+++ /dev/null
-/* Manage function descriptors. Generic version.
- Copyright (C) 1999-2024 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, see
- <https://www.gnu.org/licenses/>. */
-
-#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 <dl-unmap-segments.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) \
- (catomic_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 (__glibc_unlikely (ftab == NULL))
- 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))
- {
- /* No one 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;
-
- _dl_unmap_segments (map);
-
- 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;
-}
git://sourceware.org / glibc.git / commitdiff