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The set_loc array attached to eh-frame sec_info isn't freed, and is
used in _bfd_elf_eh_frame_section_offset. Rather than finding a
suitable late stage of linking past any b_e_e_f_s_o use, I decided
this might as well persist until the bfd is closed.
Some memory is freed in _bfd_elf_discard_section_eh_frame_hdr, but
the function isn't always called, so fix that too.
* elf-eh-frame.c (_bfd_elf_parse_eh_frame): bfd_alloc the
set_loc array.
(find_merged_cie): Use bfd_malloc rather than malloc.
(_bfd_elf_discard_section_eh_frame_hdr): Move condition under
which this function does anything except free memory from..
* elflink.c (bfd_elf_discard_info): ..here.
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The GNU_PROPERTY_MEMORY_SEAL gnu property is a way to mark binaries
to be memory sealed by the loader, to avoid further changes of
PT_LOAD segments (such as unmapping or change permission flags).
This is done along with Linux kernel (the mseal syscall [1]), and
C runtime supports to instruct the kernel on the correct time during
program startup (for instance, after RELRO handling). This support
is added along the glibc support to handle the new gnu property [2].
This is a opt-in security features, like other security hardening
ones like NX-stack or RELRO.
The new property is ignored if present on ET_REL objects, and only
added on ET_EXEC/ET_DYN if the linker option is used. A gnu property
is used instead of DT_FLAGS_1 flag to allow memory sealing to work
with ET_EXEC without PT_DYNAMIC support (at least on glibc some ports
still do no support static-pie).
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8be7258aad44b5e25977a98db136f677fa6f4370
[2] https://sourceware.org/pipermail/libc-alpha/2024-September/160291.html
Change-Id: Id47fadabecd24be0e83cff45653f7ce9a900ecf4
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This patch adds a new CFI directive (cfi_negate_ra_state_with_pc) which
set an additional bit in the RA state to inform that RA was signed with
SP but also PC as an additional diversifier.
RA state | Description
0b00 | Return address not signed (default if no cfi_negate_ra_state*)
0b01 | Return address signed with SP (cfi_negate_ra_state)
0b10 | Invalid state
0b11 | Return address signed with SP+PC (cfi_negate_ra_state_with_pc)
Approved-by: Indu Bhagat <indu.bhagat@oracle.com>
Approved-by: Jan Beulich <jbeulich@suse.com>
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Link with mixed IR/non-IR objects
* 2 kinds of object files
o non-IR object file has
* non-IR sections
o IR object file has
* IR sections
* non-IR sections
* The output of "ld -r" with mixed IR/non-IR objects should work with:
o Compilers/linkers with IR support.
o Compilers/linkers without IR support.
* Add the mixed object file which has
o IR sections
o non-IR sections:
* Object codes from IR sections.
* Object codes from non-IR object files.
o Object-only section:
* With section name ".gnu_object_only" and SHT_GNU_OBJECT_ONLY type
on ELF:
https://gitlab.com/x86-psABIs/Linux-ABI
#define SHT_GNU_OBJECT_ONLY 0x6ffffff8 /* Object only */
* Contain non-IR object file.
* Input is discarded after link.
* Linker action:
o Classify each input object file:
* If there is a ".gnu_object_only" section, it is a mixed object file.
* If there is a IR section, it is an IR object file.
* Otherwise, it is a non-IR object file.
o Relocatable non-IR link:
* Prepare for an object-only output.
* Prepare for a regular output.
* For each mixed object file:
* Add IR and non-IR sections to the regular output.
* For object-only section:
* Extract object only file.
* Add it to the object-only output.
* Discard object-only section.
* For each IR object file:
* Add IR and non-IR sections to the regular output.
* For each non-IR object file:
* Add non-IR sections to the regular output.
* Add non-IR sections to the object-only output.
* Final output:
* If there are IR objects, non-IR objects and the object-only
output isn't empty:
* Put the object-only output into the object-only section.
* Add the object-only section to the regular output.
* Remove the object-only output.
o Normal link and relocatable IR link:
* Prepare for output.
