lib/csu/x86_64/crt1.c

   1 /*-
   2  * Copyright 1996-1998 John D. Polstra.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef __GNUC__
  27 #error "GCC is needed to compile this file"
  28 #endif
  29
  30 #include <sys/cdefs.h>
  31 #include <machine/tls.h>
  32 #include <elf.h>
  33 #include <stdlib.h>
  34
  35 #include "libc_private.h"
  36 #include "initfini.c"
  37 #include "crtbrand.c"
  38
  39 typedef void (*fptr)(void);
  40
  41 #ifdef GCRT
  42 extern void _mcleanup(void);
  43 extern void monstartup(void *, void *);
  44 extern int eprol;
  45 extern int etext;
  46 #endif
  47
  48 /* static ifunc reloc support */
  49 extern const Elf_Rela __rela_iplt_start[] __dso_hidden __weak_symbol;
  50 extern const Elf_Rela __rela_iplt_end[] __dso_hidden __weak_symbol;
  51 static void fix_iplta(void) __noinline;
  52
  53 static void
  54 fix_iplta(void)
  55 {
  56         const Elf_Rela *rela, *relalim;
  57         Elf_Addr *where, target, *ptr;
  58
  59         rela = __rela_iplt_start;
  60         relalim = __rela_iplt_end;
  61         for (; rela < relalim; ++rela) {
  62                 if (ELF_R_TYPE(rela->r_info) != R_X86_64_IRELATIVE)
  63                         abort();
  64                 ptr = (Elf_Addr *)rela->r_addend;
  65                 where = (Elf_Addr *)rela->r_offset;
  66                 target = ((Elf_Addr (*)(void))ptr)();
  67                 *where = target;
  68         }
  69 }
  70
  71 void _start(char **, void (*)(void));
  72
  73 /* The entry function. */
  74 void
  75 _start(char **ap, void (*cleanup)(void))
  76 {
  77         int argc;
  78         char **argv;
  79         char **env;
  80
  81         argc = *(long *)(void *)ap;
  82         argv = ap + 1;
  83         env = ap + 2 + argc;
  84         handle_argv(argc, argv, env);
  85
  86         /*
  87          * Setup the initial TLS space.  The RTLD does not set up our TLS
  88          * (it can't, it doesn't know how our errno is declared).  It simply
  89          * does all the groundwork required so that we can call
  90          * _rtld_allocate_tls().
  91          */
  92         _init_tls();
  93         _rtld_call_init();
  94
  95         if (&_DYNAMIC != NULL)
  96                 atexit(cleanup);
  97         else
  98                 fix_iplta();
  99
 100 #ifdef GCRT
 101         atexit(_mcleanup);
 102         monstartup(&eprol, &etext);
 103 #endif
 104
 105         handle_static_init(argc, argv, env);
 106 #ifdef GCRT
 107         /*
 108          * This label was previously located just after the monstartup
 109          * function.  It was relocated after the handle_static_init function
 110          * to avoid an alternative conditional optimization performed by
 111          * clang.  The optimization cause the compilation to fail with a
 112          * label redefinition error.  The impact of the label relocation is
 113          * the loss of profiling of handle_static_init function.
 114          */
 115 __asm__("eprol:");
 116 #endif
 117         exit(main(argc, argv, env));
 118 }