[Patch macho/bfd/gas] .indirect_symbol, take 3.
Iain Sandoe
developer@sandoe-acoustics.co.uk
Thu Jan 12 08:37:00 GMT 2012
On 10 Jan 2012, at 13:03, Tristan Gingold wrote:
>> Here is a different implementation of the .indirect_symbol patch.
V3 ;-)
>> In this we keep indirect_symbols in a linked list in the section to
>> which they belong.
>
> I don't think that linked list is the best choice. The overhead is
> large (at least 2x), and the list structure is useful only for
> creating it (i.e. for gas). I would prefer to have an array in BFD,
> and the linked list in GAS.
well, it's a bit like a balloon - push in one place and it pops out in
another - this version is lighter in BFD, but heavier in GAS.
>> If this is OK, then a TODO would be to populate the list when a
>> mach-o file is read in -
>> - this is nicely symmetrical -
>> - and means that sections can be reordered/removed without having
>> to cross-check the dysymtab.
>>
>> The only thing that is less satisfactory, is that there is no way
>> (AFAICS) to mark a symbol as 'referenced by an indirect' which
>> means if one deletes (or wishes to delete) symbols - then one
>> should cross-check the usage from the indirect tables.
>
> Yes, this is an issue. I need to investigate how to address that.
I guess we could request a bit in the symbol flags...
>
> Use bfd_assert instead.
>
> Note that we should take care of local and absolute symbols.
I think locals are now done.. I will investigate ABS as a follow-on...
>>
>> case OBJ_MACH_O_SYM_PRIV_EXT:
>> s->n_type |= BFD_MACH_O_N_PEXT ;
>> + s->n_desc &= ~LAZY; /* The native tool swithes this off too. */
>> /* We follow the system tools in marking PEXT as also global. */
>> /* Fall through. */
>
> Unrelated chunk ?
no, symbol stubs and lazy pointer section symbols are, by default,
lazy but this gets cancelled if they are defined (or local).
>>
>> + if (nactual != ncalc)
>> + as_bad (_("there %s %d indirect_symbol%sin section %s but"
>> + " %d %s expected"), (nactual == 1)?"is":"are", nactual,
>
> "is":"are" don't make sense with other languages !
... and in some languages plurals are indicated by additional words ...
Does this not get handled by the translation process?
I don't especially like grammatically incorrect error/warning messages..
If it is un-handled, what is the usual solution?
====
Naturally, the changelog needs some tweaking, but I trust that we can
do this once we're agreed on the basic patch...
OK for this version?
Iain
bfd/mach-o.c | 64 +++++++++++-
bfd/mach-o.h | 34 ++++---
gas/config/obj-macho.c | 257 +++++++++++++++++++++++++++++++++++++++
+++------
gas/config/obj-macho.h | 3 +
4 files changed, 310 insertions(+), 48 deletions(-)
diff --git a/bfd/mach-o.c b/bfd/mach-o.c
index 6913b1d..9511665 100644
--- a/bfd/mach-o.c
+++ b/bfd/mach-o.c
@@ -2079,6 +2079,33 @@ bfd_mach_o_build_seg_command (const char
*segment,
return TRUE;
}
+/* Count the number of indirect symbols in the image.
