/* On-demand PLT fixup for shared objects.
- Copyright (C) 1995-1999, 2000 Free Software Foundation, Inc.
+ Copyright (C) 1995-2009, 2010, 2011 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 Library General Public License as
- published by the Free Software Foundation; either version 2 of the
- License, or (at your option) any later version.
+ 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
- Library General Public License for more details.
+ Lesser General Public License for more details.
- You should have received a copy of the GNU Library General Public
- License along with the GNU C Library; see the file COPYING.LIB. If not,
- write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA. */
+ 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. */
+
+#define IN_DL_RUNTIME 1 /* This can be tested in dl-machine.h. */
#include <alloca.h>
#include <stdlib.h>
#include <unistd.h>
+#include <sys/param.h>
#include <ldsodefs.h>
+#include <sysdep-cancel.h>
#include "dynamic-link.h"
+#include <tls.h>
+
-#if !defined ELF_MACHINE_NO_RELA || ELF_MACHINE_NO_REL
+#if (!defined ELF_MACHINE_NO_RELA && !defined ELF_MACHINE_PLT_REL) \
+ || ELF_MACHINE_NO_REL
# define PLTREL ElfW(Rela)
#else
# define PLTREL ElfW(Rel)
# define VERSYMIDX(sym) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (sym))
#endif
+/* The fixup functions might have need special attributes. If none
+ are provided define the macro as empty. */
+#ifndef ARCH_FIXUP_ATTRIBUTE
+# define ARCH_FIXUP_ATTRIBUTE
+#endif
+
+#ifndef reloc_offset
+# define reloc_offset reloc_arg
+# define reloc_index reloc_arg / sizeof (PLTREL)
+#endif
+
+
/* This function is called through a special trampoline from the PLT the
first time each PLT entry is called. We must perform the relocation
function. */
#ifndef ELF_MACHINE_NO_PLT
-static ElfW(Addr) __attribute__ ((unused))
-fixup (
+DL_FIXUP_VALUE_TYPE
+__attribute ((noinline)) ARCH_FIXUP_ATTRIBUTE
+_dl_fixup (
# ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS
- ELF_MACHINE_RUNTIME_FIXUP_ARGS,
+ ELF_MACHINE_RUNTIME_FIXUP_ARGS,
# endif
- struct link_map *l, ElfW(Word) reloc_offset)
+ /* GKM FIXME: Fix trampoline to pass bounds so we can do
+ without the `__unbounded' qualifier. */
+ struct link_map *__unbounded l, ElfW(Word) reloc_arg)
{
const ElfW(Sym) *const symtab
= (const void *) D_PTR (l, l_info[DT_SYMTAB]);
const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
void *const rel_addr = (void *)(l->l_addr + reloc->r_offset);
lookup_t result;
- ElfW(Addr) value;
-
- /* The use of `alloca' here looks ridiculous but it helps. The goal is
- to prevent the function from being inlined and thus optimized out.
- There is no official way to do this so we use this trick. gcc never
- inlines functions which use `alloca'. */
- alloca (sizeof (int));
+ DL_FIXUP_VALUE_TYPE value;
/* Sanity check that we're really looking at a PLT relocation. */
assert (ELFW(R_TYPE)(reloc->r_info) == ELF_MACHINE_JMP_SLOT);
used don't look in the global scope. */
if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
{
- switch (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
+ const struct r_found_version *version = NULL;
+
+ if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
+ {
+ const ElfW(Half) *vernum =
