[PATCH v2 7/8] newlib: libc: aeabi_memmove M-profile PACBTI-enablement

[Victor Do Nascimento <victor.donascimento@arm.com>]

Add function prologue/epilogue to conditionally add BTI landing pads
and/or PAC code generation & authentication instructions depending on
compilation flags.
---
 .../libc/machine/arm/aeabi_memmove-thumb2.S   | 54 +++++++++++++++++--
 1 file changed, 49 insertions(+), 5 deletions(-)

diff --git a/newlib/libc/machine/arm/aeabi_memmove-thumb2.S b/newlib/libc/machine/arm/aeabi_memmove-thumb2.S
index e9504437b..34054d96c 100644
--- a/newlib/libc/machine/arm/aeabi_memmove-thumb2.S
+++ b/newlib/libc/machine/arm/aeabi_memmove-thumb2.S
@@ -26,6 +26,8 @@
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+	#include "pacbti.h"
+
 	.thumb
 	.syntax unified
 	.global __aeabi_memmove
@@ -33,8 +35,28 @@
 	ASM_ALIAS __aeabi_memmove4 __aeabi_memmove
 	ASM_ALIAS __aeabi_memmove8 __aeabi_memmove
 __aeabi_memmove:
-	cmp	r0, r1
+	.fnstart
+	.cfi_startproc
+#if __HAVE_PAC_LEAF
+#if __ARM_FEATURE_BTI_DEFAULT
+	pacbti ip, lr, sp
+#else
+	pac ip, lr, sp
+#endif /* __ARM_FEATURE_BTI_DEFAULT */
+	.cfi_register 143, 12
+	push	{r4, ip}
+	.save {r4, ra_auth_code}
+	.cfi_def_cfa_offset 8
+	.cfi_offset 4, -8
+	.cfi_offset 143, -4
+#elif __ARM_FEATURE_BTI_DEFAULT
+	bti
 	push	{r4}
+	.save   {r4}
+	.cfi_def_cfa_offset 4
+	.cfi_offset 4, -4
+#endif /* __HAVE_PAC_LEAF */
+	cmp	r0, r1
 	bls	3f
 	adds	r3, r1, r2
 	cmp	r0, r3
@@ -48,8 +70,18 @@ __aeabi_memmove:
 	strb	r4, [r1, #-1]!
 	bne	1b
 2:
-	pop	{r4}
-	bx	lr
+#if __HAVE_PAC_LEAF
+	pop {r4, ip}
+	.cfi_restore 4
+	.cfi_restore 143
+	.cfi_def_cfa_offset 0
+	aut ip, lr, sp
+#else
+	pop {r4}
+	.cfi_restore 4
+	.cfi_def_cfa_offset 0
+#endif /* __HAVE_PAC_LEAF */
+	bx lr
 3:
 	cmp	r2, #0
 	beq	2b
@@ -60,6 +92,18 @@ __aeabi_memmove:
 	cmp	r2, r1
 	strb	r4, [r3, #1]!
 	bne	4b
-	pop	{r4}
-	bx	lr
+#if __HAVE_PAC_LEAF
+	pop {r4, ip}
+	.cfi_restore 4
+	.cfi_restore 143
+	.cfi_def_cfa_offset 0
+	aut ip, lr, sp
+#else
+	pop {r4}
+	.cfi_restore 4
+	.cfi_def_cfa_offset 0
+#endif /* __HAVE_PAC_LEAF */
+	bx lr
+	.cfi_endproc
+	.fnend
 	.size __aeabi_memmove, . - __aeabi_memmove
-- 
2.36.1