+ Requires that the sections are in their final order. */
+
+static unsigned int
+bfd_mach_o_count_indirect_symbols (bfd *abfd, bfd_mach_o_data_struct
*mdata)
+{
+ unsigned int i;
+ unsigned int nisyms = 0;
+
+ for (i = 0; i < mdata->nsects; ++i)
+ {
+ bfd_mach_o_section *sec = mdata->sections[i];
+
+ switch (sec->flags & BFD_MACH_O_SECTION_TYPE_MASK)
+ {
+ case BFD_MACH_O_S_NON_LAZY_SYMBOL_POINTERS:
+ case BFD_MACH_O_S_LAZY_SYMBOL_POINTERS:
+ case BFD_MACH_O_S_SYMBOL_STUBS:
+ nisyms += bfd_mach_o_section_get_nbr_indirect (abfd, sec);
+ break;
+ default:
+ break;
+ }
+ }
+ return nisyms;
+}
+
static bfd_boolean
bfd_mach_o_build_dysymtab_command (bfd *abfd,
bfd_mach_o_data_struct *mdata,
@@ -2135,9 +2162,11 @@ bfd_mach_o_build_dysymtab_command (bfd *abfd,
dsym->nundefsym = 0;
}
+ dsym->nindirectsyms = bfd_mach_o_count_indirect_symbols (abfd,
mdata);
if (dsym->nindirectsyms > 0)
{
unsigned i;
+ unsigned n;
mdata->filelen = FILE_ALIGN (mdata->filelen, 2);
dsym->indirectsymoff = mdata->filelen;
@@ -2146,11 +2175,38 @@ bfd_mach_o_build_dysymtab_command (bfd *abfd,
dsym->indirect_syms = bfd_zalloc (abfd, dsym->nindirectsyms *
4);
if (dsym->indirect_syms == NULL)
return FALSE;
-
- /* So fill in the indices. */
- for (i = 0; i < dsym->nindirectsyms; ++i)
+
+ n = 0;
+ for (i = 0; i < mdata->nsects; ++i)
{
- /* TODO: fill in the table. */
+ bfd_mach_o_section *sec = mdata->sections[i];
+
+ switch (sec->flags & BFD_MACH_O_SECTION_TYPE_MASK)
+ {
+ case BFD_MACH_O_S_NON_LAZY_SYMBOL_POINTERS:
+ case BFD_MACH_O_S_LAZY_SYMBOL_POINTERS:
+ case BFD_MACH_O_S_SYMBOL_STUBS:
+ {
+ unsigned j, num;
+ bfd_mach_o_asymbol **isyms = sec->indirect_syms;
+
+ num = bfd_mach_o_section_get_nbr_indirect (abfd, sec);
+ if (isyms == NULL || num == 0)
+ break;
+ /* Record the starting index in the reserved1 field. */
+ sec->reserved1 = n;
+ for (j = 0; j < num; j++, n++)
+ {
+ if (isyms[j] == NULL)
+ dsym->indirect_syms[n] = 0x80000000;
+ else
+ dsym->indirect_syms[n] = isyms[j]->symbol.udata.i;
+ }
+ }
+ break;
+ default:
+ break;
+ }
}
}
diff --git a/bfd/mach-o.h b/bfd/mach-o.h
index ca810a0..7f54961 100644
--- a/bfd/mach-o.h
+++ b/bfd/mach-o.h
@@ -42,6 +42,18 @@ typedef struct bfd_mach_o_header
}
bfd_mach_o_header;
+typedef struct bfd_mach_o_asymbol
+{
+ /* The actual symbol which the rest of BFD works with. */
+ asymbol symbol;
+
+ /* Mach-O symbol fields. */
+ unsigned char n_type;
+ unsigned char n_sect;
+ unsigned short n_desc;
+}
+bfd_mach_o_asymbol;
+
#define BFD_MACH_O_SEGNAME_SIZE 16
#define BFD_MACH_O_SECTNAME_SIZE 16
@@ -64,6 +76,12 @@ typedef struct bfd_mach_o_section
/* Corresponding bfd section. */
asection *bfdsection;
+ /* An array holding the indirect symbols for this section.
+ NULL values indicate local symbols.
+ The number of symbols is determined from the section size and
type. */
+
+ bfd_mach_o_asymbol **indirect_syms;
+
/* Simply linked list. */
struct bfd_mach_o_section *next;
}
@@ -105,26 +123,12 @@ typedef struct bfd_mach_o_reloc_info
}
bfd_mach_o_reloc_info;
-typedef struct bfd_mach_o_asymbol
-{
- /* The actual symbol which the rest of BFD works with. */
- asymbol symbol;
-
- /* Mach-O symbol fields. */
- unsigned char n_type;
- unsigned char n_sect;
- unsigned short n_desc;
-}
-bfd_mach_o_asymbol;
-
/* The symbol table is sorted like this:
(1) local.
