This generates a page of 340 trampolines, aligned within one page. The
trampolines use pc-relative addressing to reference config data
(context, jump address) from a page placed directly prior to the
trampoline page. This can be used on systems -- such as iOS -- that do not
support writable, executable memory by remapping the executable page
containing the trampolines directly above a newly allocated writable
config page.
This adds the FFI_EXEC_TRAMPOLINE_TABLE. The flag is enabled for
arm-apple-darwin, where PROT_EXEC on writable (or formerly writable) pages is
not permitted for sandboxed binaries.
Landon Fuller