How to do a elf linker in a C kernel ?
Posted: Fri Nov 06, 2009 11:54 am
Hello everybody, for my os, i want to do a elf linker to load dynamic library, i have already a elf loader but i don't how the dynamic elf works,
This is my elf loader code to load static elf :
sorry for my english, i'm french
This is my elf loader code to load static elf :
sorry for my english, i'm french
Code: Select all
u32 load_elf(char *file, struct process *proc)
{
char *p;
u32 v_begin, v_end;
Elf32_Ehdr *hdr;
Elf32_Phdr *p_entry;
int i, pe;
hdr = (Elf32_Ehdr *) file;
p_entry = (Elf32_Phdr *) (file + hdr->e_phoff); /* Program header table offset */
if (!is_elf(file)) {
printk("INFO: load_elf(): file not in ELF format !\n");
return 0;
}
for (pe = 0; pe < hdr->e_phnum; pe++, p_entry++) { /* Read each entry */
if (p_entry->p_type == PT_LOAD) {
v_begin = p_entry->p_vaddr;
v_end = p_entry->p_vaddr + p_entry->p_memsz;
if (v_begin < USER_OFFSET) {
printk ("INFO: load_elf(): can't load executable below %p\n", USER_OFFSET);
return 0;
}
if (v_end > USER_STACK) {
printk ("INFO: load_elf(): can't load executable above %p\n", USER_STACK);
return 0;
}
/* Description de la zone exec + rodata */
if (p_entry->p_flags == PF_X + PF_R) {
proc->b_exec = (char*) v_begin;
proc->e_exec = (char*) v_end;
}
/* Description de la zone bss */
if (p_entry->p_flags == PF_W + PF_R) {
proc->b_bss = (char*) v_begin;
proc->e_bss = (char*) v_end;
}
memcpy((char *) v_begin, (char *) (file + p_entry->p_offset), p_entry->p_filesz);
if (p_entry->p_memsz > p_entry->p_filesz)
for (i = p_entry->p_filesz, p = (char *) p_entry->p_vaddr; i < (int)(p_entry->p_memsz); i++)
p[i] = 0;
}
}
/* Return program entry point */
return hdr->e_entry;
}