/*
* fixup_section() does the fixups of the frags and prepares the fixes so
* relocation entries can be created from them. The fixups cause the contents
* of the frag to have the value for the fixup expression. A fix structure that
* ends up with a non-NULL fx_addsy will have a relocation entry created for it.
*/
static
void
fixup_section(
fixS *fixP,
int nsect)
{
symbolS *add_symbolP;
symbolS *sub_symbolP;
signed_expr_t value;
int size;
char *place;
int32_t where;
char pcrel;
fragS *fragP;
int add_symbol_N_TYPE;
int add_symbol_nsect;
#ifndef SPARC
int sub_symbol_nsect;
#endif
/*
* The general fix expression is "fx_addsy - fx_subsy + fx_offset".
* The goal is to put the result of this expression into the frag at
* "place" for size "size". The value of the expression is calculated
* in the variable "value" and starts with just the fx_offset.
*/
for( ; fixP != NULL; fixP = fixP->fx_next){
fragP = fixP->fx_frag;
know(fragP);
where = fixP->fx_where;
place = fragP->fr_literal + where;
size = fixP->fx_size;
#ifdef TC_FIXUP_SYMBOL
fixP->fx_offset += TC_FIXUP_SYMBOL(fixP, nsect, &fixP->fx_addsy);
fixP->fx_offset -= TC_FIXUP_SYMBOL(fixP, nsect, &fixP->fx_subsy);
#endif
#if defined(I386) && defined(ARCH64)
if(fixP->fx_addsy == fixP->fx_subsy){
/*
* If we've fixed up both symbols to the same location,
* we don't need a relocation entry.
*/
fixP->fx_addsy = NULL;
fixP->fx_subsy = NULL;
}
#endif
add_symbolP = fixP->fx_addsy;
sub_symbolP = fixP->fx_subsy;
value = fixP->fx_offset;
pcrel = fixP->fx_pcrel;
#if ARM
/* If the symbol is defined in this file, the linker won't set the
low-order bit for a Thumb symbol, so we have to do it here. */
if(add_symbolP != NULL && add_symbolP->sy_desc & N_ARM_THUMB_DEF &&
!(sub_symbolP != NULL && sub_symbolP->sy_desc & N_ARM_THUMB_DEF) &&
!pcrel){
value |= 1;
}
#endif
add_symbol_N_TYPE = 0;
add_symbol_nsect = 0;
if(add_symbolP != NULL){
add_symbol_N_TYPE = add_symbolP->sy_type & N_TYPE;
if(add_symbol_N_TYPE == N_SECT)
add_symbol_nsect = add_symbolP->sy_other;
}
/*
* Is there a subtract symbol?
*/
if(sub_symbolP){
/* is it just -sym ? */
if(add_symbolP == NULL){
if(sub_symbolP->sy_type != N_ABS)
as_warn("Negative of non-absolute symbol %s",
sub_symbolP->sy_name);
#if !(defined(I386) && defined(ARCH64))
/* Symbol offsets are not part of fixups for x86_64. */
value -= sub_symbolP->sy_value;
#endif
fixP->fx_subsy = NULL;
}
/*
* There are both an add symbol and a subtract symbol at this
* point.
*
* If both symbols are absolute then just calculate the
* value of the fix expression and no relocation entry will be
* needed.
*/
else if((sub_symbolP->sy_type & N_TYPE) == N_ABS &&
(add_symbolP->sy_type & N_TYPE) == N_ABS){
value += add_symbolP->sy_value - sub_symbolP->sy_value;
add_symbolP = NULL;
fixP->fx_addsy = NULL; /* no relocation entry */
fixP->fx_subsy = NULL;
}
/*
* If both symbols are defined in a section then calculate the
* value of the fix expression and let a section difference
* relocation entry be created.
*/
else if((sub_symbolP->sy_type & N_TYPE) == N_SECT &&
(add_symbolP->sy_type & N_TYPE) == N_SECT){
/*
* We are use the new features that are incompatible with
* 3.2 then just calculate the value and let this create a
* SECTDIFF relocation type.
