}
#define MY_write_object_contents i386linux_write_object_contents
+\f
+/* Code to link against Linux a.out shared libraries. */
+
+/* See if a symbol name is a reference to the global offset table. */
+
+#ifndef GOT_REF_PREFIX
+#define GOT_REF_PREFIX "__GOT_"
+#endif
+
+#define IS_GOT_SYM(name) \
+ (strncmp (name, GOT_REF_PREFIX, sizeof GOT_REF_PREFIX - 1) == 0)
+
+/* See if a symbol name is a reference to the procedure linkage table. */
+
+#ifndef PLT_REF_PREFIX
+#define PLT_REF_PREFIX "__PLT_"
+#endif
+
+#define IS_PLT_SYM(name) \
+ (strncmp (name, PLT_REF_PREFIX, sizeof PLT_REF_PREFIX - 1) == 0)
+
+/* This special symbol is a set vector that contains a list of
+ pointers to fixup tables. It will be present in any dynamicly
+ linked file. The linker generated fixup table should also be added
+ to the list, and it should always appear in the second slot (the
+ first one is a dummy with a magic number that is defined in
+ crt0.o). */
+
+#ifndef SHARABLE_CONFLICTS
+#define SHARABLE_CONFLICTS "__SHARABLE_CONFLICTS__"
+#endif
+
+/* We keep a list of fixups. The terminology is a bit strange, but
+ each fixup contains two 32 bit numbers. A regular fixup contains
+ an address and a pointer, and at runtime we should store the
+ address at the location pointed to by the pointer. A builtin fixup
+ contains two pointers, and we should read the address using one
+ pointer and store it at the location pointed to by the other
+ pointer. Builtin fixups come into play when we have duplicate
+ __GOT__ symbols for the same variable. The builtin fixup will copy
+ the GOT pointer from one over into the other. */
+
+struct fixup
+{
+ struct fixup *next;
+ struct linux_link_hash_entry *h;
+ bfd_vma value;
+
+ /* Nonzero if this is a jump instruction that needs to be fixed,
+ zero if this is just a pointer */
+ char jump;
+
+ char builtin;
+};
+
+/* We don't need a special hash table entry structure, but we do need
+ to keep some information between linker passes, so we use a special
+ hash table. */
+
+struct linux_link_hash_entry
+{
+ struct aout_link_hash_entry root;
+};
+
+struct linux_link_hash_table
+{
+ struct aout_link_hash_table root;
+
+ /* First dynamic object found in link. */
+ bfd *dynobj;
+
+ /* Number of fixups. */
+ size_t fixup_count;
+
+ /* Number of builtin fixups. */
+ size_t local_builtins;
+
+ /* List of fixups. */
+ struct fixup *fixup_list;
+};
+
+static struct bfd_hash_entry *linux_link_hash_newfunc
+ PARAMS ((struct bfd_hash_entry *, struct bfd_hash_table *, const char *));
+static struct bfd_link_hash_table *linux_link_hash_table_create
+ PARAMS ((bfd *));
+static struct fixup *new_fixup
+ PARAMS ((struct bfd_link_info *, struct linux_link_hash_entry *,
+ bfd_vma, int));
+static boolean linux_link_create_dynamic_sections
+ PARAMS ((bfd *, struct bfd_link_info *));
+static boolean linux_add_one_symbol
+ PARAMS ((struct bfd_link_info *, bfd *, const char *, flagword, asection *,
+ bfd_vma, const char *, boolean, boolean,
+ struct bfd_link_hash_entry **));
+static boolean linux_tally_symbols
+ PARAMS ((struct linux_link_hash_entry *, PTR));
+static boolean linux_finish_dynamic_link
+ PARAMS ((bfd *, struct bfd_link_info *));
+
+/* Routine to create an entry in an Linux link hash table. */
+
+static struct bfd_hash_entry *
+linux_link_hash_newfunc (entry, table, string)
+ struct bfd_hash_entry *entry;
+ struct bfd_hash_table *table;
+ const char *string;
+{
+ struct linux_link_hash_entry *ret = (struct linux_link_hash_entry *) entry;
+
+ /* Allocate the structure if it has not already been allocated by a
+ subclass. */
+ if (ret == (struct linux_link_hash_entry *) NULL)
+ ret = ((struct linux_link_hash_entry *)
+ bfd_hash_allocate (table, sizeof (struct linux_link_hash_entry)));
+ if (ret == NULL)
+ return (struct bfd_hash_entry *) ret;
