCSAN for several incompatible compilation units. Recent GCC version(at least GCC10) made outline-atomics as the default option(unlike Clang), which will cause linker errors for kernel/kcsan/core.o. Disables the out-of-line atomics by no-outline-atomics to fix the linker errors. Meanwhile, as Mark said[1], some latent issues are needed to be fixed which isn't just a KCSAN problem, we make the KCSAN depends on EXPERT for now. Tested selftest and kcsan_test(built with GCC11 and Clang 13), and all passed. [1] https://lkml.kernel.org/r/YadiUPpJ0gADbiHQ@FVFF77S0Q05N Acked-by: Marco Elver # kernel/kcsan Tested-by: Joey Gouly Signed-off-by: Kefeng Wang Link: https://lore.kernel.org/r/20211211131734.126874-1-wangkefeng.wang@huawei.com [catalin.marinas@arm.com: added comment to justify EXPERT] Signed-off-by: Catalin Marinas

kcsan: Only test clear_bit_unlock_is_negative_byte if arch defines it

2021-12-10T00:42:29Z

Some architectures do not define clear_bit_unlock_is_negative_byte(). Only test it when it is actually defined (similar to other usage, such as in lib/test_kasan.c). Link: https://lkml.kernel.org/r/202112050757.x67rHnFU-lkp@intel.com Reported-by: kernel test robot Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: Avoid nested contexts reading inconsistent reorder_access

2021-12-10T00:42:29Z

Nested contexts, such as nested interrupts or scheduler code, share the same kcsan_ctx. When such a nested context reads an inconsistent reorder_access due to an interrupt during set_reorder_access(), we can observe the following warning: | ------------[ cut here ]------------ | Cannot find frame for torture_random kernel/torture.c:456 in stack trace | WARNING: CPU: 13 PID: 147 at kernel/kcsan/report.c:343 replace_stack_entry kernel/kcsan/report.c:343 | ... | Call Trace: | | sanitize_stack_entries kernel/kcsan/report.c:351 [inline] | print_report kernel/kcsan/report.c:409 | kcsan_report_known_origin kernel/kcsan/report.c:693 | kcsan_setup_watchpoint kernel/kcsan/core.c:658 | rcutorture_one_extend kernel/rcu/rcutorture.c:1475 | rcutorture_loop_extend kernel/rcu/rcutorture.c:1558 [inline] | ... | | ---[ end trace ee5299cb933115f5 ]--- | ================================================================== | BUG: KCSAN: data-race in _raw_spin_lock_irqsave / rcutorture_one_extend | | write (reordered) to 0xffffffff8c93b300 of 8 bytes by task 154 on cpu 12: | queued_spin_lock include/asm-generic/qspinlock.h:80 [inline] | do_raw_spin_lock include/linux/spinlock.h:185 [inline] | __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:111 [inline] | _raw_spin_lock_irqsave kernel/locking/spinlock.c:162 | try_to_wake_up kernel/sched/core.c:4003 | sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1097 | asm_sysvec_apic_timer_interrupt arch/x86/include/asm/idtentry.h:638 | set_reorder_access kernel/kcsan/core.c:416 [inline] <-- inconsistent reorder_access | kcsan_setup_watchpoint kernel/kcsan/core.c:693 | rcutorture_one_extend kernel/rcu/rcutorture.c:1475 | rcutorture_loop_extend kernel/rcu/rcutorture.c:1558 [inline] | rcu_torture_one_read kernel/rcu/rcutorture.c:1600 | rcu_torture_reader kernel/rcu/rcutorture.c:1692 | kthread kernel/kthread.c:327 | ret_from_fork arch/x86/entry/entry_64.S:295 | | read to 0xffffffff8c93b300 of 8 bytes by task 147 on cpu 13: | rcutorture_one_extend kernel/rcu/rcutorture.c:1475 | rcutorture_loop_extend kernel/rcu/rcutorture.c:1558 [inline] | ... The warning is telling us that there was a data race which KCSAN wants to report, but the function where the original access (that is now reordered) happened cannot be found in the stack trace, which prevents KCSAN from generating the right stack trace. The stack trace of "write (reordered)" now only shows where the access was reordered to, but should instead show the stack trace of the original write, with a final line saying "reordered to". At the point where set_reorder_access() is interrupted, it just set reorder_access->ptr and size, at which point size is non-zero. This is sufficient (if ctx->disable_scoped is zero) for further accesses from nested contexts to perform checking of this reorder_access. That then happened in _raw_spin_lock_irqsave(), which is called by scheduler code. However, since reorder_access->ip is still stale (ptr and size belong to a different ip not yet set) this finally leads to replace_stack_entry() not finding the frame in reorder_access->ip and generating the above warning. Fix it by ensuring that a nested context cannot access reorder_access while we update it in set_reorder_access(): set ctx->disable_scoped for the duration that reorder_access is updated, which effectively locks reorder_access and prevents concurrent use by nested contexts. Note, set_reorder_access() can do the update only if disabled_scoped is zero on entry, and must therefore set disable_scoped back to non-zero after the initial check in set_reorder_access(). Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: Make barrier tests compatible with lockdep

2021-12-10T00:42:28Z

The barrier tests in selftest and the kcsan_test module only need the spinlock and mutex to test correct barrier instrumentation. Therefore, these were initially placed on the stack. However, lockdep asserts that locks are in static storage, and will generate this warning: | INFO: trying to register non-static key. | The code is fine but needs lockdep annotation, or maybe | you didn't initialize this object before use? | turning off the locking correctness validator. | CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.16.0-rc1+ #3208 | Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014 | Call Trace: | | dump_stack_lvl+0x88/0xd8 | dump_stack+0x15/0x1b | register_lock_class+0x6b3/0x840 | ... | test_barrier+0x490/0x14c7 | kcsan_selftest+0x47/0xa0 | ... To fix, move the test locks into static storage. Fixing the above also revealed that lock operations are strengthened on first use with lockdep enabled, due to lockdep calling out into non-instrumented files (recall that kernel/locking/lockdep.c is not instrumented with KCSAN). Only kcsan_test checks for over-instrumentation of *_lock() operations, where we can simply "warm up" the test locks to avoid the test case failing with lockdep. Reported-by: Paul E. McKenney Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: selftest: Add test case to check memory barrier instrumentation

2021-12-10T00:42:27Z

Memory barrier instrumentation is crucial to avoid false positives. To avoid surprises, run a simple test case in the boot-time selftest to ensure memory barriers are still instrumented correctly. Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: test: Add test cases for memory barrier instrumentation

2021-12-10T00:42:27Z

Adds test cases to check that memory barriers are instrumented correctly, and detection of missing memory barriers is working as intended if CONFIG_KCSAN_STRICT=y. Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney