Subject: Re: [PATCH 3/5] kexec: Add bit definitions for kimage entry flags

From: Vivek Goyal <[email-masked]>
Date: Mon, 25 Aug 2014 13:52:57 -0400

On Fri, Aug 22, 2014 at 06:39:47PM +0000, Geoff Levand wrote:
> Define new kexec preprocessor macros IND_*_BIT that define the bit position of
> the kimage entry flags.  Change the existing IND_* flag macros to be defined as
> bit shifts of the corresponding IND_*_BIT macros.  Also wrap all C language code
> in kexec.h with #if !defined(__ASSEMBLY__) so assembly files can include kexec.h
> to get the IND_* and IND_*_BIT macros.
> 
> Some CPU instruction sets have tests for bit position which are convenient in
> implementing routines that operate on the kimage entry list.  The addition of
> these bit position macros in a common location will avoid duplicate definitions
> and the chance that changes to the IND_* flags will not be propagated to
> assembly files.
> 
> Signed-off-by: Geoff Levand <[email-masked]>

Looks good to me.

Acked-by: Vivek Goyal <[email-masked]>

Vivek

> ---
>  include/linux/kexec.h | 19 +++++++++++++++----
>  1 file changed, 15 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 4b2a0e1..8c628ca 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -1,6 +1,18 @@
>  #ifndef LINUX_KEXEC_H
>  #define LINUX_KEXEC_H
>  
> +#define IND_DESTINATION_BIT 0
> +#define IND_INDIRECTION_BIT 1
> +#define IND_DONE_BIT        2
> +#define IND_SOURCE_BIT      3
> +
> +#define IND_DESTINATION  (1 << IND_DESTINATION_BIT)
> +#define IND_INDIRECTION  (1 << IND_INDIRECTION_BIT)
> +#define IND_DONE         (1 << IND_DONE_BIT)
> +#define IND_SOURCE       (1 << IND_SOURCE_BIT)
> +
> +#if !defined(__ASSEMBLY__)
> +
>  #include <uapi/linux/kexec.h>
>  
>  #ifdef CONFIG_KEXEC
> @@ -64,10 +76,6 @@
>   */
>  
>  typedef unsigned long kimage_entry_t;
> -#define IND_DESTINATION  0x1
> -#define IND_INDIRECTION  0x2
> -#define IND_DONE         0x4
> -#define IND_SOURCE       0x8
>  
>  struct kexec_segment {
>  	/*
> @@ -312,4 +320,7 @@ struct task_struct;
>  static inline void crash_kexec(struct pt_regs *regs) { }
>  static inline int kexec_should_crash(struct task_struct *p) { return 0; }
>  #endif /* CONFIG_KEXEC */
> +
> +#endif /* !defined(__ASSEBMLY__) */
> +
>  #endif /* LINUX_KEXEC_H */
> -- 
> 1.9.1
> 
> 
> 
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