1KSelfTest arm64/signal/ 2======================= 3 4Signals Tests 5+++++++++++++ 6 7- Tests are built around a common main compilation unit: such shared main 8 enforces a standard sequence of operations needed to perform a single 9 signal-test (setup/trigger/run/result/cleanup) 10 11- The above mentioned ops are configurable on a test-by-test basis: each test 12 is described (and configured) using the descriptor signals.h::struct tdescr 13 14- Each signal testcase is compiled into its own executable: a separate 15 executable is used for each test since many tests complete successfully 16 by receiving some kind of fatal signal from the Kernel, so it's safer 17 to run each test unit in its own standalone process, so as to start each 18 test from a clean slate. 19 20- New tests can be simply defined in testcases/ dir providing a proper struct 21 tdescr overriding all the defaults we wish to change (as of now providing a 22 custom run method is mandatory though) 23 24- Signals' test-cases hereafter defined belong currently to two 25 principal families: 26 27 - 'mangle_' tests: a real signal (SIGUSR1) is raised and used as a trigger 28 and then the test case code modifies the signal frame from inside the 29 signal handler itself. 30 31 - 'fake_sigreturn_' tests: a brand new custom artificial sigframe structure 32 is placed on the stack and a sigreturn syscall is called to simulate a 33 real signal return. This kind of tests does not use a trigger usually and 34 they are just fired using some simple included assembly trampoline code. 35 36 - Most of these tests are successfully passing if the process gets killed by 37 some fatal signal: usually SIGSEGV or SIGBUS. Since while writing this 38 kind of tests it is extremely easy in fact to end-up injecting other 39 unrelated SEGV bugs in the testcases, it becomes extremely tricky to 40 be really sure that the tests are really addressing what they are meant 41 to address and they are not instead falling apart due to unplanned bugs 42 in the test code. 43 In order to alleviate the misery of the life of such test-developer, a few 44 helpers are provided: 45 46 - a couple of ASSERT_BAD/GOOD_CONTEXT() macros to easily parse a ucontext_t 47 and verify if it is indeed GOOD or BAD (depending on what we were 48 expecting), using the same logic/perspective as in the arm64 Kernel signals 49 routines. 50 51 - a sanity mechanism to be used in 'fake_sigreturn_'-alike tests: enabled by 52 default it takes care to verify that the test-execution had at least 53 successfully progressed up to the stage of triggering the fake sigreturn 54 call. 55 56 In both cases test results are expected in terms of: 57 - some fatal signal sent by the Kernel to the test process 58 or 59 - analyzing some final regs state 60