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outmacho: always use symbol-relative relocations for MachO64

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It seems that the MachO64 linker really doesn't like segment-relative
relocations under certain circumstances, so force relocations to be converted
to "external" (symbol-relative); error out if no symbol is available
(if this is a problem, we can consider inserting a synthetic symbol if
necessary.)

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
H. Peter Anvin
2017-06-22 23:36:34 -07:00
parent 1669cb04a5
commit 58d2ab176f
1 changed files with 52 additions and 30 deletions
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82
output/outmacho.c
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@@ -138,6 +138,7 @@ struct macho_fmt {
uint32_t reloc_abs; /* Absolute relocation type */
uint32_t reloc_rel; /* Relative relocation type */
uint32_t reloc_tlv; /* Thread local relocation type */
bool forcesym; /* Always use "external" (symbol-relative) relocations */
};
static struct macho_fmt fmt;
@@ -154,7 +155,7 @@ struct section {
int32_t index;
int32_t fileindex;
struct reloc *relocs;
struct rbtree *gsyms; /* Global symbols in section */
struct rbtree *syms[2]; /* All/global symbols symbols in section */
int align;
bool by_name; /* This section was specified by full MachO name */
@@ -215,7 +216,7 @@ struct reloc {
struct symbol {
/* nasm internal data */
struct rbtree symv; /* Global symbol rbtree; "key" contains the
struct rbtree symv[2]; /* All/global symbol rbtrees; "key" contains the
symbol offset. */
struct symbol *next; /* next symbol in the list */
char *name; /* name of this symbol */
@@ -412,21 +413,22 @@ static void sect_write(struct section *sect,
/*
* Find a suitable global symbol for a ..gotpcrel or ..tlvp reference
*/
static struct symbol *macho_find_gsym(struct section *s,
uint64_t offset, bool exact)
static struct symbol *macho_find_sym(struct section *s, uint64_t offset,
bool global, bool exact)
{
struct rbtree *srb;
srb = rb_search(s->gsyms, offset);
srb = rb_search(s->syms[global], offset);
if (!srb || (exact && srb->key != offset)) {
nasm_error(ERR_NONFATAL, "unable to find a suitable %s symbol"
nasm_error(ERR_NONFATAL, "unable to find a suitable%s%s symbol"
" for this reference",
s == &absolute_sect ? "absolute" : "global");
global ? " global" : "",
s == &absolute_sect ? " absolute " : "");
return NULL;
}
return container_of(srb, struct symbol, symv);
return container_of(srb - global, struct symbol, symv);
}
static int64_t add_reloc(struct section *sect, int32_t section,
@@ -469,7 +471,7 @@ static int64_t add_reloc(struct section *sect, int32_t section,
if (section == NO_SEG) {
/* absolute (can this even happen?) */
r->ext = 0;
r->snum = R_ABS;
r->snum = NO_SECT;
} else if (fi == NO_SECT) {
/* external */
r->snum = raa_read(extsyms, section);
@@ -493,8 +495,8 @@ static int64_t add_reloc(struct section *sect, int32_t section,
#if 0
/* This "seems" to be how it ought to work... */
struct symbol *sym = macho_find_gsym(&absolute_sect,
offset, false);
struct symbol *sym = macho_find_sym(&absolute_sect, offset,
false, false);
if (!sym)
goto bail;
@@ -543,15 +545,27 @@ static int64_t add_reloc(struct section *sect, int32_t section,
/* external */
r->snum = raa_read(extsyms, section);
} else {
/* internal */
struct symbol *sym = macho_find_gsym(s, offset, reltype != RL_TLV);
/* internal - does it really need to be global? */
struct symbol *sym = macho_find_sym(s, offset, true,
reltype != RL_TLV);
if (!sym)
goto bail;
r->snum = sym->initial_snum;
}
break;
}
/* For 64-bit Mach-O, force a symbol reference if at all possible */
if (!r->ext && r->snum != NO_SECT && fmt.forcesym) {
struct symbol *sym = macho_find_sym(s, offset, false, false);
if (sym) {
adjust = bytes - sym->symv[0].key;
r->snum = sym->initial_snum;
r->ext = 1;
}
}
