Re: [PATCH v2 1/5] elf: Merge dl-sysdep.c into the Linux version

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 03/02/2022 08:08, Florian Weimer via Libc-alpha wrote:
> The generic version is the de-facto Linux implementation.  It
> requires an auxiliary vector, so Hurd does not use it.

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  elf/dl-sysdep.c                     | 352 +---------------------------
>  sysdeps/unix/sysv/linux/dl-sysdep.c | 347 ++++++++++++++++++++++++++-
>  2 files changed, 337 insertions(+), 362 deletions(-)
> 
> diff --git a/elf/dl-sysdep.c b/elf/dl-sysdep.c
> index f1dba8ef24..7aa90ad6ee 100644
> --- a/elf/dl-sysdep.c
> +++ b/elf/dl-sysdep.c
> @@ -1,4 +1,4 @@
> -/* Operating system support for run-time dynamic linker.  Generic Unix version.
> +/* Operating system support for run-time dynamic linker.  Stub version.
>     Copyright (C) 1995-2022 Free Software Foundation, Inc.
>     This file is part of the GNU C Library.
>  
> @@ -16,352 +16,4 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> -/* We conditionalize the whole of this file rather than simply eliding it
> -   from the static build, because other sysdeps/ versions of this file
> -   might define things needed by a static build.  */
> -
> -#ifdef SHARED
> -
> -#include <assert.h>
> -#include <elf.h>
> -#include <errno.h>
> -#include <fcntl.h>
> -#include <libintl.h>
> -#include <stdlib.h>
> -#include <string.h>
> -#include <unistd.h>
> -#include <sys/types.h>
> -#include <sys/stat.h>
> -#include <sys/mman.h>
> -#include <ldsodefs.h>
> -#include <_itoa.h>
> -#include <fpu_control.h>
> -
> -#include <entry.h>
> -#include <dl-machine.h>
> -#include <dl-procinfo.h>
> -#include <dl-osinfo.h>
> -#include <libc-internal.h>
> -#include <tls.h>
> -
> -#include <dl-tunables.h>
> -#include <dl-auxv.h>
> -#include <dl-hwcap-check.h>
> -
> -extern char **_environ attribute_hidden;
> -extern char _end[] attribute_hidden;
> -
> -/* Protect SUID program against misuse of file descriptors.  */
> -extern void __libc_check_standard_fds (void);
> -
> -int __libc_enable_secure attribute_relro = 0;
> -rtld_hidden_data_def (__libc_enable_secure)
> -/* This variable contains the lowest stack address ever used.  */
> -void *__libc_stack_end attribute_relro = NULL;
> -rtld_hidden_data_def(__libc_stack_end)
> -void *_dl_random attribute_relro = NULL;
> -
> -#ifndef DL_FIND_ARG_COMPONENTS
> -# define DL_FIND_ARG_COMPONENTS(cookie, argc, argv, envp, auxp)	\
> -  do {									      \
> -    void **_tmp;							      \
> -    (argc) = *(long int *) cookie;					      \
> -    (argv) = (char **) ((long int *) cookie + 1);			      \
> -    (envp) = (argv) + (argc) + 1;					      \
> -    for (_tmp = (void **) (envp); *_tmp; ++_tmp)			      \
> -      continue;								      \
> -    (auxp) = (void *) ++_tmp;						      \
> -  } while (0)
> -#endif
> -
> -#ifndef DL_STACK_END
> -# define DL_STACK_END(cookie) ((void *) (cookie))
> -#endif
> -
> -ElfW(Addr)
> -_dl_sysdep_start (void **start_argptr,
> -		  void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
> -				   ElfW(Addr) *user_entry, ElfW(auxv_t) *auxv))
> -{
