S/390: Add support for pgste marker

This patch adds a new S/390 specific segment type: PT_S390_PGSTE.  For
binaries marked with that segment the kernel will allocate 4k page
tables.  The only user so far will be qemu.

ld/ChangeLog:

2017-06-23  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* Makefile.in: Add s390.em as build dependency.
	* emulparams/elf64_s390.sh (EXTRA_EM_FILE): Add s390.em.
	* emultempl/s390.em: New file.
	* gen-doc.texi: Add documentation for --s390-pgste option.
	* ld.texinfo: Likewise.

include/ChangeLog:

2017-06-23  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* elf/s390.h (PT_S390_PGSTE): Define macro.

binutils/ChangeLog:

2017-06-23  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* readelf.c (get_s390_segment_type): Add support for the new
	segment type PT_S390_PGSTE.
	(get_segment_type): Call get_s390_segment_type.

elfcpp/ChangeLog:

2017-06-23  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* elfcpp.h (enum PT): Add PT_S390_PGSTE to enum.

bfd/ChangeLog:

2017-06-23  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* elf-s390.h: New file.
	* elf64-s390.c (struct elf_s390_link_hash_table): Add params
	field.
	(elf_s390_additional_program_headers): New function.
	(elf_s390_modify_segment_map): New function.
	(bfd_elf_s390_set_options): New function.
	(elf_backend_additional_program_headers)
	(elf_backend_modify_segment_map): Add macro definitions.

bfd/elf-s390.h

@@ -0,0 +1,29 @@
+/* S/390-specific support for ELF.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+
+   This file is part of BFD, the Binary File Descriptor library.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+   MA 02110-1301, USA.  */
+
+/* Used to pass info between ld and bfd.  */
+struct s390_elf_params
+{
+  /* Tell the kernel to allocate 4k page tables.  */
+  int pgste;
+};
+
+bfd_boolean bfd_elf_s390_set_options (struct bfd_link_info *info,
+				      struct s390_elf_params *params);

bfd/elf64-s390.c

@@ -25,6 +25,7 @@
 #include "libbfd.h"
 #include "elf-bfd.h"
 #include "elf/s390.h"
+#include "elf-s390.h"
 #include <stdarg.h>
 
 /* In case we're on a 32-bit machine, construct a 64-bit "-1" value
@@ -660,6 +661,9 @@ struct elf_s390_link_hash_table
 
   /* Small local sym cache.  */
   struct sym_cache sym_cache;
+
+  /* Options passed from the linker.  */
+  struct s390_elf_params *params;
 };
 
 /* Get the s390 ELF linker hash table from a link_info structure.  */
@@ -3966,6 +3970,70 @@ elf64_s390_merge_private_bfd_data (bfd *ibfd, struct bfd_link_info *info)
   return elf_s390_merge_obj_attributes (ibfd, info);
 }
 
