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[PATCH] Support .gnu.lto_.lto section in ELF files (PR 24768).
- From: Martin Liška <mliska at suse dot cz>
- To: binutils at sourceware dot org
- Cc: amodra at gmail dot com
- Date: Mon, 22 Jul 2019 16:01:15 +0200
- Subject: [PATCH] Support .gnu.lto_.lto section in ELF files (PR 24768).
Hi.
The patch adds detection of a new LTO ELF section that will eventually
replace presence of the __gnu_lto_slim symbol detection. So, first I would
like to teach binutils about the section and later then (after some years),
detection based on __gnu_lto_slim symbol can be removed.
Ready for trunk?
Thanks,
Martin
bfd/ChangeLog:
2019-07-22 Martin Liska <mliska@suse.cz>
PR 24768
* archive.c (_bfd_compute_and_write_armap): Come up with
report_plugin_err variable.
* bfd-in2.h (struct bfd): Add lto_slim_object flag.
* elf.c (struct lto_section): New.
(_bfd_elf_make_section_from_shdr): Parse content of
.gnu_lto_.lto section.
* elflink.c: Report error for a missing LTO plugin.
* linker.c (_bfd_generic_link_add_one_symbol): Likewise.
binutils/ChangeLog:
2019-07-22 Martin Liska <mliska@suse.cz>
PR 24768
* nm.c (filter_symbols): Set report_plugin_err if
error is reported.
(display_rel_file): Report error for a missing LTO plugin.
gold/ChangeLog:
2019-07-22 Martin Liska <mliska@suse.cz>
PR 24768
* layout.h (class Layout): Add is_lto_slim_object and
set_lto_slim_object.
* object.cc (struct lto_section): Add lto_slim_object_.
(big_endian>::do_layout): Parse content of
.gnu_lto_.lto section.
(big_endian>::do_add_symbols): Report error for a missing
LTO plugin.
---
bfd/archive.c | 21 +++++++++++++++++----
bfd/bfd-in2.h | 3 +++
bfd/elf.c | 23 +++++++++++++++++++++++
bfd/elflink.c | 6 ++++++
bfd/linker.c | 24 ++++++++++++++++++------
binutils/nm.c | 23 ++++++++++++++++++++---
gold/layout.h | 10 ++++++++++
gold/object.cc | 31 ++++++++++++++++++++++++++++++-
8 files changed, 127 insertions(+), 14 deletions(-)
diff --git a/bfd/archive.c b/bfd/archive.c
index 68a92a3e36..0a7da3a0cb 100644
--- a/bfd/archive.c
+++ b/bfd/archive.c
@@ -2236,6 +2236,7 @@ _bfd_compute_and_write_armap (bfd *arch, unsigned int elength)
long syms_max = 0;
bfd_boolean ret;
bfd_size_type amt;
+ static bfd_boolean report_plugin_err = TRUE;
/* Dunno if this is the best place for this info... */
if (elength != 0)
@@ -2270,6 +2271,14 @@ _bfd_compute_and_write_armap (bfd *arch, unsigned int elength)
long symcount;
long src_count;
+ if (current->lto_slim_object && report_plugin_err)
+ {
+ report_plugin_err = FALSE;
+ _bfd_error_handler
+ (_("%pB: plugin needed to handle lto object"),
+ current);
+ }
+
storage = bfd_get_symtab_upper_bound (current);
if (storage < 0)
goto error_return;
@@ -2322,10 +2331,14 @@ _bfd_compute_and_write_armap (bfd *arch, unsigned int elength)
&& syms[src_count]->name[1] == '_'
&& strcmp (syms[src_count]->name
+ (syms[src_count]->name[2] == '_'),
- "__gnu_lto_slim") == 0)
- _bfd_error_handler
- (_("%pB: plugin needed to handle lto object"),
- current);
+ "__gnu_lto_slim") == 0
+ && report_plugin_err)
+ {
+ report_plugin_err = FALSE;
+ _bfd_error_handler
+ (_("%pB: plugin needed to handle lto object"),
+ current);
+ }
namelen = strlen (syms[src_count]->name);
amt = sizeof (char *);
map[orl_count].name = (char **) bfd_alloc (arch, amt);
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index 8374390e60..7e6dad78d4 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -7196,6 +7196,9 @@ struct bfd
/* Set if this is a plugin output file. */
unsigned int lto_output : 1;
+ /* Set if this is a slim LTO object not loaded with a compiler plugin. */
+ unsigned int lto_slim_object: 1;
+
/* Set to dummy BFD created when claimed by a compiler plug-in
library. */
bfd *plugin_dummy_bfd;
diff --git a/bfd/elf.c b/bfd/elf.c
