linux-kernel - Re: [PATCH v4 1/9] kexec_file: Allow arch-specific memory walking for kexec_add

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Message-ID: <20160711032115.GB2850@dhcp-128-65.nay.redhat.com>
Date:	Mon, 11 Jul 2016 11:21:15 +0800
From:	Dave Young <dyoung@...hat.com>
To:	Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
Cc:	linuxppc-dev@...ts.ozlabs.org, kexec@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Eric Biederman <ebiederm@...ssion.com>
Subject: Re: [PATCH v4 1/9] kexec_file: Allow arch-specific memory walking
 for kexec_add_buffer

On 07/07/16 at 01:23pm, Thiago Jung Bauermann wrote:
> Allow architectures to specify a different memory walking function for
> kexec_add_buffer. x86 uses iomem to track reserved memory ranges, but
> PowerPC uses the memblock subsystem.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@...ssion.com>
> Cc: Dave Young <dyoung@...hat.com>
> ---
>  include/linux/kexec.h   | 29 ++++++++++++++++++++++++++++-
>  kernel/kexec_file.c     | 30 ++++++++++++++++++++++--------
>  kernel/kexec_internal.h | 16 ----------------
>  3 files changed, 50 insertions(+), 25 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index e8acb2b43dd9..2549a99a748c 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -146,7 +146,34 @@ struct kexec_file_ops {
>  	kexec_verify_sig_t *verify_sig;
>  #endif
>  };
> -#endif
> +
> +/**
> + * struct kexec_buf - parameters for finding a place for a buffer in memory
> + * @image:	kexec image in which memory to search.
> + * @buffer:	Contents which will be copied to the allocated memory.
> + * @bufsz:	Size of @buffer.
> + * @mem:	On return will have address of the buffer in memory.
> + * @memsz:	Size for the buffer in memory.
> + * @buf_align:	Minimum alignment needed.
> + * @buf_min:	The buffer can't be placed below this address.
> + * @buf_max:	The buffer can't be placed above this address.
> + * @top_down:	Allocate from top of memory.
> + */
> +struct kexec_buf {
> +	struct kimage *image;
> +	char *buffer;
> +	unsigned long bufsz;
> +	unsigned long mem;
> +	unsigned long memsz;
> +	unsigned long buf_align;
> +	unsigned long buf_min;
> +	unsigned long buf_max;
> +	bool top_down;
> +};
> +
> +int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
> +			       int (*func)(u64, u64, void *));
> +#endif /* CONFIG_KEXEC_FILE */
>  
>  struct kimage {
>  	kimage_entry_t head;
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 01ab82a40d22..9c0c565a08db 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
>  	return locate_mem_hole_bottom_up(start, end, kbuf);
>  }
>  
> +/**
> + * arch_kexec_walk_mem - call func(data) on free memory regions
> + * @kbuf:	Context info for the search. Also passed to @func.
> + * @func:	Function to call for each memory region.
> + *
> + * Return: The memory walk will stop when func returns a non-zero value
> + * and that value will be returned. If all free regions are visited without
> + * func returning non-zero, then zero will be returned.
> + */
> +int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
> +			       int (*func)(u64, u64, void *))
> +{
> +	if (kbuf->image->type == KEXEC_TYPE_CRASH)
> +		return walk_iomem_res_desc(crashk_res.desc,
> +					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
> +					   crashk_res.start, crashk_res.end,
> +					   kbuf, func);
> +	else
> +		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
> +}
> +
>  /*
>   * Helper function for placing a buffer in a kexec segment. This assumes
>   * that kexec_mutex is held.
> @@ -474,14 +495,7 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  	kbuf->top_down = top_down;
>  
>  	/* Walk the RAM ranges and allocate a suitable range for the buffer */
> -	if (image->type == KEXEC_TYPE_CRASH)
> -		ret = walk_iomem_res_desc(crashk_res.desc,
> -				IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
> -				crashk_res.start, crashk_res.end, kbuf,
> -				locate_mem_hole_callback);
> -	else
> -		ret = walk_system_ram_res(0, -1, kbuf,
> -					  locate_mem_hole_callback);
> +	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
>  	if (ret != 1) {
>  		/* A suitable memory range could not be found for buffer */
>  		return -EADDRNOTAVAIL;
> diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
> index 0a52315d9c62..4cef7e4706b0 100644
> --- a/kernel/kexec_internal.h
> +++ b/kernel/kexec_internal.h
> @@ -20,22 +20,6 @@ struct kexec_sha_region {
>  	unsigned long len;
>  };
>  
> -/*
> - * Keeps track of buffer parameters as provided by caller for requesting
> - * memory placement of buffer.
> - */
> -struct kexec_buf {
> -	struct kimage *image;
> -	char *buffer;
> -	unsigned long bufsz;
> -	unsigned long mem;
> -	unsigned long memsz;
> -	unsigned long buf_align;
> -	unsigned long buf_min;
> -	unsigned long buf_max;
> -	bool top_down;		/* allocate from top of memory hole */
> -};
> -
>  void kimage_file_post_load_cleanup(struct kimage *image);
>  #else /* CONFIG_KEXEC_FILE */
>  static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
> -- 
> 1.9.1
> 

Acked-by: Dave Young <dyoung@...hat.com>

Thanks
Dave