From 415ac3df9b10ae426d4f71f9d48003f6a3c7bd8d Mon Sep 17 00:00:00 2001 From: Ulrich Drepper Date: Thu, 9 Jul 2009 23:52:22 -0700 Subject: Implement STB_GNU_UNIQUE handling. Some symbols have to be identified process-wide by their name. This is particularly important for some C++ features (e.g., class local static data and static variables in inline functions). This cannot completely be implemented with ELF functionality so far. The STB_GNU_UNIQUE binding helps by ensuring the dynamic linker will always use the same definition for all symbols with the same name and this binding. --- elf/Makefile | 18 ++++++-- elf/dl-lookup.c | 6 +-- elf/dl-open.c | 7 ++- elf/do-lookup.h | 118 +++++++++++++++++++++++++++++++++++++++++++++++++- elf/rtld.c | 7 ++- elf/tst-unique1.c | 40 +++++++++++++++++ elf/tst-unique1mod1.c | 21 +++++++++ elf/tst-unique1mod2.c | 20 +++++++++ elf/tst-unique2.c | 32 ++++++++++++++ elf/tst-unique2mod1.c | 13 ++++++ elf/tst-unique2mod2.c | 20 +++++++++ 11 files changed, 291 insertions(+), 11 deletions(-) create mode 100644 elf/tst-unique1.c create mode 100644 elf/tst-unique1mod1.c create mode 100644 elf/tst-unique1mod2.c create mode 100644 elf/tst-unique2.c create mode 100644 elf/tst-unique2mod1.c create mode 100644 elf/tst-unique2mod2.c (limited to 'elf') diff --git a/elf/Makefile b/elf/Makefile index 57febea..cc5caeb 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -111,7 +111,9 @@ distribute := rtld-Rules \ ifuncdep5.c ifuncdep5pic.c ifuncmod5.c \ ifuncmain6pie.c ifuncmod6.c \ ifuncmain7.c ifuncmain7pic.c ifuncmain7picstatic.c \ - ifuncmain7pie.c ifuncmain7static.c + ifuncmain7pie.c ifuncmain7static.c \ + tst-unique1.c tst-unique1mod1.c tst-unique1mod2.c \ + tst-unique2.c tst-unique2mod1.c tst-unique2mod2.c CFLAGS-dl-runtime.c = -fexceptions -fasynchronous-unwind-tables CFLAGS-dl-lookup.c = -fexceptions -fasynchronous-unwind-tables @@ -190,7 +192,8 @@ tests += loadtest restest1 preloadtest loadfail multiload origtest resolvfail \ tst-dlmopen1 tst-dlmopen2 tst-dlmopen3 \ unload3 unload4 unload5 unload6 unload7 tst-global1 order2 \ tst-audit1 tst-audit2 \ - tst-stackguard1 tst-addr1 tst-thrlock + tst-stackguard1 tst-addr1 tst-thrlock \ + tst-unique1 tst-unique2 # reldep9 test-srcs = tst-pathopt tests-execstack-yes = tst-execstack tst-execstack-needed tst-execstack-prog @@ -239,7 +242,9 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \ unload4mod1 unload4mod2 unload4mod3 unload4mod4 \ unload6mod1 unload6mod2 unload6mod3 \ unload7mod1 unload7mod2 \ - order2mod1 order2mod2 order2mod3 order2mod4 + order2mod1 order2mod2 order2mod3 order2mod4 \ + tst-unique1mod1 tst-unique1mod2 \ + tst-unique2mod1 tst-unique2mod2 ifeq (yes,$(have-initfini-array)) modules-names += tst-array2dep tst-array5dep endif @@ -1103,3 +1108,10 @@ $(objpfx)ifuncmain5pic: $(addprefix $(objpfx),ifuncmod5.so) $(objpfx)ifuncmain5static: $(addprefix $(objpfx),ifuncdep5.o) $(objpfx)ifuncmain5staticpic: $(addprefix $(objpfx),ifuncdep5pic.o) $(objpfx)ifuncmain5picstatic: $(addprefix $(objpfx),ifuncdep5pic.o) + +$(objpfx)tst-unique1: $(libdl) +$(objpfx)tst-unique1.out: $(objpfx)tst-unique1mod1.so \ + $(objpfx)tst-unique1mod2.so + +$(objpfx)tst-unique2: $(libdl) $(objpfx)tst-unique2mod1.so +$(objpfx)tst-unique2.out: $(objpfx)tst-unique2mod2.so diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c index 707d650..2ba885a 100644 --- a/elf/dl-lookup.c +++ b/elf/dl-lookup.c @@ -337,7 +337,7 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map, { int res = do_lookup_x (undef_name, new_hash, &old_hash, *ref, ¤t_value, *scope, start, version, flags, - skip_map, type_class); + skip_map, type_class, undef_map); if (res > 0) break; @@ -410,7 +410,7 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map, for (scope = symbol_scope; *scope != NULL; i = 0, ++scope) if (do_lookup_x (undef_name, new_hash, &old_hash, *ref, &protected_value, *scope, i, version, flags, - skip_map, ELF_RTYPE_CLASS_PLT) != 0) + skip_map, ELF_RTYPE_CLASS_PLT, NULL) != 0) break; if (protected_value.s != NULL && protected_value.m != undef_map) @@ -536,7 +536,7 @@ _dl_debug_bindings (const char *undef_name, struct link_map *undef_map, do_lookup_x (undef_name, new_hash, &old_hash, *ref, &val, undef_map->l_local_scope[0], 0, version, 0, NULL, - type_class); + type_class, undef_map); if (val.s != value->s || val.m != value->m) conflict = 1; diff --git a/elf/dl-open.c b/elf/dl-open.c index c3f0e42..b8ebfe0 100644 --- a/elf/dl-open.c +++ b/elf/dl-open.c @@ -569,7 +569,7 @@ _dl_open (const char *file, int mode, const void *caller_dlopen, Lmid_t nsid, if (GL(dl_ns)[nsid]._ns_loaded == NULL) break; - if (nsid == DL_NNS) + if (__builtin_expect (nsid == DL_NNS, 0)) { /* No more namespace available. */ __rtld_lock_unlock_recursive (GL(dl_load_lock)); @@ -579,7 +579,10 @@ no more namespaces available for dlmopen()")); } if (nsid == GL(dl_nns)) - ++GL(dl_nns); + { + __rtld_lock_initialize (GL(dl_ns)[nsid]._ns_unique_sym_table.lock); + ++GL(dl_nns); + } _dl_debug_initialize (0, nsid)->r_state = RT_CONSISTENT; } diff --git a/elf/do-lookup.h b/elf/do-lookup.h index acbc53d..782f490 100644 --- a/elf/do-lookup.h +++ b/elf/do-lookup.h @@ -27,7 +27,7 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash, unsigned long int *old_hash, const ElfW(Sym) *ref, struct sym_val *result, struct r_scope_elem *scope, size_t i, const struct r_found_version *const version, int flags, - struct link_map *skip, int type_class) + struct link_map *skip, int type_class, struct link_map *undef_map) { size_t n = scope->r_nlist; /* Make sure we read the value before proceeding. Otherwise we @@ -233,7 +233,7 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash, if (sym != NULL) { found_it: - switch (ELFW(ST_BIND) (sym->st_info)) + switch (__builtin_expect (ELFW(ST_BIND) (sym->st_info), STB_GLOBAL)) { case STB_WEAK: /* Weak definition. Use this value if we don't find another. */ @@ -248,10 +248,124 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash, } /* FALLTHROUGH */ case STB_GLOBAL: + success: /* Global definition. Just what we need. */ result->s = sym; result->m = (struct link_map *) map; return 1; + + case STB_GNU_UNIQUE:; + /* We have to determine whether we already found a + symbol with this name before. If not then we have to + add it to the search table. If we already found a + definition