> -  const ElfW(Phdr) *phdr = NULL;
> -  ElfW(Word) phnum = 0;
> -  ElfW(Addr) user_entry;
> -  ElfW(auxv_t) *av;
> -#ifdef HAVE_AUX_SECURE
> -# define set_seen(tag) (tag)	/* Evaluate for the side effects.  */
> -# define set_seen_secure() ((void) 0)
> -#else
> -  uid_t uid = 0;
> -  gid_t gid = 0;
> -  unsigned int seen = 0;
> -# define set_seen_secure() (seen = -1)
> -# ifdef HAVE_AUX_XID
> -#  define set_seen(tag) (tag)	/* Evaluate for the side effects.  */
> -# else
> -#  define M(type) (1 << (type))
> -#  define set_seen(tag) seen |= M ((tag)->a_type)
> -# endif
> -#endif
> -#ifdef NEED_DL_SYSINFO
> -  uintptr_t new_sysinfo = 0;
> -#endif
> -
> -  __libc_stack_end = DL_STACK_END (start_argptr);
> -  DL_FIND_ARG_COMPONENTS (start_argptr, _dl_argc, _dl_argv, _environ,
> -			  GLRO(dl_auxv));
> -
> -  user_entry = (ElfW(Addr)) ENTRY_POINT;
> -  GLRO(dl_platform) = NULL; /* Default to nothing known about the platform.  */
> -
> -  /* NB: Default to a constant CONSTANT_MINSIGSTKSZ.  */
> -  _Static_assert (__builtin_constant_p (CONSTANT_MINSIGSTKSZ),
> -		  "CONSTANT_MINSIGSTKSZ is constant");
> -  GLRO(dl_minsigstacksize) = CONSTANT_MINSIGSTKSZ;
> -
> -  for (av = GLRO(dl_auxv); av->a_type != AT_NULL; set_seen (av++))
> -    switch (av->a_type)
> -      {
> -      case AT_PHDR:
> -	phdr = (void *) av->a_un.a_val;
> -	break;
> -      case AT_PHNUM:
> -	phnum = av->a_un.a_val;
> -	break;
> -      case AT_PAGESZ:
> -	GLRO(dl_pagesize) = av->a_un.a_val;
> -	break;
> -      case AT_ENTRY:
> -	user_entry = av->a_un.a_val;
> -	break;
> -#ifndef HAVE_AUX_SECURE
> -      case AT_UID:
> -      case AT_EUID:
> -	uid ^= av->a_un.a_val;
> -	break;
> -      case AT_GID:
> -      case AT_EGID:
> -	gid ^= av->a_un.a_val;
> -	break;
> -#endif
> -      case AT_SECURE:
> -#ifndef HAVE_AUX_SECURE
> -	seen = -1;
> -#endif
> -	__libc_enable_secure = av->a_un.a_val;
> -	break;
> -      case AT_PLATFORM:
> -	GLRO(dl_platform) = (void *) av->a_un.a_val;
> -	break;
> -      case AT_HWCAP:
> -	GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
> -	break;
> -      case AT_HWCAP2:
> -	GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
> -	break;
> -      case AT_CLKTCK:
> -	GLRO(dl_clktck) = av->a_un.a_val;
> -	break;
> -      case AT_FPUCW:
> -	GLRO(dl_fpu_control) = av->a_un.a_val;
> -	break;
> -#ifdef NEED_DL_SYSINFO
> -      case AT_SYSINFO:
> -	new_sysinfo = av->a_un.a_val;
> -	break;
> -#endif
> -#ifdef NEED_DL_SYSINFO_DSO
> -      case AT_SYSINFO_EHDR:
> -	GLRO(dl_sysinfo_dso) = (void *) av->a_un.a_val;
> -	break;
> -#endif
> -      case AT_RANDOM:
> -	_dl_random = (void *) av->a_un.a_val;
> -	break;
> -      case AT_MINSIGSTKSZ:
> -	GLRO(dl_minsigstacksize) = av->a_un.a_val;
> -	break;
> -      DL_PLATFORM_AUXV
> -      }
> -
> -  dl_hwcap_check ();
> -
> -#ifndef HAVE_AUX_SECURE
> -  if (seen != -1)
> -    {
> -      /* Fill in the values we have not gotten from the kernel through the
> -	 auxiliary vector.  */
> -# ifndef HAVE_AUX_XID
> -#  define SEE(UID, var, uid) \
> -   if ((seen & M (AT_##UID)) == 0) var ^= __get##uid ()
> -      SEE (UID, uid, uid);
> -      SEE (EUID, uid, euid);
> -      SEE (GID, gid, gid);