+
+ /* Call the allocation method of the superclass. */
+ ret = ((struct linux_link_hash_entry *)
+ NAME(aout,link_hash_newfunc) ((struct bfd_hash_entry *) ret,
+ table, string));
+ if (ret != NULL)
+ {
+ /* Set local fields; there aren't any. */
+ }
+
+ return (struct bfd_hash_entry *) ret;
+}
+
+/* Create a Linux link hash table. */
+
+static struct bfd_link_hash_table *
+linux_link_hash_table_create (abfd)
+ bfd *abfd;
+{
+ struct linux_link_hash_table *ret;
+
+ ret = ((struct linux_link_hash_table *)
+ malloc (sizeof (struct linux_link_hash_table)));
+ if (ret == (struct linux_link_hash_table *) NULL)
+ {
+ bfd_set_error (bfd_error_no_memory);
+ return (struct bfd_link_hash_table *) NULL;
+ }
+ if (! NAME(aout,link_hash_table_init) (&ret->root, abfd,
+ linux_link_hash_newfunc))
+ {
+ free (ret);
+ return (struct bfd_link_hash_table *) NULL;
+ }
+
+ ret->dynobj = NULL;
+ ret->fixup_count = 0;
+ ret->local_builtins = 0;
+ ret->fixup_list = NULL;
+
+ return &ret->root.root;
+}
+
+/* Look up an entry in a Linux link hash table. */
+
+#define linux_link_hash_lookup(table, string, create, copy, follow) \
+ ((struct linux_link_hash_entry *) \
+ aout_link_hash_lookup (&(table)->root, (string), (create), (copy),\
+ (follow)))
+
+/* Traverse a Linux link hash table. */
+
+#define linux_link_hash_traverse(table, func, info) \
+ (aout_link_hash_traverse \
+ (&(table)->root, \
+ (boolean (*) PARAMS ((struct aout_link_hash_entry *, PTR))) (func), \
+ (info)))
+
+/* Get the Linux link hash table from the info structure. This is
+ just a cast. */
+
+#define linux_hash_table(p) ((struct linux_link_hash_table *) ((p)->hash))
+
+/* Store the information for a new fixup. */
+
+static struct fixup *
+new_fixup (info, h, value, builtin)
+ struct bfd_link_info *info;
+ struct linux_link_hash_entry *h;
+ bfd_vma value;
+ int builtin;
+{
+ struct fixup *f;
+
+ f = (struct fixup *) bfd_hash_allocate (&info->hash->table,
+ sizeof (struct fixup));
+ if (f == NULL)
+ return f;
+ f->next = linux_hash_table (info)->fixup_list;
+ linux_hash_table (info)->fixup_list = f;
+ f->h = h;
+ f->value = value;
+ f->builtin = builtin;
+ f->jump = 0;
+ ++linux_hash_table (info)->fixup_count;
+ return f;
+}
+
+/* We come here once we realize that we are going to link to a shared
+ library. We need to create a special section that contains the
+ fixup table, and we ultimately need to add a pointer to this into
+ the set vector for SHARABLE_CONFLICTS. At this point we do not
+ know the size of the section, but that's OK - we just need to
+ create it for now. */
+
+static boolean
+linux_link_create_dynamic_sections (abfd, info)
+ bfd *abfd;
+ struct bfd_link_info *info;
+{
+ flagword flags;
+ register asection *s;
+
+ /* Note that we set the SEC_IN_MEMORY flag. */
+ flags = SEC_ALLOC | SEC_LOAD | SEC_HAS_CONTENTS | SEC_IN_MEMORY;
+
+ /* We choose to use the name ".dynamic" for the fixup table. Why
+ not? */
+ s = bfd_make_section (abfd, ".dynamic");
+ if (s == NULL
+ || ! bfd_set_section_flags (abfd, s, flags)
+ || ! bfd_set_section_alignment (abfd, s, 2))
+ return false;
+ s->_raw_size = 0;
+ s->contents = 0;
+
+ return true;
+}
+
+/* Function to add a single symbol to the linker hash table. This is
+ a wrapper around _bfd_generic_link_add_one_symbol which handles the
+ tweaking needed for dynamic linking support. */
+
+static boolean
+linux_add_one_symbol (info, abfd, name, flags, section, value, string,
+ copy, collect, hashp)
+ struct bfd_link_info *info;
+ bfd *abfd;
+ const char *name;
+ flagword flags;
+ asection *section;
+ bfd_vma value;
+ const char *string;
+ boolean copy;
+ boolean collect;
+ struct bfd_link_hash_entry **hashp;
+{
+ struct linux_link_hash_entry *h;
+ boolean insert;
+
+ /* Look up and see if we already have this symbol in the hash table.
