bfd: linker: merge .sframe sections

The linker merges all the input .sframe sections.  When merging, the
linker verifies that all the input .sframe sections have the same
abi/arch.

The linker uses libsframe library to perform key actions on the
.sframe sections - decode, read, and create output data.  This
implies buildsystem changes to make and install libsframe before
libbfd.

The linker places the output .sframe section in a new segment of its
own: PT_GNU_SFRAME.  A new segment is not added, however, if the
generated .sframe section is empty.

When a section is discarded from the final link, the corresponding
entries in the .sframe section for those functions are also deleted.

The linker sorts the SFrame FDEs on start address by default and sets
the SFRAME_F_FDE_SORTED flag in the .sframe section.

This patch also adds support for generation of SFrame unwind
information for the .plt* sections on x86_64.  SFrame unwind info is
generated for IBT enabled PLT, lazy/non-lazy PLT.

The existing linker option --no-ld-generated-unwind-info has been
adapted to include the control of whether .sframe unwind information
will be generated for the linker generated sections like PLT.

Changes to the linker script have been made as necessary.

ChangeLog:

	* Makefile.def: Add install dependency on libsframe for libbfd.
	* Makefile.in: Regenerated.
	* bfd/Makefile.am: Add elf-sframe.c
	* bfd/Makefile.in: Regenerated.
	* bfd/bfd-in2.h (SEC_INFO_TYPE_SFRAME): Regenerated.
	* bfd/configure: Regenerate.
	* bfd/configure.ac: Add elf-sframe.lo.
	* bfd/elf-bfd.h (struct sframe_func_bfdinfo): New struct.
	(struct sframe_dec_info): Likewise.
	(struct sframe_enc_info): Likewise.
	(struct elf_link_hash_table): New member for encoded .sframe
	object.
	(struct output_elf_obj_tdata): New member.
	(elf_sframe): New access macro.
	(_bfd_elf_set_section_sframe): New declaration.
	* bfd/elf.c (get_segment_type): Handle new segment
	PT_GNU_SFRAME.
	(bfd_section_from_phdr): Likewise.
	(get_program_header_size): Likewise.
	(_bfd_elf_map_sections_to_segments): Likewise.
	* bfd/elf64-x86-64.c (elf_x86_64_link_setup_gnu_properties): Add
	contents to the .sframe sections or .plt* entries.
	* bfd/elflink.c (elf_section_ignore_discarded_relocs): Handle
	SEC_INFO_TYPE_SFRAME.
	(_bfd_elf_default_action_discarded): Handle .sframe section.
	(elf_link_input_bfd): Merge .sframe section.
	(bfd_elf_final_link): Write the output .sframe section.
	(bfd_elf_discard_info): Handle discarding .sframe section.
	* bfd/elfxx-x86.c (_bfd_x86_elf_size_dynamic_sections): Create
	.sframe section for .plt and .plt.sec.
	(_bfd_x86_elf_finish_dynamic_sections): Handle .sframe from
	.plt* sections.
	* bfd/elfxx-x86.h (PLT_SFRAME_FDE_START_OFFSET): New
	definition.
	(SFRAME_PLT0_MAX_NUM_FRES): Likewise.
	(SFRAME_PLTN_MAX_NUM_FRES): Likewise.
	(struct elf_x86_sframe_plt): New structure.
	(struct elf_x86_link_hash_table): New member.
	(struct elf_x86_init_table): New members for .sframe
	creation.
	* bfd/section.c: Add new definition SEC_INFO_TYPE_SFRAME.
	* binutils/readelf.c (get_segment_type): Handle new segment
	PT_GNU_SFRAME.
	* ld/ld.texi: Update documentation for
	--no-ld-generated-unwind-info.
	* ld/scripttempl/elf.sc: Support .sframe sections.
	* ld/Makefile.am (TESTSFRAMELIB): Use it.
	(check-DEJAGNU): Likewise.
	* ld/Makefile.in: Regenerated.
	* ld/configure.ac (TESTSFRAMELIB): Set to the .so or .a like TESTBFDLIB.
	* ld/configure: Regenerated.
	* bfd/elf-sframe.c: New file.

include/ChangeLog:

	* elf/common.h (PT_GNU_SFRAME): New definition.
	* elf/internal.h (struct elf_segment_map): Handle new segment
	type PT_GNU_SFRAME.

ld/testsuite/ChangeLog:

