On Thu, 15 Nov 2012 16:12:17 +0100, grischka wrote:
[SNIP]
Well, why not. It doesn't cover yet consequent pass-trough of the
AttributeDef but it could be a step in the right direction.
Good, I did it in the mean time.
I'd suggest changing
static void put_got_offset(TCCState *s1, int index, unsigned long
val);
into a more general
static struct sym_attribute *get_sym_attribute(TCCState *s1, int
index);
which would expand the array with an empty entry if needed.
Thus the currently single instance of usage
put_got_offset(s1, sym_index, s1->got->data_offset);
would become
get_sym_attribute(s1, sym_index)->got_offset =
s1->got->data_offset;
I already did a general function to store a value but I adopted a
different approach:
#define put_sym_attr(s,index,field,val) \
alloc_sym_attr(s, index); \
s->sym_attrs[index].field = val
where alloc_sym_attr is the old put_got_offset without the assignment
line at the end. See attached file for the full patch (only tested on
x86-64 so far, I'll try to compile it on arm later).
If this is not fine for you, I'll change it happily.
Anyway, just my 2 cents of completely untested suggestions. ;)
--- grischka
Thomas
diff --git a/tcc.h b/tcc.h
index 4e88782..0d17769 100644
--- a/tcc.h
+++ b/tcc.h
@@ -524,11 +524,16 @@ struct TCCState {
Section **priv_sections;
int nb_priv_sections; /* number of private sections */
- /* got handling */
+ /* got & plt handling */
Section *got;
Section *plt;
- unsigned long *got_offsets;
- int nb_got_offsets;
+ struct {
+ unsigned long got_offset;
+#ifdef TCC_TARGET_ARM
+ unsigned char plt_thumb_stub:1;
+#endif
+ } *sym_attrs;
+ int nb_sym_attrs;
/* give the correspondance from symtab indexes to dynsym indexes */
int *symtab_to_dynsym;
diff --git a/tccelf.c b/tccelf.c
index c5690dd..0e1ea39 100644
--- a/tccelf.c
+++ b/tccelf.c
@@ -581,7 +581,7 @@ ST_FUNC void relocate_section(TCCState *s1, Section *s)
break;
case R_386_GOT32:
/* we load the got offset */
- *(int *)ptr += s1->got_offsets[sym_index];
+ *(int *)ptr += s1->sym_attrs[sym_index].got_offset;
break;
case R_386_16:
if (s1->output_format != TCC_OUTPUT_FORMAT_BINARY) {
@@ -760,7 +760,7 @@ ST_FUNC void relocate_section(TCCState *s1, Section *s)
break;
case R_ARM_GOT_BREL:
/* we load the got offset */
- *(int *)ptr += s1->got_offsets[sym_index];
+ *(int *)ptr += s1->sym_attrs[sym_index].got_offset;
break;
case R_ARM_COPY:
break;
@@ -866,14 +866,14 @@ ST_FUNC void relocate_section(TCCState *s1, Section *s)
}
#endif
*(int *)ptr += (s1->got->sh_addr - addr +
- s1->got_offsets[sym_index] - 4);
+ s1->sym_attrs[sym_index].got_offset - 4);
break;
case R_X86_64_GOTTPOFF:
*(int *)ptr += val - s1->got->sh_addr;
break;
case R_X86_64_GOT32:
/* we load the got offset */
- *(int *)ptr += s1->got_offsets[sym_index];
+ *(int *)ptr += s1->sym_attrs[sym_index].got_offset;
break;
#else
#error unsupported processor
@@ -943,25 +943,28 @@ static int prepare_dynamic_rel(TCCState *s1, Section *sr)
return count;
}
-static void put_got_offset(TCCState *s1, int index, unsigned long val)
+static void alloc_sym_attr(TCCState *s1, int index)
{
int n;
- unsigned long *tab;
+ typeof(s1->sym_attrs) tab;
- if (index >= s1->nb_got_offsets) {
+ if (index >= s1->nb_sym_attrs) {
/* find immediately bigger power of 2 and reallocate array */
n = 1;
while (index >= n)
n *= 2;
- tab = tcc_realloc(s1->got_offsets, n * sizeof(unsigned long));
- s1->got_offsets = tab;
- memset(s1->got_offsets + s1->nb_got_offsets, 0,