*/
#ifdef SPARC
/*
* Special case dealing with assembler internal relocation
* entries SPARC_RELOC_13 and RELOC_22. The can not be
* output and must be resolved.
*/
if((fixP->fx_r_type == SPARC_RELOC_13) ||
(fixP->fx_r_type == SPARC_RELOC_22)){
if(sub_symbolP->sy_other == add_symbolP->sy_other){
value += add_symbolP->sy_value -
sub_symbolP->sy_value;
add_symbolP = NULL;
fixP->fx_addsy = NULL; /* no relocation entry */
fixP->fx_subsy = NULL;
}
else{
as_warn("Can't emit reloc type %u {-symbol \"%s\"} "
"@ file address %llu (mode?).",
fixP->fx_r_type, sub_symbolP->sy_name,
fragP->fr_address + where);
}
}
else
value += add_symbolP->sy_value - sub_symbolP->sy_value;
#else
#if !(defined(I386) && defined(ARCH64))
/*
* Special case for x86_64. 'value' doesn't include
* the difference between the two symbols because
* that's handled by the subtractor/vanilla reloc pair.
*/
value += add_symbolP->sy_value;
value -= sub_symbolP->sy_value;
#else
/*
* But for x86_64 expressions in the debug section must
* be the actual value of the expression.
*/
if(is_section_debug(nsect)){
value += add_symbolP->sy_value;
value -= sub_symbolP->sy_value;
}
#endif
sub_symbol_nsect = sub_symbolP->sy_other;
/*
* If we have the special assembly time constant expression
* of the difference of two symbols defined in the same
* section then divided by exactly 2 adjust the value and
* make sure these symbols will produce an assembly time
* constant.
*/
if(fixP->fx_sectdiff_divide_by_two == 1){
value = value / 2;
if(is_assembly_time_constant_subtraction_expression(
add_symbolP, add_symbol_nsect,
sub_symbolP, sub_symbol_nsect) == TRUE){
fixP->fx_addsy = NULL; /* no relocation entry */
goto down;
}
else{
layout_line = fixP->line;
layout_file = fixP->file;
as_warn("section difference divide by two "
"expression, \"%s\" minus \"%s\" divide by "
"2 will not produce an assembly time "
"constant", add_symbolP->sy_name,
sub_symbolP->sy_name);
}
}
if(is_end_section_address(add_symbol_nsect,
add_symbolP->sy_value) ||
is_end_section_address(sub_symbol_nsect,
sub_symbolP->sy_value)){
if(is_assembly_time_constant_subtraction_expression(
add_symbolP, add_symbol_nsect,
sub_symbolP, sub_symbol_nsect) == TRUE){
fixP->fx_addsy = NULL; /* no relocation entry */
goto down;
}
if(is_section_debug(nsect) &&
strcmp(add_symbolP->sy_name, FAKE_LABEL_NAME) == 0 &&
strcmp(sub_symbolP->sy_name, FAKE_LABEL_NAME) == 0){
fixP->fx_addsy = NULL; /* no relocation entry */
goto down;
}
layout_line = fixP->line;
layout_file = fixP->file;
as_warn("section difference relocatable subtraction "
"expression, \"%s\" minus \"%s\" using a "
"symbol at the end of section will not "
"produce an assembly time constant",
add_symbolP->sy_name, sub_symbolP->sy_name);
as_warn("use a symbol with a constant value created "
"with an assignment instead of the expression, "
"L_const_sym = %s - %s", add_symbolP->sy_name,
sub_symbolP->sy_name);
layout_line = 0;
layout_file = NULL;
}
#endif
goto down;
}
/*
* If the subtract symbol is absolute subtract it's value from
* the fix expression and let a relocation entry get created
* that is not a section difference type.
