When libgcc is built with pac-ret, it requires to autenticate the
unwinding frame based on CFI information. The _dl_tlsdesc_dynamic
uses a custom calling convention, where it is responsible to save
and restore all registers it might use (even volatile).
The pac-ret support added by 1be3d6eb82
was added only on the slow-path, but the fast path also adds DWARF
Register Rule Instruction (cfi_adjust_cfa_offset) since it requires
to save/restore some auxiliary register. It seems that this is not
fully supported neither by libgcc nor AArch64 ABI [1].
Instead, move paciasp/autiasp to function prologue/epilogue to be
used on both fast and slow paths.
I also corrected the _dl_tlsdesc_dynamic comment description, it was
copied from i386 implementation without any adjustment.
Checked on aarch64-linux-gnu with a toolchain built with
--enable-standard-branch-protection on a system with pac-ret
support.
[1] https://github.com/ARM-software/abi-aa/blob/main/aadwarf64/aadwarf64.rst#id1
Reviewed-by: Yury Khrustalev <yury.khrustalev@arm.com>
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