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