*/
else if(sub_symbolP->sy_type == N_ABS){
value -= sub_symbolP->sy_value;
fixP->fx_subsy = NULL; /* no SECTDIFF relocation entry */
}
/*
* At this point we have something we can't generate a
* relocation entry for (two undefined symbols, etc.).
*/
else{
layout_line = fixP->line;
layout_file = fixP->file;
as_bad("non-relocatable subtraction expression, \"%s\" "
"minus \"%s\"", add_symbolP->sy_name,
sub_symbolP->sy_name);
if((add_symbolP->sy_type & N_TYPE) == N_UNDF)
as_bad("symbol: \"%s\" can't be undefined in a "
"subtraction expression", add_symbolP->sy_name);
if((sub_symbolP->sy_type & N_TYPE) == N_UNDF)
as_bad("symbol: \"%s\" can't be undefined in a "
"subtraction expression", sub_symbolP->sy_name);
layout_line = 0;
layout_file = NULL;
}
}
/*
* If a there is an add symbol in the fixup expression then add
* the symbol value into the fixup expression's value.
*/
if(add_symbolP){
/*
* If this symbol is in this section and is pc-relative and we
* do not want to force a pc-relative relocation entry (to
* support scattered loading) then just calculate the value.
*/
if(add_symbol_nsect == nsect
/* FROM write.c line 2659 */
#ifdef ARM
&& !TC_FORCE_RELOCATION_LOCAL (fixP)
#else
&& pcrel
#endif
&& !(fixP->fx_pcrel_reloc)){
/*
* This fixup was made when the symbol's section was
* unknown, but it is now in this section. So we know how
* to do the address without relocation.
*/
value += add_symbolP->sy_value;
#ifdef ARM
/* FROM write.c line 2667 */
value -= MD_PCREL_FROM_SECTION (fixP, nsect);
#else
value -= size + where + fragP->fr_address;
#endif
pcrel = 0; /* Lie. Don't want further pcrel processing. */
fixP->fx_addsy = NULL; /* No relocations please. */
/*
* It would be nice to check that the address does not
* overflow.
* I didn't do this check because:
* + It is machine dependent in the general case (eg 32032)
* + Compiler output will never need this checking, so why
* slow down the usual case?
*/
}
else{
switch(add_symbol_N_TYPE){
case N_ABS:
/*
* If the value of the symbol was an expression then
* now evaluate the expression now. This can happen
* when symbols like:
* .set x,a-b
* are used and the value of x is not known till all
* of the symbols are seen and had their values set.
*/
if(add_symbolP->expression != NULL){
expressionS *exp;
exp = (expressionS *)add_symbolP->expression;
value +=
exp->X_add_symbol->sy_value +
exp->X_add_number -
exp->X_subtract_symbol->sy_value;
}
else
{
value += add_symbolP->sy_value;
}
fixP->fx_addsy = NULL; /* no relocation entry */
add_symbolP = NULL;
break;
case N_SECT:
#if (defined(I386) && defined(ARCH64))
/*
* Symbol offsets are not part of fixups for external
* symbols for x86_64.
*/
if((is_section_debug(nsect) &&
add_symbol_N_TYPE != N_UNDF) ||
(add_symbol_N_TYPE == N_SECT &&
is_local_symbol(add_symbolP) &&
!is_section_cstring_literals(add_symbol_nsect)) )
#else
if(((add_symbolP->sy_type & N_EXT) != N_EXT ||
add_symbol_N_TYPE != N_SECT ||
!is_section_coalesced(add_symbol_nsect)) &&
(add_symbolP->sy_desc & N_WEAK_DEF) != N_WEAK_DEF)
#endif
value += add_symbolP->sy_value;
break;
case N_UNDF:
break;
default:
BAD_CASE(add_symbol_N_TYPE);
break;
}
}
}
down:
/*
* If the fixup expression is pc-relative then the value of the pc
* will be added to the expression when the machine executes the
* the instruction so we adjust the fixup expression's value by
* subtracting off the pc value (where) and adjust for insn size.
