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Remove gaps between RELX sections

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These gaps are a result of final_sections_reloc. Here some relocs are removed.
The gaps are then filled with 0 in tcc_output_elf. The 0 is intepreted as
R_...NONE reloc. This does work on most targets but on OpenBSD/arm64 this
is illegal.
This commit is contained in:
herman ten brugge 2021-01-12 06:59:51 +01:00
parent cd91ea658a
commit c9bdfcedb4
1 changed files with 33 additions and 14 deletions
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47
tccelf.c
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@ -1863,8 +1863,7 @@ struct ro_inf {
static int layout_sections(TCCState *s1, ElfW(Phdr) *phdr, static int layout_sections(TCCState *s1, ElfW(Phdr) *phdr,
int phnum, int phfill, int phnum, int phfill,
Section *interp, Section* strsec, Section *interp, Section* strsec,
struct dyn_inf *dyninf, struct ro_inf *roinf, struct ro_inf *roinf, int *sec_order)
int *sec_order)
{ {
int i, sh_order_index, file_offset; int i, sh_order_index, file_offset;
Section *s; Section *s;
@ -1912,9 +1911,6 @@ static int layout_sections(TCCState *s1, ElfW(Phdr) *phdr,
if (interp) if (interp)
ph += 2; ph += 2;
/* dynamic relocation table information, for .dynamic section */
dyninf->rel_addr = dyninf->rel_size = 0;
/* read only segment mapping for GNU_RELRO */ /* read only segment mapping for GNU_RELRO */
roinf->sh_offset = roinf->sh_addr = roinf->sh_size = 0; roinf->sh_offset = roinf->sh_addr = roinf->sh_size = 0;
@ -2001,12 +1997,6 @@ static int layout_sections(TCCState *s1, ElfW(Phdr) *phdr,
ph->p_vaddr = addr; ph->p_vaddr = addr;
ph->p_paddr = ph->p_vaddr; ph->p_paddr = ph->p_vaddr;
} }
/* update dynamic relocation infos */
if (s->sh_type == SHT_RELX && s != relocplt) {
if (dyninf->rel_size == 0)
dyninf->rel_addr = addr;
dyninf->rel_size = (addr - dyninf->rel_addr) + s->sh_size;
}
if (s == data_ro_section || if (s == data_ro_section ||
#ifdef CONFIG_TCC_BCHECK #ifdef CONFIG_TCC_BCHECK
s == bounds_section || s == bounds_section ||
@ -2248,6 +2238,32 @@ static int final_sections_reloc(TCCState *s1)
} }
return 0; return 0;
} }
/* Remove gaps between RELX sections.
These gaps are a result of final_sections_reloc. Here some relocs are removed.
The gaps are then filled with 0 in tcc_output_elf. The 0 is intepreted as
R_...NONE reloc. This does work on most targets but on OpenBSD/arm64 this
is illegal. */
static void update_reloc_sections(TCCState *s1, struct dyn_inf *dyninf)
{
int i;
Section *s;
Section *relocplt = s1->got ? s1->got->relocplt : NULL;
/* dynamic relocation table information, for .dynamic section */
dyninf->rel_addr = dyninf->rel_size = 0;
for(i = 1; i < s1->nb_sections; i++) {
s = s1->sections[i];
if (s->sh_type == SHT_RELX && s != relocplt) {
if (dyninf->rel_size == 0)
dyninf->rel_addr = s->sh_addr;
else
s->sh_addr = dyninf->rel_addr + dyninf->rel_size;
dyninf->rel_size += s->sh_size;
}
}
}
#endif #endif
/* Create an ELF file on disk. /* Create an ELF file on disk.
@ -2671,7 +2687,7 @@ static int elf_output_file(TCCState *s1, const char *filename)
/* compute section to program header mapping */ /* compute section to program header mapping */
file_offset = layout_sections(s1, phdr, phnum, phfill, interp, strsec, file_offset = layout_sections(s1, phdr, phnum, phfill, interp, strsec,
&dyninf, &roinf, sec_order); &roinf, sec_order);
#ifndef ELF_OBJ_ONLY #ifndef ELF_OBJ_ONLY
/* Fill remaining program header and finalize relocation related to dynamic /* Fill remaining program header and finalize relocation related to dynamic
@ -2680,8 +2696,6 @@ static int elf_output_file(TCCState *s1, const char *filename)
fill_unloadable_phdr(phdr, phnum, interp, dynamic, note, roinf_use); fill_unloadable_phdr(phdr, phnum, interp, dynamic, note, roinf_use);
if (dynamic) { if (dynamic) {
ElfW(Sym) *sym; ElfW(Sym) *sym;
dynamic->data_offset = dyninf.data_offset;
fill_dynamic(s1, &dyninf);
/* put in GOT the dynamic section address and relocate PLT */ /* put in GOT the dynamic section address and relocate PLT */
write32le(s1->got->data, dynamic->sh_addr); write32le(s1->got->data, dynamic->sh_addr);
@ -2703,6 +2717,11 @@ static int elf_output_file(TCCState *s1, const char *filename)
ret = final_sections_reloc(s1); ret = final_sections_reloc(s1);
if (ret) if (ret)
goto the_end; goto the_end;
if (dynamic) {
update_reloc_sections (s1, &dyninf);
dynamic->data_offset = dyninf.data_offset;
fill_dynamic(s1, &dyninf);
}
tidy_section_headers(s1, sec_order); tidy_section_headers(s1, sec_order);
/* Perform relocation to GOT or PLT entries */ /* Perform relocation to GOT or PLT entries */