60 lines
2.7 KiB
Plaintext
60 lines
2.7 KiB
Plaintext
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KSelfTest arm64/signal/
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=======================
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Signals Tests
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+++++++++++++
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- Tests are built around a common main compilation unit: such shared main
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enforces a standard sequence of operations needed to perform a single
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signal-test (setup/trigger/run/result/cleanup)
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- The above mentioned ops are configurable on a test-by-test basis: each test
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is described (and configured) using the descriptor signals.h::struct tdescr
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- Each signal testcase is compiled into its own executable: a separate
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executable is used for each test since many tests complete successfully
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by receiving some kind of fatal signal from the Kernel, so it's safer
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to run each test unit in its own standalone process, so as to start each
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test from a clean slate.
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- New tests can be simply defined in testcases/ dir providing a proper struct
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tdescr overriding all the defaults we wish to change (as of now providing a
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custom run method is mandatory though)
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- Signals' test-cases hereafter defined belong currently to two
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principal families:
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- 'mangle_' tests: a real signal (SIGUSR1) is raised and used as a trigger
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and then the test case code modifies the signal frame from inside the
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signal handler itself.
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- 'fake_sigreturn_' tests: a brand new custom artificial sigframe structure
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is placed on the stack and a sigreturn syscall is called to simulate a
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real signal return. This kind of tests does not use a trigger usually and
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they are just fired using some simple included assembly trampoline code.
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- Most of these tests are successfully passing if the process gets killed by
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some fatal signal: usually SIGSEGV or SIGBUS. Since while writing this
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kind of tests it is extremely easy in fact to end-up injecting other
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unrelated SEGV bugs in the testcases, it becomes extremely tricky to
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be really sure that the tests are really addressing what they are meant
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to address and they are not instead falling apart due to unplanned bugs
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in the test code.
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In order to alleviate the misery of the life of such test-developer, a few
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helpers are provided:
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- a couple of ASSERT_BAD/GOOD_CONTEXT() macros to easily parse a ucontext_t
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and verify if it is indeed GOOD or BAD (depending on what we were
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expecting), using the same logic/perspective as in the arm64 Kernel signals
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routines.
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- a sanity mechanism to be used in 'fake_sigreturn_'-alike tests: enabled by
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default it takes care to verify that the test-execution had at least
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successfully progressed up to the stage of triggering the fake sigreturn
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call.
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In both cases test results are expected in terms of:
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- some fatal signal sent by the Kernel to the test process
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or
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- analyzing some final regs state
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