> -      SEE (EGID, gid, egid);
> -# endif
> -
> -      /* If one of the two pairs of IDs does not match this is a setuid
> -	 or setgid run.  */
> -      __libc_enable_secure = uid | gid;
> -    }
> -#endif
> -
> -#ifndef HAVE_AUX_PAGESIZE
> -  if (GLRO(dl_pagesize) == 0)
> -    GLRO(dl_pagesize) = __getpagesize ();
> -#endif
> -
> -#ifdef NEED_DL_SYSINFO
> -  if (new_sysinfo != 0)
> -    {
> -# ifdef NEED_DL_SYSINFO_DSO
> -      /* Only set the sysinfo value if we also have the vsyscall DSO.  */
> -      if (GLRO(dl_sysinfo_dso) != 0)
> -# endif
> -        GLRO(dl_sysinfo) = new_sysinfo;
> -    }
> -#endif
> -
> -  __tunables_init (_environ);
> -
> -  /* Initialize DSO sorting algorithm after tunables.  */
> -  _dl_sort_maps_init ();
> -
> -#ifdef DL_SYSDEP_INIT
> -  DL_SYSDEP_INIT;
> -#endif
> -
> -#ifdef DL_PLATFORM_INIT
> -  DL_PLATFORM_INIT;
> -#endif
> -
> -  /* Determine the length of the platform name.  */
> -  if (GLRO(dl_platform) != NULL)
> -    GLRO(dl_platformlen) = strlen (GLRO(dl_platform));
> -
> -  if (__sbrk (0) == _end)
> -    /* The dynamic linker was run as a program, and so the initial break
> -       starts just after our bss, at &_end.  The malloc in dl-minimal.c
> -       will consume the rest of this page, so tell the kernel to move the
> -       break up that far.  When the user program examines its break, it
> -       will see this new value and not clobber our data.  */
> -    __sbrk (GLRO(dl_pagesize)
> -	    - ((_end - (char *) 0) & (GLRO(dl_pagesize) - 1)));
> -
> -  /* If this is a SUID program we make sure that FDs 0, 1, and 2 are
> -     allocated.  If necessary we are doing it ourself.  If it is not
> -     possible we stop the program.  */
> -  if (__builtin_expect (__libc_enable_secure, 0))
> -    __libc_check_standard_fds ();
> -
> -  (*dl_main) (phdr, phnum, &user_entry, GLRO(dl_auxv));
> -  return user_entry;
> -}
> -
> -void
> -_dl_sysdep_start_cleanup (void)
> -{
> -}
> -
> -void
> -_dl_show_auxv (void)
> -{
> -  char buf[64];
> -  ElfW(auxv_t) *av;
> -
> -  /* Terminate string.  */
> -  buf[63] = '\0';
> -
> -  /* The following code assumes that the AT_* values are encoded
> -     starting from 0 with AT_NULL, 1 for AT_IGNORE, and all other values
> -     close by (otherwise the array will be too large).  In case we have
> -     to support a platform where these requirements are not fulfilled
> -     some alternative implementation has to be used.  */
> -  for (av = GLRO(dl_auxv); av->a_type != AT_NULL; ++av)
> -    {
> -      static const struct
> -      {
> -	const char label[22];
> -	enum { unknown = 0, dec, hex, str, ignore } form : 8;
> -      } auxvars[] =
> -	{
> -	  [AT_EXECFD - 2] =		{ "EXECFD:            ", dec },
> -	  [AT_EXECFN - 2] =		{ "EXECFN:            ", str },
> -	  [AT_PHDR - 2] =		{ "PHDR:              0x", hex },
> -	  [AT_PHENT - 2] =		{ "PHENT:             ", dec },
> -	  [AT_PHNUM - 2] =		{ "PHNUM:             ", dec },
> -	  [AT_PAGESZ - 2] =		{ "PAGESZ:            ", dec },
> -	  [AT_BASE - 2] =		{ "BASE:              0x", hex },
> -	  [AT_FLAGS - 2] =		{ "FLAGS:             0x", hex },
> -	  [AT_ENTRY - 2] =		{ "ENTRY:             0x", hex },
