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-rw-r--r--elf/dl-fptr.c323
1 files changed, 323 insertions, 0 deletions
diff --git a/elf/dl-fptr.c b/elf/dl-fptr.c
new file mode 100644
index 0000000..78beecf
--- /dev/null
+++ b/elf/dl-fptr.c
@@ -0,0 +1,323 @@
+/* Manage function descriptors. Generic version.
+ Copyright (C) 1999,2000,2001,2002,2003,2004 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <libintl.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/param.h>
+#include <sys/mman.h>
+#include <link.h>
+#include <ldsodefs.h>
+#include <elf/dynamic-link.h>
+#include <dl-fptr.h>
+#include <atomic.h>
+
+#ifndef ELF_MACHINE_BOOT_FPTR_TABLE_LEN
+/* ELF_MACHINE_BOOT_FPTR_TABLE_LEN should be greater than the number of
+ dynamic symbols in ld.so. */
+# define ELF_MACHINE_BOOT_FPTR_TABLE_LEN 256
+#endif
+
+#ifndef ELF_MACHINE_LOAD_ADDRESS
+# error "ELF_MACHINE_LOAD_ADDRESS is not defined."
+#endif
+
+#ifndef COMPARE_AND_SWAP
+# define COMPARE_AND_SWAP(ptr, old, new) \
+ (atomic_compare_and_exchange_bool_acq (ptr, new, old) == 0)
+#endif
+
+ElfW(Addr) _dl_boot_fptr_table [ELF_MACHINE_BOOT_FPTR_TABLE_LEN];
+
+static struct local
+ {
+ struct fdesc_table *root;
+ struct fdesc *free_list;
+ unsigned int npages; /* # of pages to allocate */
+ /* the next to members MUST be consecutive! */
+ struct fdesc_table boot_table;
+ struct fdesc boot_fdescs[1024];
+ }
+local =
+ {
+ .root = &local.boot_table,
+ .npages = 2,
+ .boot_table =
+ {
+ .len = sizeof (local.boot_fdescs) / sizeof (local.boot_fdescs[0]),
+ .first_unused = 0
+ }
+ };
+
+/* Create a new fdesc table and return a pointer to the first fdesc
+ entry. The fdesc lock must have been acquired already. */
+
+static struct fdesc_table *
+new_fdesc_table (struct local *l, size_t *size)
+{
+ size_t old_npages = l->npages;
+ size_t new_npages = old_npages + old_npages;
+ struct fdesc_table *new_table;
+
+ /* If someone has just created a new table, we return NULL to tell
+ the caller to use the new table. */
+ if (! COMPARE_AND_SWAP (&l->npages, old_npages, new_npages))
+ return (struct fdesc_table *) NULL;
+
+ *size = old_npages * GLRO(dl_pagesize);
+ new_table = __mmap (NULL, *size,
+ PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
+ if (new_table == MAP_FAILED)
+ _dl_signal_error (errno, NULL, NULL,
+ N_("cannot map pages for fdesc table"));
+
+ new_table->len
+ = (*size - sizeof (*new_table)) / sizeof (struct fdesc);
+ new_table->first_unused = 1;
+ return new_table;
+}
+
+
+static ElfW(Addr)
+make_fdesc (ElfW(Addr) ip, ElfW(Addr) gp)
+{
+ struct fdesc *fdesc = NULL;
+ struct fdesc_table *root;
+ unsigned int old;
+ struct local *l;
+
+ ELF_MACHINE_LOAD_ADDRESS (l, local);
+
+ retry:
+ root = l->root;
+ while (1)
+ {
+ old = root->first_unused;
+ if (old >= root->len)
+ break;
+ else if (COMPARE_AND_SWAP (&root->first_unused, old, old + 1))
+ {
+ fdesc = &root->fdesc[old];
+ goto install;
+ }
+ }
+
+ if (l->free_list)
+ {
+ /* Get it from free-list. */
+ do
+ {
+ fdesc = l->free_list;
+ if (fdesc == NULL)
+ goto retry;
+ }
+ while (! COMPARE_AND_SWAP ((ElfW(Addr) *) &l->free_list,
+ (ElfW(Addr)) fdesc, fdesc->ip));
+ }
+ else
+ {
+ /* Create a new fdesc table. */
+ size_t size;
+ struct fdesc_table *new_table = new_fdesc_table (l, &size);
+
+ if (new_table == NULL)
+ goto retry;
+
+ new_table->next = root;
+ if (! COMPARE_AND_SWAP ((ElfW(Addr) *) &l->root,
+ (ElfW(Addr)) root,
+ (ElfW(Addr)) new_table))
+ {
+ /* Someone has just installed a new table. Return NULL to
+ tell the caller to use the new table. */
+ __munmap (new_table, size);
+ goto retry;
+ }
+
+ /* Note that the first entry was reserved while allocating the
+ memory for the new page. */
+ fdesc = &new_table->fdesc[0];
+ }
+
+ install:
+ fdesc->ip = ip;
+ fdesc->gp = gp;
+
+ return (ElfW(Addr)) fdesc;
+}
+
+
+static inline ElfW(Addr) * __attribute__ ((always_inline))
+make_fptr_table (struct link_map *map)
+{
+ const ElfW(Sym) *symtab
+ = (const void *) D_PTR (map, l_info[DT_SYMTAB]);
+ const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
+ ElfW(Addr) *fptr_table;
+ size_t size;
+ size_t len;
+
+ /* XXX Apparently the only way to find out the size of the dynamic
+ symbol section is to assume that the string table follows right
+ afterwards... */
+ len = ((strtab - (char *) symtab)
+ / map->l_info[DT_SYMENT]->d_un.d_val);
+ size = ((len * sizeof (fptr_table[0]) + GLRO(dl_pagesize) - 1)
+ & -GLRO(dl_pagesize));
+ /* XXX We don't support here in the moment systems without MAP_ANON.
