x86: Add a GNU_PROPERTY_X86_ISA_1_USED note if needed

When -z separate-code, which is enabled by default for Linux/x86, is
used to create executable, ld won't place any data in the code-only
PT_LOAD segment.  If there are no data sections placed before the
code-only PT_LOAD segment, the program headers won't be mapped into
any PT_LOAD segment.  When the executable tries to access it (based
on the program header address passed in AT_PHDR), it will lead to
segfault.  This patch inserts a GNU_PROPERTY_X86_ISA_1_USED note if
there may be no data sections before the text section so that the
first PT_LOAD segment won't be code-only and will contain the program
header.

Testcases are adjusted to either pass "-z noseparate-code" to ld or
discard the .note.gnu.property section.  A Linux/x86 run-time test is
added.

bfd/

	PR ld/23428
	* elfxx-x86.c (_bfd_x86_elf_link_setup_gnu_properties): If the
	separate code program header is needed, make sure that the first
	read-only PT_LOAD segment has no code by adding a
	GNU_PROPERTY_X86_ISA_1_USED note.

ld/

	PR ld/23428
	* testsuite/ld-elf/linux-x86.S: New file.
	* testsuite/ld-elf/linux-x86.exp: Likewise.
	* testsuite/ld-elf/pr23428.c: Likewise.
	* testsuite/ld-elf/sec64k.exp: Pass "-z noseparate-code" to ld
	for Linux/x86 targets.
	* testsuite/ld-i386/abs-iamcu.d: Likewise.
	* testsuite/ld-i386/abs.d: Likewise.
	* testsuite/ld-i386/pr12718.d: Likewise.
	* testsuite/ld-i386/pr12921.d: Likewise.
	* testsuite/ld-x86-64/abs-k1om.d: Likewise.
	* testsuite/ld-x86-64/abs-l1om.d: Likewise.
	* testsuite/ld-x86-64/abs.d: Likewise.
	* testsuite/ld-x86-64/pr12718.d: Likewise.
	* testsuite/ld-x86-64/pr12921.d: Likewise.
	* testsuite/ld-linkonce/zeroeh.ld: Discard .note.gnu.property
	section.
	* testsuite/ld-scripts/print-memory-usage.t: Likewise.
	* testsuite/ld-scripts/size-2.t: Likewise.
	* testsuite/lib/ld-lib.exp (run_ld_link_exec_tests): Use ld
	to create executable if language is "asm".

bfd/ChangeLog

@@ -1,3 +1,11 @@
+2018-07-20  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/23428
+	* elfxx-x86.c (_bfd_x86_elf_link_setup_gnu_properties): If the
+	separate code program header is needed, make sure that the first
+	read-only PT_LOAD segment has no code by adding a
+	GNU_PROPERTY_X86_ISA_1_USED note.
+
 2018-07-20  Chenghua Xu  <paul.hua.gm@gmail.com>
 	    Maciej W. Rozycki  <macro@mips.com>
 

bfd/elfxx-x86.c

@@ -2524,6 +2524,7 @@ _bfd_x86_elf_link_setup_gnu_properties
   const struct elf_backend_data *bed;
   unsigned int class_align = ABI_64_P (info->output_bfd) ? 3 : 2;
   unsigned int got_align;
+  bfd_boolean has_text = FALSE;
 
   features = 0;
   if (info->ibt)
@@ -2538,13 +2539,30 @@ _bfd_x86_elf_link_setup_gnu_properties
     if (bfd_get_flavour (pbfd) == bfd_target_elf_flavour
 	&& bfd_count_sections (pbfd) != 0)
       {
+	if (!has_text)
+	  {
+	    /* Check if there is no non-empty text section.  */
+	    sec = bfd_get_section_by_name (pbfd, ".text");
+	    if (sec != NULL && sec->size != 0)
+	      has_text = TRUE;
+	  }
+
 	ebfd = pbfd;
 
