* after resolving ELF shared library symbols
*
* Copyright (C) 2005 by Joakim Tjernlund
- * Copyright (C) 2000-200
4 by Erik Andersen <andersen@codepoet.org>
+ * Copyright (C) 2000-200
6 by Erik Andersen <andersen@codepoet.org>
* Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
* David Engel, Hongjiu Lu and Mitch D'Souza
*
/*
* The main trick with this program is that initially, we ourselves are not
- * dynamicly linked. This means that we cannot access any global variables or
- * call any functions. No globals initially, since the Global Offset Table
+ * dynamically linked. This means that we cannot access any global variables
+ * or call any functions. No globals initially, since the Global Offset Table
* (GOT) is initialized by the linker assuming a virtual address of 0, and no
* function calls initially since the Procedure Linkage Table (PLT) is not yet
* initialized.
*
* Fortunately, the linker itself leaves a few clues lying around, and when the
* kernel starts the image, there are a few further clues. First of all, there
- * is Auxiliary Vector Table information sitting on which is provided to us by
- * the kernel, and which includes information about the load address that the
- * program interpreter was loaded at, the number of sections, the address the
- * application was loaded at and so forth. Here this information is stored in
- * the array auxvt. For details see linux/fs/binfmt_elf.c where it calls
- * NEW_AUX_ENT() a bunch of time....
+ * is Auxiliary Vector Table information sitting on the stack which is provided
+ * to us by the kernel, and which includes information about the address
+ * that the program interpreter was loaded at, the number of sections, the
+ * address the application was loaded at, and so forth. Here this information
+ * is stored in the array auxvt. For details see linux/fs/binfmt_elf.c where
+ * it calls NEW_AUX_ENT() a bunch of times....
*
* Next, we need to find the GOT. On most arches there is a register pointing
* to the GOT, but just in case (and for new ports) I've added some (slow) C
/* Pull in all the arch specific stuff */
#include "dl-startup.h"
+#ifdef __LDSO_PRELINK_SUPPORT__
+/* These defined magically in the linker script. */
+extern char _begin[] attribute_hidden;
+#endif
+
/* Static declarations */
-int (*_dl_elf_main) (int, char **, char **);
+static int (*_dl_elf_main) (int, char **, char **);
static void* __rtld_stack_end; /* Points to argc on stack, e.g *((long *)__rtld_stackend) == argc */
strong_alias(__rtld_stack_end, __libc_stack_end) /* Exported version of __rtld_stack_end */
/* When we enter this piece of code, the program stack looks like this:
argc argument counter (integer)
argv[0] program name (pointer)
- argv[1...N] program args (pointers)
- argv[argc-1] end of args (integer)
+ argv[1..argc-1] program args (pointers)
NULL
env[0...N] environment variables (pointers)
NULL
auxvt[0...N] Auxiliary Vector Table elements (mixed types)
*/
-static void * __attribute_used__ _dl_start(unsigned long args)
+DL_START(unsigned long args)
{
unsigned int argc;
char **argv, **envp;
- ElfW(Addr) load_addr;
+ DL_LOADADDR_TYPE load_addr;
ElfW(Addr) got;
unsigned long *aux_dat;
ElfW(Ehdr) *header;
struct elf_resolve *tpnt = &tpnt_tmp;
ElfW(auxv_t) auxvt[AT_EGID + 1];
ElfW(Dyn) *dpnt;
+ uint32_t *p32;
- /* WARNING! -- we cannot make _any_ funtion calls until we have
+ /* WARNING! -- we cannot make _any_ function calls until we have
* taken care of fixing up our own relocations. Making static
* inline calls is ok, but _no_ function calls. Not yet
* anyways. */
/* First obtain the information on the stack that tells us more about
what binary is loaded, where it is loaded, etc, etc */
GET_ARGV(aux_dat, args);
- argc = *(aux_dat - 1);
+ argc = aux_dat[-1];
argv = (char **) aux_dat;
aux_dat += argc; /* Skip over the argv pointers */
aux_dat++; /* Skip over NULL at end of argv */
envp = (char **) aux_dat;
-#ifndef NO_EARLY_SEND_STDERR
- SEND_STDERR_DEBUG("argc=");
+#if !defined(NO_EARLY_SEND_STDERR)
+ SEND_EARLY_STDERR_DEBUG("argc=");
SEND_NUMBER_STDERR_DEBUG(argc, 0);
- SEND_STDERR_DEBUG(" argv=");
+ SEND_EARLY_STDERR_DEBUG(" argv=");
SEND_ADDRESS_STDERR_DEBUG(argv, 0);
- SEND_STDERR_DEBUG(" envp=");
+ SEND_EARLY_STDERR_DEBUG(" envp=");
SEND_ADDRESS_STDERR_DEBUG(envp, 1);
#endif
while (*aux_dat)
aux_dat += 2;
}
- /* locate the ELF header. We need this done as soon as possible
- * (esp since SEND_STDERR() needs this on some platforms... */
+ /*
+ * Locate the dynamic linker ELF header. We need this done as soon as
+ * possible (esp since SEND_STDERR() needs this on some platforms...