+/* We may add a PT_S390_PGSTE program header.  */
+
+static int
+elf_s390_additional_program_headers (bfd *abfd ATTRIBUTE_UNUSED,
+				     struct bfd_link_info *info)
+{
+  struct elf_s390_link_hash_table *htab;
+
+  htab = elf_s390_hash_table (info);
+  return htab->params->pgste;
+}
+
+
+/* Add the PT_S390_PGSTE program header.  */
+
+static bfd_boolean
+elf_s390_modify_segment_map (bfd *abfd ATTRIBUTE_UNUSED,
+			     struct bfd_link_info *info)
+{
+  struct elf_s390_link_hash_table *htab;
+  struct elf_segment_map *m, *pm = NULL;
+
+  htab = elf_s390_hash_table (info);
+  if (!htab->params->pgste)
+    return TRUE;
+
+  /* If there is already a PT_S390_PGSTE header, avoid adding
+     another.  */
+  m = elf_seg_map (abfd);
+  while (m && m->p_type != PT_S390_PGSTE)
+    {
+      pm = m;
+      m = m->next;
+    }
+
+  if (m)
+    return TRUE;
+
+  m = (struct elf_segment_map *)
+    bfd_zalloc (abfd, sizeof (struct elf_segment_map));
+  if (m == NULL)
+    return FALSE;
+  m->p_type = PT_S390_PGSTE;
+  m->count = 0;
+  m->next = NULL;
+  if (pm)
+    pm->next = m;
+
+  return TRUE;
+}
+
+bfd_boolean
+bfd_elf_s390_set_options (struct bfd_link_info *info,
+			  struct s390_elf_params *params)
+{
+  struct elf_s390_link_hash_table *htab;
+
+  htab = elf_s390_hash_table (info);
+  htab->params = params;
+
+  return TRUE;
+}
+
+
 /* Why was the hash table entry size definition changed from
    ARCH_SIZE/8 to 4? This breaks the 64 bit dynamic linker and
    this is the only reason for the s390_elf64_size_info structure.  */
@@ -4046,6 +4114,8 @@ const struct elf_size_info s390_elf64_size_info =
 #define elf_backend_plt_sym_val		      elf_s390_plt_sym_val
 #define elf_backend_add_symbol_hook           elf_s390_add_symbol_hook
 #define elf_backend_sort_relocs_p             elf_s390_elf_sort_relocs_p
+#define elf_backend_additional_program_headers elf_s390_additional_program_headers
+#define elf_backend_modify_segment_map	      elf_s390_modify_segment_map
 
 #define bfd_elf64_mkobject		elf_s390_mkobject
 #define elf_backend_object_p		elf_s390_object_p

binutils/readelf.c

@@ -3725,6 +3725,16 @@ get_arm_segment_type (unsigned long type)
     }
 }
 
+static const char *
+get_s390_segment_type (unsigned long type)
+{
+  switch (type)
+    {
+    case PT_S390_PGSTE: return "S390_PGSTE";
+    default:            return NULL;
+    }
+}
+
 static const char *
 get_mips_segment_type (unsigned long type)
 {
@@ -3858,6 +3868,10 @@ get_segment_type (unsigned long p_type)
 	    case EM_TI_C6000:
 	      result = get_tic6x_segment_type (p_type);
 	      break;
+	    case EM_S390:
+	    case EM_S390_OLD:
+	      result = get_s390_segment_type (p_type);
+	      break;
 	    default:
 	      result = NULL;
 	      break;

elfcpp/elfcpp.h

@@ -515,7 +515,9 @@ enum PT
   // Platform architecture compatibility information
   PT_AARCH64_ARCHEXT = 0x70000000,
   // Exception unwind tables
-  PT_AARCH64_UNWIND = 0x70000001
+  PT_AARCH64_UNWIND = 0x70000001,
+  // 4k page table size
+  PT_S390_PGSTE = 0x70000000,
 };
 
 // The valid bit flags found in the Phdr p_flags field.

include/elf/s390.h

@@ -37,6 +37,9 @@
 
 #define EF_S390_HIGH_GPRS        0x00000001
 
+/* Request 4k page table size.  */
+#define PT_S390_PGSTE (PT_LOPROC + 0)
+
 /* Relocation types.  */
 
 START_RELOC_NUMBERS (elf_s390_reloc_type)

ld/Makefile.in

@@ -3502,6 +3502,7 @@ eelf64_ia64_vms.c: $(srcdir)/emulparams/elf64_ia64_vms.sh \
   $(srcdir)/scripttempl/ia64vms.sc ${GEN_DEPENDS}
 
 eelf64_s390.c: $(srcdir)/emulparams/elf64_s390.sh \
+  $(srcdir)/emultempl/s390.em \
   $(ELF_DEPS) $(srcdir)/scripttempl/elf.sc ${GEN_DEPENDS}
 
 eelf64_sparc.c: $(srcdir)/emulparams/elf64_sparc.sh \

ld/emulparams/elf64_s390.sh

@@ -12,6 +12,7 @@ TEMPLATE_NAME=elf32
 GENERATE_SHLIB_SCRIPT=yes
 GENERATE_PIE_SCRIPT=yes
 NO_SMALL_DATA=yes
+EXTRA_EM_FILE=s390
 IREL_IN_PLT=
 
