[Bug target/94515] aarch64: broken unwind information for pac-ret

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94515

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Szabolcs Nagy <nsz@gcc.gnu.org>:

https://gcc.gnu.org/g:acdf733634745548c0167c40bad80e6140ac2eeb

commit r10-7986-gacdf733634745548c0167c40bad80e6140ac2eeb
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Mon Apr 27 09:07:15 2020 +0100

    aarch64: Fix .cfi_window_save with pac-ret [PR94515]

    On aarch64 -mbranch-protection=pac-ret reuses the dwarf
    opcode for window_save to mean "toggle the return address
    mangle state", but in the dwarf2cfi internal logic the
    state was not updated when an opcode was emitted, the
    currently present update logic is only valid for the
    original sparc use of window_save so a separate bool is
    used on aarch64 to track the state.

    This bug can cause the unwinder not to authenticate return
    addresses that were signed (or vice versa) which means a
    runtime crash on a pauth enabled system.

    Currently only aarch64 pac-ret uses REG_CFA_TOGGLE_RA_MANGLE.

    This should be backported to gcc-9 and gcc-8 branches.

    gcc/ChangeLog:

            PR target/94515
            * dwarf2cfi.c (struct GTY): Add ra_mangled.
            (cfi_row_equal_p): Check ra_mangled.
            (dwarf2out_frame_debug_cfa_window_save): Remove the argument,
            this only handles the sparc logic now.
            (dwarf2out_frame_debug_cfa_toggle_ra_mangle): New function for
            the aarch64 specific logic.
            (dwarf2out_frame_debug): Update to use the new subroutines.
            (change_cfi_row): Check ra_mangled.

    gcc/testsuite/ChangeLog:

            PR target/94515
            * g++.target/aarch64/pr94515-1.C: New test.
            * g++.target/aarch64/pr94515-2.C: New test.