Hi,

This patch adds the assembler support for the new unwinder directive
".pacspval" and encodes this directives with opcode "0xb5". This opcode
indicates the unwinder to use effective vsp as modifier for PAC validation.

Regression testing for arm-none-eabi target and found no regressions.

Ok for binutils-master?

Regards,
Srinath.

gas/ChangeLog:

2022-11-07  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

        * doc/c-arm.texi: Document directive.
        * config/tc-arm.c (s_arm_unwind_pacspval): Define function.
        (md_pseudo_table): Add entry for pacspval directive.
        * testsuite/gas/arm/ehabi-pacbti-m.d: New test.
        * testsuite/gas/arm/ehabi-pacbti-m.s: Likewise.


###############     Attachment also inlined for ease of reply    ###############


diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c
index 0f7d7695c0eb9b2eb5431ca314c54edfed9b633e..c7837195e667a03d3f8f6d16b62c01ac875ee5fd 100644
--- a/gas/config/tc-arm.c
+++ b/gas/config/tc-arm.c
@@ -4929,6 +4929,22 @@ s_arm_unwind_pad (int ignored ATTRIBUTE_UNUSED)
   demand_empty_rest_of_line ();
 }
 
+/* Parse an unwind_pacspval directive.  */
+
+static void
+s_arm_unwind_pacspval (int ignored ATTRIBUTE_UNUSED)
+{
+  valueT op;
+
+  if (!unwind.proc_start)
+    as_bad (MISSING_FNSTART);
+
+  demand_empty_rest_of_line ();
+
+  op = 0xb5;
+  add_unwind_opcode (op, 1);
+}
+
 /* Parse an unwind_setfp directive.  */
 
 static void
@@ -5205,6 +5221,7 @@ const pseudo_typeS md_pseudo_table[] =
   { "vsave",		s_arm_unwind_save,	1 },
   { "movsp",		s_arm_unwind_movsp,	0 },
   { "pad",		s_arm_unwind_pad,	0 },
+  { "pacspval",		s_arm_unwind_pacspval,	0 },
   { "setfp",		s_arm_unwind_setfp,	0 },
   { "unwind_raw",	s_arm_unwind_raw,	0 },
   { "eabi_attribute",	s_arm_eabi_attribute,	0 },
diff --git a/gas/doc/c-arm.texi b/gas/doc/c-arm.texi
index 4016d3a76957e545ad8d3f1fad2067b94bb9b83e..8e00ccf55a5c86443e2977c3b8c6f4e6d7ef39d9 100644
--- a/gas/doc/c-arm.texi
+++ b/gas/doc/c-arm.texi
@@ -1085,6 +1085,12 @@ This directive writes 12-byte packed floating-point values to the
 output section.  These are not compatible with current ARM processors
 or ABIs.
 
+@anchor{arm_pacspval}
+@cindex @code{.pacspval} directive, ARM
+@item .pacspval
+Generate unwinder annotations to use effective vsp as modifier in PAC
+validation.
+
 @anchor{arm_pad}
 @cindex @code{.pad} directive, ARM
 @item .pad #@var{count}
diff --git a/gas/testsuite/gas/arm/ehabi-pacbti-m.d b/gas/testsuite/gas/arm/ehabi-pacbti-m.d
new file mode 100644
index 0000000000000000000000000000000000000000..6039945f931a2975ae4752a5f711e62a00b6ce69
--- /dev/null
+++ b/gas/testsuite/gas/arm/ehabi-pacbti-m.d
@@ -0,0 +1,15 @@
+# name: Unwind Stack Frame information for Armv8.1-M.Mainline PAC extension
+# source: ehabi-pacbti-m.s
+# as: -march=armv8.1-m.main+mve+pacbti
+# readelf: -u
+
+Unwind section '.ARM.exidx' at offset 0x5c contains 1 entry:
+
+0x0: @0x0
+  Compact model index: 1
+  0xb1 0x08 pop {r3}
+  0x80 0x08 pop {r7}
+  0xb4      pop {ra_auth_code}
+  0x84 0x00 pop {r14}
+  0xb1 0x0f pop {r0, r1, r2, r3}
+  0xb5      vsp as modifier for PAC validation
diff --git a/gas/testsuite/gas/arm/ehabi-pacbti-m.s b/gas/testsuite/gas/arm/ehabi-pacbti-m.s
new file mode 100644
index 0000000000000000000000000000000000000000..10185484c8c9716c394ab0cbe171c626b9847bfc
--- /dev/null
+++ b/gas/testsuite/gas/arm/ehabi-pacbti-m.s
@@ -0,0 +1,38 @@
+        .syntax unified
+        .thumb
+        .thumb_func
+	.fnstart
+	.cfi_startproc
+	.pacspval
+	pac	ip, lr, sp
+	.cfi_register 143, 12
+	push	{r0, r1, r2, r3}
+	.save {r0, r1, r2, r3}
+	.cfi_def_cfa_offset 16
+	.cfi_offset 0, -16
+	.cfi_offset 1, -12
+	.cfi_offset 2, -8
+	.cfi_offset 3, -4
+	push	{r3, r7, ip, lr}
+	.save {r3, r7, ra_auth_code, lr}
+	.cfi_def_cfa_offset 32
+	.cfi_offset 3, -32
+	.cfi_offset 7, -28
+	.cfi_offset 143, -24
+	.cfi_offset 14, -20
+	pop	{r3, r7, ip, lr}
+	.cfi_restore 14
+	.cfi_restore 143
+	.cfi_restore 7
+	.cfi_restore 3
+	.cfi_def_cfa_offset 0
+	add	sp, sp, #16
+	.cfi_restore 3
+	.cfi_restore 2
+	.cfi_restore 1
+	.cfi_restore 0
+	.cfi_def_cfa_offset -16
+	aut	ip, lr, sp
+	bx	lr
+	.cfi_endproc
+	.fnend