From: Fangrui Song <maskray@google.com>
To: binutils@sourceware.org
Cc: Fangrui Song <maskray@google.com>
Subject: [PATCH] PR30592 objcopy: allow --set-section-flags to add or remove SHF_X86_64_LARGE
Date: Tue, 27 Jun 2023 18:06:34 -0700 [thread overview]
Message-ID: <20230628010634.1147958-1-maskray@google.com> (raw)
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.
bfd/
* bfd-in2.h: Define SEC_ELF_LARGE.
* elf.c (_bfd_elf_make_section_from_shdr): Check SHF_X86_64_LARGE.
(elf_fake_sections): Check SEC_ELF_LARGE.
(_bfd_elf_init_private_section_data): Drop SHF_X86_64_LARGE for
x86-64.
binutils/
* doc/binutils.texi: Mention "large".
* objcopy.c (parse_flags): Parse "large".
* 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-2.d: New.
* testsuite/binutils-all/x86-64/large-sections-2.s: New.
include/
* elf/common.h: Define SHF_X86_64_LARGE to be used by elf.c.
---
bfd/bfd-in2.h | 3 +++
bfd/elf.c | 9 +++++++++
binutils/doc/binutils.texi | 15 ++++++++-------
binutils/objcopy.c | 3 ++-
.../binutils-all/x86-64/large-sections-2.d | 15 +++++++++++++++
.../binutils-all/x86-64/large-sections-2.s | 4 ++++
.../binutils-all/x86-64/large-sections.d | 14 ++++++++++++++
.../binutils-all/x86-64/large-sections.s | 8 ++++++++
include/elf/common.h | 2 ++
9 files changed, 65 insertions(+), 8 deletions(-)
create mode 100644 binutils/testsuite/binutils-all/x86-64/large-sections-2.d
create mode 100644 binutils/testsuite/binutils-all/x86-64/large-sections-2.s
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 7399fb0fa60..2507716899c 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -633,6 +633,9 @@ typedef struct bfd_section
/* This section contains vliw code. This is for Toshiba MeP only. */
#define SEC_MEP_VLIW 0x20000000
+ /* This section has the SHF_X86_64_LARGE flag. This is ELF x86-64 only. */
+#define SEC_ELF_LARGE 0x20000000
+
/* All symbols, sizes and relocations in this section are octets
instead of bytes. Required for DWARF debug sections as DWARF
information is organized in octets, not bytes. */
diff --git a/bfd/elf.c b/bfd/elf.c
index 8f6d7d1adba..d6e21b11419 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -1034,6 +1034,10 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
if ((hdr->sh_flags & SHF_EXCLUDE) != 0)
flags |= SEC_EXCLUDE;
+ if (get_elf_backend_data (abfd)->elf_machine_code == EM_X86_64)
+ if ((hdr->sh_flags & SHF_X86_64_LARGE) != 0)
+ flags |= SEC_ELF_LARGE;
+
switch (elf_elfheader (abfd)->e_ident[EI_OSABI])
{
/* FIXME: We should not recognize SHF_GNU_MBIND for ELFOSABI_NONE,
@@ -3351,6 +3355,8 @@ elf_fake_sections (bfd *abfd, asection *asect, void *fsarg)
}
if ((asect->flags & (SEC_GROUP | SEC_EXCLUDE)) == SEC_EXCLUDE)
this_hdr->sh_flags |= SHF_EXCLUDE;
+ if (asect->flags & SEC_ELF_LARGE)
+ this_hdr->sh_flags |= SHF_X86_64_LARGE;
/* If the section has relocs, set up a section header for the
SHT_REL[A] section. If two relocation sections are required for
@@ -7940,6 +7946,9 @@ _bfd_elf_init_private_section_data (bfd *ibfd,
elf_section_flags (osec) = (elf_section_flags (isec)
& (SHF_MASKOS | SHF_MASKPROC));
+ if (get_elf_backend_data (ibfd)->elf_machine_code == EM_X86_64)
+ elf_section_flags (osec) = (elf_section_flags (isec) & ~SHF_X86_64_LARGE);
+
/* Copy sh_info from input for mbind section. */
if ((elf_tdata (ibfd)->has_gnu_osabi & elf_gnu_osabi_mbind) != 0
&& elf_section_flags (isec) & SHF_GNU_MBIND)
diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi
index 8c14d1121d9..4dd7b83aaa6 100644
--- a/binutils/doc/binutils.texi
+++ b/binutils/doc/binutils.texi
@@ -1740,13 +1740,14 @@ 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. @samp{large} is an ELF x86-64 specific flag that 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 414007780a8..40496f8f792 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -797,6 +797,7 @@ 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
{
@@ -807,7 +808,7 @@ parse_flags (const char *s)
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");
+ "alloc, load, noload, readonly, debug, code, data, rom, exclude, share, contents, merge, strings, large");
}
s = snext;
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-2.s b/binutils/testsuite/binutils-all/x86-64/large-sections-2.s
new file mode 100644
index 00000000000..6f31aa93701
--- /dev/null
+++ b/binutils/testsuite/binutils-all/x86-64/large-sections-2.s
@@ -0,0 +1,4 @@
+ .section .text, "axl"
+ nop
+ .section .data, "awl"
+ .byte 1
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
diff --git a/include/elf/common.h b/include/elf/common.h
index ffa6b60bd2b..1397d60402e 100644
--- a/include/elf/common.h
+++ b/include/elf/common.h
@@ -588,6 +588,8 @@
#define SHF_GNU_MBIND 0x01000000 /* Mbind section. */
+#define SHF_X86_64_LARGE 0x10000000
+
/* Compression types. */
#define ELFCOMPRESS_ZLIB 1 /* Compressed with zlib. */
#define ELFCOMPRESS_ZSTD 2 /* Compressed with zstd */
--
2.41.0.162.gfafddb0af9-goog
next reply other threads:[~2023-06-28 1:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-28 1:06 Fangrui Song [this message]
2023-06-28 7:29 ` Andreas Schwab
2023-06-28 23:17 ` Fangrui Song
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230628010634.1147958-1-maskray@google.com \
--to=maskray@google.com \
--cc=binutils@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).