binutils-gdb/ld/emultempl/armcoff.em
Nick Alcock 1ff6de0312 bfd, ld: add CTF section linking
This is quite complicated because the CTF section's contents depend on
the final contents of the symtab and strtab, because it has two sections
whose contents are shuffled to be in 1:1 correspondence with the symtab,
and an internal strtab that gets deduplicated against the ELF strtab
(with offsets adjusted to point into the ELF strtab instead).  It is
also compressed if large enough, so its size depends on its contents!

So we cannot construct it as early as most sections: we cannot even
*begin* construction until after the symtab and strtab are finalized.
Thankfully there is already one section treated similarly: compressed
debugging sections: the only differences are that compressed debugging
sections have extra handling to deal with their changing name if
compressed (CTF sections are always called ".ctf" for now, though we
have reserved ".ctf.*" against future use), and that compressed
debugging sections have previously-uncompressed content which has to be
stashed away for later compression, while CTF sections have no content
at all until we generate it (very late).

BFD also cannot do the link itself: libctf knows how to do it, and BFD
cannot call libctf directly because libctf already depends on bfd for
file I/O.  So we have to use a pair of callbacks, one, examine_strtab,
which allows a caller to examine the symtab and strtab after
finalization (called from elf_link_swap_symbols_out(), right before the
symtabs are written, and after the strtab has been finalized), and one
which actually does the emission (called emit_ctf simply because it is
grouped with a bunch of section-specific late-emission function calls at
the bottom of bfd_elf_final_link, and a section-specific name seems best
for that).  emit_ctf is actually called *twice*: once from lang_process
if the emulation suggests that this bfd target does not examine the
symtab or strtab, and once via a bfd callback if it does.  (This means
that non-ELF targets still get CTF emitted, even though the late CTF
emission stage is never called for them).

v2: merged with non-ELF support patch: slight commit message
    adjustments.
v3: do not spend time merging CTF, or crash, if the CTF section is
    explicitly discarded.  Do not try to merge or compress CTF unless
    linking.
v4: add CTF_COMPRESSION_THRESHOLD.  Annul the freed input ctf_file_t's
    after writeout: set SEC_IN_MEMORY on the output contents so a future
    bfd enhancement knows it could free it.  Add SEC_LINKER_CREATED |
    SEC_KEEP to avoid having to add .ctf to the linker script.  Drop
    now-unnecessary ldlang.h-level elf-bfd.h include and hackery around
    it.  Adapt to elf32.em->elf.em and elf-generic.em->ldelf*.c
    changes.
v5: fix tabdamage.  Drop #inclusions in .h files: include in .c files,
    .em files, and use struct forwards instead.  Use bfd_section_is_ctf
    inline function rather than SECTION_IS_CTF macro.  Move a few
    comments.

	* Makefile.def (dependencies): all-ld depends on all-libctf.
	* Makefile.in: Regenerated.

include/
	* bfdlink.h (elf_strtab_hash): New forward.
	(elf_sym_strtab): Likewise.
	(struct bfd_link_callbacks <examine_strtab>): New.
	(struct bfd_link_callbacks <emit_ctf>): Likewise.

bfd/
	* elf-bfd.h (bfd_section_is_ctf): New inline function.
	* elf.c (special_sections_c): Add ".ctf".
	(assign_file_positions_for_non_load_sections): Note that
	compressed debugging sections etc are not assigned here.  Treat
	CTF sections like SEC_ELF_COMPRESS sections when is_linker_output:
	sh_offset -1.
	(assign_file_positions_except_relocs): Likewise.
	(find_section_in_list): Note that debugging and CTF sections, as
	well as reloc sections, are assigned later.
	(_bfd_elf_assign_file_positions_for_non_load): CTF sections get
	their size and contents updated.
	(_bfd_elf_set_section_contents): Skip CTF sections: unlike
	compressed sections, they have no uncompressed content to copy at
	this stage.
	* elflink.c (elf_link_swap_symbols_out): Call the examine_strtab
	callback right before the strtab is written out.
	(bfd_elf_final_link): Don't cache the section contents of CTF
	sections: they are not populated yet.  Call the emit_ctf callback
	right at the end, after all the symbols and strings are flushed
	out.

