Re: [PATCH v5 8/8] remoteproc: Adapt coredump to generate correct elf type

[Mathieu Poirier <mathieu.poirier@linaro.org>]

On Mon, Mar 02, 2020 at 10:39:02AM +0100, Clement Leger wrote:
> Now that remoteproc can load an elf64, coredump elf class should be
> the same as the loaded elf class. In order to do that, add a
> elf_class field to rproc with default values. If an elf is loaded
> successfully, this field will be updated with the loaded elf class.
> Then, the coredump core code has been modified to use the generic elf
> macro in order to create an elf file with correct class.
> 
> Signed-off-by: Clement Leger <cleger@kalray.eu>
> ---
>  drivers/remoteproc/remoteproc_core.c       | 67 ++++++++++++++++--------------
>  drivers/remoteproc/remoteproc_elf_loader.c |  3 ++
>  include/linux/remoteproc.h                 |  1 +
>  3 files changed, 39 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
> index b932a64a2be2..f923355aa3f9 100644
> --- a/drivers/remoteproc/remoteproc_core.c
> +++ b/drivers/remoteproc/remoteproc_core.c
> @@ -38,6 +38,7 @@
>  #include <linux/platform_device.h>
>  
>  #include "remoteproc_internal.h"
> +#include "remoteproc_elf_helpers.h"
>  
>  #define HIGH_BITS_MASK 0xFFFFFFFF00000000ULL
>  
> @@ -1566,20 +1567,21 @@ EXPORT_SYMBOL(rproc_coredump_add_custom_segment);
>  static void rproc_coredump(struct rproc *rproc)
>  {
>  	struct rproc_dump_segment *segment;
> -	struct elf32_phdr *phdr;
> -	struct elf32_hdr *ehdr;
> +	void *phdr;
> +	void *ehdr;
>  	size_t data_size;
>  	size_t offset;
>  	void *data;
>  	void *ptr;
> +	u8 class = rproc->elf_class;
>  	int phnum = 0;
>  
>  	if (list_empty(&rproc->dump_segments))
>  		return;
>  
> -	data_size = sizeof(*ehdr);
> +	data_size = elf_size_of_hdr(class);
>  	list_for_each_entry(segment, &rproc->dump_segments, node) {
> -		data_size += sizeof(*phdr) + segment->size;
> +		data_size += elf_size_of_phdr(class) + segment->size;
>  
>  		phnum++;
>  	}
> @@ -1590,33 +1592,33 @@ static void rproc_coredump(struct rproc *rproc)
>  
>  	ehdr = data;
>  
> -	memset(ehdr, 0, sizeof(*ehdr));
> -	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
> -	ehdr->e_ident[EI_CLASS] = ELFCLASS32;
> -	ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
> -	ehdr->e_ident[EI_VERSION] = EV_CURRENT;
> -	ehdr->e_ident[EI_OSABI] = ELFOSABI_NONE;
> -	ehdr->e_type = ET_CORE;
> -	ehdr->e_machine = EM_NONE;
> -	ehdr->e_version = EV_CURRENT;
> -	ehdr->e_entry = rproc->bootaddr;
> -	ehdr->e_phoff = sizeof(*ehdr);
> -	ehdr->e_ehsize = sizeof(*ehdr);
> -	ehdr->e_phentsize = sizeof(*phdr);
> -	ehdr->e_phnum = phnum;
> -
> -	phdr = data + ehdr->e_phoff;
> -	offset = ehdr->e_phoff + sizeof(*phdr) * ehdr->e_phnum;
> +	memset(ehdr, 0, elf_size_of_hdr(class));
> +	/* e_ident field is common for both elf32 and elf64 */
> +	elf_hdr_init_ident(ehdr, class);
> +
> +	elf_hdr_set_e_type(class, ehdr, ET_CORE);
> +	elf_hdr_set_e_machine(class, ehdr, EM_NONE);
> +	elf_hdr_set_e_version(class, ehdr, EV_CURRENT);
> +	elf_hdr_set_e_entry(class, ehdr, rproc->bootaddr);
> +	elf_hdr_set_e_phoff(class, ehdr, elf_size_of_hdr(class));
> +	elf_hdr_set_e_ehsize(class, ehdr, elf_size_of_hdr(class));
> +	elf_hdr_set_e_phentsize(class, ehdr, elf_size_of_phdr(class));
> +	elf_hdr_set_e_phnum(class, ehdr, phnum);
> +
> +	phdr = data + elf_hdr_get_e_phoff(class, ehdr);
> +	offset = elf_hdr_get_e_phoff(class, ehdr);
> +	offset += elf_size_of_phdr(class) * elf_hdr_get_e_phnum(class, ehdr);
> +
>  	list_for_each_entry(segment, &rproc->dump_segments, node) {
> -		memset(phdr, 0, sizeof(*phdr));
> -		phdr->p_type = PT_LOAD;
> -		phdr->p_offset = offset;
> -		phdr->p_vaddr = segment->da;
> -		phdr->p_paddr = segment->da;
> -		phdr->p_filesz = segment->size;
> -		phdr->p_memsz = segment->size;
> -		phdr->p_flags = PF_R | PF_W | PF_X;
> -		phdr->p_align = 0;
> +		memset(phdr, 0, elf_size_of_phdr(class));
> +		elf_phdr_set_p_type(class, phdr, PT_LOAD);
> +		elf_phdr_set_p_offset(class, phdr, offset);
> +		elf_phdr_set_p_vaddr(class, phdr, segment->da);
> +		elf_phdr_set_p_paddr(class, phdr, segment->da);
> +		elf_phdr_set_p_filesz(class, phdr, segment->size);
> +		elf_phdr_set_p_memsz(class, phdr, segment->size);
> +		elf_phdr_set_p_flags(class, phdr, PF_R | PF_W | PF_X);
> +		elf_phdr_set_p_align(class, phdr, 0);
>  
>  		if (segment->dump) {
>  			segment->dump(rproc, segment, data + offset);
> @@ -1632,8 +1634,8 @@ static void rproc_coredump(struct rproc *rproc)
>  			}
>  		}
>  
> -		offset += phdr->p_filesz;
> -		phdr++;
> +		offset += elf_phdr_get_p_filesz(class, phdr);
> +		phdr += elf_size_of_phdr(class);
>  	}
>  
>  	dev_coredumpv(&rproc->dev, data, data_size, GFP_KERNEL);
> @@ -2031,6 +2033,7 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
>  	rproc->name = name;
>  	rproc->priv = &rproc[1];
>  	rproc->auto_boot = true;
> +	rproc->elf_class = ELFCLASS32;