* IR link:
* For each mixed object file:
* Compile and add IR sections to the output.
* Discard non-IR sections.
* Object-only section:
* Extract object only file.
* Add it to the output.
* Discard object-only section.
* For each IR object file:
* Compile and add IR sections to the output.
* Discard non-IR sections.
* For each non-IR object file:
* Add non-IR sections to the output.
* Non-IR link:
* For each mixed object file:
* Add non-IR sections to the output.
* Discard IR sections and object-only section.
* For each IR object file:
* Add non-IR sections to the output.
* Discard IR sections.
* For each non-IR object file:
* Add non-IR sections to the output.
This is useful for Linux kernel build with LTO.
bfd/
PR ld/12291
PR ld/12430
PR ld/13298
* bfd.c (bfd_lto_object_type): Add lto_mixed_object.
(bfd): Add object_only_section.
(bfd_group_signature): New.
* elf.c (special_sections_g): Add .gnu_object_only.
* format.c: Include "plugin-api.h" and "plugin.h" if
BFD_SUPPORTS_PLUGINS is defined.
(bfd_set_lto_type): Set type to lto_mixed_object for
GNU_OBJECT_ONLY_SECTION_NAME section.
(bfd_check_format_matches): Don't check the plugin target twice
if the plugin target is explicitly specified.
* opncls.c (bfd_extract_object_only_section): New.
* plugin.c (bfd_plugin_fake_text_section): New.
(bfd_plugin_fake_data_section): Likewise.
(bfd_plugin_fake_bss_section): Likewise.
(bfd_plugin_fake_common_section): Likewise.
(bfd_plugin_get_symbols_in_object_only): Likewise.
* plugin.c (add_symbols): Call
bfd_plugin_get_symbols_in_object_only and count
plugin_data->object_only_nsyms.
(bfd_plugin_get_symtab_upper_bound): Count
plugin_data->object_only_nsyms.
bfd_plugin_get_symbols_in_object_only and add symbols from
object only section.
(bfd_plugin_canonicalize_symtab): Remove fake_section,
fake_data_section, fake_bss_section and fake_common_section.
Set udata.p to NULL. Use bfd_plugin_fake_text_section,
bfd_plugin_fake_data_section, bfd_plugin_fake_bss_section and
bfd_plugin_fake_common_section.
Set udata.p to NULL.
* plugin.h (plugin_data_struct): Add object_only_nsyms and
object_only_syms.
* section.c (GNU_OBJECT_ONLY_SECTION_NAME): New.
* bfd-in2.h: Regenerated.
binutils/
PR ld/12291
PR ld/12430
PR ld/13298
* objcopy.c (group_signature): Removed.
(is_strip_section): Replace group_signature with
bfd_group_signature.
(setup_section): Likewise.
* readelf.c (get_os_specific_section_type_name): Handle
SHT_GNU_OBJECT_ONLY.
gas/
PR ld/12291
PR ld/12430
PR ld/13298
* testsuite/gas/elf/section9.s: Add the .gnu_object_only test.
* testsuite/gas/elf/section9.d: Updated.
include/
PR ld/12291
PR ld/12430
PR ld/13298
* elf/common.h (SHT_GNU_OBJECT_ONLY): New.
ld/
PR ld/12291
PR ld/12430
PR ld/13298
* ld.h (ld_config_type): Add emit_gnu_object_only and
emitting_gnu_object_only.
* ldelf.c (orphan_init_done): Make it file scope.
(ldelf_place_orphan): Rename hold to orig_hold. Initialize hold
from orig_hold at run-time.
(ldelf_finish): New.
* ldelf.h (ldelf_finish): New.
* ldexp.c (ldexp_init): Take a bfd_boolean argument to supprt
object-only output.
(ldexp_finish): Likewise.
* ldexp.h (ldexp_init): Take a bfd_boolean argument.
(ldexp_finish): Likewise.
* ldfile.c (ldfile_try_open_bfd): Call
cmdline_check_object_only_section.