+ There probably are none for IA-64. In case this is proven wrong
+ we will have to open /dev/null here and use the file descriptor
+ instead of the hard-coded -1. */
+ fptr_table = __mmap (NULL, size,
+ PROT_READ | PROT_WRITE, MAP_ANON | MAP_PRIVATE,
+ -1, 0);
+ if (fptr_table == MAP_FAILED)
+ _dl_signal_error (errno, NULL, NULL,
+ N_("cannot map pages for fptr table"));
+
+ if (COMPARE_AND_SWAP ((ElfW(Addr) *) &map->l_mach.fptr_table,
+ (ElfW(Addr)) NULL, (ElfW(Addr)) fptr_table))
+ map->l_mach.fptr_table_len = len;
+ else
+ __munmap (fptr_table, len * sizeof (fptr_table[0]));
+
+ return map->l_mach.fptr_table;
+}
+
+
+ElfW(Addr)
+_dl_make_fptr (struct link_map *map, const ElfW(Sym) *sym,
+ ElfW(Addr) ip)
+{
+ ElfW(Addr) *ftab = map->l_mach.fptr_table;
+ const ElfW(Sym) *symtab;
+ Elf_Symndx symidx;
+ struct local *l;
+
+ if (__builtin_expect (ftab == NULL, 0))
+ ftab = make_fptr_table (map);
+
+ symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]);
+ symidx = sym - symtab;
+
+ if (symidx >= map->l_mach.fptr_table_len)
+ _dl_signal_error (0, NULL, NULL,
+ N_("internal error: symidx out of range of fptr table"));
+
+ while (ftab[symidx] == 0)
+ {
+ /* GOT has already been relocated in elf_get_dynamic_info -
+ don't try to relocate it again. */
+ ElfW(Addr) fdesc
+ = make_fdesc (ip, map->l_info[DT_PLTGOT]->d_un.d_ptr);
+
+ if (__builtin_expect (COMPARE_AND_SWAP (&ftab[symidx], (ElfW(Addr)) NULL,
+ fdesc), 1))
+ {
+ /* Noone has updated the entry and the new function
+ descriptor has been installed. */
+#if 0
+ const char *strtab
+ = (const void *) D_PTR (map, l_info[DT_STRTAB]);
+
+ ELF_MACHINE_LOAD_ADDRESS (l, local);
+ if (l->root != &l->boot_table
+ || l->boot_table.first_unused > 20)
+ _dl_debug_printf ("created fdesc symbol `%s' at %lx\n",
+ strtab + sym->st_name, ftab[symidx]);
+#endif
+ break;
+ }
+ else
+ {
+ /* We created a duplicated function descriptor. We put it on
+ free-list. */
+ struct fdesc *f = (struct fdesc *) fdesc;
+
+ ELF_MACHINE_LOAD_ADDRESS (l, local);
+
+ do
+ f->ip = (ElfW(Addr)) l->free_list;
+ while (! COMPARE_AND_SWAP ((ElfW(Addr) *) &l->free_list,
+ f->ip, fdesc));
+ }
+ }
+
+ return ftab[symidx];
+}
+
+
+void
+_dl_unmap (struct link_map *map)
+{
+ ElfW(Addr) *ftab = map->l_mach.fptr_table;
+ struct fdesc *head = NULL, *tail = NULL;
+ size_t i;
+
+ __munmap ((void *) map->l_map_start,
+ map->l_map_end - map->l_map_start);
+
+ if (ftab == NULL)
+ return;
+
+ /* String together the fdesc structures that are being freed. */
+ for (i = 0; i < map->l_mach.fptr_table_len; ++i)
+ {
+ if (ftab[i])
+ {
+ *(struct fdesc **) ftab[i] = head;
+ head = (struct fdesc *) ftab[i];
+ if (tail == NULL)
+ tail = head;
+ }
+ }
+
+ /* Prepend the new list to the free_list: */
+ if (tail)
+ do
+ tail->ip = (ElfW(Addr)) local.free_list;
+ while (! COMPARE_AND_SWAP ((ElfW(Addr) *) &local.free_list,
+ tail->ip, (ElfW(Addr)) head));
+
+ __munmap (ftab, (map->l_mach.fptr_table_len
+ * sizeof (map->l_mach.fptr_table[0])));
+
+ map->l_mach.fptr_table = NULL;
+}
+
+
+ElfW(Addr)
+_dl_lookup_address (const void *address)
+{
+ ElfW(Addr) addr = (ElfW(Addr)) address;
+ struct fdesc_table *t;
+ unsigned long int i;
+
+ for (t = local.root; t != NULL; t = t->next)
+ {
+ i = (struct fdesc *) addr - &t->fdesc[0];
+ if (i < t->first_unused && addr == (ElfW(Addr)) &t->fdesc[i])
+ {
+ addr = t->fdesc[i].ip;
+ break;
+ }
+ }
+
+ return addr;
+}
generated by cgit v1.1 at 2024-12-20 14:19:35 +0000