[PATCH v4] PR30592 objcopy: allow --set-section-flags to add or remove SHF_X86_64_LARGE
Fangrui Song
maskray@google.com
Sat Jul 8 05:30:35 GMT 2023
For example, objcopy --set-section-flags .data=alloc,large will add
SHF_X86_64_LARGE to the .data section. Omitting "large" will drop the
SHF_X86_64_LARGE flag.
The bfd_section flag is named generically, SEC_ELF_LARGE, in case other
processors want to follow SHF_X86_64_LARGE. SEC_ELF_LARGE has the same value
as SEC_TIC54X_CLINK and SEC_MEP_VLIW.
bfd/
* section.c: Define SEC_ELF_LARGE.
* bfd-in2.h: Regenerate.
* elf64-x86-64.c (elf_x86_64_section_flags, elf_x86_64_fake_sections,
elf_x86_64_copy_private_section_data): New.
binutils/
* NEWS: Mention the new feature for objcopy.
* doc/binutils.texi: Mention "large".
* objcopy.c (parse_flags): Parse "large".
(check_new_section_flags): Error if "large" is used with a
non-x86-64 ELF target.
* testsuite/binutils-all/x86-64/large-sections.d: New.
* testsuite/binutils-all/x86-64/large-sections.s: New.
* testsuite/binutils-all/x86-64/large-sections-i386.d: New.
* testsuite/binutils-all/x86-64/large-sections-2.d: New.
* testsuite/binutils-all/x86-64/large-sections-2-x32.d: New.
--
Changes from v1:
* Add an entry to binutils/NEWS
* Adjust doc/binutils.texi wording
* Guard a SEC_ELF_LARGE branch with EM_X86_64 check
Changes from v2:
* Address Jan's comments https://sourceware.org/pipermail/binutils/2023-July/128303.html
Changes from v3:
* Address Alan's comments. Define elf_x86_64_section_flags, elf_x86_64_fake_sections,
elf_x86_64_copy_private_section_data instead of adding x86-64 flags to generic code.
* Add an error when 'large' is used by other targets (e.g. EM_386,
EM_AARCH64).
---
bfd/bfd-in2.h | 3 ++
bfd/elf64-x86-64.c | 36 +++++++++++++++++++
bfd/section.c | 3 ++
binutils/NEWS | 3 ++
binutils/doc/binutils.texi | 15 ++++----
binutils/objcopy.c | 22 ++++++++++--
.../x86-64/large-sections-2-x32.d | 15 ++++++++
.../binutils-all/x86-64/large-sections-2.d | 15 ++++++++
.../binutils-all/x86-64/large-sections-i386.d | 6 ++++
.../binutils-all/x86-64/large-sections.d | 14 ++++++++
.../binutils-all/x86-64/large-sections.s | 8 +++++
11 files changed, 130 insertions(+), 10 deletions(-)
create mode 100644 binutils/testsuite/binutils-all/x86-64/large-sections-2-x32.d
create mode 100644 binutils/testsuite/binutils-all/x86-64/large-sections-2.d
create mode 100644 binutils/testsuite/binutils-all/x86-64/large-sections-i386.d
create mode 100644 binutils/testsuite/binutils-all/x86-64/large-sections.d
create mode 100644 binutils/testsuite/binutils-all/x86-64/large-sections.s
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index b34c8ef9fc9..1b9a801966c 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -625,6 +625,9 @@ typedef struct bfd_section
TMS320C54X only. */
#define SEC_TIC54X_BLOCK 0x10000000
+ /* This section has the SHF_X86_64_LARGE flag. This is ELF x86-64 only. */
+#define SEC_ELF_LARGE 0x10000000
+
/* Conditionally link this section; do not link if there are no
references found to any symbol in the section. This is for TI
TMS320C54X only. */
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index f926464d812..2d7092c42c0 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -5281,6 +5281,36 @@ elf_x86_64_merge_symbol (struct elf_link_hash_entry *h,
return true;
}
+static bool
+elf_x86_64_section_flags (const Elf_Internal_Shdr *hdr)
+{
+ if ((hdr->sh_flags & SHF_X86_64_LARGE) != 0)
+ hdr->bfd_section->flags |= SEC_ELF_LARGE;