* ldlang.c: Include "ldwrite.h" and elf-bfd.h.
* ldlang.c (cmdline_object_only_file_list): New.
(cmdline_object_only_archive_list): Likewise.
(cmdline_temp_object_only_list): Likewise.
(cmdline_lists_init): Likewise.
(cmdline_list_new): Likewise.
(cmdline_list_append): Likewise.
(print_cmdline_list): Likewise.
(cmdline_on_object_only_archive_list_p): Likewise.
(cmdline_object_only_list_append): Likewise.
(cmdline_get_object_only_input_files): Likewise.
(cmdline_arg): Likewise.
(setup_section): Likewise.
(copy_section): Likewise.
(cmdline_fopen_temp): Likewise.
(cmdline_add_object_only_section): Likewise.
(cmdline_emit_object_only_section): Likewise.
(cmdline_extract_object_only_section): Likewise.
(cmdline_check_object_only_section): Likewise.
(cmdline_remove_object_only_files): Likewise.
(lang_init): Take a bfd_boolean argument to supprt object-only
output. Call cmdline_lists_init.
(load_symbols): Call cmdline_on_object_only_archive_list_p
to check if an archive member should be loaded.
(lang_process): Handle object-only link.
* ldlang.h (lang_init): Take a bfd_boolean argument.
(cmdline_enum_type): New.
(cmdline_header_type): Likewise.
(cmdline_file_type): Likewise.
(cmdline_bfd_type): Likewise.
(cmdline_union_type): Likewise.
(cmdline_list_type): Likewise.
(cmdline_emit_object_only_section): Likewise.
(cmdline_check_object_only_section): Likewise.
(cmdline_remove_object_only_files): Likewise.
* ldmain.c (main): Call xatexit with
cmdline_remove_object_only_files. Pass FALSE to lang_init,
ldexp_init and ldexp_finish. Use ld_parse_linker_script.
Set link_info.output_bfd to NULL after close. Call
cmdline_emit_object_only_section if needed.
(add_archive_element): Call cmdline_check_object_only_section.
(ld_parse_linker_script): New.
* ldmain.h (ld_parse_linker_script): New.
* plugin.c (plugin_maybe_claim): Call
cmdline_check_object_only_section on claimed IR files.
* scripttempl/elf.sc: Also discard .gnu_object_only sections.
* scripttempl/elf64hppa.sc: Likewise.
* scripttempl/elfxtensa.sc: Likewise.
* scripttempl/mep.sc: Likewise.
* scripttempl/pe.sc: Likewise.
* scripttempl/pep.sc: Likewise.
* emultempl/aarch64elf.em (gld${EMULATION_NAME}_finish): Replace
finish_default with ldelf_finish.
* emultempl/alphaelf.em (alpha_finish): Likewise.
* emultempl/avrelf.em (avr_finish): Likewise.
* emultempl/elf.em (ld_${EMULATION_NAME}_emulation): Likewise.
* emultempl/ppc32elf.em (ppc_finish): Likewise.
* emultempl/ppc64elf.em (gld${EMULATION_NAME}_finish): Likewise.
* emultempl/spuelf.em (gld${EMULATION_NAME}_finish): Likewise.
* testsuite/ld-plugin/lto-10.out: New file.
* testsuite/ld-plugin/lto-10a.c: Likewise.
* testsuite/ld-plugin/lto-10b.c: Likewise.
* testsuite/ld-plugin/lto-10r.d: Likewise.
* testsuite/ld-plugin/lto-4.out: Likewise.
* testsuite/ld-plugin/lto-4a.c: Likewise.
* testsuite/ld-plugin/lto-4b.c: Likewise.
* testsuite/ld-plugin/lto-4c.c: Likewise.
* testsuite/ld-plugin/lto-4r-a.d: Likewise.
* testsuite/ld-plugin/lto-4r-b.d: Likewise.
* testsuite/ld-plugin/lto-4r-c.d: Likewise.
* testsuite/ld-plugin/lto-4r-d.d: Likewise.