 # Treat a host that matches the target with the possible exception of "x"

ld/emultempl/s390.em

@@ -0,0 +1,64 @@
+# This shell script emits a C file. -*- C -*-
+# Copyright (C) 2017 Free Software Foundation, Inc.
+#
+# This file is part of the GNU Binutils.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the license, or
+# (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; see the file COPYING3. If not,
+# see <http://www.gnu.org/licenses/>.
+#
+
+# This file is sourced from elf-generic.em, and defines S/390
+# specific routines.
+#
+fragment <<EOF
+
+#include "ldctor.h"
+#include "elf-s390.h"
+
+static struct s390_elf_params params = { 0 };
+
+/* This is a convenient point to tell BFD about target specific flags.
+   After the output has been created, but before inputs are read.  */
+static void
+s390_elf_create_output_section_statements (void)
+{
+  if (!bfd_elf_s390_set_options (&link_info, &params))
+    einfo ("%F%P: can not init BFD: %E\n");
+}
+
+EOF
+
+# Define some shell vars to insert bits of code into the standard elf
+# parse_args and list_options functions.
+#
+PARSE_AND_LIST_PROLOGUE='
+#define OPTION_PGSTE	301
+'
+
+PARSE_AND_LIST_LONGOPTS='
+  { "s390-pgste", no_argument, NULL, OPTION_PGSTE},
+'
+
+PARSE_AND_LIST_OPTIONS='
+  fprintf (file, _("  --s390-pgste                Tell the kernel to "
+		   "allocate 4k page tables\n"));
+'
+
+PARSE_AND_LIST_ARGS_CASES='
+    case OPTION_PGSTE:
+      params.pgste = 1;
+      break;
+'
+
+LDEMUL_CREATE_OUTPUT_SECTION_STATEMENTS=s390_elf_create_output_section_statements

ld/gen-doc.texi

@@ -21,6 +21,7 @@
 @set POWERPC
 @set POWERPC64
 @set Renesas
+@set S/390
 @set SPU
 @set TICOFF
 @set WIN32

ld/ld.texinfo

@@ -34,6 +34,7 @@
 @set POWERPC
 @set POWERPC64
 @set Renesas
+@set S/390
 @set SPU
 @set TICOFF
 @set WIN32
@@ -158,6 +159,9 @@ in the section entitled ``GNU Free Documentation License''.
 @ifset POWERPC64
 * PowerPC64 ELF64::             ld and PowerPC64 64-bit ELF Support
 @end ifset
+@ifset S/390
+* S/390 ELF::			ld and S/390 ELF Support
+@end ifset
 @ifset SPU
 * SPU ELF::			ld and SPU ELF Support
 @end ifset
@@ -6565,6 +6569,9 @@ functionality are not listed.
 @ifset POWERPC64
 * PowerPC64 ELF64::		@command{ld} and PowerPC64 64-bit ELF Support
 @end ifset
+@ifset S/390
+* S/390 ELF::			@command{ld} and S/390 ELF Support
+@end ifset
 @ifset SPU
 * SPU ELF::			@command{ld} and SPU ELF Support
 @end ifset
@@ -7600,6 +7607,30 @@ default behaviour.
 @end ifclear
 @end ifset
 
+@ifset S/390
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node S/390 ELF
+@section @command{ld} and S/390 ELF Support
+
+@cindex S/390 ELF options
+@table @option
+
+@cindex S/390
+@kindex --s390-pgste
+@item --s390-pgste
+This option marks the result file with a @code{PT_S390_PGSTE}
+segment.  The Linux kernel is supposed to allocate 4k page tables for
+binaries marked that way.
+@end table
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
 @ifset SPU
 @ifclear GENERIC
 @raisesections