*/
if(pcrel){
#ifdef ARM
/* This should work for both */
/* FROM write.c line 2688 */
value -= MD_PCREL_FROM_SECTION (fixP, nsect);
#elif !(defined(I386) && defined(ARCH64))
/* Symbol offsets are not part of fixups for x86_64. */
value -= size + where + fragP->fr_address;
#endif
if(add_symbolP == NULL){
fixP->fx_addsy = &abs_symbol; /* force relocation entry */
}
}
if((size == 1 && (value & 0xffffff00) &&
((value & 0xffffff80) != 0xffffff80)) ||
(size == 2 && (value & 0xffff0000) &&
((value & 0xffff8000) != 0xffff8000))){
layout_line = fixP->line;
layout_file = fixP->file;
as_bad("Fixup of %lld too large for field width of %d",
value, size);
layout_line = 0;
layout_file = NULL;
}
/*
* Now place the fix expression's value in the place for the size.
* And save the fix expression's value to be used when creating
* a relocation entry if required.
*/
md_number_to_imm((unsigned char *)place, value, size, fixP, nsect);
fixP->fx_value = value;
/*
* If this is a non-lazy pointer section and this fix is for a
* local symbol without an subtract symbol then cause this not to
* generate a relocation entry. This is used with code gen for
* fix-n-continue where the compiler generates indirection for
* static data references. So the assembly looks like this:
*
* .non_lazy_symbol_pointer
* L_i$non_lazy_ptr:
* .indirect_symbol _i
* .long _i
*
* this allows the value of the symbol to be set into the pointer
* but not cause the relocation entry to be created. The code in
* write_object() then changes the indirect symbol table entry to
* INDIRECT_SYMBOL_LOCAL when the symbol is local. This is what
* the static and dynamic linkers expect and will then cause the
* pointer to be correctly relocated.
*/
if(is_section_non_lazy_symbol_pointers(nsect) &&
(add_symbolP->sy_type & N_EXT) != N_EXT &&
sub_symbolP == NULL){
fixP->fx_addsy = NULL; /* no relocation entry */
}
}
}
/*
* fixup_section() does the fixups of the frags and prepares the fixes so
* relocation entries can be created from them. The fixups cause the contents
* of the frag to have the value for the fixup expression. A fix structure that
* ends up with a non NULL fx_addsy will have a relocation entry created for it.
*/
static
void
fixup_section(
fixS *fixP,
int nsect)
{
symbolS *add_symbolP;
symbolS *sub_symbolP;
long value;
int size;
char *place;
long where;
char pcrel;
fragS *fragP;
int add_symbol_N_TYPE;
int add_symbol_nsect;
#ifndef SPARC
int sub_symbol_nsect;
#endif
/*
* The general fix expression is "fx_addsy - fx_subsy + fx_offset".
* The goal is to put the result of this expression into the frag at
* "place" for size "size". The value of the expression is calculated
* in the variable "value" and starts with just the fx_offset.
*/
for( ; fixP != NULL; fixP = fixP->fx_next){
fragP = fixP->fx_frag;
know(fragP);
where = fixP->fx_where;
place = fragP->fr_literal + where;
size = fixP->fx_size;
add_symbolP = fixP->fx_addsy;
sub_symbolP = fixP->fx_subsy;
value = fixP->fx_offset;
pcrel = fixP->fx_pcrel;
add_symbol_N_TYPE = 0;
add_symbol_nsect = 0;
if(add_symbolP != NULL){
add_symbol_N_TYPE = add_symbolP->sy_type & N_TYPE;
if(add_symbol_N_TYPE == N_SECT)
add_symbol_nsect = add_symbolP->sy_other;
}
/*
* Is there a subtract symbol?