+ If we do, and the defining entry is from a shared library, we
+ need to create the dynamic sections.
+
+ FIXME: What if abfd->xvec != info->hash->creator? We may want to
+ be able to link Linux a.out and ELF objects together, but serious
+ confusion is possible. */
+
+ insert = false;
+
+ if (! info->relocateable
+ && linux_hash_table (info)->dynobj == NULL
+ && strcmp (name, SHARABLE_CONFLICTS) == 0)
+ {
+ if (! linux_link_create_dynamic_sections (abfd, info))
+ return false;
+ linux_hash_table (info)->dynobj = abfd;
+ insert = true;
+ }
+
+ if (section == &bfd_abs_section
+ && (IS_GOT_SYM (name) || IS_PLT_SYM (name)))
+ {
+ h = linux_link_hash_lookup (linux_hash_table (info), name, false,
+ false, false);
+ if (h != NULL
+ && h->root.root.type == bfd_link_hash_defined)
+ {
+ if (new_fixup (info, h, value, ! IS_PLT_SYM(name)) == NULL)
+ return false;
+ return true;
+ }
+ if (hashp != NULL)
+ *hashp = (struct bfd_link_hash_entry *) h;
+ }
+
+ /* Do the usual procedure for adding a symbol. */
+ if (! _bfd_generic_link_add_one_symbol (info, abfd, name, flags, section,
+ value, string, copy, collect,
+ hashp))
+ return false;
+
+ /* Insert a pointer to our table in the set vector. The dynamic
+ linker requires this information */
+ if (insert)
+ {
+ asection *s;
+
+ /* Here we do our special thing to add the pointer to the
+ dynamic section in the SHARABLE_CONFLICTS set vector. */
+ s = bfd_get_section_by_name (linux_hash_table (info)->dynobj,
+ ".dynamic");
+ BFD_ASSERT (s != NULL);
+
+ if (! (_bfd_generic_link_add_one_symbol
+ (info, linux_hash_table (info)->dynobj, SHARABLE_CONFLICTS,
+ BSF_GLOBAL | BSF_CONSTRUCTOR, s, 0, NULL, false, false, NULL)))
+ return false;
+ }
+
+ return true;
+}
+
+/* We will crawl the hash table and come here for every global symbol.
+ We will examine each entry and see if there are indications that we
+ need to add a fixup. There are two possible cases - one is where
+ you have duplicate definitions of PLT or GOT symbols - these will
+ have already been caught and added as "builtin" fixups. If we find
+ that the corresponding non PLT/GOT symbol is also present, we
+ convert it to a regular fixup instead.
+
+ This function is called via linux_link_hash_traverse. */
+
+static boolean
+linux_tally_symbols (h, data)
+ struct linux_link_hash_entry *h;
+ PTR data;
+{
+ struct bfd_link_info *info = (struct bfd_link_info *) data;
+ struct fixup *f, *f1;
+ int is_plt;
+ struct linux_link_hash_entry *h1, *h2;
+
+ /* If this symbol is not a PLT/GOT, we do not even need to look at it */
+ is_plt = IS_PLT_SYM (h->root.root.root.string);
+
+ if (is_plt || IS_GOT_SYM (h->root.root.root.string))
+ {
+ /* Look up this symbol twice. Once just as a regular lookup,
+ and then again following all of the indirect links until we
+ reach a real symbol. */
+ h1 = linux_link_hash_lookup (linux_hash_table (info),
+ (h->root.root.root.string
+ + sizeof PLT_REF_PREFIX - 1),
+ false, false, true);
+ /* h2 does not follow indirect symbols. */
+ h2 = linux_link_hash_lookup (linux_hash_table (info),
+ (h->root.root.root.string
+ + sizeof PLT_REF_PREFIX - 1),
+ false, false, false);
+
+ /* The real symbol must exist but if it is also an ABS symbol,
+ there is no need to have a fixup. This is because they both
+ came from the same library. If on the other hand, we had to
+ use an indirect symbol to get to the real symbol, we add the