 	if (elf_properties (pbfd) != NULL)
 	  break;
       }
 
-  if (ebfd != NULL && features)
+  bed = get_elf_backend_data (info->output_bfd);
+
+  htab = elf_x86_hash_table (info, bed->target_id);
+  if (htab == NULL)
+    return pbfd;
+
+  if (ebfd != NULL)
+    {
+      prop = NULL;
+      if (features)
 	{
 	  /* If features is set, add GNU_PROPERTY_X86_FEATURE_1_IBT and
 	     GNU_PROPERTY_X86_FEATURE_1_SHSTK.  */
@@ -2553,9 +2571,27 @@ _bfd_x86_elf_link_setup_gnu_properties
 					4);
 	  prop->u.number |= features;
 	  prop->pr_kind = property_number;
+	}
+      else if (has_text
+	       && elf_properties (ebfd) == NULL
+	       && elf_tdata (info->output_bfd)->o->build_id.sec == NULL
+	       && !htab->elf.dynamic_sections_created
+	       && !info->traditional_format
+	       && (info->output_bfd->flags & D_PAGED) != 0
+	       && info->separate_code)
+	{
+	  /* If the separate code program header is needed, make sure
+	     that the first read-only PT_LOAD segment has no code by
+	     adding a GNU_PROPERTY_X86_ISA_1_USED note.  */
+	  prop = _bfd_elf_get_property (ebfd,
+					GNU_PROPERTY_X86_ISA_1_USED,
+					4);
+	  prop->u.number = GNU_PROPERTY_X86_ISA_1_486;
+	  prop->pr_kind = property_number;
+	}
 
       /* Create the GNU property note section if needed.  */
-      if (pbfd == NULL)
+      if (prop != NULL && pbfd == NULL)
 	{
 	  sec = bfd_make_section_with_flags (ebfd,
 					     NOTE_GNU_PROPERTY_SECTION_NAME,
@@ -2581,12 +2617,6 @@ error_alignment:
 
   pbfd = _bfd_elf_link_setup_gnu_properties (info);
 
-  bed = get_elf_backend_data (info->output_bfd);
-
-  htab = elf_x86_hash_table (info, bed->target_id);
-  if (htab == NULL)
-    return pbfd;
-
   htab->r_info = init_table->r_info;
   htab->r_sym = init_table->r_sym;
 

ld/ChangeLog

@@ -1,3 +1,27 @@
+2018-07-20  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/23428
+	* testsuite/ld-elf/linux-x86.S: New file.
+	* testsuite/ld-elf/linux-x86.exp: Likewise.
+	* testsuite/ld-elf/pr23428.c: Likewise.
+	* testsuite/ld-elf/sec64k.exp: Pass "-z noseparate-code" to ld
+	for Linux/x86 targets.
+	* testsuite/ld-i386/abs-iamcu.d: Likewise.
+	* testsuite/ld-i386/abs.d: Likewise.
+	* testsuite/ld-i386/pr12718.d: Likewise.
+	* testsuite/ld-i386/pr12921.d: Likewise.
+	* testsuite/ld-x86-64/abs-k1om.d: Likewise.
+	* testsuite/ld-x86-64/abs-l1om.d: Likewise.
+	* testsuite/ld-x86-64/abs.d: Likewise.
+	* testsuite/ld-x86-64/pr12718.d: Likewise.
+	* testsuite/ld-x86-64/pr12921.d: Likewise.
+	* testsuite/ld-linkonce/zeroeh.ld: Discard .note.gnu.property
+	section.
+	* testsuite/ld-scripts/print-memory-usage.t: Likewise.
+	* testsuite/ld-scripts/size-2.t: Likewise.
+	* testsuite/lib/ld-lib.exp (run_ld_link_exec_tests): Use ld to
+	create executable if language is "asm".
+
 2018-07-20  Maciej W. Rozycki  <macro@mips.com>
 
 	* testsuite/ld-elf/reloc-discard.d: New test.

