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outmac: generate section-relative relocations for local symbols

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We generate section-relative relocations for local symbols for all
the other output formats, and we should do the same for MachO;
this was done in MachO-32 but not in MachO-64, presumably because
the MachO spec implies that such relocations shouldn't exist in
64-bit code.  They are indeed rare, but that is a programmer's
decision, and the spec is clear that they are legal.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
H. Peter Anvin 2016-02-12 15:06:23 -08:00
parent ca351fa175
commit 941356b2ca
1 changed files with 13 additions and 42 deletions
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55
output/outmac.c
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@ -328,26 +328,6 @@ static uint8_t get_section_fileindex_by_index(const int32_t index)
return NO_SECT;
}
static struct symbol *get_closest_section_symbol_by_offset(uint8_t fileindex, int64_t offset)
{
struct symbol *nearest = NULL;
struct symbol *sym;
for (sym = syms; sym; sym = sym->next) {
if ((sym->sect != NO_SECT) && (sym->sect == fileindex)) {
if ((int64_t)sym->value > offset)
break;
nearest = sym;
}
}
if (!nearest)
nasm_error(ERR_FATAL, "No section for index %x offset %llx found\n",
fileindex, (long long)offset);
return nearest;
}
/*
* Special section numbers which are used to define Mach-O special
* symbols, which can be used with WRT to provide PIC relocation
@ -390,16 +370,11 @@ enum reltype {
RL_GOTLOAD, /* X86_64_RELOC_GOT_LOAD */
};
static int32_t add_reloc(struct section *sect, int32_t section,
enum reltype reltype, int bytes, int64_t reloff)
static void add_reloc(struct section *sect, int32_t section,
enum reltype reltype, int bytes)
{
struct reloc *r;
struct symbol *sym;
int32_t fi;
int32_t adjustment = 0;
if (section == NO_SEG)
return 0;
/* 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
@ -427,20 +402,19 @@ static int32_t add_reloc(struct section *sect, int32_t section,
switch (reltype) {
case RL_ABS:
if (section == NO_SEG) {
/* intra-section */
/* absolute (can this even happen?) */
r->ext = 0;
r->snum = R_ABS;
} else {
/* inter-section */
fi = get_section_fileindex_by_index(section);
if (fi == NO_SECT) {
/* external */
r->snum = raa_read(extsyms, section);
} else {
/* local */
sym = get_closest_section_symbol_by_offset(fi, reloff);
r->snum = sym->initial_snum;
adjustment = sym->value;
r->ext = 0;
r->snum = fi;
}
}
break;
@ -461,9 +435,8 @@ static int32_t add_reloc(struct section *sect, int32_t section,
r->snum = raa_read(extsyms, section);
} else {
/* local */
sym = get_closest_section_symbol_by_offset(fi, reloff);
r->snum = sym->initial_snum;
adjustment = sym->value;
r->ext = 0;
r->snum = fi;
}
}
break;
@ -487,8 +460,6 @@ static int32_t add_reloc(struct section *sect, int32_t section,
}
++sect->nreloc;
return adjustment;
}
static void macho_output(int32_t secto, const void *data,
@ -564,7 +535,7 @@ static void macho_output(int32_t secto, const void *data,
nasm_error(ERR_NONFATAL, "Mach-O 64-bit format does not support"
" 32-bit absolute addresses");
} else {
addr -= add_reloc(s, section, RL_ABS, asize, addr);
add_reloc(s, section, RL_ABS, asize);
}
} else {
nasm_error(ERR_NONFATAL, "Mach-O format does not support"
@ -595,7 +566,7 @@ static void macho_output(int32_t secto, const void *data,
" this use of WRT");
wrt = NO_SEG; /* we can at least _try_ to continue */
} else {
addr -= add_reloc(s, section, RL_REL, 2, addr);
add_reloc(s, section, RL_REL, 2);
}
WRITESHORT(p, addr);
@ -613,7 +584,7 @@ static void macho_output(int32_t secto, const void *data,
" section base references");
} else if (wrt == NO_SEG) {
/* Plain relative relocation */
addr -= add_reloc(s, section, RL_REL, 4, addr);
add_reloc(s, section, RL_REL, 4);
} else if (wrt == macho_gotpcrel_sect) {
if (s->data->datalen > 1) {
/* Retrieve instruction opcode */
@ -623,10 +594,10 @@ static void macho_output(int32_t secto, const void *data,
}
if (gotload == 0x8B) {
/* Check for MOVQ Opcode -> X86_64_RELOC_GOT_LOAD */
addr -= add_reloc(s, section, RL_GOTLOAD, 4, addr);
add_reloc(s, section, RL_GOTLOAD, 4);
} else {
/* X86_64_RELOC_GOT */
addr -= add_reloc(s, section, RL_GOT, 4, addr);
add_reloc(s, section, RL_GOT, 4);
}
} else {
nasm_error(ERR_NONFATAL, "Mach-O format does not support"