Thread (23 messages) 23 messages, 4 authors, 2022-11-14

Re: [PATCH v5 02/16] powerpc: Override __ALIGN and __ALIGN_STR macros

From: Christophe Leroy <hidden>
Date: 2022-11-02 12:35:24
Also in: lkml


Le 28/10/2022 à 16:33, Sathvika Vasireddy a écrit :
In a subsequent patch, we would want to annotate powerpc assembly functions
with SYM_FUNC_START_LOCAL macro. This macro depends on __ALIGN macro.

The default expansion of __ALIGN macro is:
         #define __ALIGN      .align 4,0x90

So, override __ALIGN and __ALIGN_STR macros to use the same alignment as
that of the existing _GLOBAL macro. Also, do not pad with 0x90, because
repeated 0x90s are not a nop or trap on powerpc.
By the way, do we know what the instruction 0x90909090 is on powerpc ? 
Is that something valid or not ?
quoted hunk ↗ jump to hunk
Tested-by: Naveen N. Rao <redacted>
Reviewed-by: Naveen N. Rao <redacted>
Reviewed-by: Christophe Leroy <redacted>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Sathvika Vasireddy <redacted>
---
  arch/powerpc/include/asm/linkage.h | 3 +++
  1 file changed, 3 insertions(+)
diff --git a/arch/powerpc/include/asm/linkage.h b/arch/powerpc/include/asm/linkage.h
index b71b9582e754..b88d1d2cf304 100644
--- a/arch/powerpc/include/asm/linkage.h
+++ b/arch/powerpc/include/asm/linkage.h
@@ -4,6 +4,9 @@
  
  #include <asm/types.h>
  
+#define __ALIGN		.align 2
+#define __ALIGN_STR	".align 2"
+
  #ifdef CONFIG_PPC64_ELF_ABI_V1
  #define cond_syscall(x) \
  	asm ("\t.weak " #x "\n\t.set " #x ", sys_ni_syscall\n"		\
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