diff mbox series

[v2] AArch64: Reset HWCAP2_AFP bits in FPCR for default fenv

Message ID 20220705103524.18268-1-tejas.belagod@arm.com
State Committed
Commit 05844d18f7893bf96965f163c428214fd5ebe10a
Headers
Series [v2] AArch64: Reset HWCAP2_AFP bits in FPCR for default fenv |

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent
dj/TryBot-32bit success Build for i686

Commit Message

Tejas Belagod July 5, 2022, 10:35 a.m. UTC 
  The AFP feature (Alternate floating-point behavior) was added in armv8.7 and
introduced new FPCR bits.

Currently, HWCAP2_AFP bits (bit 0, 1, 2) in FPCR are preserved when fenv is
set to default environment.  This is a deviation from standard behaviour.
Clear these bits when setting the fenv to default.

There is no libc API to modify the new FPCR bits.  Restoring those bits matters
if the user changed them directly.
---
 sysdeps/aarch64/fpu/fpu_control.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Szabolcs Nagy July 5, 2022, 1:04 p.m. UTC | #1 
The 07/05/2022 11:35, Tejas Belagod wrote:
> The AFP feature (Alternate floating-point behavior) was added in armv8.7 and
> introduced new FPCR bits.
> 
> Currently, HWCAP2_AFP bits (bit 0, 1, 2) in FPCR are preserved when fenv is
> set to default environment.  This is a deviation from standard behaviour.
> Clear these bits when setting the fenv to default.
> 
> There is no libc API to modify the new FPCR bits.  Restoring those bits matters
> if the user changed them directly.

thanks.
this looks ok, committed it for you.

> ---
>  sysdeps/aarch64/fpu/fpu_control.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sysdeps/aarch64/fpu/fpu_control.h b/sysdeps/aarch64/fpu/fpu_control.h
> index 764ed5cdbb..429f4910e7 100644
> --- a/sysdeps/aarch64/fpu/fpu_control.h
> +++ b/sysdeps/aarch64/fpu/fpu_control.h
> @@ -46,7 +46,7 @@
>     contents. These two masks indicate which bits in each of FPCR and
>     FPSR should not be changed.  */
>  
> -#define _FPU_RESERVED		0xfe0fe0ff
> +#define _FPU_RESERVED		0xfe0fe0f8
>  #define _FPU_FPSR_RESERVED	0x0fffffe0
>  
>  #define _FPU_DEFAULT		0x00000000
> -- 
> 2.17.1
>
diff mbox series

Patch

diff --git a/sysdeps/aarch64/fpu/fpu_control.h b/sysdeps/aarch64/fpu/fpu_control.h
index 764ed5cdbb..429f4910e7 100644
--- a/sysdeps/aarch64/fpu/fpu_control.h
+++ b/sysdeps/aarch64/fpu/fpu_control.h
@@ -46,7 +46,7 @@ 
    contents. These two masks indicate which bits in each of FPCR and
    FPSR should not be changed.  */
 
-#define _FPU_RESERVED		0xfe0fe0ff
+#define _FPU_RESERVED		0xfe0fe0f8
 #define _FPU_FPSR_RESERVED	0x0fffffe0
 
 #define _FPU_DEFAULT		0x00000000