Add support for an ARM specific 'y' section attribute flag to mark the section as NOREAD.

bfd/ChangeLog:
      * elf32-arm.c ((elf32_arm_special_sections): Remove catch of noread
      section using '.text.noread' pattern.

gas/ChangeLog:
      * config/obj-elf.c (obj_elf_change_section) : Allow arm section with
      SHF_ARM_NOREAD section flag.
      * config/tc-arm.h (md_elf_section_letter) : Implement this hook to
      handle letter 'y'.
     (arm_elf_section_letter) : Declare it.
      * config/tc-arm.c (arm_elf_section_letter): Handle letter 'y' to set
      SHF_ARM_NOREAD section flag.
      * doc/c-arm.texi (ARM section attribute 'y'): Document it.

gas/testsuite/ChangeLog:
      * gas/arm/section-execute-only.s: New test case.
      * gas/arm/section-execute-only.d: Expected output.

ld/testsuite/ChangeLog:
      * ld-arm/thumb1-noread-not-present-mixing-two-section.s: Add 'y'
      attribute usage.
      * ld-arm/thumb1-noread-present-one-section.s: Likewise.
      * ld-arm/thumb1-noread-present-two-section.s: Likewise.
      * ld-arm/thumb1-input-section-flag-match.s: Likewise.

binutils/ChangeLog:
      * readelf.c (get_elf_section_flags): Display y letter for section
      with SHF_ARM_NOREAD section flag in readelf section output.
      (process_section_headers): Add y letter in readelf section output
      key mapping for ARM architecture.

7 files changed, 106 insertions, 0 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index a905d6f..75bee53 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,18 @@
+2016-01-20  Mickael Guene  <mickael.guene@st.com>
+	    Terry Guo  <terry.guo@arm.com>
+
+	* config/obj-elf.c (obj_elf_change_section) : Allow arm section with
+	SHF_ARM_NOREAD section flag.
+	* config/tc-arm.h (md_elf_section_letter) : Implement this hook to
+	handle letter 'y'.
+	(arm_elf_section_letter) : Declare it.
+	* config/tc-arm.c (arm_elf_section_letter): Handle letter 'y' to set
+	SHF_ARM_NOREAD section flag.
+	* doc/c-arm.texi (ARM section attribute): Document the 'y' attribute.
+
+	* testsuite/gas/arm/section-execute-only.s: New test case.
+	* testsuite/gas/arm/section-execute-only.d: Expected output.
+
 2016-01-18  Maciej W. Rozycki  <macro@imgtec.com>
 
 	* config/tc-mips.c (micromips_insn_length): Remove the mention
diff --git a/gas/config/obj-elf.c b/gas/config/obj-elf.c
index f4726ff..6d6d5f3 100644
--- a/gas/config/obj-elf.c
+++ b/gas/config/obj-elf.c
@@ -64,6 +64,10 @@
 #include "elf/nios2.h"
 #endif
 
+#ifdef TC_ARM
+#include "elf/arm.h"
+#endif
+
 static void obj_elf_line (int);
 static void obj_elf_size (int);
 static void obj_elf_type (int);
@@ -674,6 +678,11 @@ obj_elf_change_section (const char *name,
 	    /* RX init/fini arrays can and should have the "awx" attributes set.  */
 	    ;
 #endif
+#ifdef TC_ARM
+	  else if (attr == (SHF_EXECINSTR | SHF_ARM_NOREAD | SHF_ALLOC))
+	    /* ARM can have code section with SHF_ARM_NOREAD attribute.  */
+	    ;
+#endif
 	  else
 	    {
 	      if (group_name == NULL)
diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c
index 046abe5..4a16267 100644
--- a/gas/config/tc-arm.c
+++ b/gas/config/tc-arm.c
@@ -24091,6 +24091,15 @@ arm_fix_adjustable (fixS * fixP)
 #endif /* defined (OBJ_ELF) || defined (OBJ_COFF) */
 
 #ifdef OBJ_ELF
+bfd_vma
+arm_elf_section_letter (int letter, char **ptrmsg)
+{
+  if (letter == 'y')
+    return SHF_ARM_NOREAD;
+
+  *ptrmsg = _("unrecognized .section attribute: want a,e,w,x,y,M,S,G,T");
+  return -1;
+}
 
 const char *
 elf32_arm_target_format (void)
diff --git a/gas/config/tc-arm.h b/gas/config/tc-arm.h
index 319b2c2..749629c 100644
--- a/gas/config/tc-arm.h
+++ b/gas/config/tc-arm.h
@@ -114,6 +114,9 @@ extern bfd_boolean tc_start_label_without_colon (void);
 #define tc_frob_fake_label(S) arm_frob_label (S)
 
