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[Qemu-commits] [qemu/qemu] fc3d1b: oslib-posix: Use MAP_STACK in qemu_al
[Qemu-commits] [qemu/qemu] fc3d1b: oslib-posix: Use MAP_STACK in qemu_alloc_stack() o...
Tue, 06 Nov 2018 03:42:39 -0800
Author: Brad Smith <address@hidden>
Date: 2018-11-06 (Tue, 06 Nov 2018)
oslib-posix: Use MAP_STACK in qemu_alloc_stack() on OpenBSD
Use MAP_STACK in qemu_alloc_stack() on OpenBSD.
Added to our 6.4 release.
MAP_STACK Indicate that the mapping is used as a stack. This
flag must be used in combination with MAP_ANON and
Implement MAP_STACK option for mmap(). Synchronous faults (pagefault and
syscall) confirm the stack register points at MAP_STACK memory, otherwise
SIGSEGV is delivered. sigaltstack() and pthread_attr_setstack() are modified
to create a MAP_STACK sub-region which satisfies alignment requirements.
Observe that MAP_STACK can only be set/cleared by mmap(), which zeroes the
contents of the region -- there is no mprotect() equivalent operation, so
there is no MAP_STACK-adding gadget.
Signed-off-by: Brad Smith <address@hidden>
Reviewed-by: Kamil Rytarowski <address@hidden>
Reviewed-by: Peter Maydell <address@hidden>
Signed-off-by: Peter Maydell <address@hidden>
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