> -	  [AT_NOTELF - 2] =		{ "NOTELF:            ", hex },
> -	  [AT_UID - 2] =		{ "UID:               ", dec },
> -	  [AT_EUID - 2] =		{ "EUID:              ", dec },
> -	  [AT_GID - 2] =		{ "GID:               ", dec },
> -	  [AT_EGID - 2] =		{ "EGID:              ", dec },
> -	  [AT_PLATFORM - 2] =		{ "PLATFORM:          ", str },
> -	  [AT_HWCAP - 2] =		{ "HWCAP:             ", hex },
> -	  [AT_CLKTCK - 2] =		{ "CLKTCK:            ", dec },
> -	  [AT_FPUCW - 2] =		{ "FPUCW:             ", hex },
> -	  [AT_DCACHEBSIZE - 2] =	{ "DCACHEBSIZE:       0x", hex },
> -	  [AT_ICACHEBSIZE - 2] =	{ "ICACHEBSIZE:       0x", hex },
> -	  [AT_UCACHEBSIZE - 2] =	{ "UCACHEBSIZE:       0x", hex },
> -	  [AT_IGNOREPPC - 2] =		{ "IGNOREPPC", ignore },
> -	  [AT_SECURE - 2] =		{ "SECURE:            ", dec },
> -	  [AT_BASE_PLATFORM - 2] =	{ "BASE_PLATFORM:     ", str },
> -	  [AT_SYSINFO - 2] =		{ "SYSINFO:           0x", hex },
> -	  [AT_SYSINFO_EHDR - 2] =	{ "SYSINFO_EHDR:      0x", hex },
> -	  [AT_RANDOM - 2] =		{ "RANDOM:            0x", hex },
> -	  [AT_HWCAP2 - 2] =		{ "HWCAP2:            0x", hex },
> -	  [AT_MINSIGSTKSZ - 2] =	{ "MINSIGSTKSZ:       ", dec },
> -	  [AT_L1I_CACHESIZE - 2] =	{ "L1I_CACHESIZE:     ", dec },
> -	  [AT_L1I_CACHEGEOMETRY - 2] =	{ "L1I_CACHEGEOMETRY: 0x", hex },
> -	  [AT_L1D_CACHESIZE - 2] =	{ "L1D_CACHESIZE:     ", dec },
> -	  [AT_L1D_CACHEGEOMETRY - 2] =	{ "L1D_CACHEGEOMETRY: 0x", hex },
> -	  [AT_L2_CACHESIZE - 2] =	{ "L2_CACHESIZE:      ", dec },
> -	  [AT_L2_CACHEGEOMETRY - 2] =	{ "L2_CACHEGEOMETRY:  0x", hex },
> -	  [AT_L3_CACHESIZE - 2] =	{ "L3_CACHESIZE:      ", dec },
> -	  [AT_L3_CACHEGEOMETRY - 2] =	{ "L3_CACHEGEOMETRY:  0x", hex },
> -	};
> -      unsigned int idx = (unsigned int) (av->a_type - 2);
> -
> -      if ((unsigned int) av->a_type < 2u
> -	  || (idx < sizeof (auxvars) / sizeof (auxvars[0])
> -	      && auxvars[idx].form == ignore))
> -	continue;
> -
> -      assert (AT_NULL == 0);
> -      assert (AT_IGNORE == 1);
> -
> -      /* Some entries are handled in a special way per platform.  */
> -      if (_dl_procinfo (av->a_type, av->a_un.a_val) == 0)
> -	continue;
> -
> -      if (idx < sizeof (auxvars) / sizeof (auxvars[0])
> -	  && auxvars[idx].form != unknown)
> -	{
> -	  const char *val = (char *) av->a_un.a_val;
> -
> -	  if (__builtin_expect (auxvars[idx].form, dec) == dec)
> -	    val = _itoa ((unsigned long int) av->a_un.a_val,
> -			 buf + sizeof buf - 1, 10, 0);
> -	  else if (__builtin_expect (auxvars[idx].form, hex) == hex)
> -	    val = _itoa ((unsigned long int) av->a_un.a_val,
> -			 buf + sizeof buf - 1, 16, 0);
> -
> -	  _dl_printf ("AT_%s%s\n", auxvars[idx].label, val);
> -
> -	  continue;
> -	}
> -
> -      /* Unknown value: print a generic line.  */
> -      char buf2[17];
> -      buf2[sizeof (buf2) - 1] = '\0';
> -      const char *val2 = _itoa ((unsigned long int) av->a_un.a_val,
> -				buf2 + sizeof buf2 - 1, 16, 0);
> -      const char *val =  _itoa ((unsigned long int) av->a_type,
> -				buf + sizeof buf - 1, 16, 0);
> -      _dl_printf ("AT_??? (0x%s): 0x%s\n", val, val2);
> -    }
> -}
> -
> -#endif
> +#error dl-sysdep support missing.