* testsuite/ld-plugin/lto.exp (lto_link_tests): Prepare for
"LTO 4[acd]", "lto-4r-[abcd]" and "LTO 10" tests.
(lto_run_tests): Add "LTO 4[acd]" and "LTO 10" tests.
Build liblto-4.a. Run "lto-4r-[abcd]" tests.
Run lto-10r and create tmpdir/lto-10.o.
Add test for nm on mixed LTO/non-LTO object.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
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PR gas/32435
Commit 1f1b5e506bf0 ("bfd/ELF: restrict file alignment for object
files") caused an issue in the Linux kernels modpost utility, which was
building upon .rodata sections to be 4-byte aligned in the file when
they have 4-byte alignment. While we don't want to revert back to
original behavior, apply the same alignment "capping" as done originally
in two other places also for "ordinary" sections.
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Commit cb001c0d283d made code added in 64bfc2584c01 dead. Remove it.
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ar is supposed to make archives containing any sort of file, and it
generally does that. It also tries to make archives suited to target
object files stored. Some targets have peculiar archives.
In one particular case we get into trouble trying to suit archives to
object files: where the target object file is recognised but that
target doesn't happen to support archives, and the default target has
a special archive format. For example, we'll get failures on
rs6000-aix if trying to add tekhex objects to a new archive. What
happens in that the tekhex object is recognised and its target vector
used to create an empty archive, ie. with _bfd_generic_mkarchive and
_bfd_write_archive_contents. An attempt is then made to open the
newly created archive. The tekhex target vector does not have a
check_format function to recognise generic archives, nor as it happens
do any of the xcoff or other targets built for rs6000-aix.
It seems to me the simplest fix is to not use any target vector to
create archives where that vector can't also recognise them. That's
what this patch does, and to reinforce that I've removed target vector
support for creating empty archives from such targets.
bfd/
* i386msdos.c (i386_msdos_vec): Remove support for creating
empty archives.
* ihex.c (ihex_vec): Likewise.
* srec.c (srec_vec, symbolsrec_vec): Likewise.
* tekhex.c (tekhex_vec): Likewise.
* wasm-module.c (wasm_vec): Likewise.
* ptrace-core.c (core_ptrace_vec): Tidy.
* targets.c (bfd_target_supports_archives): New inline function.
* bfd-in2.h: Regenerate.
binutils/
* ar.c (open_inarch): Don't select a target from the first
object file that can't read archives. Set output_filename
earlier.
* testsuite/binutils-all/ar.exp (thin_archive_with_nested):
Don't repeat --thin test using T.
(foreign_object): New test.
* testsuite/binutils-all/tek1.obj,
* testsuite/binutils-all/tek2.obj: New files.
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Use the bfd's objalloc memory so we don't need to free anything
attached to elf_section_data sec_info. Other uses of sec_info that
need to allocate memory already use bfd_alloc.
* elf-eh-frame.c (_bfd_elf_parse_eh_frame): bfd_alloc sec_info.
* elf-sframe.c (_bfd_elf_parse_sframe): Likewise.
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This has been broken since commit 8f95b6e44955 in 2010, and apparently
nobody has noticed. How we write archive headers depends on the
archive, not the contents.
* libbfd-in.h (_bfd_write_ar_hdr): Correct.
* libbfd.h: Regenerate.
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My recent change to closing archives showed some problems with the way
we stash errors for archive elements. The most obvious thing found
by oss-fuzz, is that if output archive elements are closed during
bfd_close of an archive, then we can't access the element filename
when printing the element. So change bfd_set_input_error to stash the
entire error message instead of input bfd and input error.
* bfd.c (input_bfd, input_error): Delete.
(bfd_error, _bfd_error_buf): Move.
(_bfd_clear_error_data): Move. Make static. Clear bfd_error too.
(bfd_set_input_error): Print the error use bfd_asprintf here..
(bfd_errmsg): ..not here.
(bfd_init): Update.
* opncls.c (bfd_close_all_done): Don't call _bfd_clear_error_data.
* libbfd.h: Regenerate.