we have to use it. */ + void enter (struct unique_sym *table, size_t size, + unsigned int hash, const char *name, + const ElfW(Sym) *sym, const struct link_map *map) + { + size_t idx = hash % size; + size_t hash2 = 1 + hash % (size - 2); + while (1) + { + if (table[idx].hashval == 0) + { + table[idx].hashval = hash; + table[idx].name = strtab + sym->st_name; + if ((type_class & ELF_RTYPE_CLASS_COPY) != 0) + { + table[idx].sym = ref; + table[idx].map = undef_map; + } + else + { + table[idx].sym = sym; + table[idx].map = map; + } + return; + } + + idx += hash2; + if (idx >= size) + idx -= size; + } + } + + struct unique_sym_table *tab + = &GL(dl_ns)[map->l_ns]._ns_unique_sym_table; + + __rtld_lock_lock_recursive (tab->lock); + + struct unique_sym *entries = tab->entries; + size_t size = tab->size; + if (entries != NULL) + { + size_t idx = new_hash % size; + size_t hash2 = 1 + new_hash % (size - 2); + while (1) + { + if (entries[idx].hashval == new_hash + && strcmp (entries[idx].name, undef_name) == 0) + { + result->s = entries[idx].sym; + result->m = (struct link_map *) entries[idx].map; + __rtld_lock_unlock_recursive (tab->lock); + return 1; + } + + if (entries[idx].hashval == 0 + && entries[idx].name == NULL) + break; + + idx += hash2; + if (idx >= size) + idx -= size; + } + + if (size * 3 <= tab->n_elements) + { + /* Expand the table. */ + size_t newsize = _dl_higher_prime_number (size); + struct unique_sym *newentries + = calloc (sizeof (struct unique_sym), newsize); + if (newentries == NULL) + { + nomem: + __rtld_lock_unlock_recursive (tab->lock); + _dl_fatal_printf ("out of memory\n"); + } + + for (idx = 0; idx < size; ++idx) + if (entries[idx].hashval != 0) + enter (newentries, newsize, entries[idx].hashval, + entries[idx].name, entries[idx].sym, + entries[idx].map); + + tab->free (entries); + tab->size = newsize; + entries = tab->entries = newentries; + tab->free = free; + } + } + else + { +#define INITIAL_NUNIQUE_SYM_TABLE 31 + size = INITIAL_NUNIQUE_SYM_TABLE; + entries = calloc (sizeof (struct unique_sym), size); + if (entries == NULL) + goto nomem; + + tab->entries = entries; + tab->size = size; + tab->free = free; + } + + enter (entries, size, new_hash, strtab + sym->st_name, sym, map); + ++tab->n_elements; + + __rtld_lock_unlock_recursive (tab->lock); + + goto success; + default: /* Local symbols are ignored. */ break; diff --git a/elf/rtld.c b/elf/rtld.c index f97de9a..55b84c3 100644 --- a/elf/rtld.c +++ b/elf/rtld.c @@ -127,7 +127,12 @@ struct rtld_global _rtld_global = #ifdef _LIBC_REENTRANT ._dl_load_lock = _RTLD_LOCK_RECURSIVE_INITIALIZER, #endif - ._dl_nns = 1 + ._dl_nns = 1, + ._dl_ns = + { + [LM_ID_BASE] = { ._ns_unique_sym_table + = { .lock = _RTLD_LOCK_RECURSIVE_INITIALIZER } } + } }; /* If we would use strong_alias here the compiler would see a non-hidden definition. This would undo the effect of the previous diff --git a/elf/tst-unique1.c b/elf/tst-unique1.c new file mode 100644 index 0000000..9b7996c --- /dev/null +++ b/elf/tst-unique1.c @@ -0,0 +1,40 @@ +#include +#include +#include + +static int +do_test (void) +{ +#ifdef HAVE_ASM_UNIQUE_OBJECT + void *h1 = dlopen ("tst-unique1mod1.so", RTLD_LAZY); + if (h1 == NULL) + { + puts ("cannot load tst-unique1mod1"); + return 1; + } + int *(*f1) (void) = dlsym (h1, "f"); + if (f1 == NULL) + { + puts ("cannot locate f in tst-unique1mod1"); + return 1; + } + void *h2 = dlopen ("tst-unique1mod2.so", RTLD_LAZY); + if (h2 == NULL) + { + puts ("cannot load tst-unique1mod2"); + return 1; + } + int (*f2) (int *) = dlsym (h2, "f"); + if (f2 == NULL) + { + puts ("cannot locate f in tst-unique1mod2"); + return 1; + } + return f2 (f1 ()); +#else + return 0; +#endif +} + +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c" diff --git a/elf/tst-unique1mod1.c b/elf/tst-unique1mod1.c new file mode 100644 index 0000000..16de28d --- /dev/null +++ b/elf/tst-unique1mod1.c @@ -0,0 +1,21 @@ +#include + +#ifdef HAVE_ASM_UNIQUE_OBJECT +# define S(s) _S (s) +# define _S(s) #s + +asm (".data;" + S (ASM_GLOBAL_DIRECTIVE) " var\n" + ".type var, " S (ASM_TYPE_DIRECTIVE_PREFIX) "gnu_unique_object\n" + ".size var, 4\n" + "var:.zero 4\n" + ".previous"); +extern int var; + +int * +f (void) +{ + var = 1; + return &var; +} +#endif diff --git a/elf/tst-unique1mod2.c b/elf/tst-unique1mod2.c new file mode 100644 index 0000000..c075515 --- /dev/null +++ b/elf/tst-unique1mod2.c @@ -0,0 +1,20 @@ +#include + +#ifdef HAVE_ASM_UNIQUE_OBJECT +# define S(s) _S (s) +# define _S(s) #s + +asm (".data;" + S (ASM_GLOBAL_DIRECTIVE) " var\n" + ".type var, " S (ASM_TYPE_DIRECTIVE_PREFIX) "gnu_unique_object\n" + ".size var, 4\n" + "var:.zero 4\n" + ".previous"); +extern int var; + +int +f (int *p) +{ + return &var != p || *p != 1; +} +#endif diff --git a/elf/tst-unique2.c b/elf/tst-unique2.c new file mode 100644 index 0000000..7bb0687 --- /dev/null +++ b/elf/tst-unique2.c @@ -0,0 +1,32 @@ +#include +#include +#include + +extern int var; + +static int +do_test (void) +{ +#ifdef HAVE_ASM_UNIQUE_OBJECT + var = 1; + + void *h = dlopen ("tst-unique2mod2.so", RTLD_LAZY); + if (h == NULL) + { + puts ("cannot load tst-unique2mod2"); + return 1; + } + int (*f) (int *) = dlsym (h, "f"); + if (f == NULL) + { + puts ("cannot locate f in tst-unique2mod2"); + return 1; + } + return f (&var); +#else + return 0; +#endif +} + +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c" diff --git a/elf/tst-unique2mod1.c b/elf/tst-unique2mod1.c new file mode 100644 index 0000000..5e4ac4d --- /dev/null +++ b/elf/tst-unique2mod1.c @@ -0,0 +1,13 @@ +#include + +#ifdef HAVE_ASM_UNIQUE_OBJECT +# define S(s) _S (s) +# define _S(s) #s + +asm (".data;" + S (ASM_GLOBAL_DIRECTIVE) " var\n" + ".type var, " S (ASM_TYPE_DIRECTIVE_PREFIX) "gnu_unique_object\n" + ".size var, 4\n" + "var:.zero 4\n" + ".previous"); +#endif diff --git a/elf/tst-unique2mod2.c b/elf/tst-unique2mod2.c new file mode 100644 index 0000000..c075515 --- /dev/null +++ b/elf/tst-unique2mod2.c @@ -0,0 +1,20 @@ +#include + +#ifdef HAVE_ASM_UNIQUE_OBJECT +# define S(s) _S (s) +# define _S(s) #s + +asm (".data;" + S (ASM_GLOBAL_DIRECTIVE) " var\n" + ".type var, " S (ASM_TYPE_DIRECTIVE_PREFIX) "gnu_unique_object\n" + ".size var, 4\n" + "var:.zero 4\n" + ".previous"); +extern int var; + +int +f (int *p) +{ + return &var != p || *p != 1; +} +#endif -- cgit v1.1