+ */
+
+#ifdef __LDSO_PRELINK_SUPPORT__
+ /*
+ * The `_begin' symbol created by the linker script points to ld.so ELF
+ * We use it if the kernel is not passing a valid address through the auxvt.
+ */
+
+ if (!auxvt[AT_BASE].a_un.a_val)
+ auxvt[AT_BASE].a_un.a_val = (Elf32_Addr) &_begin;
+ /* Note: if the dynamic linker itself is prelinked, the load_addr is 0 */
+ DL_INIT_LOADADDR_BOOT(load_addr, elf_machine_load_address());
+#else
if (!auxvt[AT_BASE].a_un.a_val)
auxvt[AT_BASE].a_un.a_val = elf_machine_load_address();
- load_addr = auxvt[AT_BASE].a_un.a_val;
+ DL_INIT_LOADADDR_BOOT(load_addr, auxvt[AT_BASE].a_un.a_val);
+#endif
header = (ElfW(Ehdr) *) auxvt[AT_BASE].a_un.a_val;
/* Check the ELF header to make sure everything looks ok. */
/* Do not use an inline _dl_strncmp here or some arches
* will blow chunks, i.e. those that need to relocate all
* string constants... */
- || header->e_ident[EI_MAG0] != ELFMAG0
- || header->e_ident[EI_MAG1] != ELFMAG1
- || header->e_ident[EI_MAG2] != ELFMAG2
- || header->e_ident[EI_MAG3] != ELFMAG3)
- {
- SEND_STDERR("Invalid ELF header\n");
+ || *(p32 = (uint32_t*)&header->e_ident) != ELFMAG_U32
+ ) {
+ SEND_EARLY_STDERR("Invalid ELF header\n");
_dl_exit(0);
}
- SEND_STDERR_DEBUG("ELF header=");
- SEND_ADDRESS_STDERR_DEBUG(load_addr, 1);
+ SEND_EARLY_STDERR_DEBUG("ELF header=");
+ SEND_ADDRESS_STDERR_DEBUG(DL_LOADADDR_BASE(header), 1);
/* Locate the global offset table. Since this code must be PIC
* we can take advantage of the magic offset register, if we
* happen to know what that is for this architecture. If not,
* we can always read stuff out of the ELF file to find it... */
- got = elf_machine_dynamic();
- dpnt = (ElfW(Dyn) *) (got + load_addr);
- SEND_STDERR_DEBUG("First Dynamic section entry=");
+ DL_BOOT_COMPUTE_GOT(got);
+
+ /* Now, finally, fix up the location of the dynamic stuff */
+ DL_BOOT_COMPUTE_DYN(dpnt, got, (DL_LOADADDR_TYPE)header);
+
+ SEND_EARLY_STDERR_DEBUG("First Dynamic section entry=");
SEND_ADDRESS_STDERR_DEBUG(dpnt, 1);
_dl_memset(tpnt, 0, sizeof(struct elf_resolve));
tpnt->loadaddr = load_addr;
/* OK, that was easy. Next scan the DYNAMIC section of the image.