> diff --git a/sysdeps/unix/sysv/linux/dl-sysdep.c b/sysdeps/unix/sysv/linux/dl-sysdep.c
> index 66ba489cd3..4f60cecf98 100644
> --- a/sysdeps/unix/sysv/linux/dl-sysdep.c
> +++ b/sysdeps/unix/sysv/linux/dl-sysdep.c
> @@ -16,29 +16,352 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> -/* Linux needs some special initialization, but otherwise uses
> -   the generic dynamic linker system interface code.  */
> -
> -#include <string.h>
> +#include <_itoa.h>
> +#include <assert.h>
> +#include <dl-auxv.h>
> +#include <dl-hwcap-check.h>
> +#include <dl-osinfo.h>
> +#include <dl-procinfo.h>
> +#include <dl-tunables.h>
> +#include <elf.h>
> +#include <entry.h>
> +#include <errno.h>
>  #include <fcntl.h>
> -#include <unistd.h>
> -#include <sys/param.h>
> -#include <sys/utsname.h>
> +#include <fpu_control.h>
>  #include <ldsodefs.h>
> +#include <libc-internal.h>
> +#include <libintl.h>
>  #include <not-cancel.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <string.h>
> +#include <sys/mman.h>
> +#include <sys/param.h>
> +#include <sys/stat.h>
> +#include <sys/types.h>
> +#include <sys/utsname.h>
> +#include <tls.h>
> +#include <unistd.h>
> +
> +#include <dl-machine.h>
>  
>  #ifdef SHARED
> -# define DL_SYSDEP_INIT frob_brk ()
> +extern char **_environ attribute_hidden;
> +extern char _end[] attribute_hidden;
> +
> +/* Protect SUID program against misuse of file descriptors.  */
> +extern void __libc_check_standard_fds (void);
>  
> -static inline void
> -frob_brk (void)
> +int __libc_enable_secure attribute_relro = 0;
> +rtld_hidden_data_def (__libc_enable_secure)
> +/* This variable contains the lowest stack address ever used.  */
> +void *__libc_stack_end attribute_relro = NULL;
> +rtld_hidden_data_def(__libc_stack_end)
> +void *_dl_random attribute_relro = NULL;
> +
> +#ifndef DL_FIND_ARG_COMPONENTS
> +# define DL_FIND_ARG_COMPONENTS(cookie, argc, argv, envp, auxp)	\
> +  do {									      \
> +    void **_tmp;							      \
> +    (argc) = *(long int *) cookie;					      \
> +    (argv) = (char **) ((long int *) cookie + 1);			      \
> +    (envp) = (argv) + (argc) + 1;					      \
> +    for (_tmp = (void **) (envp); *_tmp; ++_tmp)			      \
> +      continue;								      \
> +    (auxp) = (void *) ++_tmp;						      \
> +  } while (0)
> +#endif
> +
> +#ifndef DL_STACK_END
> +# define DL_STACK_END(cookie) ((void *) (cookie))
> +#endif
> +
> +ElfW(Addr)
> +_dl_sysdep_start (void **start_argptr,
> +		  void (*dl_main) (const ElfW(Phdr) *phdr, ElfW(Word) phnum,
> +				   ElfW(Addr) *user_entry, ElfW(auxv_t) *auxv))
>  {
> +  const ElfW(Phdr) *phdr = NULL;
> +  ElfW(Word) phnum = 0;
> +  ElfW(Addr) user_entry;
> +  ElfW(auxv_t) *av;
> +#ifdef HAVE_AUX_SECURE
> +# define set_seen(tag) (tag)	/* Evaluate for the side effects.  */
> +# define set_seen_secure() ((void) 0)
> +#else
> +  uid_t uid = 0;
> +  gid_t gid = 0;
> +  unsigned int seen = 0;
> +# define set_seen_secure() (seen = -1)
> +# ifdef HAVE_AUX_XID
> +#  define set_seen(tag) (tag)	/* Evaluate for the side effects.  */