- (n - s1->nb_got_offsets) * sizeof(unsigned long));
- s1->nb_got_offsets = n;
+ tab = tcc_realloc(s1->sym_attrs, n * sizeof(*s1->sym_attrs));
+ s1->sym_attrs = tab;
+ memset(s1->sym_attrs + s1->nb_sym_attrs, 0,
+ (n - s1->nb_sym_attrs) * sizeof(*s1->sym_attrs));
+ s1->nb_sym_attrs = n;
}
- s1->got_offsets[index] = val;
}
+#define put_sym_attr(s,index,field,val) \
+ alloc_sym_attr(s, index); \
+ s->sym_attrs[index].field = val
+
/* XXX: suppress that */
static void put32(unsigned char *p, uint32_t val)
{
@@ -1023,11 +1026,11 @@ static void put_got_entry(TCCState *s1,
build_got(s1);
/* if a got entry already exists for that symbol, no need to add one */
- if (sym_index < s1->nb_got_offsets &&
- s1->got_offsets[sym_index] != 0)
+ if (sym_index < s1->nb_sym_attrs &&
+ s1->sym_attrs[sym_index].got_offset)
return;
-
- put_got_offset(s1, sym_index, s1->got->data_offset);
+
+ put_sym_attr(s1, sym_index, got_offset, s1->got->data_offset);
if (s1->dynsym) {
sym = &((ElfW(Sym) *)symtab_section->data)[sym_index];
@@ -1104,10 +1107,13 @@ static void put_got_entry(TCCState *s1,
put32(p + 12, 0xe5bef008);
}
- p = section_ptr_add(plt, 20);
- put32(p , 0x4778); // bx pc
- put32(p+2, 0x46c0); // nop
- p += 4;
+ if (s1->sym_attrs[sym_index].plt_thumb_stub) {
+ p = section_ptr_add(plt, 20);
+ put32(p , 0x4778); // bx pc
+ put32(p+2, 0x46c0); // nop
+ p += 4;
+ } else
+ p = section_ptr_add(plt, 16);
put32(p , 0xe59fc004); // ldr ip, [pc, #4] // offset in GOT
put32(p+4, 0xe08fc00c); // add ip, pc, ip // absolute address or offset
put32(p+8, 0xe59cf000); // ldr pc, [ip] // load absolute address or load offset
@@ -1494,9 +1500,9 @@ ST_FUNC void fill_got_entry(TCCState *s1, ElfW_Rel *rel)
ElfW(Sym) *sym = &((ElfW(Sym) *) symtab_section->data)[sym_index];
unsigned long offset;
- if (sym_index >= s1->nb_got_offsets)
+ if (sym_index >= s1->nb_sym_attrs)
return;
- offset = s1->got_offsets[sym_index];
+ offset = s1->sym_attrs[sym_index].got_offset;
section_reserve(s1->got, offset + PTR_SIZE);
#ifdef TCC_TARGET_X86_64
/* only works for x86-64 */
@@ -2070,7 +2076,8 @@ static int elf_output_file(TCCState *s1, const char *filename)
x=s1->got->sh_addr - s1->plt->sh_addr - 12;
p += 16;
while (p < p_end) {
- p += 4;
+ if (get32(p) == 0x46c04778) /* PLT Thumb stub present */
+ p += 4;
put32(p + 12, x + get32(p + 12) + s1->plt->data - p);
p += 16;
}
@@ -2304,7 +2311,7 @@ static int elf_output_file(TCCState *s1, const char *filename)
tcc_free(s1->symtab_to_dynsym);
tcc_free(section_order);
tcc_free(phdr);
- tcc_free(s1->got_offsets);
+ tcc_free(s1->sym_attrs);
return ret;
}
@@ -2599,6 +2606,18 @@ ST_FUNC int tcc_load_object_file(TCCState *s1,
rel->r_info = ELFW(R_INFO)(sym_index, type);
/* offset the relocation offset */
rel->r_offset += offseti;
+#ifdef TCC_TARGET_ARM
+ /* Jumps and branches from a Thumb code to a PLT entry need
+ special handling since PLT entries are ARM code.
+ Unconditional bl instructions referencing PLT entries are
+ handled by converting these instructions into blx
+ instructions. Other case of instructions referencing a PLT
+ entry require to add a Thumb stub before the PLT entry to
+ switch to ARM mode. We set bit 0 of the got offset of a
+ symbol to indicate such a case. */
+ if (type == R_ARM_THM_JUMP24)
+ put_sym_attr(s1, sym_index, plt_thumb_stub, 1);
+#endif
}
break;
default:
_______________________________________________
Tinycc-devel mailing list
[email protected]
https://lists.nongnu.org/mailman/listinfo/tinycc-devel
