diff mbox series

AArch64: Remove zva_128 from memset

Message ID PAWPR08MB8982D282C63421DE9232C0EB832F2@PAWPR08MB8982.eurprd08.prod.outlook.com
State New
Headers show
Series AArch64: Remove zva_128 from memset | expand

Commit Message

Wilco Dijkstra Nov. 26, 2024, 11:49 p.m. UTC 
Remove ZVA 128 support from memset - the new memset no longer
guarantees count >= 256, which can result in underflow and a
crash if ZVA size is 128 ([1]).  Since only one CPU uses a ZVA
size of 128 and its memcpy implementation was removed in commit
e162ab2bf1b82c40f29e1925986582fa07568ce8, remove this special
case too.

Passes regress, OK for commit?

[1] https://sourceware.org/pipermail/libc-alpha/2024-November/161626.html

---

Comments

Andrew Pinski Nov. 26, 2024, 11:56 p.m. UTC | #1 
On Tue, Nov 26, 2024 at 3:51 PM Wilco Dijkstra <Wilco.Dijkstra@arm.com> wrote:
>
>
> Remove ZVA 128 support from memset - the new memset no longer
> guarantees count >= 256, which can result in underflow and a
> crash if ZVA size is 128 ([1]).  Since only one CPU uses a ZVA
> size of 128 and its memcpy implementation was removed in commit
> e162ab2bf1b82c40f29e1925986582fa07568ce8, remove this special
> case too.

Note the one CPU is a thunderx 1 based on reading the midr_el1. From
my point of view this is ok.

Reviewed-by: Andrew Pinski <quic_apinski@quicinc.com>

Thanks,
Andrew Pinski


>
> Passes regress, OK for commit?
>
> [1] https://sourceware.org/pipermail/libc-alpha/2024-November/161626.html
>
> ---
>
> diff --git a/sysdeps/aarch64/memset.S b/sysdeps/aarch64/memset.S
> index b76dde1557ed8fb195c24a13a06f8d0d9ab126fa..8402219b1874b00a10ea460e278edbf54c6140f6 100644
> --- a/sysdeps/aarch64/memset.S
> +++ b/sysdeps/aarch64/memset.S
> @@ -103,7 +103,7 @@ L(set_long):
>         mrs     zva_val, dczid_el0
>         and     zva_val, zva_val, 31
>         cmp     zva_val, 4              /* ZVA size is 64 bytes.  */
> -       b.ne    L(zva_128)
> +       b.ne    L(no_zva)
>  #endif
>         stp     q0, q0, [dst, 32]
>         bic     dst, dstin, 63
> @@ -136,28 +136,5 @@ L(no_zva_loop):
>         stp     q0, q0, [dstend, -32]
>         ret
>
> -#ifndef ZVA64_ONLY
> -       .p2align 4
> -L(zva_128):
> -       cmp     zva_val, 5              /* ZVA size is 128 bytes.  */
> -       b.ne    L(no_zva)
> -
> -       stp     q0, q0, [dst, 32]
> -       stp     q0, q0, [dst, 64]
> -       stp     q0, q0, [dst, 96]
> -       bic     dst, dst, 127
> -       sub     count, dstend, dst      /* Count is now 128 too large.  */
> -       sub     count, count, 128 + 128 /* Adjust count and bias for loop.  */
> -1:     add     dst, dst, 128
> -       dc      zva, dst
> -       subs    count, count, 128
> -       b.hi    1b
> -       stp     q0, q0, [dstend, -128]
> -       stp     q0, q0, [dstend, -96]
> -       stp     q0, q0, [dstend, -64]
> -       stp     q0, q0, [dstend, -32]
> -       ret
> -#endif
> -
>  END (MEMSET)
>  libc_hidden_builtin_def (MEMSET)
>
>
diff mbox series

Patch

diff --git a/sysdeps/aarch64/memset.S b/sysdeps/aarch64/memset.S
index b76dde1557ed8fb195c24a13a06f8d0d9ab126fa..8402219b1874b00a10ea460e278edbf54c6140f6 100644
--- a/sysdeps/aarch64/memset.S
+++ b/sysdeps/aarch64/memset.S
@@ -103,7 +103,7 @@  L(set_long):
 	mrs	zva_val, dczid_el0
 	and	zva_val, zva_val, 31
 	cmp	zva_val, 4		/* ZVA size is 64 bytes.  */
-	b.ne	L(zva_128)
+	b.ne	L(no_zva)
 #endif
 	stp	q0, q0, [dst, 32]
 	bic	dst, dstin, 63
@@ -136,28 +136,5 @@  L(no_zva_loop):
 	stp	q0, q0, [dstend, -32]
 	ret
 
-#ifndef ZVA64_ONLY
-	.p2align 4
-L(zva_128):
-	cmp	zva_val, 5		/* ZVA size is 128 bytes.  */
-	b.ne	L(no_zva)
-
-	stp	q0, q0, [dst, 32]
-	stp	q0, q0, [dst, 64]
-	stp	q0, q0, [dst, 96]
-	bic	dst, dst, 127
-	sub	count, dstend, dst	/* Count is now 128 too large.	*/
-	sub	count, count, 128 + 128	/* Adjust count and bias for loop.  */
-1:	add	dst, dst, 128
-	dc	zva, dst
-	subs	count, count, 128
-	b.hi	1b
-	stp	q0, q0, [dstend, -128]
-	stp	q0, q0, [dstend, -96]
-	stp	q0, q0, [dstend, -64]
-	stp	q0, q0, [dstend, -32]
-	ret
-#endif
-
 END (MEMSET)
 libc_hidden_builtin_def (MEMSET)