ld/
	* ldlang.h: (struct lang_input_statement_struct): Add the_ctf.
	(struct elf_sym_strtab): Add forward.
	(struct elf_strtab_hash): Likewise.
	(ldlang_ctf_apply_strsym): Declare.
	(ldlang_write_ctf_late): Likewise.
	* ldemul.h (ldemul_emit_ctf_early): New.
	(ldemul_examine_strtab_for_ctf): Likewise.
	(ld_emulation_xfer_type) <emit_ctf_early>: Likewise.
	(ld_emulation_xfer_type) <examine_strtab_for_ctf>: Likewise.
	* ldemul.c (ldemul_emit_ctf_early): New.
	(ldemul_examine_strtab_for_ctf): Likewise.
	* ldlang.c: Include ctf-api.h.
	(CTF_COMPRESSION_THRESHOLD): New.
	(ctf_output): New. Initialized in...
	(ldlang_open_ctf): ... this new function.  Open all the CTF
	sections in the input files: mark them non-loaded and empty
	so as not to copy their contents to the output, but linker-created
	so the section gets created in the target.
	(ldlang_merge_ctf): New, merge types via ctf_link_add_ctf and
	ctf_link.
	(ldlang_ctf_apply_strsym): New, an examine_strtab callback: wrap
	ldemul_examine_strtab_for_ctf.
	(lang_write_ctf): New, write out the CTF section.
	(ldlang_write_ctf_late): New, late call via bfd's emit_ctf hook.
	(lang_process): Call ldlang_open_ctf, ldlang_merge_ctf, and
	lang_write_ctf.
	* ldmain.c (link_callbacks): Add ldlang_ctf_apply_strsym,
	ldlang_write_ctf_late.
	* emultempl/aix.em: Add ctf-api.h.
	* emultempl/armcoff.em: Likewise.
	* emultempl/beos.em: Likewise.
	* emultempl/elf.em: Likewise.
	* emultempl/generic.em: Likewise.
	* emultempl/linux.em: Likewise.
	* emultempl/msp430.em: Likewise.
	* emultempl/pe.em: Likewise.
	* emultempl/pep.em: Likewise.
	* emultempl/ticoff.em: Likewise.
	* emultempl/vanilla.em: Likewise.
	* ldcref.c: Likewise.
	* ldctor.c: Likewise.
	* ldelf.c: Likewise.
	* ldelfgen.c: Likewise.
	* ldemul.c: Likewise.
	* ldexp.c: Likewise.
	* ldfile.c: Likewise.
	* ldgram.c: Likewise.
	* ldlex.l: Likewise.
	* ldmain.c: Likewise.
	* ldmisc.c: Likewise.
	* ldver.c: Likewise.
	* ldwrite.c: Likewise.
	* lexsup.c: Likewise.
	* mri.c: Likewise.
	* pe-dll.c: Likewise.
	* plugin.c: Likewise.

	* ldelfgen.c (ldelf_emit_ctf_early): New.
	(ldelf_examine_strtab_for_ctf): tell libctf about the symtab and
	strtab.
	(struct ctf_strsym_iter_cb_arg): New, state to do so.
	(ldelf_ctf_strtab_iter_cb): New: tell libctf about
	each string in the strtab in turn.
	(ldelf_ctf_symbols_iter_cb): New, tell libctf
	about each symbol in the symtab in turn.
	* ldelfgen.h (struct elf_sym_strtab): Add forward.
	(struct elf_strtab_hash): Likewise.
	(struct ctf_file): Likewise.
	(ldelf_emit_ctf_early): Declare.
	(ldelf_examine_strtab_for_ctf): Likewise.
	* emultempl/elf-generic.em (LDEMUL_EMIT_CTF_EARLY): Set it.
	(LDEMUL_EXAMINE_STRTAB_FOR_CTF): Likewise.
	* emultempl/aix.em (ld_${EMULATION_NAME}_emulation): Add
	emit_ctf_early and examine_strtab_for_ctf, NULL by default.
	* emultempl/armcoff.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/beos.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/elf.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/generic.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/linux.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/msp430.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/pe.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/pep.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/ticoff.em (ld_${EMULATION_NAME}_emulation): Likewise.
	* emultempl/vanilla.em (ld_vanilla_emulation): Likewise.