We are only doing ourself right now - we will have to do the rest later */
- SEND_STDERR_DEBUG("Scanning DYNAMIC section\n");
+ SEND_EARLY_STDERR_DEBUG("Scanning DYNAMIC section\n");
tpnt->dynamic_addr = dpnt;
#if defined(NO_FUNCS_BEFORE_BOOTSTRAP)
/* Some architectures cannot call functions here, must inline */
_dl_parse_dynamic_info(dpnt, tpnt->dynamic_info, NULL, load_addr);
#endif
- SEND_STDERR_DEBUG("Done scanning DYNAMIC section\n");
+ /*
+ * BIG ASSUMPTION: We assume that the dynamic loader does not
+ * have any TLS data itself. If this ever occurs
+ * more work than what is done below for the
+ * loader will have to happen.
+ */
+#if defined(USE_TLS) && USE_TLS
+ /* This was done by _dl_memset above. */
+ /* tpnt->l_tls_modid = 0; */
+# if NO_TLS_OFFSET != 0
+ tpnt->l_tls_offset = NO_TLS_OFFSET;
+# endif
+#endif
+
+ SEND_EARLY_STDERR_DEBUG("Done scanning DYNAMIC section\n");
#if defined(PERFORM_BOOTSTRAP_GOT)
-
- SEND_STDERR_DEBUG("About to do specific GOT bootstrap\n");
+ SEND_EARLY_STDERR_DEBUG("About to do specific GOT bootstrap\n");
/* some arches (like MIPS) we have to tweak the GOT before relocations */
PERFORM_BOOTSTRAP_GOT(tpnt);
+#endif
-#else
+#if !defined(PERFORM_BOOTSTRAP_GOT) || defined(__avr32__) || defined(__mips__)
/* OK, now do the relocations. We do not do a lazy binding here, so
that once we are done, we have considerably more flexibility. */
- SEND_STDERR_DEBUG("About to do library loader relocations\n");
+ SEND_EARLY_STDERR_DEBUG("About to do library loader relocations\n");
{
- int goof, indx;
-#ifdef ELF_MACHINE_PLTREL_OVERLAP
+ int indx;
+#if defined(ELF_MACHINE_PLTREL_OVERLAP)
# define INDX_MAX 1
#else
# define INDX_MAX 2
#endif
- goof = 0;
for (indx = 0; indx < INDX_MAX; indx++) {
- unsigned int i;
- unsigned long *reloc_addr;
- unsigned long symbol_addr;
- int symtab_index;
- ElfW(Sym) *sym;
- ELF_RELOC *rpnt;
unsigned long rel_addr, rel_size;
ElfW(Word) relative_count = tpnt->dynamic_info[DT_RELCONT_IDX];
if (!rel_addr)
continue;
- /* Now parse the relocation information */
- /* Since ldso is linked with -Bsymbolic, all relocs will be RELATIVE(for those archs that have
- RELATIVE relocs) which means that the for(..) loop below has nothing to do and can be deleted.
- Possibly one should add a HAVE_RELATIVE_RELOCS directive and #ifdef away some code. */
if (!indx && relative_count) {
rel_size -= relative_count * sizeof(ELF_RELOC);
- elf_machine_relative(load_addr, rel_addr, relative_count);
+ if (load_addr
+#ifdef __LDSO_PRELINK_SUPPORT__
+ || !tpnt->dynamic_info[DT_GNU_PRELINKED_IDX]
+#endif
+ )
+ elf_machine_relative(load_addr, rel_addr, relative_count);
rel_addr += relative_count * sizeof(ELF_RELOC);
}
- rpnt = (ELF_RELOC *) (rel_addr + load_addr);
- for (i = 0; i < rel_size; i += sizeof(ELF_RELOC), rpnt++) {
- reloc_addr = (unsigned long *) (load_addr + (unsigned long) rpnt->r_offset);
- symtab_index = ELF_R_SYM(rpnt->r_info);
- symbol_addr = 0;
- sym = NULL;
- if (symtab_index) {
- char *strtab;
- ElfW(Sym) *symtab;
-
- symtab = (ElfW(Sym) *) tpnt->dynamic_info[DT_SYMTAB];
- strtab = (char *) tpnt->dynamic_info[DT_STRTAB];
- sym = &symtab[symtab_index];
- symbol_addr = load_addr + sym->st_value;
-
- SEND_STDERR_DEBUG("relocating symbol: ");
- SEND_STDERR_DEBUG(strtab + sym->st_name);
- SEND_STDERR_DEBUG("\n");
- } else
- SEND_STDERR_DEBUG("relocating unknown symbol\n");
- /* Use this machine-specific macro to perform the actual relocation. */
- PERFORM_BOOTSTRAP_RELOC(rpnt, reloc_addr, symbol_addr, load_addr, sym);
+ /*
+ * Since ldso is linked with -Bsymbolic, all relocs should be RELATIVE. All archs
+ * that need bootstrap relocations need to define ARCH_NEEDS_BOOTSTRAP_RELOCS.
