Subject: Re: [PATCH v5 4/8] remoteproc: Add elf helpers to access elf64 and elf32 fields

From: Mathieu Poirier <[email-masked]>
Date: Mon, 9 Mar 2020 13:56:53 -0600

On Mon, Mar 02, 2020 at 10:38:58AM +0100, Clement Leger wrote:
> elf32 and elf64 mainly differ by their types. In order to avoid
> copy/pasting the whole loader code, generate static inline functions
> which will access values according to the elf class. It allows to
> keep a common loader basis.
> In order to accommodate both elf types sizes, the maximum size for a
> elf header member is chosen using the maximum value of the field for
> both elf class.
> 
> Signed-off-by: Clement Leger <[email-masked]>

Reviewed-by: Mathieu Poirier <[email-masked]>

> ---
>  drivers/remoteproc/remoteproc_elf_helpers.h | 96 +++++++++++++++++++++++++++++
>  1 file changed, 96 insertions(+)
>  create mode 100644 drivers/remoteproc/remoteproc_elf_helpers.h
> 
> diff --git a/drivers/remoteproc/remoteproc_elf_helpers.h b/drivers/remoteproc/remoteproc_elf_helpers.h
> new file mode 100644
> index 000000000000..4b6be7b6bf4d
> --- /dev/null
> +++ b/drivers/remoteproc/remoteproc_elf_helpers.h
> @@ -0,0 +1,96 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Remote processor elf helpers defines
> + *
> + * Copyright (C) 2020 Kalray, Inc.
> + */
> +
> +#ifndef REMOTEPROC_ELF_LOADER_H
> +#define REMOTEPROC_ELF_LOADER_H
> +
> +#include <linux/elf.h>
> +#include <linux/types.h>
> +
> +/**
> + * fw_elf_get_class - Get elf class
> + * @fw: the ELF firmware image
> + *
> + * Note that we use and elf32_hdr to access the class since the start of the
> + * struct is the same for both elf class
> + *
> + * Return: elf class of the firmware
> + */
> +static inline u8 fw_elf_get_class(const struct firmware *fw)
> +{
> +	struct elf32_hdr *ehdr = (struct elf32_hdr *)fw->data;
> +
> +	return ehdr->e_ident[EI_CLASS];
> +}
> +
> +static inline void elf_hdr_init_ident(struct elf32_hdr *hdr, u8 class)
> +{
> +	memcpy(hdr->e_ident, ELFMAG, SELFMAG);
> +	hdr->e_ident[EI_CLASS] = class;
> +	hdr->e_ident[EI_DATA] = ELFDATA2LSB;
> +	hdr->e_ident[EI_VERSION] = EV_CURRENT;
> +	hdr->e_ident[EI_OSABI] = ELFOSABI_NONE;
> +}
> +
> +/* Generate getter and setter for a specific elf struct/field */
> +#define ELF_GEN_FIELD_GET_SET(__s, __field, __type) \
> +static inline __type elf_##__s##_get_##__field(u8 class, const void *arg) \
> +{ \
> +	if (class == ELFCLASS32) \
> +		return (__type) ((const struct elf32_##__s *) arg)->__field; \
> +	else \
> +		return (__type) ((const struct elf64_##__s *) arg)->__field; \
> +} \
> +static inline void elf_##__s##_set_##__field(u8 class, void *arg, \
> +					     __type value) \
> +{ \
> +	if (class == ELFCLASS32) \
> +		((struct elf32_##__s *) arg)->__field = (__type) value; \
> +	else \
> +		((struct elf64_##__s *) arg)->__field = (__type) value; \
> +}
> +
> +ELF_GEN_FIELD_GET_SET(hdr, e_entry, u64)
> +ELF_GEN_FIELD_GET_SET(hdr, e_phnum, u16)
> +ELF_GEN_FIELD_GET_SET(hdr, e_shnum, u16)
> +ELF_GEN_FIELD_GET_SET(hdr, e_phoff, u64)
> +ELF_GEN_FIELD_GET_SET(hdr, e_shoff, u64)
> +ELF_GEN_FIELD_GET_SET(hdr, e_shstrndx, u16)
> +ELF_GEN_FIELD_GET_SET(hdr, e_machine, u16)
> +ELF_GEN_FIELD_GET_SET(hdr, e_type, u16)
> +ELF_GEN_FIELD_GET_SET(hdr, e_version, u32)
> +ELF_GEN_FIELD_GET_SET(hdr, e_ehsize, u32)
> +ELF_GEN_FIELD_GET_SET(hdr, e_phentsize, u16)
> +
> +ELF_GEN_FIELD_GET_SET(phdr, p_paddr, u64)
> +ELF_GEN_FIELD_GET_SET(phdr, p_vaddr, u64)
> +ELF_GEN_FIELD_GET_SET(phdr, p_filesz, u64)
> +ELF_GEN_FIELD_GET_SET(phdr, p_memsz, u64)
> +ELF_GEN_FIELD_GET_SET(phdr, p_type, u32)
> +ELF_GEN_FIELD_GET_SET(phdr, p_offset, u64)
> +ELF_GEN_FIELD_GET_SET(phdr, p_flags, u32)
> +ELF_GEN_FIELD_GET_SET(phdr, p_align, u64)
> +
> +ELF_GEN_FIELD_GET_SET(shdr, sh_size, u64)
> +ELF_GEN_FIELD_GET_SET(shdr, sh_offset, u64)
> +ELF_GEN_FIELD_GET_SET(shdr, sh_name, u32)
> +ELF_GEN_FIELD_GET_SET(shdr, sh_addr, u64)
> +
> +#define ELF_STRUCT_SIZE(__s) \
> +static inline unsigned long elf_size_of_##__s(u8 class) \
> +{ \
> +	if (class == ELFCLASS32)\
> +		return sizeof(struct elf32_##__s); \
> +	else \
> +		return sizeof(struct elf64_##__s); \
> +}
> +
> +ELF_STRUCT_SIZE(shdr)
> +ELF_STRUCT_SIZE(phdr)
> +ELF_STRUCT_SIZE(hdr)
> +
> +#endif /* REMOTEPROC_ELF_LOADER_H */
> -- 
> 2.15.0.276.g89ea799
> 

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