+ (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
+ ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
+ version = &l->l_versions[ndx];
+ if (version->hash == 0)
+ version = NULL;
+ }
+
+ /* We need to keep the scope around so do some locking. This is
+ not necessary for objects which cannot be unloaded or when
+ we are not using any threads (yet). */
+ int flags = DL_LOOKUP_ADD_DEPENDENCY;
+ if (!RTLD_SINGLE_THREAD_P)
{
- default:
- {
- const ElfW(Half) *vernum =
- (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
- ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)];
- const struct r_found_version *version = &l->l_versions[ndx];
-
- if (version->hash != 0)
- {
- result = _dl_lookup_versioned_symbol (strtab + sym->st_name,
- l, &sym, l->l_scope,
- version,
- ELF_MACHINE_JMP_SLOT);
- break;
- }
- }
- case 0:
- result = _dl_lookup_symbol (strtab + sym->st_name, l, &sym,
- l->l_scope, ELF_MACHINE_JMP_SLOT);
+ THREAD_GSCOPE_SET_FLAG ();
+ flags |= DL_LOOKUP_GSCOPE_LOCK;
}
+#ifdef RTLD_ENABLE_FOREIGN_CALL
+ RTLD_ENABLE_FOREIGN_CALL;
+#endif
+
+ result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym, l->l_scope,
+ version, ELF_RTYPE_CLASS_PLT, flags, NULL);
+
+ /* We are done with the global scope. */
+ if (!RTLD_SINGLE_THREAD_P)
+ THREAD_GSCOPE_RESET_FLAG ();
+
+#ifdef RTLD_FINALIZE_FOREIGN_CALL
+ RTLD_FINALIZE_FOREIGN_CALL;
+#endif
+
/* Currently result contains the base load address (or link map)
of the object that defines sym. Now add in the symbol
offset. */
- value = (sym ? LOOKUP_VALUE_ADDRESS (result) + sym->st_value : 0);
+ value = DL_FIXUP_MAKE_VALUE (result,
+ sym ? (LOOKUP_VALUE_ADDRESS (result)
+ + sym->st_value) : 0);
}
else
{
- /* We already found the symbol. The module (and therefore its load
- address) is also known. */
- value = l->l_addr + sym->st_value;
-#ifdef DL_LOOKUP_RETURNS_MAP
+ /* We already found the symbol. The module (and therefore its load
+ address) is also known. */
+ value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + sym->st_value);
result = l;
-#endif
}
/* And now perhaps the relocation addend. */
value = elf_machine_plt_value (l, reloc, value);
+ if (sym != NULL
+ && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0))
+ value = ((DL_FIXUP_VALUE_TYPE (*) (void)) DL_FIXUP_VALUE_ADDR (value)) ();
+
/* Finally, fix up the plt itself. */
+ if (__builtin_expect (GLRO(dl_bind_not), 0))
+ return value;
+
return elf_machine_fixup_plt (l, result, reloc, rel_addr, value);
}
#endif
-#if !defined PROF && !defined ELF_MACHINE_NO_PLT
-
-static ElfW(Addr) __attribute__ ((unused))
-profile_fixup (
+#if !defined PROF && !defined ELF_MACHINE_NO_PLT && !__BOUNDED_POINTERS__
+DL_FIXUP_VALUE_TYPE
+__attribute ((noinline)) ARCH_FIXUP_ATTRIBUTE
+_dl_profile_fixup (
#ifdef ELF_MACHINE_RUNTIME_FIXUP_ARGS
- ELF_MACHINE_RUNTIME_FIXUP_ARGS,
+ ELF_MACHINE_RUNTIME_FIXUP_ARGS,
#endif
- struct link_map *l, ElfW(Word) reloc_offset, ElfW(Addr) retaddr)
+ struct link_map *l, ElfW(Word) reloc_arg,
+ ElfW(Addr) retaddr, void *regs, long int *framesizep)
{
- void (*mcount_fct) (ElfW(Addr), ElfW(Addr)) = _dl_mcount;
- ElfW(Addr) *resultp;
- lookup_t result;
- ElfW(Addr) value;
-
- /* The use of `alloca' here looks ridiculous but it helps. The goal is
- to prevent the function from being inlined, and thus optimized out.