> +# else
> +#  define M(type) (1 << (type))
> +#  define set_seen(tag) seen |= M ((tag)->a_type)
> +# endif
> +#endif
> +#ifdef NEED_DL_SYSINFO
> +  uintptr_t new_sysinfo = 0;
> +#endif
> +
> +  __libc_stack_end = DL_STACK_END (start_argptr);
> +  DL_FIND_ARG_COMPONENTS (start_argptr, _dl_argc, _dl_argv, _environ,
> +			  GLRO(dl_auxv));
> +
> +  user_entry = (ElfW(Addr)) ENTRY_POINT;
> +  GLRO(dl_platform) = NULL; /* Default to nothing known about the platform.  */
> +
> +  /* NB: Default to a constant CONSTANT_MINSIGSTKSZ.  */
> +  _Static_assert (__builtin_constant_p (CONSTANT_MINSIGSTKSZ),
> +		  "CONSTANT_MINSIGSTKSZ is constant");
> +  GLRO(dl_minsigstacksize) = CONSTANT_MINSIGSTKSZ;
> +
> +  for (av = GLRO(dl_auxv); av->a_type != AT_NULL; set_seen (av++))
> +    switch (av->a_type)
> +      {
> +      case AT_PHDR:
> +	phdr = (void *) av->a_un.a_val;
> +	break;
> +      case AT_PHNUM:
> +	phnum = av->a_un.a_val;
> +	break;
> +      case AT_PAGESZ:
> +	GLRO(dl_pagesize) = av->a_un.a_val;
> +	break;
> +      case AT_ENTRY:
> +	user_entry = av->a_un.a_val;
> +	break;
> +#ifndef HAVE_AUX_SECURE
> +      case AT_UID:
> +      case AT_EUID:
> +	uid ^= av->a_un.a_val;
> +	break;
> +      case AT_GID:
> +      case AT_EGID:
> +	gid ^= av->a_un.a_val;
> +	break;
> +#endif
> +      case AT_SECURE:
> +#ifndef HAVE_AUX_SECURE
> +	seen = -1;
> +#endif
> +	__libc_enable_secure = av->a_un.a_val;
> +	break;
> +      case AT_PLATFORM:
> +	GLRO(dl_platform) = (void *) av->a_un.a_val;
> +	break;
> +      case AT_HWCAP:
> +	GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
> +	break;
> +      case AT_HWCAP2:
> +	GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
> +	break;
> +      case AT_CLKTCK:
> +	GLRO(dl_clktck) = av->a_un.a_val;
> +	break;
> +      case AT_FPUCW:
> +	GLRO(dl_fpu_control) = av->a_un.a_val;
> +	break;
> +#ifdef NEED_DL_SYSINFO
> +      case AT_SYSINFO:
> +	new_sysinfo = av->a_un.a_val;
> +	break;
> +#endif
> +#ifdef NEED_DL_SYSINFO_DSO
> +      case AT_SYSINFO_EHDR:
> +	GLRO(dl_sysinfo_dso) = (void *) av->a_un.a_val;
> +	break;
> +#endif
> +      case AT_RANDOM:
> +	_dl_random = (void *) av->a_un.a_val;
> +	break;
> +      case AT_MINSIGSTKSZ:
> +	GLRO(dl_minsigstacksize) = av->a_un.a_val;
> +	break;
> +      DL_PLATFORM_AUXV
> +      }
> +
> +  dl_hwcap_check ();
> +
> +#ifndef HAVE_AUX_SECURE
> +  if (seen != -1)
> +    {
> +      /* Fill in the values we have not gotten from the kernel through the
> +	 auxiliary vector.  */
> +# ifndef HAVE_AUX_XID
> +#  define SEE(UID, var, uid) \
> +   if ((seen & M (AT_##UID)) == 0) var ^= __get##uid ()
> +      SEE (UID, uid, uid);
> +      SEE (EUID, uid, euid);
> +      SEE (GID, gid, gid);
> +      SEE (EGID, gid, egid);
> +# endif
> +
> +      /* If one of the two pairs of IDs does not match this is a setuid
> +	 or setgid run.  */
> +      __libc_enable_secure = uid | gid;
> +    }
> +#endif
> +
> +#ifndef HAVE_AUX_PAGESIZE
> +  if (GLRO(dl_pagesize) == 0)
> +    GLRO(dl_pagesize) = __getpagesize ();
