[gcc r11-8903] arm: add erratum mitigation to __gnu_cmse_nonsecure_call [PR102035]

[Richard Earnshaw <rearnsha@gcc.gnu.org>]

https://gcc.gnu.org/g:2539763c89a6777502f16457269e2c31d6d95b67

commit r11-8903-g2539763c89a6777502f16457269e2c31d6d95b67
Author: Richard Earnshaw <rearnsha@arm.com>
Date:   Fri Jun 18 17:16:25 2021 +0100

    arm: add erratum mitigation to __gnu_cmse_nonsecure_call [PR102035]
    
    Add the recommended erratum mitigation sequence to
    __gnu_cmse_nonsecure_call for use on Armv8-m.main devices. Since this
    is in the library code we cannot know in advance whether the core we
    are running on will be affected by this, so always enable it.
    
    libgcc:
            PR target/102035
            * config/arm/cmse_nonsecure_call.S (__gnu_cmse_nonsecure_call):
            Add vlldm erratum work-around.
    (cherry picked from commit 574e7950bd6b34e9e2cacce18c802b45505d1d0a)

Diff:
---
 libgcc/config/arm/cmse_nonsecure_call.S | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libgcc/config/arm/cmse_nonsecure_call.S b/libgcc/config/arm/cmse_nonsecure_call.S
index 00830ade98e..c8e0fbbe665 100644
--- a/libgcc/config/arm/cmse_nonsecure_call.S
+++ b/libgcc/config/arm/cmse_nonsecure_call.S
@@ -102,6 +102,11 @@ blxns	    r4
 #ifdef __ARM_PCS_VFP
 vpop.f64    {d8-d15}
 #else
+/* VLLDM erratum mitigation sequence. */
+mrs	    r5, control
+tst	    r5, #8	  /* CONTROL_S.SFPA */
+it	    ne
+.inst.w	    0xeeb00a40	  /* vmovne s0, s0 */
 vlldm	    sp		  /* Lazy restore of d0-d16 and FPSCR.  */
 add	    sp, sp, #0x88 /* Free space used to save floating point registers.  */
 #endif /* __ARM_PCS_VFP */