arm64: deliver guest signals to handlers, with nested-signal support#77
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this needs to cover both ARM64 and AMD64 |
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Implement guest signal-handler delivery on ARM64.
tgkill(131) redirects EL0 to a registered handler:Signals::entersaves the interrupted frame, setsx0=sig/x30=SIGRETURN_ADDR/pc=handler(optionally on theSA_ONSTACKaltstack), and anrt_sigreturn(139) syscall restores the frame.SIG_DFL/SIG_IGNand default-ignored signals keep their dispositions; unhandled fatal signals terminate with128+sig.Nested signals supported:
sigretis a stack of frames, so a handler raising another signal doesn't clobber the outer return frame. Also fixes a pre-existing amd64Signals::enteroff-by-one.Tests:
tests/unit/arm64_signals.cpp(8 cases). Known gaps (in TODO.md):SA_SIGINFOargs and signal masking.