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[PATCH] x86: Add a GNU_PROPERTY_X86_ISA_1_USED note if needed

From: "H.J. Lu" <hongjiu dot lu at intel dot com>
To: binutils at sourceware dot org
Date: Thu, 19 Jul 2018 10:36:43 -0700
Subject: [PATCH] x86: Add a GNU_PROPERTY_X86_ISA_1_USED note if needed
Reply-to: "H.J. Lu" <hjl dot tools at gmail dot com>
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 pass "-z noseparate-code" to ld. A Linux/x86
run-time test is added.

Any comments?


H.J.
---
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-start.S: New file.
	* testsuite/ld-elf/linux-x86-syscall.S: Likewise.
	* testsuite/ld-elf/linux-x86.exp: Likewise.
	* testsuite/ld-elf/pr23428.c: Likewise.
	* testsuite/ld-elf/sec64k.exp: Pass "-z noseparate-code" to ld.
	* 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-linkonce/zeroehl32.d: Likewise.
	* testsuite/ld-scripts/size-2.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.
	* : Likewise.
	* : Likewise.
	* testsuite/ld-scripts/print-memory-usage.t: Discard oorphaned
	sections.
	* testsuite/lib/ld-lib.exp (run_ld_link_exec_tests): Use ld
	to create executable if language is "asm".
---
 bfd/elfxx-x86.c                              | 60 +++++++++++++++-----
 ld/testsuite/ld-elf/linux-x86-start.S        | 27 +++++++++
 ld/testsuite/ld-elf/linux-x86-syscall.S      | 34 +++++++++++
 ld/testsuite/ld-elf/linux-x86.exp            | 47 +++++++++++++++
 ld/testsuite/ld-elf/pr23428.c                | 43 ++++++++++++++
 ld/testsuite/ld-elf/sec64k.exp               |  2 +-
 ld/testsuite/ld-i386/abs-iamcu.d             |  2 +-
 ld/testsuite/ld-i386/abs.d                   |  2 +-
 ld/testsuite/ld-i386/pr12718.d               |  2 +-
 ld/testsuite/ld-i386/pr12921.d               |  2 +-
 ld/testsuite/ld-linkonce/zeroehl32.d         |  2 +-
 ld/testsuite/ld-scripts/print-memory-usage.t |  2 +
 ld/testsuite/ld-scripts/size-2.d             |  2 +-
 ld/testsuite/ld-x86-64/abs-k1om.d            |  2 +-
 ld/testsuite/ld-x86-64/abs-l1om.d            |  2 +-
 ld/testsuite/ld-x86-64/abs.d                 |  2 +-
 ld/testsuite/ld-x86-64/pr12718.d             |  2 +-
 ld/testsuite/ld-x86-64/pr12921.d             |  2 +-
 ld/testsuite/lib/ld-lib.exp                  |  5 +-
 19 files changed, 214 insertions(+), 28 deletions(-)
 create mode 100644 ld/testsuite/ld-elf/linux-x86-start.S
 create mode 100644 ld/testsuite/ld-elf/linux-x86-syscall.S
 create mode 100644 ld/testsuite/ld-elf/linux-x86.exp
 create mode 100644 ld/testsuite/ld-elf/pr23428.c

diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index a2497aab86..2e4ff88f1f 100644
--- a/bfd/elfxx-x86.c
+++ b/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)
@@ -2538,24 +2539,59 @@ _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)
     {
-      /* If features is set, add GNU_PROPERTY_X86_FEATURE_1_IBT and
-	 GNU_PROPERTY_X86_FEATURE_1_SHSTK.  */
-      prop = _bfd_elf_get_property (ebfd,
-				    GNU_PROPERTY_X86_FEATURE_1_AND,
-				    4);
-      prop->u.number |= features;
-      prop->pr_kind = property_number;
+      prop = NULL;
+      if (features)
+	{
+	  /* If features is set, add GNU_PROPERTY_X86_FEATURE_1_IBT and
+	     GNU_PROPERTY_X86_FEATURE_1_SHSTK.  */
+	  prop = _bfd_elf_get_property (ebfd,
+					GNU_PROPERTY_X86_FEATURE_1_AND,
+					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;
 