I would initialise this to ELFCLASSNONE to make sure that if a platform driver
overwrites rproc_elf_load_segments or doesn't provide one, we don't falsely
deduce the elf type.  It goes without saying that if elf_class == ELFCLASSNONE,
a coredump is not generated. 

Unless you think this is a seriously bad idea or Bjorn over rules me,

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>

Thanks,
Mathieu

>  
>  	device_initialize(&rproc->dev);
>  	rproc->dev.parent = dev;
> diff --git a/drivers/remoteproc/remoteproc_elf_loader.c b/drivers/remoteproc/remoteproc_elf_loader.c
> index 4869fb7d8fe4..16e2c496fd45 100644
> --- a/drivers/remoteproc/remoteproc_elf_loader.c
> +++ b/drivers/remoteproc/remoteproc_elf_loader.c
> @@ -248,6 +248,9 @@ int rproc_elf_load_segments(struct rproc *rproc, const struct firmware *fw)
>  			memset(ptr + filesz, 0, memsz - filesz);
>  	}
>  
> +	if (ret == 0)
> +		rproc->elf_class = class;
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL(rproc_elf_load_segments);
> diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
> index 1683d6c386a6..ed127b2d35ca 100644
> --- a/include/linux/remoteproc.h
> +++ b/include/linux/remoteproc.h
> @@ -514,6 +514,7 @@ struct rproc {
>  	bool auto_boot;
>  	struct list_head dump_segments;
>  	int nb_vdev;
> +	u8 elf_class;
>  };
>  
>  /**
> -- 
> 2.15.0.276.g89ea799
>