commit 4b9cd5465d5158dad7b4f0762bc70a3a1209b481

Author: Florian Weimer <fweimer@redhat.com>

Date:   Thu Feb 3 10:58:59 2022 +0100

    Linux: Consolidate auxiliary vector parsing

    And optimize it slightly.

    The large switch statement in _dl_sysdep_start can be replaced with

    a large array.  This reduces source code and binary size.  On

    i686-linux-gnu:

    Before:

       text    data     bss     dec     hex filename

       7791      12       0    7803    1e7b elf/dl-sysdep.os

    After:

       text    data     bss     dec     hex filename

       7135      12       0    7147    1beb elf/dl-sysdep.os

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

    (cherry picked from commit 8c8510ab2790039e58995ef3a22309582413d3ff)

diff --git a/elf/dl-support.c b/elf/dl-support.c

index f29dc965f4d10648..40ef07521336857d 100644

--- a/elf/dl-support.c

+++ b/elf/dl-support.c

@@ -241,93 +241,21 @@ __rtld_lock_define_initialized_recursive (, _dl_load_tls_lock)

 #ifdef HAVE_AUX_VECTOR

+#include <dl-parse_auxv.h>

+

 int _dl_clktck;

 void

 _dl_aux_init (ElfW(auxv_t) *av)

 {

-  int seen = 0;

-  uid_t uid = 0;

-  gid_t gid = 0;

-

 #ifdef NEED_DL_SYSINFO

   /* NB: Avoid RELATIVE relocation in static PIE.  */

   GL(dl_sysinfo) = DL_SYSINFO_DEFAULT;

 #endif

   _dl_auxv = av;

-  for (; av->a_type != AT_NULL; ++av)

-    switch (av->a_type)

-      {

-      case AT_PAGESZ:

-	if (av->a_un.a_val != 0)

-	  GLRO(dl_pagesize) = av->a_un.a_val;

-	break;

-      case AT_CLKTCK:

-	GLRO(dl_clktck) = av->a_un.a_val;

-	break;

-      case AT_PHDR:

-	GL(dl_phdr) = (const void *) av->a_un.a_val;

-	break;

-      case AT_PHNUM:

-	GL(dl_phnum) = 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_FPUCW:

-	GLRO(dl_fpu_control) = av->a_un.a_val;

-	break;

-#ifdef NEED_DL_SYSINFO

-      case AT_SYSINFO:

-	GL(dl_sysinfo) = av->a_un.a_val;

-	break;

-#endif

-#ifdef NEED_DL_SYSINFO_DSO

-      case AT_SYSINFO_EHDR:

-	GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;

-	break;

-#endif

-      case AT_UID:

-	uid ^= av->a_un.a_val;

-	seen |= 1;

-	break;

-      case AT_EUID:

-	uid ^= av->a_un.a_val;

-	seen |= 2;

-	break;

-      case AT_GID:

-	gid ^= av->a_un.a_val;

-	seen |= 4;

-	break;

-      case AT_EGID:

-	gid ^= av->a_un.a_val;

-	seen |= 8;

-	break;

-      case AT_SECURE:

-	seen = -1;

-	__libc_enable_secure = av->a_un.a_val;

-	__libc_enable_secure_decided = 1;

-	break;

-      case AT_RANDOM:

-	_dl_random = (void *) av->a_un.a_val;

-	break;

-      case AT_MINSIGSTKSZ:

-	_dl_minsigstacksize = av->a_un.a_val;

-	break;

-      DL_PLATFORM_AUXV

-      }

-  if (seen == 0xf)

-    {

-      __libc_enable_secure = uid != 0 || gid != 0;

-      __libc_enable_secure_decided = 1;

-    }

+  dl_parse_auxv_t auxv_values = { 0, };

+  _dl_parse_auxv (av, auxv_values);

 }

 #endif

diff --git a/sysdeps/unix/sysv/linux/alpha/dl-auxv.h b/sysdeps/unix/sysv/linux/alpha/dl-auxv.h

index 1aa9dca80d189ebe..8c99e776a0af9cef 100644

--- a/sysdeps/unix/sysv/linux/alpha/dl-auxv.h

+++ b/sysdeps/unix/sysv/linux/alpha/dl-auxv.h

@@ -20,16 +20,8 @@

 extern long __libc_alpha_cache_shape[4];

-#define DL_PLATFORM_AUXV				\

-      case AT_L1I_CACHESHAPE:				\

-	__libc_alpha_cache_shape[0] = av->a_un.a_val;	\

-	break;						\

-      case AT_L1D_CACHESHAPE:				\

-	__libc_alpha_cache_shape[1] = av->a_un.a_val;	\

-	break;						\

-      case AT_L2_CACHESHAPE:				\

-	__libc_alpha_cache_shape[2] = av->a_un.a_val;	\

-	break;						\

-      case AT_L3_CACHESHAPE:				\

-	__libc_alpha_cache_shape[3] = av->a_un.a_val;	\

-	break;