+
+ return true;
+}
+
+static bool
+elf_x86_64_fake_sections (bfd *abfd ATTRIBUTE_UNUSED,
+ Elf_Internal_Shdr *hdr, asection *sec)
+{
+ if (sec->flags & SEC_ELF_LARGE)
+ hdr->sh_flags |= SHF_X86_64_LARGE;
+
+ return true;
+}
+
+static bool
+elf_x86_64_copy_private_section_data (bfd *ibfd ATTRIBUTE_UNUSED,
+ asection *isec,
+ bfd *obfd ATTRIBUTE_UNUSED,
+ asection *osec) {
+ /* objcopy --set-section-flags without "large" drops SHF_X86_64_LARGE. */
+ elf_section_flags (osec) = (elf_section_flags (isec) & ~SHF_X86_64_LARGE);
+
+ return true;
+}
+
static int
elf_x86_64_additional_program_headers (bfd *abfd,
struct bfd_link_info *info ATTRIBUTE_UNUSED)
@@ -5408,6 +5438,8 @@ elf_x86_64_special_sections[]=
#define elf_info_to_howto elf_x86_64_info_to_howto
+#define bfd_elf64_bfd_copy_private_section_data \
+ elf_x86_64_copy_private_section_data
#define bfd_elf64_bfd_reloc_type_lookup elf_x86_64_reloc_type_lookup
#define bfd_elf64_bfd_reloc_name_lookup \
elf_x86_64_reloc_name_lookup
@@ -5448,6 +5480,8 @@ elf_x86_64_special_sections[]=
elf_x86_64_merge_symbol
#define elf_backend_special_sections \
elf_x86_64_special_sections
+#define elf_backend_section_flags elf_x86_64_section_flags
+#define elf_backend_fake_sections elf_x86_64_fake_sections
#define elf_backend_additional_program_headers \
elf_x86_64_additional_program_headers
#define elf_backend_setup_gnu_properties \
@@ -5564,6 +5598,8 @@ elf64_x86_64_copy_solaris_special_section_fields (const bfd *ibfd ATTRIBUTE_UNUS
#undef ELF_TARGET_OS
#undef ELF_OSABI
+#define bfd_elf32_bfd_copy_private_section_data \
+ elf_x86_64_copy_private_section_data
#define bfd_elf32_bfd_reloc_type_lookup \
elf_x86_64_reloc_type_lookup
#define bfd_elf32_bfd_reloc_name_lookup \
diff --git a/bfd/section.c b/bfd/section.c
index 73770294e56..e9af59dfd15 100644
--- a/bfd/section.c
+++ b/bfd/section.c
@@ -359,6 +359,9 @@ CODE_FRAGMENT
. TMS320C54X only. *}
.#define SEC_TIC54X_BLOCK 0x10000000
.
+. {* This section has the SHF_X86_64_LARGE flag. This is ELF x86-64 only. *}
+.#define SEC_ELF_LARGE 0x10000000
+.
. {* Conditionally link this section; do not link if there are no
. references found to any symbol in the section. This is for TI
. TMS320C54X only. *}
diff --git a/binutils/NEWS b/binutils/NEWS
index 563062c6904..cad877b943a 100644
--- a/binutils/NEWS
+++ b/binutils/NEWS
@@ -1,5 +1,8 @@
-*- text -*-
+* objcopy's --set-section-flags now support "large" to set SHF_X86_64_LARGE
+ for ELF x86-64 objects.
+
Changes in 2.41:
* The MIPS port now supports the Sony Interactive Entertainment Allegrex
diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi
index 8314cb57562..309bedf6110 100644
--- a/binutils/doc/binutils.texi
+++ b/binutils/doc/binutils.texi
@@ -1745,13 +1745,14 @@ Set the flags for any sections matching @var{sectionpattern}. The
@var{flags} argument is a comma separated string of flag names. The
recognized names are @samp{alloc}, @samp{contents}, @samp{load},
@samp{noload}, @samp{readonly}, @samp{code}, @samp{data}, @samp{rom},
-@samp{exclude}, @samp{share}, and @samp{debug}. You can set the
-@samp{contents} flag for a section which does not have contents, but it
-is not meaningful to clear the @samp{contents} flag of a section which
-does have contents--just remove the section instead. Not all flags are
-meaningful for all object file formats. In particular the
-@samp{share} flag is only meaningful for COFF format files and not for
-ELF format files.