ld/testsuite/ld-elf/linux-x86.S

@@ -0,0 +1,63 @@
+	.text
+	.globl _start
+	.type _start,@function
+	.p2align 4
+_start:
+	xorl %ebp, %ebp
+#ifdef __LP64__
+	popq %rdi
+	movq %rsp, %rsi
+	andq  $~15, %rsp
+#elif defined __x86_64__
+	mov (%rsp),%edi
+	addl $4,%esp
+	movl %esp, %esi
+	andl  $~15, %esp
+#else
+	popl %esi
+	movl %esp, %ecx
+	andl  $~15, %esp
+
+	subl $8,%esp
+	pushl %ecx
+	pushl %esi
+#endif
+
+	call main
+
+	hlt
+
+	.type syscall,  @function
+	.globl syscall
+	.p2align 4
+syscall:
+#ifdef __x86_64__
+	movq %rdi, %rax		/* Syscall number -> rax.  */
+	movq %rsi, %rdi		/* shift arg1 - arg5.  */
+	movq %rdx, %rsi
+	movq %rcx, %rdx
+	movq %r8, %r10
+	movq %r9, %r8
+	movq 8(%rsp),%r9	/* arg6 is on the stack.  */
+	syscall			/* Do the system call.  */
+#else
+	push %ebp
+	push %edi
+	push %esi
+	push %ebx
+	mov 0x2c(%esp),%ebp
+	mov 0x28(%esp),%edi
+	mov 0x24(%esp),%esi
+	mov 0x20(%esp),%edx
+	mov 0x1c(%esp),%ecx
+	mov 0x18(%esp),%ebx
+	mov 0x14(%esp),%eax
+	int $0x80
+	pop %ebx
+	pop %esi
+	pop %edi
+	pop %ebp
+#endif
+	ret			/* Return to caller.  */
+	.size syscall, .-syscall
+	.section .note.GNU-stack,"",@progbits

ld/testsuite/ld-elf/linux-x86.exp

@@ -0,0 +1,46 @@
+# Expect script for simple native Linux/x86 tests.
+#   Copyright (C) 2018 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; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+# MA 02110-1301, USA.
+#
+
+# Test very simple native Linux/x86 programs with linux-x86.S.
+if { ![isnative] || [which $CC] == 0 \
+     || (![istarget "i?86-*-linux*"] \
+         && ![istarget "x86_64-*-linux*"] \
+         && ![istarget "amd64-*-linux*"]) } {
+    return
+}
+
+# Add $PLT_CFLAGS if PLT is expected.
+global PLT_CFLAGS
+# Add $NOPIE_CFLAGS and $NOPIE_LDFLAGS if non-PIE is required.
+global NOPIE_CFLAGS NOPIE_LDFLAGS
+
+run_ld_link_exec_tests [list \
+    [list \
+	"Run PR ld/23428 test" \
+	"--no-dynamic-linker -z separate-code" \
+	"" \
+	{ linux-x86.S pr23428.c } \
+	"pr23428" \
+	"pass.out" \
+	"$NOPIE_CFLAGS -fno-asynchronous-unwind-tables" \
+	"asm" \
+    ] \
+]

ld/testsuite/ld-elf/pr23428.c

@@ -0,0 +1,43 @@
+#include <unistd.h>
+#include <link.h>
+#include <syscall.h>
+
+#define STRING_COMMA_LEN(STR) (STR), (sizeof (STR) - 1)
+
+int
+main (int argc, char **argv)
+{
+  char **ev = &argv[argc + 1];
+  char **evp = ev;
+  ElfW(auxv_t) *av;
+  const ElfW(Phdr) *phdr = NULL;
+  size_t phnum = 0;
+  size_t loadnum = 0;
+  int fd = STDOUT_FILENO;
+  size_t i;
+
+  while (*evp++ != NULL)
+    ;
+
+  av = (ElfW(auxv_t) *) evp;
+
+  for (; av->a_type != AT_NULL; ++av)
+    switch (av->a_type)
+      {
+      case AT_PHDR:
+	phdr = (const void *) av->a_un.a_val;
+	break;
+      case AT_PHNUM:
+	phnum = av->a_un.a_val;
+	break;
+      }
+
+  for (i = 0; i < phnum; i++, phdr++)
+    if (phdr->p_type == PT_LOAD)
+      loadnum++;
+
+  syscall (SYS_write, fd, STRING_COMMA_LEN ("PASS\n"));
+
+  syscall (SYS_exit, !loadnum);
+  return 0;
+}

ld/testsuite/ld-elf/sec64k.exp

@@ -177,6 +177,8 @@ if { ![istarget "d10v-*-*"]
     foreach sfile $sfiles { puts $ofd "#source: $sfile" }
     if { [istarget spu*-*-*] } {
 	puts $ofd "#ld: --local-store 0:0"
+    } elseif { [istarget "i?86-*-linux*"] || [istarget "x86_64-*-linux*"] } {
+	puts $ofd "#ld: -z noseparate-code"
     } else {
 	puts $ofd "#ld:"
     }

ld/testsuite/ld-i386/abs-iamcu.d

@@ -2,7 +2,7 @@
 #source: abs.s
 #source: zero.s
 #as: --32 -march=iamcu
-#ld: -m elf_iamcu
+#ld: -m elf_iamcu -z noseparate-code
 #objdump: -rs -j .text
 