	* Makefile.am: Pull in libctf (and zlib, a transitive requirement
	for compressed CTF section emission).  Pass it on to DejaGNU.
	* configure.ac: Add AM_ZLIB.
	* aclocal.m4: Added zlib.m4.
	* Makefile.in: Regenerated.
	* testsuite/ld-bootstrap/bootstrap.exp: Use it when relinking ld.
2019-10-03 17:04:56 +01:00

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# This shell script emits a C file. -*- C -*-
# It does some substitutions.
fragment <<EOF
/* This file is is generated by a shell script. DO NOT EDIT! */
/* emulate the original gld for the given ${EMULATION_NAME}
Copyright (C) 1991-2019 Free Software Foundation, Inc.
Written by Steve Chamberlain steve@cygnus.com
This file is part of the GNU Binutils.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
MA 02110-1301, USA. */
#define TARGET_IS_${EMULATION_NAME}
#include "sysdep.h"
#include "bfd.h"
#include "bfdlink.h"
#include "ctf-api.h"
#include "getopt.h"
#include "ld.h"
#include "ldmain.h"
#include "ldmisc.h"
#include "ldexp.h"
#include "ldlang.h"
#include "ldfile.h"
#include "ldemul.h"
/* If TRUE, then interworking stubs which support calls to old,
non-interworking aware ARM code should be generated. */
static int support_old_code = 0;
static char * thumb_entry_symbol = NULL;
#define OPTION_SUPPORT_OLD_CODE 300
#define OPTION_THUMB_ENTRY 301
static void
gld${EMULATION_NAME}_add_options
(int ns ATTRIBUTE_UNUSED, char **shortopts ATTRIBUTE_UNUSED, int nl,
struct option **longopts, int nrl ATTRIBUTE_UNUSED,
struct option **really_longopts ATTRIBUTE_UNUSED)
{
static const struct option xtra_long[] = {
{"support-old-code", no_argument, NULL, OPTION_SUPPORT_OLD_CODE},
{"thumb-entry", required_argument, NULL, OPTION_THUMB_ENTRY},
{NULL, no_argument, NULL, 0}
};
*longopts = xrealloc (*longopts,
nl * sizeof (struct option) + sizeof (xtra_long));
memcpy (*longopts + nl, &xtra_long, sizeof (xtra_long));
}
static void
gld${EMULATION_NAME}_list_options (FILE *file)
{
fprintf (file, _(" --support-old-code Support interworking with old code\n"));
fprintf (file, _(" --thumb-entry=<sym> Set the entry point to be Thumb symbol <sym>\n"));
}
static bfd_boolean
gld${EMULATION_NAME}_handle_option (int optc)
{
switch (optc)
{
default:
return FALSE;
case OPTION_SUPPORT_OLD_CODE:
support_old_code = 1;
break;
case OPTION_THUMB_ENTRY:
thumb_entry_symbol = optarg;
break;
}
return TRUE;
}
static void
gld${EMULATION_NAME}_before_parse (void)
{
#ifndef TARGET_ /* I.e., if not generic. */
ldfile_set_output_arch ("`echo ${ARCH}`", bfd_arch_unknown);
#endif /* not TARGET_ */
}
/* This is called after the sections have been attached to output
sections, but before any sizes or addresses have been set. */
static void
gld${EMULATION_NAME}_before_allocation (void)
{
/* we should be able to set the size of the interworking stub section */
/* Here we rummage through the found bfds to collect glue information */
/* FIXME: should this be based on a command line option? krk@cygnus.com */
{
LANG_FOR_EACH_INPUT_STATEMENT (is)
{
if (! bfd_arm_process_before_allocation
(is->the_bfd, & link_info, support_old_code))
{
/* xgettext:c-format */
einfo (_("%P: errors encountered processing file %s\n"),
is->filename);
}
}
}
/* We have seen it all. Allocate it, and carry on */
bfd_arm_allocate_interworking_sections (& link_info);
before_allocation_default ();
}
static void
gld${EMULATION_NAME}_after_open (void)
{
after_open_default ();
if (strstr (bfd_get_target (link_info.output_bfd), "arm") == NULL)
{
/* The arm backend needs special fields in the output hash structure.
These will only be created if the output format is an arm format,
hence we do not support linking and changing output formats at the
