We very intermittently see failures in the single_thread_different_keys PAC test. As noted in the comment in the test the PAC field can be quite narrow so there is a chance of collisions even with different keys with a chance of 5% for 7 bit keys, and the potential for narrower keys. The test tries to avoid this by running repeatedly, but only tries 10 times which even with a 5% chance of collisions isn't enough.
Increase the number of times we attempt to look for collisions by a factor of 100, this also affects other tests which are following a similar pattern with running the test repeatedly and either don't care like with pac_instruction_not_nop or potentially have the same issue like exec_sign_all.
The PAC tests are very fast, running in a second or two even in emulation, so the 100x increased cost is mildly irritating but not a huge issue. The bulk of the overhead is in the exec_sign_all test which does a fork() and exec() per iteration.
Signed-off-by: Mark Brown broonie@kernel.org --- tools/testing/selftests/arm64/pauth/pac.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/testing/selftests/arm64/pauth/pac.c b/tools/testing/selftests/arm64/pauth/pac.c index 5a07b3958fbf292b09c9d6b11b8f9db2880beeed..6d21b2fc758d80d0cd7d0db2859de3b308522cb4 100644 --- a/tools/testing/selftests/arm64/pauth/pac.c +++ b/tools/testing/selftests/arm64/pauth/pac.c @@ -13,7 +13,7 @@ #include "../../kselftest_harness.h" #include "helper.h"
-#define PAC_COLLISION_ATTEMPTS 10 +#define PAC_COLLISION_ATTEMPTS 1000 /* * The kernel sets TBID by default. So bits 55 and above should remain * untouched no matter what.