Re: [PATCH v2 2/7] kexec_file,x86,powerpc: factor out kexec_file_ops functions

From: Dave Young
Date: Wed Mar 07 2018 - 20:13:17 EST

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In reply to: AKASHI Takahiro: "[PATCH v2 2/7] kexec_file,x86,powerpc: factor out kexec_file_ops functions"
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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@xxxxxxxxxx>
> Cc: Dave Young <dyoung@xxxxxxxxxx>
> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
> Cc: Baoquan He <bhe@xxxxxxxxxx>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Cc: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxxxxxxx>
> ---
> 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

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In reply to: AKASHI Takahiro: "[PATCH v2 2/7] kexec_file,x86,powerpc: factor out kexec_file_ops functions"
Next in thread: AKASHI Takahiro: "[PATCH v2 4/7] x86: kexec_file: remove X86_64 dependency from prepare_elf64_headers()"
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