+@samp{exclude}, @samp{share}, @samp{debug}, and @samp{large}.
+You can set the @samp{contents} flag for a section which does not have
+contents, but it is not meaningful to clear the @samp{contents} flag of a
+section which does have contents--just remove the section instead. Not all
+flags are meaningful for all object file formats. In particular the
+@samp{share} flag is only meaningful for COFF format files and not for ELF
+format files. The ELF x86-64 specific flag @samp{large} corresponds to
+SHF_X86_64_LARGE.
@item --set-section-alignment @var{sectionpattern}=@var{align}
Set the alignment for any sections matching @var{sectionpattern}.
diff --git a/binutils/objcopy.c b/binutils/objcopy.c
index 3569b890c7d..c931f67a224 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -803,6 +803,7 @@ parse_flags (const char *s)
PARSE_FLAG ("contents", SEC_HAS_CONTENTS);
PARSE_FLAG ("merge", SEC_MERGE);
PARSE_FLAG ("strings", SEC_STRINGS);
+ PARSE_FLAG ("large", SEC_ELF_LARGE);
#undef PARSE_FLAG
else
{
@@ -812,8 +813,10 @@ parse_flags (const char *s)
strncpy (copy, s, len);
copy[len] = '\0';
non_fatal (_("unrecognized section flag `%s'"), copy);
- fatal (_("supported flags: %s"),
- "alloc, load, noload, readonly, debug, code, data, rom, exclude, share, contents, merge, strings");
+ fatal (_ ("supported flags: %s"),
+ "alloc, load, noload, readonly, debug, code, data, rom, "
+ "exclude, contents, merge, strings, (COFF specific) share, "
+ "(ELF x86-64 specific) large");
}
s = snext;
@@ -2618,7 +2621,7 @@ merge_gnu_build_notes (bfd * abfd,
}
static flagword
-check_new_section_flags (flagword flags, bfd * abfd, const char * secname)
+check_new_section_flags (flagword flags, bfd *abfd, const char * secname)
{
/* Only set the SEC_COFF_SHARED flag on COFF files.
The same bit value is used by ELF targets to indicate
@@ -2631,6 +2634,19 @@ check_new_section_flags (flagword flags, bfd * abfd, const char * secname)
bfd_get_filename (abfd), secname);
flags &= ~ SEC_COFF_SHARED;
}
+
+ /* Report a fatal error if 'large' is used with a non-x86-64 ELF target.
+ Suppress the error for non-ELF targets to allow -O binary and formats that
+ use the bit value SEC_ELF_LARGE for other purposes. */
+ if ((flags & SEC_ELF_LARGE) != 0
+ && bfd_get_flavour (abfd) == bfd_target_elf_flavour
+ && get_elf_backend_data (abfd)->elf_machine_code != EM_X86_64)
+ {
+ fatal (_ ("%s[%s]: 'large' flag is ELF x86-64 specific"),
+ bfd_get_filename (abfd), secname);
+ flags &= ~SEC_ELF_LARGE;
+ }
+
return flags;
}
diff --git a/binutils/testsuite/binutils-all/x86-64/large-sections-2-x32.d b/binutils/testsuite/binutils-all/x86-64/large-sections-2-x32.d
new file mode 100644
index 00000000000..fb28d08e6b7
--- /dev/null
+++ b/binutils/testsuite/binutils-all/x86-64/large-sections-2-x32.d
@@ -0,0 +1,15 @@
+#source: large-sections.s
+#PROG: objcopy
+#as: --x32
+#objcopy: --set-section-flags .ldata=alloc
+#readelf: -S -W
+
+#...