(otherwise in order of generation)
(2) external defined
(sorted by name)
- (3) external undefined
- (sorted by name)
- (4) common
+ (3) external undefined / common
(sorted by name)
*/
diff --git a/gas/config/obj-macho.c b/gas/config/obj-macho.c
index 43f4fba..cf94de5 100644
--- a/gas/config/obj-macho.c
+++ b/gas/config/obj-macho.c
@@ -1032,6 +1032,7 @@ obj_mach_o_set_symbol_qualifier (symbolS *sym,
int type)
case OBJ_MACH_O_SYM_PRIV_EXT:
s->n_type |= BFD_MACH_O_N_PEXT ;
+ s->n_desc &= ~LAZY; /* The native tool swithes this off too. */
/* We follow the system tools in marking PEXT as also global. */
/* Fall through. */
@@ -1131,13 +1132,79 @@ obj_mach_o_sym_qual (int ntype)
demand_empty_rest_of_line ();
}
-/* Dummy function to allow test-code to work while we are working
- on things. */
+typedef struct obj_mach_o_indirect_sym
+{
+ symbolS *sym;
+ segT sect;
+ struct obj_mach_o_indirect_sym *next;
+} obj_mach_o_indirect_sym;
+
+/* We store in order an maintain a pointer to the last one - to save
reversing
+ later. */
+obj_mach_o_indirect_sym *indirect_syms;
+obj_mach_o_indirect_sym *indirect_syms_tail;
static void
-obj_mach_o_placeholder (int arg ATTRIBUTE_UNUSED)
+obj_mach_o_indirect_symbol (int arg ATTRIBUTE_UNUSED)
{
- ignore_rest_of_line ();
+ bfd_mach_o_section *sec = bfd_mach_o_get_mach_o_section (now_seg);
+
+#ifdef md_flush_pending_output
+ md_flush_pending_output ();
+#endif
+
+ if (obj_mach_o_is_static)
+ as_bad (_("use of .indirect_symbols requires `-dynamic'"));
+
+ switch (sec->flags & BFD_MACH_O_SECTION_TYPE_MASK)
+ {
+ case BFD_MACH_O_S_SYMBOL_STUBS:
+ case BFD_MACH_O_S_LAZY_SYMBOL_POINTERS:
+ case BFD_MACH_O_S_NON_LAZY_SYMBOL_POINTERS:
+ {
+ obj_mach_o_indirect_sym *isym;
+ char *name = input_line_pointer;
+ char c = get_symbol_end ();
+ symbolS *sym = symbol_find_or_make (name);
+ unsigned int elsize =
+ bfd_mach_o_section_get_entry_size (stdoutput, sec);
+
+ if (elsize == 0)
+ {
+ as_bad (_("attempt to add an indirect_symbol to a stub or"
+ " reference section with a zero-sized element at %s"),
+ name);
+ *input_line_pointer = c;
+ ignore_rest_of_line ();
+ return;
+ }
+ *input_line_pointer = c;
+
+ isym = (obj_mach_o_indirect_sym *)
+ xmalloc (sizeof (obj_mach_o_indirect_sym));
+ if (isym == NULL)
+ abort ();
+
+ /* Just record the data for now, we will validate it when we
+ compute the output. */
+ isym->sym = sym;
+ isym->sect = now_seg;
+ isym->next = NULL;
+ if (indirect_syms == NULL)
+ indirect_syms = isym;
+ else
+ indirect_syms_tail->next = isym;
+ indirect_syms_tail = isym;
+ }
+ break;
+
+ default:
+ as_bad (_("an .indirect_symbol must be in a symbol pointer"
+ " or stub section."));
+ ignore_rest_of_line ();
+ return;
+ }
+ demand_empty_rest_of_line ();
}
const pseudo_typeS mach_o_pseudo_table[] =
@@ -1231,7 +1298,7 @@ const pseudo_typeS mach_o_pseudo_table[] =
{"no_dead_strip", obj_mach_o_sym_qual,
OBJ_MACH_O_SYM_NO_DEAD_STRIP},
{"weak", obj_mach_o_sym_qual, OBJ_MACH_O_SYM_WEAK}, /* ext */
- {"indirect_symbol", obj_mach_o_placeholder, 0},
+ {"indirect_symbol", obj_mach_o_indirect_symbol, 0},
/* File flags. */
{ "subsections_via_symbols", obj_mach_o_fileprop,
@@ -1270,15 +1337,25 @@ obj_mach_o_type_for_symbol (bfd_mach_o_asymbol
*s)
