e2bb03f175
Currently the runtime can install stack barriers in any frame. However, the frame of cgocallback_gofunc is special: it's the one function that switches from a regular G stack to the system stack on return. Hence, the return PC slot in its frame on the G stack is actually used to save getg().sched.pc (so tracebacks appear to unwind to the last Go function running on that G), and not as an actual return PC for cgocallback_gofunc. Because of this, if we install a stack barrier in cgocallback_gofunc's return PC slot, when cgocallback_gofunc does return, it will move the stack barrier stub PC in to getg().sched.pc and switch back to the system stack. The rest of the runtime doesn't know how to deal with a stack barrier stub in sched.pc: nothing knows how to match it up with the G's stack barrier array and, when the runtime removes stack barriers, it doesn't know to undo the one in sched.pc. Hence, if the C code later returns back in to Go code, it will attempt to return through the stack barrier saved in sched.pc, which may no longer have correct unwinding information. Fix this by blacklisting cgocallback_gofunc's frame so the runtime won't install a stack barrier in it's return PC slot. Fixes #12238. Change-Id: I46aa2155df2fd050dd50de3434b62987dc4947b8 Reviewed-on: https://go-review.googlesource.com/13944 Reviewed-by: Russ Cox <rsc@golang.org> |
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