>
> layout_section() called this:
>
> static long get_offset(unsigned long *size, Elf_Shdr *sechdr)
> {
> long ret;
>
> ret = ALIGN(*size, sechdr->sh_addralign ?: 1);
> *size = ret + sechdr->sh_size;
> return ret;
> }
>
> From header:
>
> typedef struct {
> Elf32_Word sh_name;
> Elf32_Word sh_type;
> Elf32_Word sh_flags;
> Elf32_Addr sh_addr;
> Elf32_Off sh_offset;
> Elf32_Word sh_size;
> Elf32_Word sh_link;
> Elf32_Word sh_info;
> Elf32_Word sh_addralign;
> Elf32_Word sh_entsize;
> } Elf32_Shdr;
>
> typedef struct elf64_shdr {
> Elf64_Word sh_name; /* Section name, index in string tbl */
> Elf64_Word sh_type; /* Type of section */
> Elf64_Xword sh_flags; /* Miscellaneous section attributes */
> Elf64_Addr sh_addr; /* Section virtual addr at execution */
> Elf64_Off sh_offset; /* Section file offset */
> Elf64_Xword sh_size; /* Size of section in bytes */
> Elf64_Word sh_link; /* Index of another section */
> Elf64_Word sh_info; /* Additional section information */
> Elf64_Xword sh_addralign; /* Section alignment */
> Elf64_Xword sh_entsize; /* Entry size if section holds table */
> } Elf64_Shdr;
>
> Which I think is responsible for the alignment of the section in memory.
>
> Two thing: memory offset and file offset - u have to distinguish
> between the two. fileoffset no alignment, but memory yes. So in
> loading process, some empty spaces have to inserted.
>
> sechdr->sh_size==> this is physical file offset (from byte 0 of the file).
> ret --> ****I THINK**** is trying to round up the current *size value
> to the next alignment value, and then add this
>
Thanks, Peter for the wonderful explanation.
I was curious how I would find the start and end of a section in
memory of ".data" section. From the code, I believe it is
sechdr->sh_addr (start). How to reach the end(in memory) since the
field sechdr->sh_size is physical as per your explanation?
Regards,
Asim
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