PATCH [4/4] arm: Add Tag_PACRET_use build attribute

[Andrea Corallo <andrea.corallo@arm.com>]

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Hi all,

last patch of the series adding 'Tag_PACRET_use' build attribute
support.

Here follows its semantic:

  0 This code is compiled without return address signing and authentication
  1 This code is compiled with return address signing and authentication

See:
- Armv8.1-M Pointer Authentication and Branch Target Identification Extension [1]
- Armv8-M Architecture Reference Manual [2]

Regtested clean on current master.

Best Regards

  Andrea

[1] <https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/armv8-1-m-pointer-authentication-and-branch-target-identification-extension>
[2] <https://developer.arm.com/documentation/ddi0553/latest>


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From 5e2aa6357180ace750e80856acd1370b07118567 Mon Sep 17 00:00:00 2001
From: Andrea Corallo <andrea.corallo@arm.com>
Date: Mon, 5 Jul 2021 17:27:00 +0200
Subject: [PATCH 4/4] PATCH [4/4] arm: Add Tag_PACRET_use build attribute

bfd/
2021-07-06  Andrea Corallo  <andrea.corallo@arm.com>

	* elf32-arm.c (elf32_arm_merge_eabi_attributes): Add
	'Tag_PACRET_use' case.

binutils/
2021-07-06  Andrea Corallo  <andrea.corallo@arm.com>

	* readelf.c (arm_attr_tag_PAC_extension): Declare.
	(arm_attr_public_tags): Add 'PAC_extension' lookup.

elfcpp/
2021-07-06  Andrea Corallo  <andrea.corallo@arm.com>

	* arm.h: Define 'Tag_PACRET_use' enum.

gas/
2021-07-06  Andrea Corallo  <andrea.corallo@arm.com>

	* config/tc-arm.c (arm_convert_symbolic_attribute): Add
	'Tag_PACRET_use' to the attribute_table.

include/
2021-07-06  Andrea Corallo  <andrea.corallo@arm.com>

	* elf/arm.h (elf_arm_reloc_type): Add 'Tag_PACRET_use'.
---
 bfd/elf32-arm.c     | 1 +
 binutils/readelf.c  | 5 +++++
 elfcpp/arm.h        | 1 +
 gas/config/tc-arm.c | 1 +
 include/elf/arm.h   | 1 +
 5 files changed, 9 insertions(+)

diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c
index 98f92401942..2cb8768868b 100644
--- a/bfd/elf32-arm.c
+++ b/bfd/elf32-arm.c
@@ -14615,6 +14615,7 @@ elf32_arm_merge_eabi_attributes (bfd *ibfd, struct bfd_link_info *info)
 	case Tag_PAC_extension:
 	case Tag_BTI_extension:
 	case Tag_BTI_use:
+	case Tag_PACRET_use:
 	  /* Use the largest value specified.  */
 	  if (in_attr[i].i > out_attr[i].i)
 	    out_attr[i].i = in_attr[i].i;
diff --git a/binutils/readelf.c b/binutils/readelf.c
index 993f3160ab6..9fbb9e7a852 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -16153,6 +16153,10 @@ static const char * arm_attr_tag_BTI_use[] =
   {"Compiled without branch target enforcement",
    "Compiled with branch target enforcement"};
 
+static const char * arm_attr_tag_PACRET_use[] =
+  {"Compiled without return address signing and authentication",
+   "Compiled with return address signing and authentication"};
+
 #define LOOKUP(id, name) \
   {id, #name, 0x80 | ARRAY_SIZE(arm_attr_tag_##name), arm_attr_tag_##name}
 static arm_attr_public_tag arm_attr_public_tags[] =
@@ -16196,6 +16200,7 @@ static arm_attr_public_tag arm_attr_public_tags[] =
   LOOKUP(50, PAC_extension),
   LOOKUP(52, BTI_extension),
   LOOKUP(74, BTI_use),
+  LOOKUP(76, PACRET_use),
   {64, "nodefaults", 0, NULL},
   {65, "also_compatible_with", 0, NULL},
   LOOKUP(66, T2EE_use),
diff --git a/elfcpp/arm.h b/elfcpp/arm.h
index 12ba3fa7a1e..db549a8ee68 100644
--- a/elfcpp/arm.h
+++ b/elfcpp/arm.h
@@ -309,6 +309,7 @@ enum
   Tag_PAC_extension = 50,
   Tag_BTI_extension = 52,
   Tag_BTI_use = 74,
+  Tag_PACRET_use = 76,
   Tag_nodefaults = 64,
   Tag_also_compatible_with = 65,
   Tag_T2EE_use = 66,
diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c
index 6248adccf2d..16959fa540c 100644
--- a/gas/config/tc-arm.c
+++ b/gas/config/tc-arm.c
@@ -33562,6 +33562,7 @@ arm_convert_symbolic_attribute (const char *name)
       T (Tag_PAC_extension),
       T (Tag_BTI_extension),
       T (Tag_BTI_use),
+      T (Tag_PACRET_use),
       /* We deliberately do not include Tag_MPextension_use_legacy.  */
 #undef T
     };
diff --git a/include/elf/arm.h b/include/elf/arm.h
index 0f6e734e6d0..299f394b7ae 100644
--- a/include/elf/arm.h
+++ b/include/elf/arm.h
@@ -330,6 +330,7 @@ enum
   Tag_PAC_extension = 50,
   Tag_BTI_extension = 52,
   Tag_BTI_use = 74,
+  Tag_PACRET_use = 76,
   Tag_nodefaults = 64,
   Tag_also_compatible_with,
   Tag_T2EE_use,
-- 
2.20.1