+ */
+#ifdef ARCH_NEEDS_BOOTSTRAP_RELOCS
+ {
+ ELF_RELOC *rpnt;
+ unsigned int i;
+ ElfW(Sym) *sym;
+ unsigned long symbol_addr;
+ int symtab_index;
+ unsigned long *reloc_addr;
+
+ /* Now parse the relocation information */
+ rpnt = (ELF_RELOC *) rel_addr;
+ for (i = 0; i < rel_size; i += sizeof(ELF_RELOC), rpnt++) {
+ reloc_addr = (unsigned long *) DL_RELOC_ADDR(load_addr, (unsigned long)rpnt->r_offset);
+ symtab_index = ELF_R_SYM(rpnt->r_info);
+ symbol_addr = 0;
+ sym = NULL;
+ if (symtab_index) {
+ char *strtab;
+ ElfW(Sym) *symtab;
+
+ symtab = (ElfW(Sym) *) tpnt->dynamic_info[DT_SYMTAB];
+ strtab = (char *) tpnt->dynamic_info[DT_STRTAB];
+ sym = &symtab[symtab_index];
+ symbol_addr = (unsigned long) DL_RELOC_ADDR(load_addr, sym->st_value);
+#if !defined(EARLY_STDERR_SPECIAL)
+ SEND_STDERR_DEBUG("relocating symbol: ");
+ SEND_STDERR_DEBUG(strtab + sym->st_name);
+ SEND_STDERR_DEBUG("\n");
+#endif
+ } else {
+ SEND_STDERR_DEBUG("relocating unknown symbol\n");
+ }
+ /* Use this machine-specific macro to perform the actual relocation. */
+ PERFORM_BOOTSTRAP_RELOC(rpnt, reloc_addr, symbol_addr, load_addr, sym);
+ }
}
- }
-
- if (goof) {
- _dl_exit(14);
+#else /* ARCH_NEEDS_BOOTSTRAP_RELOCS */
+ if (rel_size) {
+ SEND_EARLY_STDERR("Cannot continue, found non relative relocs during the bootstrap.\n");
+ _dl_exit(14);
+ }
+#endif
}
}
#endif
- /* Wahoo!!! */
SEND_STDERR_DEBUG("Done relocating ldso; we can now use globals and make function calls!\n");
/* Now we have done the mandatory linking of some things. We are now
__rtld_stack_end = (void *)(argv - 1);
- _dl_get_ready_to_run(tpnt, load_addr, auxvt, envp, argv);
-
+ _dl_elf_main = (int (*)(int, char **, char **))
+ _dl_get_ready_to_run(tpnt, (DL_LOADADDR_TYPE) header, auxvt, envp, argv
+ DL_GET_READY_TO_RUN_EXTRA_ARGS);
/* Transfer control to the application. */
SEND_STDERR_DEBUG("transfering control to application @ ");
- _dl_elf_main = (int (*)(int, char **, char **)) auxvt[AT_ENTRY].a_un.a_val;
SEND_ADDRESS_STDERR_DEBUG(_dl_elf_main, 1);
-#ifndef START
+#if !defined(START)
return _dl_elf_main;
#else
-#warning You need to update your arch ldso code
START();
#endif
}
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