/* NeXT as puts relocs in reversed order (address-wise) into the
** files, so we do the same, doesn't seem to make much of a
** difference either way */
@@ -645,7 +659,7 @@ static void macho_output(int32_t secto, const void *data,
if (section != NO_SEG) {
if (section % 2) {
nasm_error(ERR_NONFATAL, "Mach-O format does not support"
" section base references");
" section base references");
} else if (wrt == NO_SEG) {
if (fmt.ptrsize == 8 && asize != 8) {
nasm_error(ERR_NONFATAL,
@@ -968,6 +982,7 @@ static void macho_symdef(char *name, int32_t section, int64_t offset,
int is_global, char *special)
{
struct symbol *sym;
struct section *s;
if (special) {
nasm_error(ERR_NONFATAL, "The Mach-O output format does "
@@ -1000,7 +1015,8 @@ static void macho_symdef(char *name, int32_t section, int64_t offset,
sym->strx = strslen;
sym->type = 0;
sym->desc = 0;
sym->symv.key = offset;
sym->symv[0].key = offset;
sym->symv[1].key = offset;
sym->initial_snum = -1;
/* external and common symbols get N_EXT */
@@ -1013,10 +1029,9 @@ static void macho_symdef(char *name, int32_t section, int64_t offset,
sym->type |= N_ABS;
sym->sect = NO_SECT;
/* all absolute symbols are available to use as references */
absolute_sect.gsyms = rb_insert(absolute_sect.gsyms, &sym->symv);
s = &absolute_sect;
} else {
struct section *s = get_section_by_index(section);
s = get_section_by_index(section);
sym->type |= N_SECT;
@@ -1038,7 +1053,7 @@ static void macho_symdef(char *name, int32_t section, int64_t offset,
case 2:
/* there isn't actually a difference between global
** and common symbols, both even have their size in
** sym->symv.key */
** sym->symv[0].key */
sym->type = N_EXT;
break;
@@ -1049,10 +1064,15 @@ static void macho_symdef(char *name, int32_t section, int64_t offset,
nasm_panic(0, "in-file index for section %d not found, is_global = %d", section, is_global);
break;
}
} else if (is_global) {
s->gsyms = rb_insert(s->gsyms, &sym->symv);
}
}
if (s) {
s->syms[0] = rb_insert(s->syms[0], &sym->symv[0]);
if (is_global)
s->syms[1] = rb_insert(s->syms[1], &sym->symv[1]);
}
++nsyms;
}
@@ -1467,10 +1487,10 @@ static void macho_write_symtab (void)
sizes. */
if (((sym->type & N_TYPE) == N_SECT) && (sym->sect != NO_SECT)) {
nasm_assert(sym->sect <= seg_nsects);
sym->symv.key += sectstab[sym->sect]->addr;
sym->symv[0].key += sectstab[sym->sect]->addr;
}
fwriteptr(sym->symv.key, ofile); /* value (i.e. offset) */
fwriteptr(sym->symv[0].key, ofile); /* value (i.e. offset) */
}
}
@@ -1485,10 +1505,10 @@ static void macho_write_symtab (void)
sizes. */
if (((sym->type & N_TYPE) == N_SECT) && (sym->sect != NO_SECT)) {
nasm_assert(sym->sect <= seg_nsects);
sym->symv.key += sectstab[sym->sect]->addr;
sym->symv[0].key += sectstab[sym->sect]->addr;
}
fwriteptr(sym->symv.key, ofile); /* value (i.e. offset) */
fwriteptr(sym->symv[0].key, ofile); /* value (i.e. offset) */
}
for (i = 0; i < nundefsym; i++) {
@@ -1502,10 +1522,10 @@ static void macho_write_symtab (void)
sizes. */
if (((sym->type & N_TYPE) == N_SECT) && (sym->sect != NO_SECT)) {
nasm_assert(sym->sect <= seg_nsects);
sym->symv.key += sectstab[sym->sect]->addr;
sym->symv[0].key += sectstab[sym->sect]->addr;
}
fwriteptr(sym->symv.key, ofile); /* value (i.e. offset) */
fwriteptr(sym->symv[0].key, ofile); /* value (i.e. offset) */
}
}
@@ -2232,7 +2252,8 @@ static const struct macho_fmt macho32_fmt = {
RL_MAX_32,
GENERIC_RELOC_VANILLA,
GENERIC_RELOC_VANILLA,
GENERIC_RELOC_TLV
GENERIC_RELOC_TLV,
false /* Allow segment-relative relocations */
};
static void macho32_init(void)
@@ -2277,7 +2298,7 @@ const struct ofmt of_macho32 = {
null_directive,
macho_filename,
macho_cleanup,
macho_pragma_list,
macho_pragma_list
};
#endif
@@ -2294,7 +2315,8 @@ static const struct macho_fmt macho64_fmt = {
RL_MAX_64,
X86_64_RELOC_UNSIGNED,
X86_64_RELOC_SIGNED,
X86_64_RELOC_TLV
X86_64_RELOC_TLV,
true /* Force symbol-relative relocations */
};
static void macho64_init(void)