[PATCH 9/12 V2] arm: Make libgcc bti compatible

[Andrea Corallo via Gcc-patches]

Richard Earnshaw <richard.earns...@foss.arm.com> writes:

> On 28/04/2022 10:48, Andrea Corallo via Gcc-patches wrote:
>> This change add bti instructions at the beginning of arm specific
>> libgcc hand written assembly routines.
>> 2022-03-31  Andrea Corallo  <andrea.cora...@arm.com>
>>      * libgcc/config/arm/crti.S (FUNC_START): Add bti instruction
>> if
>>      necessary.
>>      * libgcc/config/arm/lib1funcs.S (THUMB_FUNC_START, FUNC_START):
>>      Likewise.
>> 
>
> +#if defined(__ARM_FEATURE_BTI)
>
> Wouldn't it be better to use __ARM_FEATURE_BTI_DEFAULT?  That way we
> only get BTI instructions in multilib variants that have asked for
> BTI.
>
> R.

Hi Richard,

good point, yes I think so.

Please find attached the updated patch.

BR

  Andrea


>From 6975c9ddbc8a4b790a765589c6fd07fea92173e5 Mon Sep 17 00:00:00 2001
From: Andrea Corallo <andrea.cora...@arm.com>
Date: Tue, 8 Feb 2022 10:58:31 +0100
Subject: [PATCH] [PATCH 9/12] arm: Make libgcc bti compatible

This change add bti instructions at the beginning of arm specific
libgcc hand written assembly routines.

2022-03-31  Andrea Corallo  <andrea.cora...@arm.com>

        * libgcc/config/arm/crti.S (FUNC_START): Add bti instruction if
        necessary.
        * libgcc/config/arm/lib1funcs.S (THUMB_FUNC_START, FUNC_START):
        Likewise.
---
 libgcc/config/arm/crti.S      | 4 +++-
 libgcc/config/arm/lib1funcs.S | 6 ++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/libgcc/config/arm/crti.S b/libgcc/config/arm/crti.S
index 0192972a7e6..4098353af1c 100644
--- a/libgcc/config/arm/crti.S
+++ b/libgcc/config/arm/crti.S
@@ -51,7 +51,9 @@
 .macro FUNC_START
 #ifdef __thumb__
        .thumb
-       
+#if defined(__ARM_FEATURE_BTI_DEFAULT)
+       bti
+#endif
        push    {r3, r4, r5, r6, r7, lr}
 #else
        .arm
diff --git a/libgcc/config/arm/lib1funcs.S b/libgcc/config/arm/lib1funcs.S
index 8c39c9f20a2..de98edcc300 100644
--- a/libgcc/config/arm/lib1funcs.S
+++ b/libgcc/config/arm/lib1funcs.S
@@ -345,6 +345,9 @@ LSYM(Ldiv0):
        TYPE    (\name)
        .thumb_func
 SYM (\name):
+#if defined(__ARM_FEATURE_BTI_DEFAULT)
+       bti
+#endif
 .endm
 
 /* Function start macros.  Variants for ARM and Thumb.  */
@@ -372,6 +375,9 @@ SYM (\name):
        THUMB_FUNC
        THUMB_SYNTAX
 SYM (__\name):
+#if defined(__ARM_FEATURE_BTI_DEFAULT)
+       bti
+#endif
 .endm
 
 .macro ARM_SYM_START name
-- 
2.25.1