+ fixup anyway, since there are cases where these symbols come
+ from different shared libraries */
+ if (h1 != NULL
+ && ((h1->root.root.type == bfd_link_hash_defined
+ && h1->root.root.u.def.section != &bfd_abs_section)
+ || h2->root.root.type == bfd_link_hash_indirect))
+ {
+ f = new_fixup (info, h1, h->root.root.u.def.value, 0);
+ if (f == NULL)
+ {
+ /* FIXME: No way to return error. */
+ abort ();
+ }
+ f->jump = is_plt;
+
+ /* See if there is a "builtin" fixup already present
+ involving this symbol. If so, convert it to a regular
+ fixup. In the end, this relaxes some of the requirements
+ about the order of performing fixups. */
+ for (f1 = linux_hash_table (info)->fixup_list;
+ f1 != NULL;
+ f1 = f1->next)
+ {
+ if (f1 == f)
+ continue;
+ if (f1->h != h)
+ continue;
+ f1->h = h1;
+ f1->jump = is_plt;
+ f1->builtin = 0;
+ }
+ }
+
+ /* Quick and dirty way of stripping these symbols from the
+ symtab. */
+ h->root.written = true;
+ }
+
+ return true;
+}
+
+/* This is called to set the size of the .dynamic section is. It is
+ called by the Linux linker emulation before_allocation routine. We
+ have finished reading all of the input files, and now we just scan
+ the hash tables to find out how many additional fixups are
+ required. */
+
+boolean
+bfd_linux_size_dynamic_sections (output_bfd, info)
+ bfd *output_bfd;
+ struct bfd_link_info *info;
+{
+ struct fixup *f;
+ asection *s;
+
+ /* First find the fixups... */
+ linux_link_hash_traverse (linux_hash_table (info),
+ linux_tally_symbols,
+ (PTR) info);
+
+ /* If there are builtin fixups, leave room for a marker. This is
+ used by the dynamic linker so that it knows that all that follow
+ are builtin fixups instead of regular fixups. */
+ for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
+ {
+ if (f->builtin)
+ {
+ ++linux_hash_table (info)->fixup_count;
+ ++linux_hash_table (info)->local_builtins;
+ break;
+ }
+ }
+
+ if (linux_hash_table (info)->dynobj == NULL)
+ {
+ if (linux_hash_table (info)->fixup_count > 0)
+ abort ();
+ return true;
+ }
+
+ /* Allocate memory for our fixup table. We will fill it in later. */
+ s = bfd_get_section_by_name (linux_hash_table (info)->dynobj, ".dynamic");
+ if (s != NULL)
+ {
+ s->_raw_size = 8 + linux_hash_table (info)->fixup_count * 8;
+ s->contents = (bfd_byte *) bfd_alloc (output_bfd, s->_raw_size);
+ if (s->contents == NULL)
+ {
+ bfd_set_error (bfd_error_no_memory);
+ return false;
+ }
+ memset (s->contents, 0, s->_raw_size);
+ }
+
+ return true;
+}
+
+/* We come here once we are ready to actually write the fixup table to
+ the output file. Scan the fixup tables and so forth and generate
+ the stuff we need. */
+
+static boolean
+linux_finish_dynamic_link (output_bfd, info)
+ bfd *output_bfd;
+ struct bfd_link_info *info;
+{
+ asection *s, *os, *is;
+ bfd_byte *fixup_table;
+ struct linux_link_hash_entry *h;
+ struct fixup *f;
+ unsigned int new_addr;
+ int section_offset;
+ int fixups_written;
+
+ if (linux_hash_table (info)->dynobj == NULL)
+ return true;
+
+ s = bfd_get_section_by_name (linux_hash_table (info)->dynobj, ".dynamic");
+ BFD_ASSERT (s != NULL);
+ os = s->output_section;
+ fixups_written = 0;
+
+#ifdef LINUX_LINK_DEBUG
+ printf ("Fixup table file offset: %x VMA: %x\n",
+ os->filepos + s->output_offset,
+ os->vma + s->output_offset);
+#endif
+
+ fixup_table = s->contents;
+ bfd_put_32 (output_bfd, linux_hash_table (info)->fixup_count, fixup_table);
