starfive-tech/linux.git/kernel/kcsan, branch visionfive_v1_5.13

kcsan: Fix debugfs initcall return type

2021-05-18T17:58:02+00:00

clang with CONFIG_LTO_CLANG points out that an initcall function should return an 'int' due to the changes made to the initcall macros in commit 3578ad11f3fb ("init: lto: fix PREL32 relocations"): kernel/kcsan/debugfs.c:274:15: error: returning 'void' from a function with incompatible result type 'int' late_initcall(kcsan_debugfs_init); ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~ include/linux/init.h:292:46: note: expanded from macro 'late_initcall' #define late_initcall(fn) __define_initcall(fn, 7) Fixes: e36299efe7d7 ("kcsan, debugfs: Move debugfs file creation out of early init") Cc: stable Reviewed-by: Greg Kroah-Hartman Reviewed-by: Marco Elver Reviewed-by: Nathan Chancellor Reviewed-by: Miguel Ojeda Signed-off-by: Arnd Bergmann Signed-off-by: Paul E. McKenney

kcsan: Fix printk format string

2021-04-22T12:36:03+00:00

Printing a 'long' variable using the '%d' format string is wrong and causes a warning from gcc: kernel/kcsan/kcsan_test.c: In function 'nthreads_gen_params': include/linux/kern_levels.h:5:25: error: format '%d' expects argument of type 'int', but argument 3 has type 'long int' [-Werror=format=] Use the appropriate format modifier. Fixes: f6a149140321 ("kcsan: Switch to KUNIT_CASE_PARAM for parameterized tests") Signed-off-by: Arnd Bergmann Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Marco Elver Acked-by: Paul E. McKenney Link: https://lkml.kernel.org/r/20210421135059.3371701-1-arnd@kernel.org

kcsan: Add missing license and copyright headers

2021-03-08T22:27:43+00:00

Adds missing license and/or copyright headers for KCSAN source files. Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: Switch to KUNIT_CASE_PARAM for parameterized tests

2021-03-08T22:27:43+00:00

Since KUnit now support parameterized tests via KUNIT_CASE_PARAM, update KCSAN's test to switch to it for parameterized tests. This simplifies parameterized tests and gets rid of the "parameters in case name" workaround (hack). At the same time, we can increase the maximum number of threads used, because on systems with too few CPUs, KUnit allows us to now stop at the maximum useful threads and not unnecessarily execute redundant test cases with (the same) limited threads as had been the case before. Reviewed-by: David Gow Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: Make test follow KUnit style recommendations

2021-03-08T22:27:43+00:00

Per recently added KUnit style recommendations at Documentation/dev-tools/kunit/style.rst, make the following changes to the KCSAN test: 1. Rename 'kcsan-test.c' to 'kcsan_test.c'. 2. Rename suite name 'kcsan-test' to 'kcsan'. 3. Rename CONFIG_KCSAN_TEST to CONFIG_KCSAN_KUNIT_TEST and default to KUNIT_ALL_TESTS. Reviewed-by: David Gow Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan, debugfs: Move debugfs file creation out of early init

2021-03-08T22:27:43+00:00

Commit 56348560d495 ("debugfs: do not attempt to create a new file before the filesystem is initalized") forbids creating new debugfs files until debugfs is fully initialized. This means that KCSAN's debugfs file creation, which happened at the end of __init(), no longer works. And was apparently never supposed to work! However, there is no reason to create KCSAN's debugfs file so early. This commit therefore moves its creation to a late_initcall() callback. Cc: "Rafael J. Wysocki" Cc: stable Fixes: 56348560d495 ("debugfs: do not attempt to create a new file before the filesystem is initalized") Reviewed-by: Greg Kroah-Hartman Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: Rewrite kcsan_prandom_u32_max() without prandom_u32_state()

2021-01-04T22:39:07+00:00

Rewrite kcsan_prandom_u32_max() to not depend on code that might be instrumented, removing any dependency on lib/random32.c. The rewrite implements a simple linear congruential generator, that is sufficient for our purposes (for udelay() and skip_watch counter randomness). The initial motivation for this was to allow enabling KCSAN for kernel/sched (remove KCSAN_SANITIZE := n from kernel/sched/Makefile), with CONFIG_DEBUG_PREEMPT=y. Without this change, we could observe recursion: check_access() [via instrumentation] kcsan_setup_watchpoint() reset_kcsan_skip() kcsan_prandom_u32_max() get_cpu_var() preempt_disable() preempt_count_add() [in kernel/sched/core.c] check_access() [via instrumentation] Note, while this currently does not affect an unmodified kernel, it'd be good to keep a KCSAN kernel working when KCSAN_SANITIZE := n is removed from kernel/sched/Makefile to permit testing scheduler code with KCSAN if desired. Fixes: cd290ec24633 ("kcsan: Use tracing-safe version of prandom") Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: Fix encoding masks and regain address bit

2020-11-07T01:19:26+00:00

The watchpoint encoding masks for size and address were off-by-one bit each, with the size mask using 1 unnecessary bit and the address mask missing 1 bit. However, due to the way the size is shifted into the encoded watchpoint, we were effectively wasting and never using the extra bit. For example, on x86 with PAGE_SIZE==4K, we have 1 bit for the is-write bit, 14 bits for the size bits, and then 49 bits left for the address. Prior to this fix we would end up with this usage: [ write<1> | size<14> | wasted<1> | address<48> ] Fix it by subtracting 1 bit from the GENMASK() end and start ranges of size and address respectively. The added static_assert()s verify that the masks are as expected. With the fixed version, we get the expected usage: [ write<1> | size<14> | address<49> ] Functionally no change is expected, since that extra address bit is insignificant for enabled architectures. Acked-by: Boqun Feng Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: Never set up watchpoints on NULL pointers

2020-11-03T01:08:51+00:00

Avoid setting up watchpoints on NULL pointers, as otherwise we would crash inside the KCSAN runtime (when checking for value changes) instead of the instrumented code. Because that may be confusing, skip any address less than PAGE_SIZE. Reviewed-by: Dmitry Vyukov Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney

kcsan: selftest: Ensure that address is at least PAGE_SIZE

2020-11-03T01:08:50+00:00

In preparation of supporting only addresses not within the NULL page, change the selftest to never use addresses that are less than PAGE_SIZE. Reviewed-by: Dmitry Vyukov Signed-off-by: Marco Elver Signed-off-by: Paul E. McKenney