[PATCH 14/16] aarch64: inline __libc_mtag_new_tag

[Szabolcs Nagy <szabolcs.nagy@arm.com>]

This is a common operation when heap tagging is enabled, so inline the
instructions instead of using an extern call.
---
 sysdeps/aarch64/Makefile         |  1 -
 sysdeps/aarch64/__mtag_new_tag.S | 37 --------------------------------
 sysdeps/aarch64/libc-mtag.h      | 14 +++++++++---
 3 files changed, 11 insertions(+), 41 deletions(-)
 delete mode 100644 sysdeps/aarch64/__mtag_new_tag.S

diff --git a/sysdeps/aarch64/Makefile b/sysdeps/aarch64/Makefile
index 5d594debea..1099f1d657 100644
--- a/sysdeps/aarch64/Makefile
+++ b/sysdeps/aarch64/Makefile
@@ -41,7 +41,6 @@ endif
 ifeq ($(subdir),misc)
 sysdep_headers += sys/ifunc.h
 sysdep_routines += __mtag_tag_zero_region \
-		   __mtag_new_tag \
 		   __mtag_tag_region
 
 endif
diff --git a/sysdeps/aarch64/__mtag_new_tag.S b/sysdeps/aarch64/__mtag_new_tag.S
deleted file mode 100644
index 72c1aded4c..0000000000
--- a/sysdeps/aarch64/__mtag_new_tag.S
+++ /dev/null
@@ -1,37 +0,0 @@
-/* Copyright (C) 2020-2021 Free Software Foundation, Inc.
-
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library.  If not, see
-   <http://www.gnu.org/licenses/>.  */
-
-#include <sysdep.h>
-
-#ifdef USE_MTAG
-
-	.arch armv8.5-a
-	.arch_extension memtag
-
-/* NB, only supported on variants with 64-bit pointers.  */
-
-#define ptr x0
-#define xset x1
-
-ENTRY(__libc_mtag_new_tag)
-	// Guarantee that the new tag is not the same as now.
-	gmi	xset, ptr, xzr
-	irg	ptr, ptr, xset
-	ret
-END (__libc_mtag_new_tag)
-#endif /* USE_MTAG */
diff --git a/sysdeps/aarch64/libc-mtag.h b/sysdeps/aarch64/libc-mtag.h
index da1b6be776..7588c6de9e 100644
--- a/sysdeps/aarch64/libc-mtag.h
+++ b/sysdeps/aarch64/libc-mtag.h
@@ -52,9 +52,17 @@ __libc_mtag_address_get_tag (void *p)
 }
 
 /* Assign a new (random) tag to a pointer P (does not adjust the tag on
-   the memory addressed).
-   void *__libc_mtag_new_tag (void*)  */
-void *__libc_mtag_new_tag (void *);
+   the memory addressed).  */
+static __always_inline void *
+__libc_mtag_new_tag (void *p)
+{
+  register void *x0 asm ("x0") = p;
+  register unsigned long x1 asm ("x1");
+  /* Guarantee that the new tag is not the same as now.  */
+  asm (".inst 0x9adf1401 /* gmi x1, x0, xzr */\n"
+       ".inst 0x9ac11000 /* irg x0, x0, x1 */" : "+r" (x0), "=r" (x1));
+  return x0;
+}
 
 #endif /* USE_MTAG */
 
-- 
2.17.1