*/
if(sub_symbolP){
/* is it just -sym ? */
if(add_symbolP == NULL){
if(sub_symbolP->sy_type != N_ABS)
as_warn("Negative of non-absolute symbol %s",
sub_symbolP->sy_name);
value -= sub_symbolP->sy_value;
fixP->fx_subsy = NULL;
}
/*
* There are both an add symbol and a subtract symbol at this
* point.
*
* If both symbols are absolute then just calculate the
* value of the fix expression and no relocation entry will be
* needed.
*/
else if((sub_symbolP->sy_type & N_TYPE) == N_ABS &&
(add_symbolP->sy_type & N_TYPE) == N_ABS){
value += add_symbolP->sy_value - sub_symbolP->sy_value;
add_symbolP = NULL;
fixP->fx_addsy = NULL; /* no relocation entry */
fixP->fx_subsy = NULL;
}
/*
* If both symbols are defined in a section then calculate the
* value of the fix expression and let a section difference
* relocation entry be created.
*/
else if((sub_symbolP->sy_type & N_TYPE) == N_SECT &&
(add_symbolP->sy_type & N_TYPE) == N_SECT){
/*
* We are use the new features that are incompatible with
* 3.2 then just calculate the value and let this create a
* SECTDIFF relocation type.
*/
#ifdef SPARC
/*
* Special case dealing with assembler internal relocation
* entries SPARC_RELOC_13 and RELOC_22. The can not be
* output and must be resolved.
*/
if((fixP->fx_r_type == SPARC_RELOC_13) ||
(fixP->fx_r_type == SPARC_RELOC_22)){
if(sub_symbolP->sy_other == add_symbolP->sy_other){
value += add_symbolP->sy_value -
sub_symbolP->sy_value;
add_symbolP = NULL;
fixP->fx_addsy = NULL; /* no relocation entry */
fixP->fx_subsy = NULL;
}
else{
as_warn("Can't emit reloc type %u {-symbol \"%s\"} "
"@ file address %ld (mode?).",
fixP->fx_r_type, sub_symbolP->sy_name,
fragP->fr_address + where);
}
}
else
value += add_symbolP->sy_value - sub_symbolP->sy_value;
#else
value += add_symbolP->sy_value - sub_symbolP->sy_value;
sub_symbol_nsect = sub_symbolP->sy_other;
if(is_end_section_address(add_symbol_nsect,
add_symbolP->sy_value) ||
is_end_section_address(sub_symbol_nsect,
sub_symbolP->sy_value)){
layout_line = fixP->line;
layout_file = fixP->file;
as_warn("section difference relocatable subtraction "
"expression, \"%s\" minus \"%s\" using a "
"symbol at the end of section will not "
"produce an assembly time constant",
add_symbolP->sy_name, sub_symbolP->sy_name);
as_warn("use a symbol with a constant value created "
"with an assignment instead of the expression, "
"L_const_sym = %s - %s", add_symbolP->sy_name,
sub_symbolP->sy_name);
layout_line = 0;
layout_file = NULL;
}
#endif
goto down;
}
/*
* If the subtract symbol is absolute subtract it's value from
* the fix expression and let a relocation entry get created
* that is not a section difference type.
*/
else if(sub_symbolP->sy_type == N_ABS){
value -= sub_symbolP->sy_value;
fixP->fx_subsy = NULL; /* no SECTDIFF relocation entry */
}
/*
* At this point we have something we can't generate a
* relocation entry for (two undefined symbols, etc.).
*/
else{
layout_line = fixP->line;
layout_file = fixP->file;
as_warn("non-relocatable subtraction expression, \"%s\" "
"minus \"%s\"", add_symbolP->sy_name,
sub_symbolP->sy_name);
if((add_symbolP->sy_type & N_TYPE) == N_UNDF)
as_warn("symbol: \"%s\" can't be undefined in a "
"subtraction expression", add_symbolP->sy_name);
if((sub_symbolP->sy_type & N_TYPE) == N_UNDF)
as_warn("symbol: \"%s\" can't be undefined in a "
"subtraction expression", sub_symbolP->sy_name);
layout_line = 0;
layout_file = NULL;
}
}
/*
* If a there is an add symbol in the fixup expression then add
* the symbol value into the fixup expression's value.
