Hi Christophe,
On 10/08/22 14:01, Christophe Leroy wrote:
Le 08/08/2022 à 13:48, Sathvika Vasireddy a écrit :
Since we need an alignment of 4 bytes, override
__ALIGN() and __ALIGN_STR() accordingly.
Why/When do we now need an alignment of 4 bytes ? Please explain the
reason in the commit message.
Powerpc instructions must be word-aligned. Currently, there is an
alignment of 16 bytes (by default),
and it is much more than what is required for powerpc (4 bytes).
The default expansion of these macros are:
#define __ALIGN .align 4,0x90
#define __ALIGN_STR ".align 4,0x90"
Since Powerpc Linux does not require a 16 byte alignment, override
_ALIGN() and __ALIGN_STR() macros
to use required 4 byte alignment.
Sure, I'll explain the reason in commit message.
Signed-off-by: Sathvika Vasireddy <s...@linux.ibm.com>
---
arch/powerpc/include/asm/linkage.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/powerpc/include/asm/linkage.h
b/arch/powerpc/include/asm/linkage.h
index b71b9582e754..8df88fe61438 100644
--- a/arch/powerpc/include/asm/linkage.h
+++ b/arch/powerpc/include/asm/linkage.h
@@ -2,8 +2,12 @@
#ifndef _ASM_POWERPC_LINKAGE_H
#define _ASM_POWERPC_LINKAGE_H
+#include <linux/stringify.h>
#include <asm/types.h>
+#define __ALIGN .align 2
+#define __ALIGN_STR __stringify(__ALIGN)
Why do you need to use __stringify ?
ARM64 does:
#define __ALIGN .align 2
#define __ALIGN_STR ".align 2"
We could use either __stringify() or quotes, both do the same thing.
While arm64 does ".align 2",
x86 does:
#define __ALIGN .p2align 4, 0x90
#define __ALIGN_STR __stringify(__ALIGN)
+
#ifdef CONFIG_PPC64_ELF_ABI_V1
#define cond_syscall(x) \
asm ("\t.weak " #x "\n\t.set " #x ", sys_ni_syscall\n" \
Thanks for reviewing!
- Sathvika
