RISC-V: Add PT_RISCV_ATTRIBUTES and add it to PHDR.

We added PT_RISCV_ATTRIBUTES to program header to make
.riscv.attribute easier to find in dynamic loader or kernel.

Ref:
https://github.com/riscv/riscv-elf-psabi-doc/pull/71

ChangeLog:

bfd/

	* elfnn-riscv.c(RISCV_ATTRIBUTES_SECTION_NAME): New.
	(riscv_elf_additional_program_headers): Ditto.
	(riscv_elf_modify_segment_map): Ditto.
	(elf_backend_additional_program_headers): Ditto.
	(elf_backend_modify_segment_map): Ditto.
	(elf_backend_obj_attrs_section): Use RISCV_ATTRIBUTES_SECTION_NAME
	rather than string literal.

binutils/

	* readelf.c(get_riscv_segment_type): New.
	(get_segment_type): Handle EM_RISCV.

include/

	* elf/riscv.h (PT_RISCV_ATTRIBUTES): New.
	* testsuite/ld-elf/orphan-region.ld: Discard .riscv.attributes
	section for simplify testcase.
	* testsuite/ld-riscv-elf/attr-phdr.d: New.
	* testsuite/ld-riscv-elf/attr-phdr.s: Ditto.
	* testsuite/ld-riscv-elf/ld-riscv-elf.exp: Add attr-phdr to
	testcase.

1 files changed, 5 insertions, 0 deletions

diff --git a/include/elf/riscv.h b/include/elf/riscv.h
index fb376a0..8082283 100644
--- a/include/elf/riscv.h
+++ b/include/elf/riscv.h
@@ -120,6 +120,11 @@ END_RELOC_NUMBERS (R_RISCV_max)
 /* Additional section types.  */
 #define SHT_RISCV_ATTRIBUTES 0x70000003 /* Section holds attributes.  */
 
+/* Processor specific program header types.  */
+
+/* Location of RISC-V ELF attribute section. */
+#define PT_RISCV_ATTRIBUTES 0x70000003
+
 /* Object attributes.  */
 enum
 {