2020-03-11 16:29:03

by Eugeniy Paltsev

Subject: [PATCH 1/2] ARC: define __ALIGN_STR and __ALIGN symbols for ARC

As of today ARC uses generic __ALIGN_STR and __ALIGN symbol
definitions from "include/linux/linkage.h"
They are defined to ".align 4,0x90" which instructed the assembler
to use `0x90` as a fill byte when aligning functions declared with
ENTRY or similar macroses. This leads to generated weird instructions
in code (when alignment is used) like "ldh_s r12,[r0,0x20]" which is
encoded as 0x9090 for ARCv2.

Let's use ".align 4" which insert a "nop_s" instruction instead.

Signed-off-by: Eugeniy Paltsev <[email protected]>
---
arch/arc/include/asm/linkage.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/arc/include/asm/linkage.h b/arch/arc/include/asm/linkage.h
index d9ee43c6b7db..fe19f1d412e7 100644
--- a/arch/arc/include/asm/linkage.h
+++ b/arch/arc/include/asm/linkage.h
@@ -29,6 +29,8 @@
.endm

#define ASM_NL ` /* use '`' to mark new line in macro */
+#define __ALIGN .align 4
+#define __ALIGN_STR __stringify(__ALIGN)

/* annotation for data we want in DCCM - if enabled in .config */
.macro ARCFP_DATA nm
--
2.21.1

2020-03-11 16:38:12

by Vineet Gupta

Subject: Re: [PATCH 1/2] ARC: define __ALIGN_STR and __ALIGN symbols for ARC

On 3/11/20 9:26 AM, Eugeniy Paltsev wrote:
> As of today ARC uses generic __ALIGN_STR and __ALIGN symbol
> definitions from "include/linux/linkage.h"
> They are defined to ".align 4,0x90" which instructed the assembler
> to use `0x90` as a fill byte when aligning functions declared with
> ENTRY or similar macroses. This leads to generated weird instructions
> in code (when alignment is used) like "ldh_s r12,[r0,0x20]" which is
> encoded as 0x9090 for ARCv2.
>
> Let's use ".align 4" which insert a "nop_s" instruction instead.
>
> Signed-off-by: Eugeniy Paltsev <[email protected]>

Acked-by: Vineet Gupta <[email protected]>

-Vineet