> +#endif
> +
> +#ifdef NEED_DL_SYSINFO
> +  if (new_sysinfo != 0)
> +    {
> +# ifdef NEED_DL_SYSINFO_DSO
> +      /* Only set the sysinfo value if we also have the vsyscall DSO.  */
> +      if (GLRO(dl_sysinfo_dso) != 0)
> +# endif
> +        GLRO(dl_sysinfo) = new_sysinfo;
> +    }
> +#endif
> +
> +  __tunables_init (_environ);
> +
> +  /* Initialize DSO sorting algorithm after tunables.  */
> +  _dl_sort_maps_init ();
> +
>    __brk (0);			/* Initialize the break.  */
> -}
>  
> -# include <elf/dl-sysdep.c>
> +#ifdef DL_PLATFORM_INIT
> +  DL_PLATFORM_INIT;
>  #endif
>  
> +  /* Determine the length of the platform name.  */
> +  if (GLRO(dl_platform) != NULL)
> +    GLRO(dl_platformlen) = strlen (GLRO(dl_platform));
> +
> +  if (__sbrk (0) == _end)
> +    /* The dynamic linker was run as a program, and so the initial break
> +       starts just after our bss, at &_end.  The malloc in dl-minimal.c
> +       will consume the rest of this page, so tell the kernel to move the
> +       break up that far.  When the user program examines its break, it
> +       will see this new value and not clobber our data.  */
> +    __sbrk (GLRO(dl_pagesize)
> +	    - ((_end - (char *) 0) & (GLRO(dl_pagesize) - 1)));
> +
> +  /* If this is a SUID program we make sure that FDs 0, 1, and 2 are
> +     allocated.  If necessary we are doing it ourself.  If it is not
> +     possible we stop the program.  */
> +  if (__builtin_expect (__libc_enable_secure, 0))
> +    __libc_check_standard_fds ();
> +
> +  (*dl_main) (phdr, phnum, &user_entry, GLRO(dl_auxv));
> +  return user_entry;
> +}
> +
> +void
> +_dl_sysdep_start_cleanup (void)
> +{
> +}
> +
> +void
> +_dl_show_auxv (void)
> +{
> +  char buf[64];
> +  ElfW(auxv_t) *av;
> +
> +  /* Terminate string.  */
> +  buf[63] = '\0';
> +
> +  /* The following code assumes that the AT_* values are encoded
> +     starting from 0 with AT_NULL, 1 for AT_IGNORE, and all other values
> +     close by (otherwise the array will be too large).  In case we have
> +     to support a platform where these requirements are not fulfilled
> +     some alternative implementation has to be used.  */
> +  for (av = GLRO(dl_auxv); av->a_type != AT_NULL; ++av)
> +    {
> +      static const struct
> +      {
> +	const char label[22];
> +	enum { unknown = 0, dec, hex, str, ignore } form : 8;
> +      } auxvars[] =
> +	{
> +	  [AT_EXECFD - 2] =		{ "EXECFD:            ", dec },
> +	  [AT_EXECFN - 2] =		{ "EXECFN:            ", str },
> +	  [AT_PHDR - 2] =		{ "PHDR:              0x", hex },
> +	  [AT_PHENT - 2] =		{ "PHENT:             ", dec },
> +	  [AT_PHNUM - 2] =		{ "PHNUM:             ", dec },
> +	  [AT_PAGESZ - 2] =		{ "PAGESZ:            ", dec },
> +	  [AT_BASE - 2] =		{ "BASE:              0x", hex },
> +	  [AT_FLAGS - 2] =		{ "FLAGS:             0x", hex },
> +	  [AT_ENTRY - 2] =		{ "ENTRY:             0x", hex },
> +	  [AT_NOTELF - 2] =		{ "NOTELF:            ", hex },
> +	  [AT_UID - 2] =		{ "UID:               ", dec },
> +	  [AT_EUID - 2] =		{ "EUID:              ", dec },