same time. Use a link followed by objcopy to change output formats. */
einfo (_("%F%P: error: cannot change output format "
"whilst linking %s binaries\n"), "ARM");
return;
}
{
LANG_FOR_EACH_INPUT_STATEMENT (is)
{
if (bfd_arm_get_bfd_for_interworking (is->the_bfd, & link_info))
break;
}
}
}
static void
gld${EMULATION_NAME}_finish (void)
{
if (thumb_entry_symbol != NULL)
{
struct bfd_link_hash_entry * h;
h = bfd_link_hash_lookup (link_info.hash, thumb_entry_symbol,
FALSE, FALSE, TRUE);
if (h != (struct bfd_link_hash_entry *) NULL
&& (h->type == bfd_link_hash_defined
|| h->type == bfd_link_hash_defweak)
&& h->u.def.section->output_section != NULL)
{
static char buffer[32];
bfd_vma val;
/* Special procesing is required for a Thumb entry symbol. The
bottom bit of its address must be set. */
val = (h->u.def.value
+ bfd_section_vma (h->u.def.section->output_section)
+ h->u.def.section->output_offset);
val |= 1;
/* Now convert this value into a string and store it in entry_symbol
where the lang_finish() function will pick it up. */
buffer[0] = '0';
buffer[1] = 'x';
sprintf_vma (buffer + 2, val);
if (entry_symbol.name != NULL && entry_from_cmdline)
einfo (_("%P: warning: '--thumb-entry %s' is overriding '-e %s'\n"),
thumb_entry_symbol, entry_symbol.name);
entry_symbol.name = buffer;
}
else
einfo (_("%P: warning: cannot find thumb start symbol %s\n"),
thumb_entry_symbol);
}
finish_default ();
}
static char *
gld${EMULATION_NAME}_get_script (int *isfile)
EOF
if test x"$COMPILE_IN" = xyes
then
# Scripts compiled in.
# sed commands to quote an ld script as a C string.
sc="-f stringify.sed"
fragment <<EOF
{
*isfile = 0;
if (bfd_link_relocatable (&link_info) && config.build_constructors)
return
EOF
sed $sc ldscripts/${EMULATION_NAME}.xu >> e${EMULATION_NAME}.c
echo ' ; else if (bfd_link_relocatable (&link_info)) return' >> e${EMULATION_NAME}.c
sed $sc ldscripts/${EMULATION_NAME}.xr >> e${EMULATION_NAME}.c
echo ' ; else if (!config.text_read_only) return' >> e${EMULATION_NAME}.c
sed $sc ldscripts/${EMULATION_NAME}.xbn >> e${EMULATION_NAME}.c
echo ' ; else if (!config.magic_demand_paged) return' >> e${EMULATION_NAME}.c
sed $sc ldscripts/${EMULATION_NAME}.xn >> e${EMULATION_NAME}.c
echo ' ; else return' >> e${EMULATION_NAME}.c
sed $sc ldscripts/${EMULATION_NAME}.x >> e${EMULATION_NAME}.c
echo '; }' >> e${EMULATION_NAME}.c
else
# Scripts read from the filesystem.
fragment <<EOF
{
*isfile = 1;
if (bfd_link_relocatable (&link_info) && config.build_constructors)
return "ldscripts/${EMULATION_NAME}.xu";
else if (bfd_link_relocatable (&link_info))
return "ldscripts/${EMULATION_NAME}.xr";
else if (!config.text_read_only)
return "ldscripts/${EMULATION_NAME}.xbn";
else if (!config.magic_demand_paged)
return "ldscripts/${EMULATION_NAME}.xn";
else
return "ldscripts/${EMULATION_NAME}.x";
}
EOF
fi
fragment <<EOF
struct ld_emulation_xfer_struct ld_${EMULATION_NAME}_emulation =
{
gld${EMULATION_NAME}_before_parse,
syslib_default,
hll_default,
after_parse_default,
gld${EMULATION_NAME}_after_open,
after_check_relocs_default,
after_allocation_default,
set_output_arch_default,
ldemul_default_target,
gld${EMULATION_NAME}_before_allocation,
gld${EMULATION_NAME}_get_script,
"${EMULATION_NAME}",
"${OUTPUT_FORMAT}",
gld${EMULATION_NAME}_finish,
NULL, /* create output section statements */
NULL, /* open dynamic archive */
NULL, /* place orphan */
NULL, /* set symbols */
NULL, /* parse_args */
gld${EMULATION_NAME}_add_options,
gld${EMULATION_NAME}_handle_option,
NULL, /* unrecognised file */
gld${EMULATION_NAME}_list_options,
NULL, /* recognized file */
NULL, /* find_potential_libraries */
NULL, /* new_vers_pattern */
NULL, /* extra_map_file_text */
${LDEMUL_EMIT_CTF_EARLY-NULL},
${LDEMUL_EXAMINE_STRTAB_FOR_CTF-NULL}
};
EOF