- There is no official way to do this so we use this trick. gcc never
- inlines functions which use `alloca'. */
- alloca (sizeof (int));
+ void (*mcount_fct) (ElfW(Addr), ElfW(Addr)) = INTUSE(_dl_mcount);
/* This is the address in the array where we store the result of previous
relocations. */
- resultp = &l->l_reloc_result[reloc_offset / sizeof (PLTREL)];
+ struct reloc_result *reloc_result = &l->l_reloc_result[reloc_index];
+ DL_FIXUP_VALUE_TYPE *resultp = &reloc_result->addr;
- value = *resultp;
- if (value == 0)
+ DL_FIXUP_VALUE_TYPE value = *resultp;
+ if (DL_FIXUP_VALUE_CODE_ADDR (value) == 0)
{
/* This is the first time we have to relocate this object. */
const ElfW(Sym) *const symtab
= (const void *) D_PTR (l, l_info[DT_SYMTAB]);
- const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
+ const char *strtab = (const char *) D_PTR (l, l_info[DT_STRTAB]);
const PLTREL *const reloc
= (const void *) (D_PTR (l, l_info[DT_JMPREL]) + reloc_offset);
- const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)];
+ const ElfW(Sym) *refsym = &symtab[ELFW(R_SYM) (reloc->r_info)];
+ const ElfW(Sym) *defsym = refsym;
+ lookup_t result;
/* Sanity check that we're really looking at a PLT relocation. */
assert (ELFW(R_TYPE)(reloc->r_info) == ELF_MACHINE_JMP_SLOT);
/* Look up the target symbol. If the symbol is marked STV_PROTECTED
don't look in the global scope. */
- if (__builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0)
+ if (__builtin_expect (ELFW(ST_VISIBILITY) (refsym->st_other), 0) == 0)
{
- switch (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
+ const struct r_found_version *version = NULL;
+
+ if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL)
+ {
+ const ElfW(Half) *vernum =
+ (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]);
+ ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff;
+ version = &l->l_versions[ndx];
+ if (version->hash == 0)
+ version = NULL;
+ }
+
+ /* We need to keep the scope around so do some locking. This is
+ not necessary for objects which cannot be unloaded or when
+ we are not using any threads (yet). */
+ int flags = DL_LOOKUP_ADD_DEPENDENCY;
+ if (!RTLD_SINGLE_THREAD_P)
{
- default:
- {
- const ElfW(Half) *vernum =
- (const void *) D_PTR (l,l_info[VERSYMIDX (DT_VERSYM)]);
- ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)];
- const struct r_found_version *version = &l->l_versions[ndx];
-
- if (version->hash != 0)
- {
- result = _dl_lookup_versioned_symbol(strtab + sym->st_name,
- l, &sym, l->l_scope,
- version,
- ELF_MACHINE_JMP_SLOT);
- break;
- }
- }
- case 0:
- result = _dl_lookup_symbol (strtab + sym->st_name, l, &sym,
- l->l_scope, ELF_MACHINE_JMP_SLOT);
+ THREAD_GSCOPE_SET_FLAG ();
+ flags |= DL_LOOKUP_GSCOPE_LOCK;
}
+ result = _dl_lookup_symbol_x (strtab + refsym->st_name, l,
+ &defsym, l->l_scope, version,
+ ELF_RTYPE_CLASS_PLT, flags, NULL);
+
+ /* We are done with the global scope. */
+ if (!RTLD_SINGLE_THREAD_P)
+ THREAD_GSCOPE_RESET_FLAG ();
+
/* Currently result contains the base load address (or link map)
of the object that defines sym. Now add in the symbol
offset. */
- value = (sym ? LOOKUP_VALUE_ADDRESS (result) + sym->st_value : 0);
+ value = DL_FIXUP_MAKE_VALUE (result,
+ defsym != NULL
+ ? LOOKUP_VALUE_ADDRESS (result)
+ + defsym->st_value : 0);
+
+ if (defsym != NULL
+ && __builtin_expect (ELFW(ST_TYPE) (defsym->st_info)
+ == STT_GNU_IFUNC, 0))
+ value = ((DL_FIXUP_VALUE_TYPE (*) (void))
+ DL_FIXUP_VALUE_ADDR (value)) ();
}
else
{
- /* We already found the symbol. The module (and therefore its load
- address) is also known. */
- value = l->l_addr + sym->st_value;