void obj_macho_frob_label (struct symbol *sp)
{
- bfd_mach_o_asymbol *s = (bfd_mach_o_asymbol *) symbol_get_bfdsym
(sp);
- /* This is the base symbol type, that we mask in. */
- unsigned base_type = obj_mach_o_type_for_symbol (s);
- bfd_mach_o_section *sec = bfd_mach_o_get_mach_o_section (s-
>symbol.section);
+ bfd_mach_o_asymbol *s;
+ unsigned base_type;
+ bfd_mach_o_section *sec;
int sectype = -1;
+ /* Leave local symbols alone. */
+
+ if (S_IS_LOCAL (sp))
+ return;
+
+ s = (bfd_mach_o_asymbol *) symbol_get_bfdsym (sp);
+ /* Leave debug symbols alone. */
if ((s->n_type & BFD_MACH_O_N_STAB) != 0)
- return; /* Leave alone. */
-
+ return;
+
+ /* This is the base symbol type, that we mask in. */
+ base_type = obj_mach_o_type_for_symbol (s);
+
+ sec = bfd_mach_o_get_mach_o_section (s->symbol.section);
if (sec != NULL)
sectype = sec->flags & BFD_MACH_O_SECTION_TYPE_MASK;
@@ -1307,34 +1384,41 @@ void obj_macho_frob_label (struct symbol *sp)
int
obj_macho_frob_symbol (struct symbol *sp)
{
- bfd_mach_o_asymbol *s = (bfd_mach_o_asymbol *) symbol_get_bfdsym
(sp);
- unsigned base_type = obj_mach_o_type_for_symbol (s);
- bfd_mach_o_section *sec = bfd_mach_o_get_mach_o_section (s-
>symbol.section);
+ bfd_mach_o_asymbol *s;
+ unsigned base_type;
+ bfd_mach_o_section *sec;
int sectype = -1;
-
+
+ /* Leave local symbols alone. */
+ if (S_IS_LOCAL (sp))
+ return 0;
+
+ s = (bfd_mach_o_asymbol *) symbol_get_bfdsym (sp);
+ /* Leave debug symbols alone. */
+ if ((s->n_type & BFD_MACH_O_N_STAB) != 0)
+ return 0;
+
+ base_type = obj_mach_o_type_for_symbol (s);
+ sec = bfd_mach_o_get_mach_o_section (s->symbol.section);
if (sec != NULL)
sectype = sec->flags & BFD_MACH_O_SECTION_TYPE_MASK;
- if ((s->n_type & BFD_MACH_O_N_STAB) != 0)
- return 0; /* Leave alone. */
- else if (s->symbol.section == bfd_und_section_ptr)
+ if (s->symbol.section == bfd_und_section_ptr)
{
/* ??? Do we really gain much from implementing this as well
as the
mach-o specific ones? */
if (s->symbol.flags & BSF_WEAK)
s->n_desc |= BFD_MACH_O_N_WEAK_REF;
- /* Undefined references, become extern. */
- if (s->n_desc & REFE)
- {
- s->n_desc &= ~REFE;
- s->n_type |= BFD_MACH_O_N_EXT;
- }
-
- /* So do undefined 'no_dead_strip's. */
- if (s->n_desc & BFD_MACH_O_N_NO_DEAD_STRIP)
- s->n_type |= BFD_MACH_O_N_EXT;
-
+ /* Undefined syms, become extern. */
+ s->n_type |= BFD_MACH_O_N_EXT;
+ S_SET_EXTERNAL (sp);
+ }
+ else if (s->symbol.section == bfd_com_section_ptr)
+ {
+ /* ... so to comm. */
+ s->n_type |= BFD_MACH_O_N_EXT;
+ S_SET_EXTERNAL (sp);
}
else
{
@@ -1353,6 +1437,7 @@ obj_macho_frob_symbol (struct symbol *sp)
{
/* Anything here that should be added that is non-standard. */
s->n_desc &= ~BFD_MACH_O_REFERENCE_MASK;
+ s->symbol.udata.i = SYM_MACHO_FIELDS_NOT_VALIDATED;
}
else if (s->symbol.udata.i == SYM_MACHO_FIELDS_NOT_VALIDATED)
{
@@ -1388,6 +1473,120 @@ obj_macho_frob_symbol (struct symbol *sp)
return 0;
}
+static void
+obj_mach_o_set_indirect_symbols (bfd *abfd, asection *sec,
+ void *xxx ATTRIBUTE_UNUSED)
+{
+ bfd_vma sect_size = bfd_section_size (abfd, sec);
+ bfd_mach_o_section *ms = bfd_mach_o_get_mach_o_section (sec);
+ unsigned lazy = 0;
+
+ /* See if we have any indirect syms to consider. */
+ if (indirect_syms == NULL)