	* ld/testsuite/ld-bootstrap/bootstrap.exp: Add SFRAMELIB.
	* ld/testsuite/ld-aarch64/aarch64-elf.exp: Add new test
	  sframe-simple-1.
	* ld/testsuite/ld-aarch64/sframe-bar.s: New file.
	* ld/testsuite/ld-aarch64/sframe-foo.s: Likewise.
	* ld/testsuite/ld-aarch64/sframe-simple-1.d: Likewise.
	* ld/testsuite/ld-sframe/sframe-empty.d: New test.
	* ld/testsuite/ld-sframe/sframe-empty.s: New file.
	* ld/testsuite/ld-sframe/sframe.exp: New testsuite.
	* ld/testsuite/ld-x86-64/sframe-bar.s: New file.
	* ld/testsuite/ld-x86-64/sframe-foo.s: Likewise.
	* ld/testsuite/ld-x86-64/sframe-simple-1.d: Likewise.
	* ld/testsuite/ld-x86-64/sframe-plt-1.d: Likewise.
	* ld/testsuite/ld-x86-64/sframe-simple-1.d: Likewise.
	* ld/testsuite/ld-x86-64/x86-64.exp: Add new tests -
	  sframe-simple-1, sframe-plt-1.
	* ld/testsuite/lib/ld-lib.exp: Add new proc to check if
	  assembler supports SFrame section.
	* ld/testsuite/ld-sframe/discard.d: New file.
	* ld/testsuite/ld-sframe/discard.ld: Likewise.
	* ld/testsuite/ld-sframe/discard.s: Likewise.

1 files changed, 54 insertions, 0 deletions

diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index fa4b9bc..fc32fbe 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -490,6 +490,40 @@ struct eh_frame_hdr_info
   u;
 };
 
+/* Additional information for each function (used at link time).  */
+struct sframe_func_bfdinfo
+{
+  /* Whether the function has been discarded from the final output.  */
+  bool func_deleted_p;
+  /* Relocation offset.  */
+  unsigned int func_r_offset;
+  /* Relocation index.  */
+  unsigned int func_reloc_index;
+};
+
+/* SFrame decoder info.
+   Contains all information for a decoded .sframe section.  */
+struct sframe_dec_info
+{
+  /* Decoder context.  */
+  struct sframe_decoder_ctx *sfd_ctx;
+  /* Number of function descriptor entries in this .sframe.  */
+  unsigned int sfd_fde_count;
+  /* Additional information for linking.  */
+  struct sframe_func_bfdinfo *sfd_func_bfdinfo;
+};
+
+/* SFrame encoder info.
+   Contains all information for an encoded .sframe section to be
+   written out.  */
+struct sframe_enc_info
+{
+  /* Encoder context.  */
+  struct sframe_encoder_ctx *sfe_ctx;
+  /* Output section.  */
+  asection *sframe_section;
+};
+
 /* Enum used to identify target specific extensions to the elf_obj_tdata
    and elf_link_hash_table structures.  Note the enums deliberately start
    from 1 so that we can detect an uninitialized field.  The generic value
@@ -668,6 +702,9 @@ struct elf_link_hash_table
   /* Used by eh_frame code when editing .eh_frame.  */
   struct eh_frame_hdr_info eh_info;
 
+  /* Used to link unwind data in .sframe sections.  */
+  struct sframe_enc_info sfe_info;
+
   /* A linked list of local symbols to be added to .dynsym.  */
   struct elf_link_local_dynamic_entry *dynlocal;
 
@@ -1944,6 +1981,10 @@ struct output_elf_obj_tdata
   /* Segment flags for the PT_GNU_STACK segment.  */
   unsigned int stack_flags;
 
+  /* Used to determine if PT_GNU_SFRAME segment header should be
+     created.  */
+  asection *sframe;
+
   /* Used to determine if the e_flags field has been initialized */
   bool flags_init;
 };
@@ -2125,6 +2166,7 @@ struct elf_obj_tdata
 #define elf_link_info(bfd)	(elf_tdata(bfd) -> o->link_info)
 #define elf_next_file_pos(bfd)	(elf_tdata(bfd) -> o->next_file_pos)
 #define elf_stack_flags(bfd)	(elf_tdata(bfd) -> o->stack_flags)
+#define elf_sframe(bfd)		(elf_tdata(bfd) -> o->sframe)
 #define elf_shstrtab(bfd)	(elf_tdata(bfd) -> o->strtab_ptr)
 #define elf_onesymtab(bfd)	(elf_tdata(bfd) -> symtab_section)
 #define elf_symtab_shndx_list(bfd)	(elf_tdata(bfd) -> symtab_shndx_list)
@@ -2439,6 +2481,18 @@ extern bool _bfd_elf_eh_frame_entry_present
 extern bool _bfd_elf_maybe_strip_eh_frame_hdr
   (struct bfd_link_info *);
 
+extern bool _bfd_elf_sframe_present
+  (struct bfd_link_info *);
+extern bool _bfd_elf_parse_sframe
+  (bfd *, struct bfd_link_info *, asection *, struct elf_reloc_cookie *);
+extern bool _bfd_elf_discard_section_sframe
+  (asection *, bool (*) (bfd_vma, void *), struct elf_reloc_cookie *);
+extern bool _bfd_elf_merge_section_sframe
+  (bfd *, struct bfd_link_info *, asection *, bfd_byte *);
+extern bool _bfd_elf_write_section_sframe
+  (bfd *, struct bfd_link_info *);
+extern bool _bfd_elf_set_section_sframe (bfd *, struct bfd_link_info *);
+
 extern bool _bfd_elf_hash_symbol (struct elf_link_hash_entry *);
 
 extern long _bfd_elf_link_lookup_local_dynindx