*/
if(add_symbolP){
/*
* If this symbol is in this section and is pc-relative and we
* do not want to force a pc-relative relocation entry (to
* support scattered loading) then just calculate the value.
*/
if(add_symbol_nsect == nsect &&
pcrel && !(fixP->fx_pcrel_reloc)){
/*
* This fixup was made when the symbol's section was
* unknown, but it is now in this section. So we know how
* to do the address without relocation.
*/
value += add_symbolP->sy_value;
value -= size + where + fragP->fr_address;
pcrel = 0; /* Lie. Don't want further pcrel processing. */
fixP->fx_addsy = NULL; /* No relocations please. */
/*
* It would be nice to check that the address does not
* overflow.
* I didn't do this check because:
* + It is machine dependent in the general case (eg 32032)
* + Compiler output will never need this checking, so why
* slow down the usual case?
*/
}
else{
switch(add_symbol_N_TYPE){
case N_ABS:
/*
* If the value of the symbol was an expression then
* now evaluate the expression now. This can happen
* when symbols like:
* .set x,a-b
* are used and the value of x is not known till all
* of the symbols are seen and had their values set.
*/
if(add_symbolP->expression != NULL){
expressionS *exp;
exp = (expressionS *)add_symbolP->expression;
value +=
exp->X_add_symbol->sy_value -
exp->X_subtract_symbol->sy_value;
}
else
value += add_symbolP->sy_value;
fixP->fx_addsy = NULL; /* no relocation entry */
add_symbolP = NULL;
break;
case N_SECT:
if((add_symbolP->sy_type & N_EXT) != N_EXT ||
add_symbol_N_TYPE != N_SECT ||
!is_section_coalesced(add_symbol_nsect))
value += add_symbolP->sy_value;
break;
case N_UNDF:
break;
default:
BAD_CASE(add_symbol_N_TYPE);
break;
}
}
}
down:
/*
* If the fixup expression is pc-relative then the value of the pc
* will be added to the expression when the machine executes the
* the instruction so we adjust the fixup expression's value by
* subtracting off the pc value (where) and adjust for insn size.
*/
if(pcrel){
value -= size + where + fragP->fr_address;
if(add_symbolP == NULL){
fixP->fx_addsy = &abs_symbol; /* force relocation entry */
}
}
if((size == 1 && (value & 0xffffff00) &&
((value & 0xffffff80) != 0xffffff80)) ||
(size == 2 && (value & 0xffff8000) &&
((value & 0xffff8000) != 0xffff8000)))
as_warn("Fixup of %ld too large for field width of %d",
value, size);
/*
* Now place the fix expression's value in the place for the size.
* And save the fix expression's value to be used when creating
* a relocation entry if required.
*/
md_number_to_imm((unsigned char *)place, value, size, fixP, nsect);
fixP->fx_value = value;
/*
* If this is a non-lazy pointer section and this fix is for a
* local symbol without an subtract symbol then cause this not to
* generate a relocation entry. This is used with code gen for
* fix-n-continue where the compiler generates indirection for
* static data references. So the assembly looks like this:
*
* .non_lazy_symbol_pointer
* L_i$non_lazy_ptr:
* .indirect_symbol _i
* .long _i
*
* this allows the value of the symbol to be set into the pointer
* but not cause the relocation entry to be created. The code in
* write_object() then changes the indirect symbol table entry to
* INDIRECT_SYMBOL_LOCAL when the symbol is local. This is what
* the static and dynamic linkers expect and will then cause the
* pointer to be correctly relocated.
*/
if(is_section_non_lazy_symbol_pointers(nsect) &&
(add_symbolP->sy_type & N_EXT) != N_EXT &&
sub_symbolP == NULL){
fixP->fx_addsy = NULL; /* no relocation entry */
}
}
}