 .*:     file format .*

ld/testsuite/ld-i386/abs.d

@@ -2,7 +2,7 @@
 #as: --32
 #source: abs.s
 #source: zero.s
-#ld: -melf_i386
+#ld: -melf_i386 -z noseparate-code
 #objdump: -rs
 
 .*:     file format .*

ld/testsuite/ld-i386/pr12718.d

@@ -1,6 +1,6 @@
 #name: PR ld/12718
 #as: --32
-#ld: -melf_i386
+#ld: -melf_i386 -z noseparate-code
 #readelf: -S
 
 There are 5 section headers, starting at offset 0x[0-9a-f]+:

ld/testsuite/ld-i386/pr12921.d

@@ -1,6 +1,6 @@
 #name: PR ld/12921
 #as: --32
-#ld: -melf_i386
+#ld: -melf_i386 -z noseparate-code
 #readelf: -S --wide
 
 There are 7 section headers, starting at offset 0x[0-9a-f]+:

ld/testsuite/ld-linkonce/zeroeh.ld

@@ -2,4 +2,5 @@ SECTIONS {
  .text 0xa00 : { *(.text); *(.gnu.linkonce.t.*) }
  .gcc_except_table 0x2000 : { *(.gcc_except_table) }
  .eh_frame 0x4000 : { *(.eh_frame) }
+  /DISCARD/ : { *(.note.gnu.property) }
 }

ld/testsuite/ld-scripts/print-memory-usage.t

@@ -11,4 +11,6 @@ SECTIONS
     *(.data)
     *(.rw)
   }
+
+  /DISCARD/ : { *(.note.gnu.property) }
 }

ld/testsuite/ld-scripts/size-2.t

@@ -18,4 +18,5 @@ SECTIONS
     LONG (SIZEOF (.tdata))
     LONG (SIZEOF (.tbss))
   } :image
+  /DISCARD/ : { *(.note.gnu.property) }
 }

ld/testsuite/ld-x86-64/abs-k1om.d

@@ -2,7 +2,7 @@
 #source: ../ld-i386/abs.s
 #source: ../ld-i386/zero.s
 #as: --64 -march=k1om
-#ld: -m elf_k1om
+#ld: -m elf_k1om -z noseparate-code
 #objdump: -rs -j .text
 
 .*:     file format .*

ld/testsuite/ld-x86-64/abs-l1om.d

@@ -2,7 +2,7 @@
 #source: ../ld-i386/abs.s
 #source: ../ld-i386/zero.s
 #as: --64 -march=l1om
-#ld: -m elf_l1om
+#ld: -m elf_l1om -z noseparate-code
 #objdump: -rs -j .text
 #target: x86_64-*-linux*
 

ld/testsuite/ld-x86-64/abs.d

@@ -1,7 +1,7 @@
 #name: Absolute non-overflowing relocs
 #source: ../ld-i386/abs.s
 #source: ../ld-i386/zero.s
-#ld:
+#ld: -z noseparate-code
 #objdump: -rs
 
 .*:     file format .*

ld/testsuite/ld-x86-64/pr12718.d

@@ -1,6 +1,6 @@
 #name: PR ld/12718
 #as: --64
-#ld: -melf_x86_64
+#ld: -melf_x86_64 -z noseparate-code
 #readelf: -S --wide
 
 There are 5 section headers, starting at offset 0x[0-9a-f]+:

ld/testsuite/ld-x86-64/pr12921.d

@@ -1,6 +1,6 @@
 #name: PR ld/12921
 #as: --64
-#ld: -melf_x86_64
+#ld: -melf_x86_64 -z noseparate-code
 #readelf: -S --wide
 
 There are 7 section headers, starting at offset 0x[0-9a-f]+:

ld/testsuite/lib/ld-lib.exp

@@ -1523,7 +1523,10 @@ proc run_ld_link_exec_tests { ldtests args } {
 	    continue
 	}
 
-	if { [ string match "c++" $lang ] } {
+	if { [ string match "asm" $lang ] } {
+	    set link_proc ld_link
+	    set link_cmd $ld
+	} elseif { [ string match "c++" $lang ] } {
 	    set link_proc ld_link
 	    set link_cmd $CXX
 	} else {