+ fixup_table += 4;
+
+ /* Fill in fixup table. */
+ for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
+ {
+ if (f->builtin)
+ continue;
+
+ if (f->h->root.root.type != bfd_link_hash_defined)
+ {
+ /* FIXME! */
+ fprintf (stderr,
+ "Symbol %s not defined for fixups\n",
+ f->h->root.root.root.string);
+ continue;
+ }
+
+ is = f->h->root.root.u.def.section;
+ section_offset = is->output_section->vma + is->output_offset;
+ new_addr = f->h->root.root.u.def.value + section_offset;
+
+#ifdef LINUX_LINK_DEBUG
+ printf ("Fixup(%d) %s: %x %x\n",f->jump, f->h->root.root.string,
+ new_addr, f->value);
+#endif
+
+ if (f->jump)
+ {
+ /* Relative address */
+ new_addr = new_addr - (f->value + 5);
+ bfd_put_32 (output_bfd, new_addr, fixup_table);
+ fixup_table += 4;
+ bfd_put_32 (output_bfd, f->value + 1, fixup_table);
+ fixup_table += 4;
+ }
+ else
+ {
+ bfd_put_32 (output_bfd, new_addr, fixup_table);
+ fixup_table += 4;
+ bfd_put_32 (output_bfd, f->value, fixup_table);
+ fixup_table += 4;
+ }
+ ++fixups_written;
+ }
+
+ if (linux_hash_table (info)->local_builtins != 0)
+ {
+ /* Special marker so we know to switch to the other type of fixup */
+ bfd_put_32 (output_bfd, 0, fixup_table);
+ fixup_table += 4;
+ bfd_put_32 (output_bfd, 0, fixup_table);
+ fixup_table += 4;
+ ++fixups_written;
+ for (f = linux_hash_table (info)->fixup_list; f != NULL; f = f->next)
+ {
+ if (! f->builtin)
+ continue;
+
+ if (f->h->root.root.type != bfd_link_hash_defined)
+ {
+ /* FIXME! */
+ fprintf (stderr,
+ "Symbol %s not defined for fixups\n",
+ f->h->root.root.root.string);
+ continue;
+ }
+
+ is = f->h->root.root.u.def.section;
+ section_offset = is->output_section->vma + is->output_offset;
+ new_addr = f->h->root.root.u.def.value + section_offset;
+
+#ifdef LINUX_LINK_DEBUG
+ printf ("Fixup(B) %s: %x %x\n", f->h->root.root.string,
+ new_addr, f->value);
+#endif
+
+ bfd_put_32 (output_bfd, new_addr, fixup_table);
+ fixup_table += 4;
+ bfd_put_32 (output_bfd, f->value, fixup_table);
+ fixup_table += 4;
+ ++fixups_written;
+ }
+ }
+
+ if (linux_hash_table (info)->fixup_count != fixups_written)
+ {
+ /* FIXME! */
+ fprintf (stderr, "Warning: fixup count mismatch\n");
+ while (linux_hash_table (info)->fixup_count > fixups_written)
+ {
+ bfd_put_32 (output_bfd, 0, fixup_table);
+ fixup_table += 4;
+ bfd_put_32 (output_bfd, 0, fixup_table);
+ fixup_table += 4;
+ ++fixups_written;
+ }
+ }
+
+ h = linux_link_hash_lookup (linux_hash_table (info),
+ "__BUILTIN_FIXUPS__",
+ false, false, false);
+
+ if (h != NULL && h->root.root.type == bfd_link_hash_defined)
+ {
+ is = h->root.root.u.def.section;
+ section_offset = is->output_section->vma + is->output_offset;
+ new_addr = h->root.root.u.def.value + section_offset;
+
+#ifdef LINUX_LINK_DEBUG
+ printf ("Builtin fixup table at %x\n", new_addr);
+#endif
+
+ bfd_put_32 (output_bfd, new_addr, fixup_table);
+ }
+ else
+ bfd_put_32 (output_bfd, 0, fixup_table);
+
+ if (bfd_seek (output_bfd, os->filepos + s->output_offset, SEEK_SET) != 0)
+ return false;
+
+ if (bfd_write ((PTR) s->contents, 1, s->_raw_size, output_bfd)
+ != s->_raw_size)
+ return false;
+
+ return true;
+}
+
+#define MY_bfd_link_hash_table_create linux_link_hash_table_create
+#define MY_add_one_symbol linux_add_one_symbol
+#define MY_finish_dynamic_link linux_finish_dynamic_link
#include "aout-target.h"
projects / binutils-gdb.git / commitdiff