This commit adds a new ABI to be selected via `extern "C-cmse-nonsecure-call"` on function pointers in order for the compiler to apply the corresponding cmse_nonsecure_call callsite attribute. For Armv8-M targets supporting TrustZone-M, this will perform a non-secure function call by saving, clearing and calling a non-secure function pointer using the BLXNS instruction. See the page on the unstable book for details. Signed-off-by: Hugues de Valon <hugues.devalon@arm.com>
librustc_target
contains some very low-level details that are
specific to different compilation targets and so forth.
For more information about how rustc works, see the rustc dev guide.