Message-ID: <20170921073516.GA6643@dhcp-128-65.nay.redhat.com>
Date:   Thu, 21 Sep 2017 15:35:16 +0800
From:   Dave Young <dyoung@...hat.com>
To:     AKASHI Takahiro <takahiro.akashi@...aro.org>
Cc:     catalin.marinas@....com, will.deacon@....com,
        bauerman@...ux.vnet.ibm.com, dhowells@...hat.com,
        vgoyal@...hat.com, herbert@...dor.apana.org.au,
        davem@...emloft.net, akpm@...ux-foundation.org, mpe@...erman.id.au,
        bhe@...hat.com, arnd@...db.de, ard.biesheuvel@...aro.org,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 03/10] kexec_file: factor out arch_kexec_kernel_*()
 from x86, powerpc

Hi AKASHI,
On 09/15/17 at 07:59pm, AKASHI Takahiro wrote:
> arch_kexec_kernel_*() and arch_kimage_file_post_load_cleanup can now be
> duplicated among some architectures, so let's factor them out.
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
> Cc: Dave Young <dyoung@...hat.com>
> Cc: Vivek Goyal <vgoyal@...hat.com>
> Cc: Baoquan He <bhe@...hat.com>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Thiago Jung Bauermann <bauerman@...ux.vnet.ibm.com>
> ---
>  arch/powerpc/include/asm/kexec.h            |  4 ++
>  arch/powerpc/kernel/machine_kexec_file_64.c | 36 ++----------------
>  arch/x86/kernel/machine_kexec_64.c          | 59 +----------------------------
>  include/linux/kexec.h                       | 26 ++++++++++---
>  kernel/kexec_file.c                         | 52 +++++++++++++++++++------
>  5 files changed, 70 insertions(+), 107 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h
> index 25668bc8cb2a..50810d24e38f 100644
> --- a/arch/powerpc/include/asm/kexec.h
> +++ b/arch/powerpc/include/asm/kexec.h
> @@ -94,6 +94,10 @@ static inline bool kdump_in_progress(void)
>  #ifdef CONFIG_KEXEC_FILE
>  extern struct kexec_file_ops kexec_elf64_ops;
>  
> +#define arch_kexec_kernel_image_probe arch_kexec_kernel_image_probe
> +int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> +				  unsigned long buf_len);
> +
>  #ifdef CONFIG_IMA_KEXEC
>  #define ARCH_HAS_KIMAGE_ARCH
>  
> diff --git a/arch/powerpc/kernel/machine_kexec_file_64.c b/arch/powerpc/kernel/machine_kexec_file_64.c
> index 992c0d258e5d..5b7c4a3fbb50 100644
> --- a/arch/powerpc/kernel/machine_kexec_file_64.c
> +++ b/arch/powerpc/kernel/machine_kexec_file_64.c
> @@ -31,8 +31,9 @@
>  
>  #define SLAVE_CODE_SIZE		256
>  
> -static struct kexec_file_ops *kexec_file_loaders[] = {
> +struct kexec_file_ops *kexec_file_loaders[] = {
>  	&kexec_elf64_ops,
> +	NULL
>  };
>  
>  int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> @@ -45,38 +46,7 @@ int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
>  	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/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
> index cb0a30473c23..f4df8315d001 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[] = {
> +struct kexec_file_ops *kexec_file_loaders[] = {
>  		&kexec_bzImage64_ops,
> +		NULL
>  };
>  #endif
>  
> @@ -361,62 +362,6 @@ 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);
> -	image->arch.elf_headers = NULL;
> -
> -	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);
> -}
> -
> -#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 dd056fab9e35..4a2b24d94e04 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -134,6 +134,26 @@ struct kexec_file_ops {
>  #endif
>  };
>  
> +int kexec_kernel_image_probe(struct kimage *image, void *buf,
> +			     unsigned long buf_len);
> +void *kexec_kernel_image_load(struct kimage *image);
> +int kexec_kernel_post_load_cleanup(struct kimage *image);
> +int kexec_kernel_verify_sig(struct kimage *image, void *buf,
> +			    unsigned long buf_len);
> +
> +#ifndef arch_kexec_kernel_image_probe
> +#define arch_kexec_kernel_image_probe kexec_kernel_image_probe
> +#endif
> +#ifndef arch_kexec_kernel_image_load
> +#define arch_kexec_kernel_image_load kexec_kernel_image_load
> +#endif
> +#ifndef arch_kimage_file_post_load_cleanup
> +#define arch_kimage_file_post_load_cleanup kexec_kernel_post_load_cleanup
> +#endif
> +#ifndef arch_kexec_kernel_verify_sig
> +#define arch_kexec_kernel_verify_sig kexec_kernel_verify_sig
> +#endif
> +
>  /**
>   * struct kexec_buf - parameters for finding a place for a buffer in memory
>   * @image:	kexec image in which memory to search.
> @@ -276,12 +296,6 @@ 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);

I thought we can keep using the __weak function in common code and drop
the arch functions, no need the #ifndef arch_kexec_kernel_image_probe
and the function renaming stuff.  But I did not notice the powerpc
_probe function checks KEXEC_ON_CRASH, that should be checked earlier
and we can fail out early if not supported, but I have no idea
how to do it gracefully for now.

Also for x86 _load function it cleanups image->arch.elf_headers, it can
not be dropped simply.

Consider the above two issues, maybe you can keep the powerpc
version of _probe() and x86 version of _load(), and still copy the common code
to kexec_file.c weak functions. I can post patch to cleanup the x86
_load function in the future.

>  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 9f48f4412297..6203b54e04c5 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -26,30 +26,60 @@
>  #include <linux/vmalloc.h>
>  #include "kexec_internal.h"
>  
> +__weak struct kexec_file_ops *kexec_file_loaders[] = {NULL};
> +
>  static int kexec_calculate_store_digests(struct kimage *image);
>  
> -/* Architectures can provide this probe function */
> -int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> -					 unsigned long buf_len)
> +int kexec_kernel_image_probe(struct kimage *image, void *buf,
> +			     unsigned long buf_len)
>  {
> -	return -ENOEXEC;
> +	int i, ret = -ENOEXEC;
> +	struct kexec_file_ops *fops;
> +
> +	for (i = 0; ; i++) {
> +		fops = kexec_file_loaders[i];
> +		if (!fops || !fops->probe)
> +			break;
> +
> +		ret = fops->probe(buf, buf_len);
> +		if (!ret) {
> +			image->fops = fops;
> +			return ret;
> +		}
> +	}
> +
> +	return ret;
>  }
>  
> -void * __weak arch_kexec_kernel_image_load(struct kimage *image)
> +void *kexec_kernel_image_load(struct kimage *image)
>  {
> -	return ERR_PTR(-ENOEXEC);
> +	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 __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
> +int kexec_kernel_post_load_cleanup(struct kimage *image)
>  {
> -	return -EINVAL;
> +	if (!image->fops || !image->fops->cleanup)
> +		return 0;
> +
> +	return image->fops->cleanup(image->image_loader_data);
>  }
>  
>  #ifdef CONFIG_KEXEC_VERIFY_SIG
> -int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> -					unsigned long buf_len)
> +int kexec_kernel_verify_sig(struct kimage *image, void *buf,
> +			    unsigned long buf_len)
>  {
> -	return -EKEYREJECTED;
> +	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);
>  }
>  #endif
>  
> -- 
> 2.14.1
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec

Thanks
Dave

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