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Date:   Fri, 2 Mar 2018 13:04:26 +0800
From:   Dave Young <dyoung@redhat.com>
To:     AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc:     vgoyal@redhat.com, bhe@redhat.com, mpe@ellerman.id.au,
        bauerman@linux.vnet.ibm.com, prudo@linux.vnet.ibm.com,
        kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org
Subject: Re: [PATCH 2/7] kexec_file,x86,powerpc: factor out kexec_file_ops
 functions
Message-ID: <20180302050426.GA2952@dhcp-128-65.nay.redhat.com>
References: <20180227044814.24808-1-takahiro.akashi@linaro.org>
 <20180227044814.24808-3-takahiro.akashi@linaro.org>
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On 02/27/18 at 01:48pm, AKASHI Takahiro wrote:
> As arch_kexec_kernel_image_{probe,load}(),
> arch_kimage_file_post_load_cleanup() and arch_kexec_kernel_verify_sig()
> are almost duplicated among architectures, they can be commonalized with
> an architecture-defined kexec_file_ops array. So let's factor them out.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: Vivek Goyal <vgoyal@redhat.com>
> Cc: Baoquan He <bhe@redhat.com>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/kexec.h            |  2 +-
>  arch/powerpc/kernel/kexec_elf_64.c          |  2 +-
>  arch/powerpc/kernel/machine_kexec_file_64.c | 39 ++------------------
>  arch/x86/include/asm/kexec-bzimage64.h      |  2 +-
>  arch/x86/kernel/kexec-bzimage64.c           |  2 +-
>  arch/x86/kernel/machine_kexec_64.c          | 45 ++---------------------
>  include/linux/kexec.h                       | 17 +++++----
>  kernel/kexec_file.c                         | 55 ++++++++++++++++++++++++++---
>  8 files changed, 70 insertions(+), 94 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
> index d8b1e8e7e035..4a585cba1787 100644
> --- a/arch/powerpc/include/asm/kexec.h
> +++ b/arch/powerpc/include/asm/kexec.h
> @@ -95,7 +95,7 @@ static inline bool kdump_in_progress(void)
>  }
>  
>  #ifdef CONFIG_KEXEC_FILE
> -extern struct kexec_file_ops kexec_elf64_ops;
> +extern const struct kexec_file_ops kexec_elf64_ops;
>  
>  #ifdef CONFIG_IMA_KEXEC
>  #define ARCH_HAS_KIMAGE_ARCH
> diff --git a/arch/powerpc/kernel/kexec_elf_64.c b/arch/powerpc/kernel/kexec_elf_64.c
> index 9a42309b091a..6c78c11c7faf 100644
> --- a/arch/powerpc/kernel/kexec_elf_64.c
> +++ b/arch/powerpc/kernel/kexec_elf_64.c
> @@ -657,7 +657,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
>  	return ret ? ERR_PTR(ret) : fdt;
>  }
>  
> -struct kexec_file_ops kexec_elf64_ops = {
> +const struct kexec_file_ops kexec_elf64_ops = {
>  	.probe = elf64_probe,
>  	.load = elf64_load,
>  };
> diff --git a/arch/powerpc/kernel/machine_kexec_file_64.c b/arch/powerpc/kernel/machine_kexec_file_64.c
> index e4395f937d63..a27ec647350c 100644
> --- a/arch/powerpc/kernel/machine_kexec_file_64.c
> +++ b/arch/powerpc/kernel/machine_kexec_file_64.c
> @@ -31,52 +31,19 @@
>  
>  #define SLAVE_CODE_SIZE		256
>  
> -static struct kexec_file_ops *kexec_file_loaders[] = {
> +const struct kexec_file_ops * const kexec_file_loaders[] = {
>  	&kexec_elf64_ops,
> +	NULL
>  };
>  
>  int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
>  				  unsigned long buf_len)
>  {
> -	int i, ret = -ENOEXEC;
> -	struct kexec_file_ops *fops;
> -
>  	/* We don't support crash kernels yet. */
>  	if (image->type == KEXEC_TYPE_CRASH)
>  		return -ENOTSUPP;
>  
> -	for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
> -		fops = kexec_file_loaders[i];
> -		if (!fops || !fops->probe)
> -			continue;
> -
> -		ret = fops->probe(buf, buf_len);
> -		if (!ret) {
> -			image->fops = fops;
> -			return ret;
> -		}
> -	}
> -
> -	return ret;
> -}
> -
> -void *arch_kexec_kernel_image_load(struct kimage *image)
> -{
> -	if (!image->fops || !image->fops->load)
> -		return ERR_PTR(-ENOEXEC);
> -
> -	return image->fops->load(image, image->kernel_buf,
> -				 image->kernel_buf_len, image->initrd_buf,
> -				 image->initrd_buf_len, image->cmdline_buf,
> -				 image->cmdline_buf_len);
> -}
> -
> -int arch_kimage_file_post_load_cleanup(struct kimage *image)