+ \[[ 0-9]+\] \.text.*[ \t]+PROGBITS[ \t0-9a-f]+AX[ \t]+.*
+#...
+ \[[ 0-9]+\] \.data.*[ \t]+PROGBITS[ \t0-9a-f]+WA[ \t]+.*
+#...
+ \[[ 0-9]+\] \.ltext.*[ \t]+PROGBITS[ \t0-9a-f]+AXl[ \t]+.*
+#...
+ \[[ 0-9]+\] \.ldata.*[ \t]+PROGBITS[ \t0-9a-f]+WA[ \t]+.*
+#pass
diff --git a/binutils/testsuite/binutils-all/x86-64/large-sections-2.d b/binutils/testsuite/binutils-all/x86-64/large-sections-2.d
new file mode 100644
index 00000000000..29ace42cc9e
--- /dev/null
+++ b/binutils/testsuite/binutils-all/x86-64/large-sections-2.d
@@ -0,0 +1,15 @@
+#source: large-sections.s
+#PROG: objcopy
+#as: --64
+#objcopy: --set-section-flags .ldata=alloc
+#readelf: -S -W
+
+#...
+ \[[ 0-9]+\] \.text.*[ \t]+PROGBITS[ \t0-9a-f]+AX[ \t]+.*
+#...
+ \[[ 0-9]+\] \.data.*[ \t]+PROGBITS[ \t0-9a-f]+WA[ \t]+.*
+#...
+ \[[ 0-9]+\] \.ltext.*[ \t]+PROGBITS[ \t0-9a-f]+AXl[ \t]+.*
+#...
+ \[[ 0-9]+\] \.ldata.*[ \t]+PROGBITS[ \t0-9a-f]+WA[ \t]+.*
+#pass
diff --git a/binutils/testsuite/binutils-all/x86-64/large-sections-i386.d b/binutils/testsuite/binutils-all/x86-64/large-sections-i386.d
new file mode 100644
index 00000000000..b06c7c993c2
--- /dev/null
+++ b/binutils/testsuite/binutils-all/x86-64/large-sections-i386.d
@@ -0,0 +1,6 @@
+#source: large-sections.s
+#PROG: objcopy
+#as: --64
+#objcopy: -O elf32-i386 --set-section-flags .data=alloc,large
+#target: x86_64-*-linux*
+#error: \A[^[]*\[.data\]: 'large' flag is ELF x86-64 specific
diff --git a/binutils/testsuite/binutils-all/x86-64/large-sections.d b/binutils/testsuite/binutils-all/x86-64/large-sections.d
new file mode 100644
index 00000000000..5d945e46ba3
--- /dev/null
+++ b/binutils/testsuite/binutils-all/x86-64/large-sections.d
@@ -0,0 +1,14 @@
+#PROG: objcopy
+#as: --64
+#objcopy: --set-section-flags .text=alloc,readonly,code,large --set-section-flags .data=alloc,large
+#readelf: -S -W
+
+#...
+ \[[ 0-9]+\] \.text.*[ \t]+PROGBITS[ \t0-9a-f]+AXl[ \t]+.*
+#...
+ \[[ 0-9]+\] \.data.*[ \t]+PROGBITS[ \t0-9a-f]+WAl[ \t]+.*
+#...
+ \[[ 0-9]+\] \.ltext.*[ \t]+PROGBITS[ \t0-9a-f]+AXl[ \t]+.*
+#...
+ \[[ 0-9]+\] \.ldata.*[ \t]+PROGBITS[ \t0-9a-f]+WAl[ \t]+.*
+#pass
diff --git a/binutils/testsuite/binutils-all/x86-64/large-sections.s b/binutils/testsuite/binutils-all/x86-64/large-sections.s
new file mode 100644
index 00000000000..072e456a1ed
--- /dev/null
+++ b/binutils/testsuite/binutils-all/x86-64/large-sections.s
@@ -0,0 +1,8 @@
+ .section .text, "ax"
+ nop
+ .section .data, "aw"
+ .byte 1
+ .section .ltext, "axl"
+ nop
+ .section .ldata, "awl"
+ .byte 1
--
2.41.0.255.g8b1d071c50-goog
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