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* opncls.c (bfd_fill_in_gnu_debuglink_section): Free section
contents on success too.
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When cleaning up an archive, close all its elements. This fixes a
number of ar memory leaks.
bfd/
* archive.c (_bfd_archive_close_and_cleanup): Close elements
of an archive open for writing.
binutils/
* objcopy.c (copy_archive): Don't close output archive
elements here.
* dlltool.c (gen_lib_file): Likewise.
ld/
* pe-dll.c (pe_dll_generate_implib): Don't close output
archive elements here.
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The only reason to keep new_areldata around was for access to the
filename, but we now always take a copy in alloc'd memory.
* archive.c (_bfd_get_elt_at_filepos): Free new_areldata when
it is not attached to bfd.
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People, including me, had forgotten that the bfd_error_handler just
handled standard printf format strings, not MSC %I64 and suchlike.
Using PRIx64 and similar in errors does not work if the host compiler
headers define those formats as the Microsoft %I64 variety. (We
handled %ll OK, editing it to %I64 on such hosts.)
PR 32507
* bfd.c (_bfd_doprnt, _bfd_doprnt_scan): Handle %I64 and %I32
in input strings if the host defines PRId64 as "I64d".
Edit %ll to %I64 on detecting PRId64 as "I64d" rather than on
a preprocessor define.
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Reporting an internal loop index isn't helpful for the user to determine
which segment the problem is with. Report the PHDR index instead.
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For PDE, "recompiling with -fPIE" just makes no sense.
For PIE, "recompiling with -fPIE" makes sense for unresolvable absolute
relocs, but not unresolveable PC-relative relocs: if the reloc is
already PC-relative, the problem is not the reloc is PC-relative or
absolute, but the reloc is not applicable for external symbols.
If we hit an unresolvable reloc in PDE or an unresolvable PC-relative
reloc in PIE, it means the programmer has somehow wrongly instructed the
compiler to treat external symbols as local symbols. A misuse of
-mdirect-extern-access can cause the issue, so we can suggest
-mno-direct-extern-access. And in all cases (DSO/PIE/PDE) a mismatching
symbol visibility can also cause the issue, so we should also suggest to
check the visibility.
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
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weak symbols for static PIE
In a static PIE, undefined weak symbols should be just resolved to
runtime address 0, like those symbols with non-default visibility. This
was silently broken in all prior Binutils releases with "-static-pie
-mdirect-extern-access":
$ cat t.c
int x (void) __attribute__ ((weak));
int
main (void)
{
__builtin_printf("%p\n", x);
}
$ gcc t.c -static-pie -mdirect-extern-access
$ ./a.out
0x7ffff1d64000
Since commit 4cb77761d687 ("LoongArch: Check PC-relative relocations for
shared libraries), the situation has been improved: the linker errors
out instead of silently producing a wrong output file.
But logically, using -mdirect-extern-access for a static PIE perfectly
makes sense, and we should not prevent that even if the programmer uses
weak symbols. Linux kernel is such an example, and Linux < 6.10 now
fails to build with Binutils trunk. (The silent breakage with prior
Binutils releases was "benign" due to some blind luck.)
While since the 6.10 release Linux has removed those potentially
undefined weak symbols (due to performance issue), we still should
support weak symbols in -mdirect-extern-access -static-pie and unbreak
building old kernels.
Link: https://lore.kernel.org/loongarch/20241206085810.112341-1-chenhuacai@loongson.cn/
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
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An undefined weak hidden/protect symbol should be resolved to runtime
address 0, but we were actually resolving it to link-time address 0. So
in PIE or DSO the runtime address would be incorrect.
Fix the issue by rewriting pcalau12i to lu12i.w, and pcaddi to addi.w.
The latter does not always work because the immediate field of addi.w is
narrower, report an error in the case the addend is too large.
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
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This patch corrects layout for a PT_LOAD header that doesn't include
the ELF file header but does contain PHDRs and sections requiring
alignment. The required alignment (which was missing) is placed
before the PHDRs.
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