rosetta/sys/ld/resolve.c

#include "elf.h"

#include <mango/log.h>
#include <stdint.h>
#include <stdio.h>

uintptr_t dl_runtime_resolve(struct elf_image *img, unsigned long sym_id)
{
	unsigned long slot_id = sym_id;
	switch (img->e_rel_entsize[ELF_RT_PLTREL]) {
	case sizeof(elf_rela_t): {
		elf_rela_t *rela
			= (elf_rela_t *)((virt_addr_t)img->e_base
		                         + img->e_rel_offset[ELF_RT_PLTREL]);
		elf_rela_t *rela_sym = &rela[sym_id];
		kern_tracef(
			"rela %u -> .dynsym %u, .got %u",
			sym_id,
			ELF64_R_SYM(rela_sym->r_info),
			slot_id);
		sym_id = ELF64_R_SYM(rela_sym->r_info);
		/* the first three entries in the GOT are not symbols. */
		slot_id += 3;
		break;
	}

	default:
		return 0;
	}

	elf_sym_t *sym
		= (elf_sym_t *)((virt_addr_t)img->e_base + img->e_dynsym);
	virt_addr_t *got
		= (virt_addr_t *)((virt_addr_t)img->e_base + img->e_got_plt);
	const char *sym_name = (const char *)img->e_base + img->e_strtab
	                     + sym[sym_id].st_name;
	kern_tracef(
		"%s: request for symbol %u: %s",
		img->e_leaf.l_name,
		sym_id,
		sym_name);
	virt_addr_t sym_addr = elf_image_find_linked_symbol(img, sym_name);
	kern_tracef("symbol %s = %zx", sym_name, sym_addr);
	kern_tracef("slot %s = %zx", sym_name, &got[slot_id]);
	got[slot_id] = sym_addr;
	return sym_addr;
}