+#define DL_PLATFORM_AUXV					\

+  __libc_alpha_cache_shape[0] = auxv_values[AT_L1I_CACHESHAPE]; \

+  __libc_alpha_cache_shape[1] = auxv_values[AT_L1D_CACHESHAPE]; \

+  __libc_alpha_cache_shape[2] = auxv_values[AT_L2_CACHESHAPE];	\

+  __libc_alpha_cache_shape[3] = auxv_values[AT_L3_CACHESHAPE];

diff --git a/sysdeps/unix/sysv/linux/dl-parse_auxv.h b/sysdeps/unix/sysv/linux/dl-parse_auxv.h

new file mode 100644

index 0000000000000000..b3d82f69946d6d2c

--- /dev/null

+++ b/sysdeps/unix/sysv/linux/dl-parse_auxv.h

@@ -0,0 +1,61 @@

+/* Parse the Linux auxiliary vector.

+   Copyright (C) 1995-2022 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 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

+   Lesser General Public License for more details.

+

+   You should have received a copy of the GNU Lesser General Public

+   License along with the GNU C Library; if not, see

+   <https://www.gnu.org/licenses/>.  */

+

+#include <elf.h>

+#include <entry.h>

+#include <fpu_control.h>

+#include <ldsodefs.h>

+#include <link.h>

+

+typedef ElfW(Addr) dl_parse_auxv_t[AT_MINSIGSTKSZ + 1];

+

+/* Copy the auxiliary vector into AUX_VALUES and set up GLRO

+   variables.  */

+static inline

+void _dl_parse_auxv (ElfW(auxv_t) *av, dl_parse_auxv_t auxv_values)

+{

+  auxv_values[AT_ENTRY] = (ElfW(Addr)) ENTRY_POINT;

+  auxv_values[AT_PAGESZ] = EXEC_PAGESIZE;

+  auxv_values[AT_FPUCW] = _FPU_DEFAULT;

+

+  /* NB: Default to a constant CONSTANT_MINSIGSTKSZ.  */

+  _Static_assert (__builtin_constant_p (CONSTANT_MINSIGSTKSZ),

+                  "CONSTANT_MINSIGSTKSZ is constant");

+  auxv_values[AT_MINSIGSTKSZ] = CONSTANT_MINSIGSTKSZ;

+

+  for (; av->a_type != AT_NULL; av++)

+    if (av->a_type <= AT_MINSIGSTKSZ)

+      auxv_values[av->a_type] = av->a_un.a_val;

+

+  GLRO(dl_pagesize) = auxv_values[AT_PAGESZ];

+  __libc_enable_secure = auxv_values[AT_SECURE];

+  GLRO(dl_platform) = (void *) auxv_values[AT_PLATFORM];

+  GLRO(dl_hwcap) = auxv_values[AT_HWCAP];

+  GLRO(dl_hwcap2) = auxv_values[AT_HWCAP2];

+  GLRO(dl_clktck) = auxv_values[AT_CLKTCK];

+  GLRO(dl_fpu_control) = auxv_values[AT_FPUCW];

+  _dl_random = (void *) auxv_values[AT_RANDOM];

+  GLRO(dl_minsigstacksize) = auxv_values[AT_MINSIGSTKSZ];

+  GLRO(dl_sysinfo_dso) = (void *) auxv_values[AT_SYSINFO_EHDR];

+#ifdef NEED_DL_SYSINFO

+  if (GLRO(dl_sysinfo_dso) != NULL)

+    GLRO(dl_sysinfo) = auxv_values[AT_SYSINFO];

+#endif

+

+  DL_PLATFORM_AUXV

+}

diff --git a/sysdeps/unix/sysv/linux/dl-sysdep.c b/sysdeps/unix/sysv/linux/dl-sysdep.c

index 1829dab4f38b560c..80aa9f6f4acb7e3c 100644

--- a/sysdeps/unix/sysv/linux/dl-sysdep.c

+++ b/sysdeps/unix/sysv/linux/dl-sysdep.c

@@ -21,13 +21,12 @@

 #include <dl-auxv.h>

 #include <dl-hwcap-check.h>

 #include <dl-osinfo.h>

+#include <dl-parse_auxv.h>

 #include <dl-procinfo.h>

 #include <dl-tunables.h>

 #include <elf.h>

-#include <entry.h>

 #include <errno.h>

 #include <fcntl.h>

-#include <fpu_control.h>

 #include <ldsodefs.h>

 #include <libc-internal.h>

 #include <libintl.h>

@@ -63,24 +62,24 @@ void *_dl_random attribute_relro = NULL;

 # 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))

+/* Arguments passed to dl_main.  */

+struct dl_main_arguments

 {

-  const ElfW(Phdr) *phdr = NULL;

-  ElfW(Word) phnum = 0;

+  const ElfW(Phdr) *phdr;

+  ElfW(Word) phnum;

   ElfW(Addr) user_entry;

-  ElfW(auxv_t) *av;

