Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 8 Mar 2018 09:13:03 +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 v2 2/7] kexec_file,x86,powerpc: factor out kexec_file_ops
 functions
Message-ID: <20180308011303.GB2600@dhcp-128-65.nay.redhat.com>
References: <20180306102303.9063-1-takahiro.akashi@linaro.org>
 <20180306102303.9063-3-takahiro.akashi@linaro.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20180306102303.9063-3-takahiro.akashi@linaro.org>
User-Agent: Mutt/1.9.1 (2017-09-22)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 03/06/18 at 07:22pm, 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                       | 13 +++----
>  kernel/kexec_file.c                         | 60 +++++++++++++++++++++++++++--
>  8 files changed, 71 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..3a962c87149a 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_image_probe_default(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..4ed18cc718fc 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -135,6 +135,11 @@ struct kexec_file_ops {
>  #endif
>  };
>  
> +extern const struct kexec_file_ops * const kexec_file_loaders[];
> +
> +int kexec_image_probe_default(struct kimage *image, void *buf,
> +			      unsigned long buf_len);
> +
>  /**
>   * struct kexec_buf - parameters for finding a place for a buffer in memory
>   * @image:	kexec image in which memory to search.
> @@ -209,7 +214,7 @@ struct kimage {
>  	unsigned long cmdline_buf_len;
>  
>  	/* File operations provided by image loader */
> -	struct kexec_file_ops *fops;
> +	const struct kexec_file_ops *fops;
>  
>  	/* Image loader handling the kernel can store a pointer here */
>  	void *image_loader_data;
> @@ -277,12 +282,6 @@ int crash_shrink_memory(unsigned long new_size);
>  size_t crash_get_memory_size(void);
>  void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);
>  
> -int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> -					 unsigned long buf_len);
> -void * __weak arch_kexec_kernel_image_load(struct kimage *image);
> -int __weak arch_kimage_file_post_load_cleanup(struct kimage *image);
> -int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> -					unsigned long buf_len);
>  int __weak arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr,
>  					Elf_Shdr *sechdrs, unsigned int relsec);
>  int __weak arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 6dbbb89cbbac..6a62c5ef8a07 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -28,28 +28,80 @@
>  
>  static int kexec_calculate_store_digests(struct kimage *image);
>  
> +/*
> + * Currently this is the only default function that is exported as some
> + * architectures need it to do additional handlings.
> + * In the future, other default functions may be exported too if required.
> + */
> +int kexec_image_probe_default(struct kimage *image, void *buf,
> +			      unsigned long buf_len)
> +{
> +	const struct kexec_file_ops * const *fops;
> +	int ret = -ENOEXEC;
> +
> +	for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
> +		ret = (*fops)->probe(buf, buf_len);
> +		if (!ret) {
> +			image->fops = *fops;
> +			return ret;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
>  /* Architectures can provide this probe function */
>  int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
>  					 unsigned long buf_len)
>  {
> -	return -ENOEXEC;
> +	return kexec_image_probe_default(image, buf, buf_len);
> +}
> +
> +static void *kexec_image_load_default(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);
>  }
>  
>  void * __weak arch_kexec_kernel_image_load(struct kimage *image)
>  {
> -	return ERR_PTR(-ENOEXEC);
> +	return kexec_image_load_default(image);
> +}
> +
> +static int kexec_image_post_load_cleanup_default(struct kimage *image)
> +{
> +	if (!image->fops || !image->fops->cleanup)
> +		return 0;
> +
> +	return image->fops->cleanup(image->image_loader_data);
>  }
>  
>  int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
>  {
> -	return -EINVAL;
> +	return kexec_image_post_load_cleanup_default(image);
>  }
>  
>  #ifdef CONFIG_KEXEC_VERIFY_SIG
> +static int kexec_image_verify_sig_default(struct kimage *image, void *buf,
> +					  unsigned long buf_len)
> +{
> +	if (!image->fops || !image->fops->verify_sig) {
> +		pr_debug("kernel loader does not support signature verification.\n");
> +		return -EKEYREJECTED;
> +	}
> +
> +	return image->fops->verify_sig(buf, buf_len);
> +}
> +
>  int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
>  					unsigned long buf_len)
>  {
> -	return -EKEYREJECTED;
> +	return kexec_image_verify_sig_default(image, buf, buf_len);
>  }
>  #endif
>  
> -- 
> 2.16.2
> 

For this patch it also needs some review from powerpc people. 

Thanks
Dave