[glibc/arm/gcs] aarch64: Add asm helpers for GCS

[glibc/arm/gcs] aarch64: Add asm helpers for GCS

[Szabolcs Nagy]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=15d1674cae644619d521af249b3a4f1c17cdcee9

commit 15d1674cae644619d521af249b3a4f1c17cdcee9
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date:   Wed Feb 22 14:35:00 2023 +0000

    aarch64: Add asm helpers for GCS
    
    The Guarded Control Stack instructions can be present even if the
    hardware does not support the extension (runtime checked feature),
    so the asm code should be backward compatible with old assemblers.

Diff:
---
 sysdeps/aarch64/sysdep.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/sysdeps/aarch64/sysdep.h b/sysdeps/aarch64/sysdep.h
index 464674e89c..661d9fe8c1 100644
--- a/sysdeps/aarch64/sysdep.h
+++ b/sysdeps/aarch64/sysdep.h
@@ -74,6 +74,13 @@ strip_pac (void *p)
 #define PACIASP		hint	25
 #define AUTIASP		hint	29
 
+/* Guarded Control Stack support.  */
+#define CHKFEAT_X16	hint	40
+#define MRS_GCSPR(x)	mrs	x, s3_3_c2_c5_1
+#define GCSPOPM(x)	sysl	x, #3, c7, c7, #1
+#define GCSSS1(x)	sys	#3, c7, c7, #2, x
+#define GCSSS2(x)	sysl	x, #3, c7, c7, #3
+
 /* GNU_PROPERTY_AARCH64_* macros from elf.h for use in asm code.  */
 #define FEATURE_1_AND 0xc0000000
 #define FEATURE_1_BTI 1