> -{
> -	if (!image->fops || !image->fops->cleanup)
> -		return 0;
> -
> -	return image->fops->cleanup(image->image_loader_data);
> +	return _kexec_kernel_image_probe(image, buf, buf_len);
>  }
>  
>  /**
> diff --git a/arch/x86/include/asm/kexec-bzimage64.h b/arch/x86/include/asm/kexec-bzimage64.h
> index 9f07cff43705..df89ee7d3e9e 100644
> --- a/arch/x86/include/asm/kexec-bzimage64.h
> +++ b/arch/x86/include/asm/kexec-bzimage64.h
> @@ -2,6 +2,6 @@
>  #ifndef _ASM_KEXEC_BZIMAGE64_H
>  #define _ASM_KEXEC_BZIMAGE64_H
>  
> -extern struct kexec_file_ops kexec_bzImage64_ops;
> +extern const struct kexec_file_ops kexec_bzImage64_ops;
>  
>  #endif  /* _ASM_KEXE_BZIMAGE64_H */
> diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> index fb095ba0c02f..705654776c0c 100644
> --- a/arch/x86/kernel/kexec-bzimage64.c
> +++ b/arch/x86/kernel/kexec-bzimage64.c
> @@ -538,7 +538,7 @@ static int bzImage64_verify_sig(const char *kernel, unsigned long kernel_len)
>  }
>  #endif
>  
> -struct kexec_file_ops kexec_bzImage64_ops = {
> +const struct kexec_file_ops kexec_bzImage64_ops = {
>  	.probe = bzImage64_probe,
>  	.load = bzImage64_load,
>  	.cleanup = bzImage64_cleanup,
> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
> index 1f790cf9d38f..2cdd29d64181 100644
> --- a/arch/x86/kernel/machine_kexec_64.c
> +++ b/arch/x86/kernel/machine_kexec_64.c
> @@ -30,8 +30,9 @@
>  #include <asm/set_memory.h>
>  
>  #ifdef CONFIG_KEXEC_FILE
> -static struct kexec_file_ops *kexec_file_loaders[] = {
> +const struct kexec_file_ops * const kexec_file_loaders[] = {
>  		&kexec_bzImage64_ops,
> +		NULL
>  };
>  #endif
>  
> @@ -363,27 +364,6 @@ void arch_crash_save_vmcoreinfo(void)
>  /* arch-dependent functionality related to kexec file-based syscall */
>  
>  #ifdef CONFIG_KEXEC_FILE
> -int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> -				  unsigned long buf_len)
> -{
> -	int i, ret = -ENOEXEC;
> -	struct kexec_file_ops *fops;
> -
> -	for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
> -		fops = kexec_file_loaders[i];
> -		if (!fops || !fops->probe)
> -			continue;
> -
> -		ret = fops->probe(buf, buf_len);
> -		if (!ret) {
> -			image->fops = fops;
> -			return ret;
> -		}
> -	}
> -
> -	return ret;
> -}
> -
>  void *arch_kexec_kernel_image_load(struct kimage *image)
>  {
>  	vfree(image->arch.elf_headers);
> @@ -398,27 +378,6 @@ void *arch_kexec_kernel_image_load(struct kimage *image)
>  				 image->cmdline_buf_len);
>  }
>  
> -int arch_kimage_file_post_load_cleanup(struct kimage *image)
> -{
> -	if (!image->fops || !image->fops->cleanup)
> -		return 0;
> -
> -	return image->fops->cleanup(image->image_loader_data);
> -}
> -
> -#ifdef CONFIG_KEXEC_VERIFY_SIG
> -int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
> -				 unsigned long kernel_len)
> -{
> -	if (!image->fops || !image->fops->verify_sig) {
> -		pr_debug("kernel loader does not support signature verification.");
> -		return -EKEYREJECTED;
> -	}
> -
> -	return image->fops->verify_sig(kernel, kernel_len);
> -}
> -#endif
> -
>  /*
>   * Apply purgatory relocations.
>   *
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index f16f6ceb3875..2e095c3b4537 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -159,6 +159,15 @@ struct kexec_buf {
>  	bool top_down;
>  };
>  
> +extern const struct kexec_file_ops * const kexec_file_loaders[];
> +
> +int _kexec_kernel_image_probe(struct kimage *image, void *buf,
> +			      unsigned long buf_len);
> +void *_kexec_kernel_image_load(struct kimage *image);
> +int _kimage_file_post_load_cleanup(struct kimage *image);
> +int _kexec_kernel_verify_sig(struct kimage *image, void *buf,
> +			     unsigned long buf_len);

AKASHI, since the above 3 functions nobody else used, suppose it is for
future use, they can be made static for now.  Later if someone needs
they can remove the static easily.

> +}
> +
>  int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
>  					unsigned long buf_len)
>  {
> -	return -EKEYREJECTED;
> +	return _kexec_kernel_verify_sig(image, buf, buf_len);
>  }
>  #endif
>  
> -- 
> 2.16.2
> 

Thanks
Dave