+ return;
+
+ /* Process indirect symbols to determine if we have errors there. */
+
+ switch (ms->flags & BFD_MACH_O_SECTION_TYPE_MASK)
+ {
+ case BFD_MACH_O_S_SYMBOL_STUBS:
+ case BFD_MACH_O_S_LAZY_SYMBOL_POINTERS:
+ lazy = LAZY;
+ /* Fall through. */
+ case BFD_MACH_O_S_NON_LAZY_SYMBOL_POINTERS:
+ {
+ unsigned int nactual = 0;
+ unsigned int ncalc;
+ obj_mach_o_indirect_sym *isym;
+ obj_mach_o_indirect_sym *list = NULL;
+ obj_mach_o_indirect_sym *list_tail = NULL;
+ unsigned long eltsiz =
+ bfd_mach_o_section_get_entry_size (abfd, ms);
+
+ for (isym = indirect_syms; isym != NULL; isym = isym->next)
+ {
+ if (isym->sect == sec)
+ {
+ nactual++;
+ if (list == NULL)
+ list = isym;
+ else
+ list_tail->next = isym;
+ list_tail = isym;
+ }
+ }
+
+ /* If none are in this section, stop here. */
+ if (nactual == 0)
+ break;
+
+ /* If we somehow added indirect symbols to a section with a zero
+ entry size, we're dead ... */
+ gas_assert (eltsiz != 0);
+
+ ncalc = (unsigned int) (sect_size / eltsiz);
+ if (nactual != ncalc)
+ as_bad (_("there %s %d indirect_symbol%sin section %s but"
+ " %d %s expected"), (nactual == 1)?"is":"are", nactual,
+ (nactual == 1)?" ":"s ", sec->name, ncalc,
+ (ncalc == 1)?"is":"are");
+ else
+ {
+ unsigned n;
+ bfd_mach_o_asymbol *sym;
+ ms->indirect_syms =
+ bfd_zalloc (abfd,
+ nactual * sizeof (bfd_mach_o_asymbol *));
+
+ gas_assert (ms->indirect_syms != NULL);
+
+ for (isym = list, n = 0; isym != NULL; isym = isym->next, n++)
+ {
+ /* Array is init to NULL & NULL signals a local symbol
+ If the section is lazy-bound, we need to keep the
+ reference to the symbol, since dyld can override. */
+ if (S_IS_LOCAL (isym->sym) && ! lazy)
+ ;
+ else
+ {
+ sym = (bfd_mach_o_asymbol *)symbol_get_bfdsym (isym->sym);
+ if (sym == NULL)
+ ;
+ /* If the symbols is external ... */
+ else if (S_IS_EXTERNAL (isym->sym)
+ || (sym->n_type & BFD_MACH_O_N_EXT)
+ || ! S_IS_DEFINED (isym->sym)
+ || lazy)
+ {
+ sym->n_desc &= ~LAZY;
+ /* ... and can be lazy, if not defined or hidden. */
+ if ((sym->n_type & BFD_MACH_O_N_TYPE)
+ == BFD_MACH_O_N_UNDF
+ && ! (sym->n_type & BFD_MACH_O_N_PEXT)
+ && (sym->n_type & BFD_MACH_O_N_EXT))
+ sym->n_desc |= lazy;
+ ms->indirect_syms[n] = sym;
+ }
+ }
+ }
+ }
+ }
+ break;
+
+ default:
+ break;
+ }
+}
+
+/* The process of relocation could alter what's externally visible,
thus we
+ leave setting the indirect symbols until last. */
+
+void
+obj_mach_o_frob_file_after_relocs (void)
+{
+ bfd_map_over_sections (stdoutput, obj_mach_o_set_indirect_symbols,
(char *) 0);
+}
+
/* Support stabs for mach-o. */
void
diff --git a/gas/config/obj-macho.h b/gas/config/obj-macho.h
index cbc3a4f..9f1f3db 100644
--- a/gas/config/obj-macho.h
+++ b/gas/config/obj-macho.h
@@ -62,6 +62,9 @@ extern void obj_macho_frob_label (struct symbol *);
#define obj_frob_symbol(s, punt) punt = obj_macho_frob_symbol(s)
extern int obj_macho_frob_symbol (struct symbol *);
+#define obj_frob_file_after_relocs obj_mach_o_frob_file_after_relocs
+extern void obj_mach_o_frob_file_after_relocs (void);
+
#define EMIT_SECTION_SYMBOLS 0
#define OBJ_PROCESS_STAB(SEG,W,S,T,O,D)
obj_mach_o_process_stab(W,S,T,O,D)
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