Add support for non-contiguous memory regions

2020-01-06  Christophe Lyon  <christophe.lyon@linaro.org>

	bfd/
	* bfd-in2.h: Regenerate.
	* section.c (asection): Add already_assigned field.
	(BFD_FAKE_SECTION): Add default initializer for it.
	* ecoff.c (bfd_debug_section): Initialize already_assigned field.
	* elf32-arm.c (arm_build_one_stub): Add support for
	non_contiguous_regions.
	* elf32-csky.c (csky_build_one_stub): Likewise.
	* elf32-hppa.c (hppa_build_one_stub): Likewise.
	* elf32-m68hc11.c (m68hc11_elf_build_one_stub): Likewise.
	* elf32-m68hc12.c (m68hc12_elf_build_one_stub): Likewise.
	* elf32-metag.c (metag_build_one_stub): Likewise.
	* elf32-nios2.c (nios2_build_one_stub): Likewise.
	* elf64-ppc.c (ppc_build_one_stub): Likewise.
	(ppc_size_one_stub): Likewise.
	* elfnn-aarch64.c (aarch64_build_one_stub): Likewise.
	* elflink.c (elf_link_input_bfd): Likewise.

	include/
	* bfdlink.h (bfd_link_info): Add non_contiguous_regions and
	non_contiguous_regions_warnings fields.

	ld/
	* ldlang.c (lang_add_section): Add support for
	non_contiguous_regions.
	(size_input_section): Likewise.
	(lang_size_sections_1): Likewise.
	(process_insert_statements): Likewise.
	* ldlex.h (option_values): Add OPTION_NON_CONTIGUOUS_REGIONS and
	OPTION_NON_CONTIGUOUS_REGIONS_WARNINGS.
	* lexsup.c (ld_options): Add entries for
	--enable-non-contiguous-regions and
	--enable-non-contiguous-regions-warnings.
	(parse_args): Handle it.
	* NEWS: Add --enable-non-contiguous-regions and
	--enable-non-contiguous-regions-warnings.
	* ld.texi: Add --enable-non-contiguous-regions and
	--enable-non-contiguous-regions-warnings documentation.
	* emultempl/armelf.em (elf32_arm_add_stub_section): Add
	SEC_LINKER_CREATED flag.
	* emultempl/xtensaelf.em (ld_build_required_section_dependence):
	Emit an error when --enable-non-contiguous-regions is used.
	* testsuite/ld-elf/non-contiguous.d: New.
	* testsuite/ld-elf/non-contiguous.ld: New.
	* testsuite/ld-elf/non-contiguous.s: New.
	* testsuite/ld-arm/arm-elf.exp: Run the new tests.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm.s: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm.d: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm.ld: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm2.d: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm3.ld: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm3.d: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm3.ld: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm4.d: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm4.ld: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm5.d: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm5.ld: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm6.d: New.
	* testsuite/ld-arm/arm-elf/non-contiguous-arm6.ld: New.
	* testsuite/ld-powerpc/powerpc.exp: Run new tests.
	* testsuite/ld-powerpc/non-contiguous-powerpc.d: New.
	* testsuite/ld-powerpc/non-contiguous-powerpc.ld: New.
	* testsuite/ld-powerpc/non-contiguous-powerpc.sd: New.
	* testsuite/ld-powerpc/non-contiguous-powerpc64.d: New.

1 files changed, 42 insertions, 0 deletions

diff --git a/ld/ld.texi b/ld/ld.texi
index 27343c7..9f56293 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -459,6 +459,48 @@ will contain a colon separated list of audit interfaces to use.  This
 option is only meaningful on ELF platforms supporting the rtld-audit interface.
 The -P option is provided for Solaris compatibility.
 
+@kindex --enable-non-contiguous-regions
+@item --enable-non-contiguous-regions
+This option avoids generating an error if an input section does not
+fit a matching output section. The linker tries to allocate the input
+section to subseque nt matching output sections, and generates an
+error only if no output section is large enough.  This is useful when
+several non-contiguous memory regions are available and the input
+section does not require a particular one.  The order in which input
+sections are evaluated does not change, for instance:
+
+@smallexample
+  MEMORY @{
+    MEM1 (rwx) : ORIGIN : 0x1000, LENGTH = 0x14
+    MEM2 (rwx) : ORIGIN : 0x1000, LENGTH = 0x40
+    MEM3 (rwx) : ORIGIN : 0x2000, LENGTH = 0x40
+  @}
+  SECTIONS @{
+    mem1 : @{ *(.data.*); @} > MEM1
+    mem2 : @{ *(.data.*); @} > MEM2
+    mem3 : @{ *(.data.*); @} > MEM2
+  @}
+
+  with input sections:
+  .data.1: size 8
+  .data.2: size 0x10
+  .data.3: size 4
+
+  results in .data.1 affected to mem1, and .data.2 and .data.3
+  affected to mem2, even though .data.3 would fit in mem3.
+@end smallexample
+
+This option is incompatible with INSERT statements because it changes
+the way input sections are mapped to output sections.
+
+@kindex --enable-non-contiguous-regions-warnings
+@item --enable-non-contiguous-regions-warnings
+This option enables warnings when
+@code{--enable-non-contiguous-regions} allows possibly unexpected
+matches in sections mapping, potentially leading to silently
+discarding a section instead of failing because it does not fit any
+output region.
+
 @cindex entry point, from command line
 @kindex -e @var{entry}
 @kindex --entry=@var{entry}