diff --git a/ld/testsuite/ld-elf/linux-x86-start.S b/ld/testsuite/ld-elf/linux-x86-start.S
new file mode 100644
index 0000000000..ecefa52150
--- /dev/null
+++ b/ld/testsuite/ld-elf/linux-x86-start.S
@@ -0,0 +1,27 @@
+	.text
+	.globl _start
+	.type _start,@function
+_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
diff --git a/ld/testsuite/ld-elf/linux-x86-syscall.S b/ld/testsuite/ld-elf/linux-x86-syscall.S
new file mode 100644
index 0000000000..37831d3c96
--- /dev/null
+++ b/ld/testsuite/ld-elf/linux-x86-syscall.S
@@ -0,0 +1,34 @@
+	.text
+	.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
diff --git a/ld/testsuite/ld-elf/linux-x86.exp b/ld/testsuite/ld-elf/linux-x86.exp
new file mode 100644
index 0000000000..48c4411408
--- /dev/null
+++ b/ld/testsuite/ld-elf/linux-x86.exp
@@ -0,0 +1,47 @@
+# 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-start.S
+# and linux-x86-syscall.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 $NOPIE_LDFLAGS if non-PIE is required.
+global NOPIE_CFLAGS NOPIE_LDFLAGS
+
+run_ld_link_exec_tests [list \
+    [list \
+	"Run PR ld/23428 test" \
+	"--no-dynamic-linker -z separate-code" \
+	"" \
+	{ linux-x86-start.S linux-x86-syscall.S pr23428.c } \
+	"pr23428" \
+	"pass.out" \
+	"$NOPIE_CFLAGS -fno-asynchronous-unwind-tables" \
+	"asm" \
+    ] \
+]
diff --git a/ld/testsuite/ld-elf/pr23428.c b/ld/testsuite/ld-elf/pr23428.c
new file mode 100644
index 0000000000..3631ed7926
--- /dev/null
+++ b/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;
+}
diff --git a/ld/testsuite/ld-elf/sec64k.exp b/ld/testsuite/ld-elf/sec64k.exp
index b58139e9dd..2568cc4635 100644
--- a/ld/testsuite/ld-elf/sec64k.exp
+++ b/ld/testsuite/ld-elf/sec64k.exp
@@ -178,7 +178,7 @@ if { ![istarget "d10v-*-*"]
     if { [istarget spu*-*-*] } {
 	puts $ofd "#ld: --local-store 0:0"
     } else {
-	puts $ofd "#ld:"
+	puts $ofd "#ld: -z noseparate-code"
     }
     puts $ofd "#readelf: -W -Ss"
     puts $ofd "There are 660.. section headers.*:"
diff --git a/ld/testsuite/ld-i386/abs-iamcu.d b/ld/testsuite/ld-i386/abs-iamcu.d
index ac9beff2e5..aba7d6b03f 100644
--- a/ld/testsuite/ld-i386/abs-iamcu.d
+++ b/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 .*
diff --git a/ld/testsuite/ld-i386/abs.d b/ld/testsuite/ld-i386/abs.d
index e660aca524..191ee4456a 100644
--- a/ld/testsuite/ld-i386/abs.d
+++ b/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 .*
diff --git a/ld/testsuite/ld-i386/pr12718.d b/ld/testsuite/ld-i386/pr12718.d
index ec51540a42..7eba52d95e 100644
--- a/ld/testsuite/ld-i386/pr12718.d
+++ b/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]+:
diff --git a/ld/testsuite/ld-i386/pr12921.d b/ld/testsuite/ld-i386/pr12921.d
index e49079b3c8..ea2da3eb51 100644
--- a/ld/testsuite/ld-i386/pr12921.d
+++ b/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]+:
diff --git a/ld/testsuite/ld-linkonce/zeroehl32.d b/ld/testsuite/ld-linkonce/zeroehl32.d
index bd8fc6f67e..33cbf75a9e 100644
--- a/ld/testsuite/ld-linkonce/zeroehl32.d
+++ b/ld/testsuite/ld-linkonce/zeroehl32.d
@@ -1,6 +1,6 @@
 #source: x.s
 #source: y.s
-#ld: -Ttext 0xa00 -T zeroeh.ld
+#ld: -Ttext 0xa00 -T zeroeh.ld -z noseparate-code
 #objdump: -s
 #target: cris-*-elf cris-*-linux* i?86-*-elf i?86-*-linux* i?86-*-gnu*
 
diff --git a/ld/testsuite/ld-scripts/print-memory-usage.t b/ld/testsuite/ld-scripts/print-memory-usage.t
index 5ff057a5e3..95d2e0f420 100644
--- a/ld/testsuite/ld-scripts/print-memory-usage.t
+++ b/ld/testsuite/ld-scripts/print-memory-usage.t
@@ -11,4 +11,6 @@ SECTIONS
     *(.data)
     *(.rw)
   }
+
+  /DISCARD/ : { *(*) }
 }
diff --git a/ld/testsuite/ld-scripts/size-2.d b/ld/testsuite/ld-scripts/size-2.d
index e89bd5aeda..82323366e8 100644
--- a/ld/testsuite/ld-scripts/size-2.d
+++ b/ld/testsuite/ld-scripts/size-2.d
@@ -1,5 +1,5 @@
 #source: size-2.s
-#ld: -T size-2.t
+#ld: -T size-2.t -z noseparate-code
 #readelf: -l --wide
 #xfail: "v850*-*-*"
 
diff --git a/ld/testsuite/ld-x86-64/abs-k1om.d b/ld/testsuite/ld-x86-64/abs-k1om.d
index 2c26639fc0..6b0fde0eed 100644
--- a/ld/testsuite/ld-x86-64/abs-k1om.d
+++ b/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 .*
diff --git a/ld/testsuite/ld-x86-64/abs-l1om.d b/ld/testsuite/ld-x86-64/abs-l1om.d
index 1fb96d44b7..f87869f9d0 100644
--- a/ld/testsuite/ld-x86-64/abs-l1om.d
+++ b/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*
 
diff --git a/ld/testsuite/ld-x86-64/abs.d b/ld/testsuite/ld-x86-64/abs.d
index b24b018639..d99ab4685d 100644
--- a/ld/testsuite/ld-x86-64/abs.d
+++ b/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 .*
diff --git a/ld/testsuite/ld-x86-64/pr12718.d b/ld/testsuite/ld-x86-64/pr12718.d
index 07d17325d0..2c503ffbaa 100644
--- a/ld/testsuite/ld-x86-64/pr12718.d
+++ b/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]+:
diff --git a/ld/testsuite/ld-x86-64/pr12921.d b/ld/testsuite/ld-x86-64/pr12921.d
index 6fe6abee09..1162d55818 100644
--- a/ld/testsuite/ld-x86-64/pr12921.d
+++ b/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]+:
diff --git a/ld/testsuite/lib/ld-lib.exp b/ld/testsuite/lib/ld-lib.exp
index 5880c67842..2e7d368ce9 100644
--- a/ld/testsuite/lib/ld-lib.exp
+++ b/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 {
-- 
2.17.1
Follow-Ups:
- Re: [PATCH] x86: Add a GNU_PROPERTY_X86_ISA_1_USED note if needed
  - From: H.J. Lu
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