 #ifdef OBJ_ELF
+#define md_elf_section_letter arm_elf_section_letter
+extern bfd_vma arm_elf_section_letter (int, char **);
+
 #define md_end arm_md_end
 extern void arm_md_end (void);
 bfd_boolean arm_is_eabi (void);
diff --git a/gas/doc/c-arm.texi b/gas/doc/c-arm.texi
index 4ee6a21..886b024 100644
--- a/gas/doc/c-arm.texi
+++ b/gas/doc/c-arm.texi
@@ -23,6 +23,7 @@
 * ARM Opcodes::              Opcodes
 * ARM Mapping Symbols::      Mapping Symbols
 * ARM Unwinding Tutorial::   Unwinding
+* ARM Section Attribute::    Section Attribute
 @end menu
 
 @node ARM Options
@@ -1237,3 +1238,15 @@ code that calls functions which may throw exceptions.  If you need to
 know more about the object-file format used to represent unwind
 information, you may consult the @cite{Exception Handling ABI for the
 ARM Architecture} available from @uref{http://infocenter.arm.com}.
+
+@node ARM Section Attribute
+@section Section Attribute
+
+@cindex ARM section attribute
+@table @code
+@item y
+This letter specifies a text section with NOREAD attribute for
+hardware that supports execute-only memory region.  If not supported
+by hardware a section with this attribute will be treated as normal
+text section.
+@end table
diff --git a/gas/testsuite/gas/arm/section-execute-only.d b/gas/testsuite/gas/arm/section-execute-only.d
new file mode 100644
index 0000000..d45a132
--- /dev/null
+++ b/gas/testsuite/gas/arm/section-execute-only.d
@@ -0,0 +1,27 @@
+# name: test executable-only section attribute
+# as:
+# readelf: -t
+# This test is only valid on EABI based ports.
+# target: *-*-*eabi* *-*-nacl*
+There are 10 section headers, starting at offset 0x16c:
+
+Section Headers:
+  \[Nr\] Name
+       Type            Addr     Off    Size   ES   Lk Inf Al
+       Flags
+  \[ 0\] 
+       NULL            00000000 000000 000000 00   0   0  0
+       \[00000000\]: 
+  \[ 1\] .text
+       PROGBITS        00000000 000034 000000 00   0   0  2
+       \[00000006\]: ALLOC, EXEC
+  \[ 2\] .data
+       PROGBITS        00000000 000034 000000 00   0   0  1
+       \[00000003\]: WRITE, ALLOC
+  \[ 3\] .bss
+       NOBITS          00000000 000034 000000 00   0   0  1
+       \[00000003\]: WRITE, ALLOC
+  \[ 4\] .text.foo
+       PROGBITS        00000000 000034 000010 00   0   0  4
+       \[20000006\]: ALLOC, EXEC, ARM_NOREAD
+#pass
diff --git a/gas/testsuite/gas/arm/section-execute-only.s b/gas/testsuite/gas/arm/section-execute-only.s
new file mode 100644
index 0000000..9d5ffc6
--- /dev/null
+++ b/gas/testsuite/gas/arm/section-execute-only.s
@@ -0,0 +1,30 @@
+        .syntax unified
+        .cpu cortex-m3
+        .fpu softvfp
+        .eabi_attribute 20, 1
+        .eabi_attribute 21, 1
+        .eabi_attribute 23, 3
+        .eabi_attribute 24, 1
+        .eabi_attribute 25, 1
+        .eabi_attribute 26, 1
+        .eabi_attribute 30, 2
+        .eabi_attribute 34, 1
+        .eabi_attribute 18, 4
+        .thumb
+        .section        .text.foo,"axy",%progbits
+        .align  2
+        .global foo
+        .thumb
+        .thumb_func
+        .type   foo, %function
+foo:
+        @ args = 0, pretend = 0, frame = 0
+        @ frame_needed = 0, uses_anonymous_args = 0
+        @ link register save eliminated.
+        movs    r0, #1
+        movs    r1, #1
+        movw    r2, #257
+        movs    r3, #1
+        b       madd
+        .size   foo, .-foo
+