linux-kernel - Re: [PATCH] objtool: replace _ASM

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Message-ID: <48ca5e9e-eb03-3fb1-96d0-4755e1d39c3f@huawei.com>
Date:   Wed, 24 Aug 2022 10:48:01 +0800
From:   Chen Zhongjin <chenzhongjin@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <linuxppc-dev@...ts.ozlabs.org>,
        "peterz@...radead.org" <peterz@...radead.org>
CC:     <jpoimboe@...nel.org>, <bp@...e.de>, <mhiramat@...nel.org>,
        <sv@...ux.ibm.com>, <christophe.leroy@...roup.eu>,
        <naveen.n.rao@...ux.vnet.ibm.com>
Subject: Re: [PATCH] objtool: replace _ASM_PTR with quad in macros

On 2022/8/23 21:31, Chen Zhongjin wrote:
> Macros STACK_FRAME_NON_STANDARD and ANNOTATE_NOENDBR uses
> _ASM_PTR. It switch between .long and .quad based on 32bit
> or 64bit. However objtool doesn't work for 32bit, so _ASM_PTR
> makes no sense.
>
> Considering that _ASM_PTR comes from asm.h, which is x86
> specific head file, while objtool.h is generic. Replace
> _ASM_PTR with quad and remove asm.h reference.
>
> Signed-off-by: Chen Zhongjin <chenzhongjin@...wei.com>
> ---
>   include/linux/objtool.h       | 6 ++----
>   tools/include/linux/objtool.h | 6 ++----
>   2 files changed, 4 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/objtool.h b/include/linux/objtool.h
> index 62c54ffbeeaa..d2413cb78037 100644
> --- a/include/linux/objtool.h
> +++ b/include/linux/objtool.h
> @@ -45,8 +45,6 @@ struct unwind_hint {
>   
>   #ifdef CONFIG_OBJTOOL
>   
> -#include <asm/asm.h>
> -
>   #ifndef __ASSEMBLY__
>   
>   #define UNWIND_HINT(sp_reg, sp_offset, type, end)		\
> @@ -87,7 +85,7 @@ struct unwind_hint {
>   #define ANNOTATE_NOENDBR					\
>   	"986: \n\t"						\
>   	".pushsection .discard.noendbr\n\t"			\
> -	_ASM_PTR " 986b\n\t"					\
> +	".quad 986b\n\t"					\
>   	".popsection\n\t"
>   
>   #define ASM_REACHABLE							\
> @@ -144,7 +142,7 @@ struct unwind_hint {
>   
>   .macro STACK_FRAME_NON_STANDARD func:req
>   	.pushsection .discard.func_stack_frame_non_standard, "aw"
> -	_ASM_PTR \func
> +	.quad \func
>   	.popsection
>   .endm
>   
> diff --git a/tools/include/linux/objtool.h b/tools/include/linux/objtool.h
> index 62c54ffbeeaa..d2413cb78037 100644
> --- a/tools/include/linux/objtool.h
> +++ b/tools/include/linux/objtool.h
> @@ -45,8 +45,6 @@ struct unwind_hint {
>   
>   #ifdef CONFIG_OBJTOOL
>   
> -#include <asm/asm.h>
> -
>   #ifndef __ASSEMBLY__
>   
>   #define UNWIND_HINT(sp_reg, sp_offset, type, end)		\
> @@ -87,7 +85,7 @@ struct unwind_hint {
>   #define ANNOTATE_NOENDBR					\
>   	"986: \n\t"						\
>   	".pushsection .discard.noendbr\n\t"			\
> -	_ASM_PTR " 986b\n\t"					\
> +	".quad 986b\n\t"					\
>   	".popsection\n\t"
>   
>   #define ASM_REACHABLE							\
> @@ -144,7 +142,7 @@ struct unwind_hint {
>   
>   .macro STACK_FRAME_NON_STANDARD func:req
>   	.pushsection .discard.func_stack_frame_non_standard, "aw"
> -	_ASM_PTR \func
> +	.quad \func
>   	.popsection
>   .endm
>   

As ppc said they will use objtool for both 32 and 64bit, maybe we still 
need a switchable symbol type for this.

How about this one?


diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index 62c54ffbeeaa..14af2bcc460b 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -45,10 +45,14 @@ struct unwind_hint {

  #ifdef CONFIG_OBJTOOL

-#include <asm/asm.h>
-
  #ifndef __ASSEMBLY__

+#ifdef CONFIG_64BIT
+#define _RELOC_PTR __stringify(.quad)
+#else
+#define _RELOC_PTR __stringify(.long)
+#endif
+
  #define UNWIND_HINT(sp_reg, sp_offset, type, end)              \
         "987: \n\t"                                             \
         ".pushsection .discard.unwind_hints\n\t"                \
@@ -87,7 +91,7 @@ struct unwind_hint {
  #define ANNOTATE_NOENDBR                                       \
         "986: \n\t"                                             \
         ".pushsection .discard.noendbr\n\t"                     \
-       _ASM_PTR " 986b\n\t"                                    \
+       _RELOC_PTR " 986b\n\t"                                  \
         ".popsection\n\t"

  #define ASM_REACHABLE                                                  \
@@ -98,6 +102,12 @@ struct unwind_hint {

  #else /* __ASSEMBLY__ */

+#ifdef CONFIG_64BIT
+#define _RELOC_PTR .quad
+#else
+#define _RELOC_PTR .long
+#endif
+
  /*
   * This macro indicates that the following intra-function call is valid.
   * Any non-annotated intra-function call will cause objtool to issue a 
warning.
@@ -144,7 +154,7 @@ struct unwind_hint {

  .macro STACK_FRAME_NON_STANDARD func:req
         .pushsection .discard.func_stack_frame_non_standard, "aw"
-       _ASM_PTR \func
+       _RELOC_PTR \func
         .popsection
  .endm