-#ifdef DL_LOOKUP_RETURNS_MAP
- result = l;
-#endif
+ /* We already found the symbol. The module (and therefore its load
+ address) is also known. */
+ value = DL_FIXUP_MAKE_VALUE (l, l->l_addr + refsym->st_value);
+
+ if (__builtin_expect (ELFW(ST_TYPE) (refsym->st_info)
+ == STT_GNU_IFUNC, 0))
+ value = ((DL_FIXUP_VALUE_TYPE (*) (void))
+ DL_FIXUP_VALUE_ADDR (value)) ();
+
+ result = l;
}
/* And now perhaps the relocation addend. */
value = elf_machine_plt_value (l, reloc, value);
+#ifdef SHARED
+ /* Auditing checkpoint: we have a new binding. Provide the
+ auditing libraries the possibility to change the value and
+ tell us whether further auditing is wanted. */
+ if (defsym != NULL && GLRO(dl_naudit) > 0)
+ {
+ reloc_result->bound = result;
+ /* Compute index of the symbol entry in the symbol table of
+ the DSO with the definition. */
+ reloc_result->boundndx = (defsym
+ - (ElfW(Sym) *) D_PTR (result,
+ l_info[DT_SYMTAB]));
+
+ /* Determine whether any of the two participating DSOs is
+ interested in auditing. */
+ if ((l->l_audit_any_plt | result->l_audit_any_plt) != 0)
+ {
+ unsigned int flags = 0;
+ struct audit_ifaces *afct = GLRO(dl_audit);
+ /* Synthesize a symbol record where the st_value field is
+ the result. */
+ ElfW(Sym) sym = *defsym;
+ sym.st_value = DL_FIXUP_VALUE_ADDR (value);
+
+ /* Keep track whether there is any interest in tracing
+ the call in the lower two bits. */
+ assert (DL_NNS * 2 <= sizeof (reloc_result->flags) * 8);
+ assert ((LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT) == 3);
+ reloc_result->enterexit = LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT;
+
+ const char *strtab2 = (const void *) D_PTR (result,
+ l_info[DT_STRTAB]);
+
+ for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
+ {
+ /* XXX Check whether both DSOs must request action or
+ only one */
+ if ((l->l_audit[cnt].bindflags & LA_FLG_BINDFROM) != 0
+ && (result->l_audit[cnt].bindflags & LA_FLG_BINDTO) != 0)
+ {
+ if (afct->symbind != NULL)
+ {
+ uintptr_t new_value
+ = afct->symbind (&sym, reloc_result->boundndx,
+ &l->l_audit[cnt].cookie,
+ &result->l_audit[cnt].cookie,
+ &flags,
+ strtab2 + defsym->st_name);
+ if (new_value != (uintptr_t) sym.st_value)
+ {
+ flags |= LA_SYMB_ALTVALUE;
+ sym.st_value = new_value;
+ }
+ }
+
+ /* Remember the results for every audit library and
+ store a summary in the first two bits. */
+ reloc_result->enterexit
+ &= flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT);
+ reloc_result->enterexit
+ |= ((flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT))
+ << ((cnt + 1) * 2));
+ }
+ else
+ /* If the bind flags say this auditor is not interested,
+ set the bits manually. */
+ reloc_result->enterexit
+ |= ((LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT)
+ << ((cnt + 1) * 2));
+
+ afct = afct->next;
+ }
+
+ reloc_result->flags = flags;
+ value = DL_FIXUP_ADDR_VALUE (sym.st_value);
+ }
+ else
+ /* Set all bits since this symbol binding is not interesting. */
+ reloc_result->enterexit = (1u << DL_NNS) - 1;
+ }
+#endif
+
/* Store the result for later runs. */
- *resultp = value;
+ if (__builtin_expect (! GLRO(dl_bind_not), 1))
+ *resultp = value;
+ }
+
+ /* By default we do not call the pltexit function. */
+ long int framesize = -1;
+
+#ifdef SHARED
+ /* Auditing checkpoint: report the PLT entering and allow the
+ auditors to change the value. */
+ if (DL_FIXUP_VALUE_CODE_ADDR (value) != 0 && GLRO(dl_naudit) > 0
+ /* Don't do anything if no auditor wants to intercept this call. */
+ && (reloc_result->enterexit & LA_SYMB_NOPLTENTER) == 0)
+ {
+ ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound,
+ l_info[DT_SYMTAB])
+ + reloc_result->boundndx);
+
+ /* Set up the sym parameter. */
+ ElfW(Sym) sym = *defsym;
+ sym.st_value = DL_FIXUP_VALUE_ADDR (value);
+
+ /* Get the symbol name. */
+ const char *strtab = (const void *) D_PTR (reloc_result->bound,
+ l_info[DT_STRTAB]);
+ const char *symname = strtab + sym.st_name;
+
+ /* Keep track of overwritten addresses. */
+ unsigned int flags = reloc_result->flags;
+
+ struct audit_ifaces *afct = GLRO(dl_audit);
+ for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
+ {
+ if (afct->ARCH_LA_PLTENTER != NULL
+ && (reloc_result->enterexit
+ & (LA_SYMB_NOPLTENTER << (2 * (cnt + 1)))) == 0)
+ {
+ long int new_framesize = -1;
+ uintptr_t new_value
+ = afct->ARCH_LA_PLTENTER (&sym, reloc_result->boundndx,
+ &l->l_audit[cnt].cookie,
+ &reloc_result->bound->l_audit[cnt].cookie,
+ regs, &flags, symname,
+ &new_framesize);
+ if (new_value != (uintptr_t) sym.st_value)
+ {
+ flags |= LA_SYMB_ALTVALUE;
+ sym.st_value = new_value;
+ }
+
+ /* Remember the results for every audit library and
+ store a summary in the first two bits. */
+ reloc_result->enterexit
+ |= ((flags & (LA_SYMB_NOPLTENTER | LA_SYMB_NOPLTEXIT))
+ << (2 * (cnt + 1)));
+
+ if ((reloc_result->enterexit & (LA_SYMB_NOPLTEXIT
+ << (2 * (cnt + 1))))
+ == 0 && new_framesize != -1 && framesize != -2)
+ {
+ /* If this is the first call providing information,
+ use it. */
+ if (framesize == -1)
+ framesize = new_framesize;
+ /* If two pltenter calls provide conflicting information,
+ use the larger value. */
+ else if (new_framesize != framesize)
+ framesize = MAX (new_framesize, framesize);
+ }
+ }
+
+ afct = afct->next;
+ }
+
+ value = DL_FIXUP_ADDR_VALUE (sym.st_value);
}
+#endif
- (*mcount_fct) (retaddr, value);
+ /* Store the frame size information. */
+ *framesizep = framesize;
+
+ (*mcount_fct) (retaddr, DL_FIXUP_VALUE_CODE_ADDR (value));
return value;
}
#endif /* PROF && ELF_MACHINE_NO_PLT */
-/* This macro is defined in dl-machine.h to define the entry point called
- by the PLT. The `fixup' function above does the real work, but a little
- more twiddling is needed to get the stack right and jump to the address
- finally resolved. */
+#include <stdio.h>
+void
+ARCH_FIXUP_ATTRIBUTE
+_dl_call_pltexit (struct link_map *l, ElfW(Word) reloc_arg,
+ const void *inregs, void *outregs)
+{
+#ifdef SHARED
+ /* This is the address in the array where we store the result of previous
+ relocations. */
+ // XXX Maybe the bound information must be stored on the stack since
+ // XXX with bind_not a new value could have been stored in the meantime.
+ struct reloc_result *reloc_result = &l->l_reloc_result[reloc_index];
+ ElfW(Sym) *defsym = ((ElfW(Sym) *) D_PTR (reloc_result->bound,
+ l_info[DT_SYMTAB])
+ + reloc_result->boundndx);
+
+ /* Set up the sym parameter. */
+ ElfW(Sym) sym = *defsym;
+ sym.st_value = DL_FIXUP_VALUE_ADDR (reloc_result->addr);
+
+ /* Get the symbol name. */
+ const char *strtab = (const void *) D_PTR (reloc_result->bound,
+ l_info[DT_STRTAB]);
+ const char *symname = strtab + sym.st_name;
+
+ struct audit_ifaces *afct = GLRO(dl_audit);
+ for (unsigned int cnt = 0; cnt < GLRO(dl_naudit); ++cnt)
+ {
+ if (afct->ARCH_LA_PLTEXIT != NULL
+ && (reloc_result->enterexit
+ & (LA_SYMB_NOPLTEXIT >> (2 * cnt))) == 0)
+ {
+ afct->ARCH_LA_PLTEXIT (&sym, reloc_result->boundndx,
+ &l->l_audit[cnt].cookie,
+ &reloc_result->bound->l_audit[cnt].cookie,
+ inregs, outregs, symname);
+ }
-ELF_MACHINE_RUNTIME_TRAMPOLINE
+ afct = afct->next;
+ }
+#endif
+}
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