> +	  [AT_GID - 2] =		{ "GID:               ", dec },
> +	  [AT_EGID - 2] =		{ "EGID:              ", dec },
> +	  [AT_PLATFORM - 2] =		{ "PLATFORM:          ", str },
> +	  [AT_HWCAP - 2] =		{ "HWCAP:             ", hex },
> +	  [AT_CLKTCK - 2] =		{ "CLKTCK:            ", dec },
> +	  [AT_FPUCW - 2] =		{ "FPUCW:             ", hex },
> +	  [AT_DCACHEBSIZE - 2] =	{ "DCACHEBSIZE:       0x", hex },
> +	  [AT_ICACHEBSIZE - 2] =	{ "ICACHEBSIZE:       0x", hex },
> +	  [AT_UCACHEBSIZE - 2] =	{ "UCACHEBSIZE:       0x", hex },
> +	  [AT_IGNOREPPC - 2] =		{ "IGNOREPPC", ignore },
> +	  [AT_SECURE - 2] =		{ "SECURE:            ", dec },
> +	  [AT_BASE_PLATFORM - 2] =	{ "BASE_PLATFORM:     ", str },
> +	  [AT_SYSINFO - 2] =		{ "SYSINFO:           0x", hex },
> +	  [AT_SYSINFO_EHDR - 2] =	{ "SYSINFO_EHDR:      0x", hex },
> +	  [AT_RANDOM - 2] =		{ "RANDOM:            0x", hex },
> +	  [AT_HWCAP2 - 2] =		{ "HWCAP2:            0x", hex },
> +	  [AT_MINSIGSTKSZ - 2] =	{ "MINSIGSTKSZ:       ", dec },
> +	  [AT_L1I_CACHESIZE - 2] =	{ "L1I_CACHESIZE:     ", dec },
> +	  [AT_L1I_CACHEGEOMETRY - 2] =	{ "L1I_CACHEGEOMETRY: 0x", hex },
> +	  [AT_L1D_CACHESIZE - 2] =	{ "L1D_CACHESIZE:     ", dec },
> +	  [AT_L1D_CACHEGEOMETRY - 2] =	{ "L1D_CACHEGEOMETRY: 0x", hex },
> +	  [AT_L2_CACHESIZE - 2] =	{ "L2_CACHESIZE:      ", dec },
> +	  [AT_L2_CACHEGEOMETRY - 2] =	{ "L2_CACHEGEOMETRY:  0x", hex },
> +	  [AT_L3_CACHESIZE - 2] =	{ "L3_CACHESIZE:      ", dec },
> +	  [AT_L3_CACHEGEOMETRY - 2] =	{ "L3_CACHEGEOMETRY:  0x", hex },
> +	};
> +      unsigned int idx = (unsigned int) (av->a_type - 2);
> +
> +      if ((unsigned int) av->a_type < 2u
> +	  || (idx < sizeof (auxvars) / sizeof (auxvars[0])
> +	      && auxvars[idx].form == ignore))
> +	continue;
> +
> +      assert (AT_NULL == 0);
> +      assert (AT_IGNORE == 1);
> +
> +      /* Some entries are handled in a special way per platform.  */
> +      if (_dl_procinfo (av->a_type, av->a_un.a_val) == 0)
> +	continue;
> +
> +      if (idx < sizeof (auxvars) / sizeof (auxvars[0])
> +	  && auxvars[idx].form != unknown)
> +	{
> +	  const char *val = (char *) av->a_un.a_val;
> +
> +	  if (__builtin_expect (auxvars[idx].form, dec) == dec)
> +	    val = _itoa ((unsigned long int) av->a_un.a_val,
> +			 buf + sizeof buf - 1, 10, 0);
> +	  else if (__builtin_expect (auxvars[idx].form, hex) == hex)
> +	    val = _itoa ((unsigned long int) av->a_un.a_val,
> +			 buf + sizeof buf - 1, 16, 0);
> +
> +	  _dl_printf ("AT_%s%s\n", auxvars[idx].label, val);
> +
> +	  continue;
> +	}
> +
> +      /* Unknown value: print a generic line.  */
> +      char buf2[17];
> +      buf2[sizeof (buf2) - 1] = '\0';
> +      const char *val2 = _itoa ((unsigned long int) av->a_un.a_val,
> +				buf2 + sizeof buf2 - 1, 16, 0);
> +      const char *val =  _itoa ((unsigned long int) av->a_type,
> +				buf + sizeof buf - 1, 16, 0);
> +      _dl_printf ("AT_??? (0x%s): 0x%s\n", val, val2);
> +    }
> +}
> +
> +#endif /* SHARED */
> +
>  
>  int
>  attribute_hidden