-#ifdef NEED_DL_SYSINFO

-  uintptr_t new_sysinfo = 0;

-#endif

+};

-  __libc_stack_end = DL_STACK_END (start_argptr);

+/* Separate function, so that dl_main can be called without the large

+   array on the stack.  */

+static void

+_dl_sysdep_parse_arguments (void **start_argptr,

+			    struct dl_main_arguments *args)

+{

   _dl_argc = (intptr_t) *start_argptr;

   _dl_argv = (char **) (start_argptr + 1); /* Necessary aliasing violation.  */

   _environ = _dl_argv + _dl_argc + 1;

-  for (char **tmp = _environ + 1; ; ++tmp)

+  for (char **tmp = _environ; ; ++tmp)

     if (*tmp == NULL)

       {

 	/* Another necessary aliasing violation.  */

@@ -88,74 +87,25 @@ _dl_sysdep_start (void **start_argptr,

 	break;

       }

-  user_entry = (ElfW(Addr)) ENTRY_POINT;

-  GLRO(dl_platform) = NULL; /* Default to nothing known about the platform.  */

+  dl_parse_auxv_t auxv_values = { 0, };

+  _dl_parse_auxv (GLRO(dl_auxv), auxv_values);

-  /* NB: Default to a constant CONSTANT_MINSIGSTKSZ.  */

-  _Static_assert (__builtin_constant_p (CONSTANT_MINSIGSTKSZ),

-		  "CONSTANT_MINSIGSTKSZ is constant");

-  GLRO(dl_minsigstacksize) = CONSTANT_MINSIGSTKSZ;

+  args->phdr = (const ElfW(Phdr) *) auxv_values[AT_PHDR];

+  args->phnum = auxv_values[AT_PHNUM];

+  args->user_entry = auxv_values[AT_ENTRY];

+}

-  for (av = GLRO(dl_auxv); av->a_type != AT_NULL; 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;

-      case AT_SECURE:

-	__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

-      case AT_SYSINFO_EHDR:

-	GLRO(dl_sysinfo_dso) = (void *) av->a_un.a_val;

-	break;

-      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

-      }

+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))

+{

+  __libc_stack_end = DL_STACK_END (start_argptr);

-  dl_hwcap_check ();

+  struct dl_main_arguments dl_main_args;

+  _dl_sysdep_parse_arguments (start_argptr, &dl_main_args);

-#ifdef NEED_DL_SYSINFO

-  if (new_sysinfo != 0)

-    {

-      /* Only set the sysinfo value if we also have the vsyscall DSO.  */

-      if (GLRO(dl_sysinfo_dso) != 0)

-        GLRO(dl_sysinfo) = new_sysinfo;

-    }

-#endif

+  dl_hwcap_check ();

   __tunables_init (_environ);

@@ -187,8 +137,9 @@ _dl_sysdep_start (void **start_argptr,

   if (__builtin_expect (__libc_enable_secure, 0))

     __libc_check_standard_fds ();

-  (*dl_main) (phdr, phnum, &user_entry, GLRO(dl_auxv));

-  return user_entry;

+  (*dl_main) (dl_main_args.phdr, dl_main_args.phnum,

+              &dl_main_args.user_entry, GLRO(dl_auxv));

+  return dl_main_args.user_entry;

 }

 void

diff --git a/sysdeps/unix/sysv/linux/powerpc/dl-auxv.h b/sysdeps/unix/sysv/linux/powerpc/dl-auxv.h

index 36ba0f3e9e45f3e2..7f35fb531ba22098 100644

--- a/sysdeps/unix/sysv/linux/powerpc/dl-auxv.h

+++ b/sysdeps/unix/sysv/linux/powerpc/dl-auxv.h

@@ -16,15 +16,5 @@

    License along with the GNU C Library; if not, see

    <https://www.gnu.org/licenses/>.  */

-#include <ldsodefs.h>

-

-#if IS_IN (libc) && !defined SHARED

-int GLRO(dl_cache_line_size);

-#endif

-

-/* Scan the Aux Vector for the "Data Cache Block Size" entry and assign it

-   to dl_cache_line_size.  */

-#define DL_PLATFORM_AUXV						      \

-      case AT_DCACHEBSIZE:						      \

-	GLRO(dl_cache_line_size) = av->a_un.a_val;			      \

-	break;

+#define DL_PLATFORM_AUXV \

+  GLRO(dl_cache_line_size) = auxv_values[AT_DCACHEBSIZE];

diff --git a/sysdeps/unix/sysv/linux/powerpc/dl-support.c b/sysdeps/unix/sysv/linux/powerpc/dl-support.c

new file mode 100644

index 0000000000000000..abe68a704946b90f

--- /dev/null

+++ b/sysdeps/unix/sysv/linux/powerpc/dl-support.c

@@ -0,0 +1,4 @@

+#include <elf/dl-support.c>

+

+/* Populated from the auxiliary vector.  */

+int _dl_cache_line_size;