index 265150d511..bb35db54ed 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -999,6 +999,18 @@ convert_zdebug_to_debug (bfd *abfd, const char *name)
return new_name;
}
+/* This a copy of lto_section defined in GCC (lto-streamer.h). */
+
+struct lto_section
+{
+ int16_t major_version;
+ int16_t minor_version;
+ unsigned char slim_object;
+
+ /* Flags is a private field that is not defined publicly. */
+ uint16_t flags;
+};
+
/* Make a BFD section from an ELF section. We store a pointer to the
BFD section in the bfd_section field of the header. */
@@ -1262,6 +1274,17 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
newsect->flags |= SEC_ELF_RENAME;
}
+ /* GCC uses .gnu.lto_.lto.<some_hash> as a LTO bytecode information
+ section. */
+ const char *lto_section_name = ".gnu.lto_.lto.";
+ if (strncmp (name, lto_section_name, strlen (lto_section_name)) == 0)
+ {
+ struct lto_section lsection;
+ if (bfd_get_section_contents (abfd, newsect, &lsection, 0,
+ sizeof (struct lto_section)))
+ abfd->lto_slim_object = lsection.slim_object;
+ }
+
return TRUE;
}
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 9175d3fa20..1c5eae143a 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -4401,6 +4401,12 @@ error_free_dyn:
goto error_free_vers;
}
+ if (abfd->lto_slim_object)
+ {
+ _bfd_error_handler
+ (_("%pB: plugin needed to handle lto object"), abfd);
+ }
+
for (isym = isymbuf, isymend = isymbuf + extsymcount;
isym < isymend;
isym++, sym_hash++, ever = (ever != NULL ? ever + 1 : NULL))
diff --git a/bfd/linker.c b/bfd/linker.c
index 1b71fcf8f0..edbd0a7df4 100644
--- a/bfd/linker.c
+++ b/bfd/linker.c
@@ -1421,12 +1421,24 @@ _bfd_generic_link_add_one_symbol (struct bfd_link_info *info,
else if (bfd_is_com_section (section))
{
row = COMMON_ROW;
- if (!bfd_link_relocatable (info)
- && name[0] == '_'
- && name[1] == '_'
- && strcmp (name + (name[2] == '_'), "__gnu_lto_slim") == 0)
- _bfd_error_handler
- (_("%pB: plugin needed to handle lto object"), abfd);
+ static bfd_boolean report_plugin_err = TRUE;
+ if (!bfd_link_relocatable (info) && report_plugin_err)
+ {
+ if (abfd->lto_slim_object)
+ {
+ report_plugin_err = FALSE;
+ _bfd_error_handler
+ (_("%pB: plugin needed to handle lto object"), abfd);
+ }
+ else if (name[0] == '_'
+ && name[1] == '_'
+ && strcmp (name + (name[2] == '_'), "__gnu_lto_slim") == 0)
+ {
+ report_plugin_err = FALSE;
+ _bfd_error_handler
+ (_("%pB: plugin needed to handle lto object"), abfd);
+ }
+ }
}
else
row = DEF_ROW;
diff --git a/binutils/nm.c b/binutils/nm.c
index fd3f73167e..5d3d647843 100644
--- a/binutils/nm.c
+++ b/binutils/nm.c
@@ -438,6 +438,10 @@ print_symdef_entry (bfd *abfd)
}
}
+
+/* True when we can report missing plugin error. */
+bfd_boolean report_plugin_err = TRUE;
+
/* Choose which symbol entries to print;
compact them downward to get rid of the rest.
Return the number of symbols to be printed. */
@@ -470,9 +474,13 @@ filter_symbols (bfd *abfd, bfd_boolean is_dynamic, void *minisyms,
if (sym->name[0] == '_'
&& sym->name[1] == '_'
- && strcmp (sym->name + (sym->name[2] == '_'), "__gnu_lto_slim") == 0)
- non_fatal (_("%s: plugin needed to handle lto object"),
- bfd_get_filename (abfd));
+ && strcmp (sym->name + (sym->name[2] == '_'), "__gnu_lto_slim") == 0
+ && report_plugin_err)
+ {
+ report_plugin_err = FALSE;
+ non_fatal (_("%s: plugin needed to handle lto object"),
+ bfd_get_filename (abfd));
+ }
if (undefined_only)
keep = bfd_is_und_section (sym->section);
@@ -1164,6 +1172,15 @@ display_rel_file (bfd *abfd, bfd *archive_bfd)
}
}
+ /* lto_slim_object is set to false when a bfd is loaded with a compiler
+ LTO plugin. */
+ if (abfd->lto_slim_object)
+ {
+ report_plugin_err = FALSE;
+ non_fatal (_("%s: plugin needed to handle lto object"),
+ bfd_get_filename (abfd));
+ }
+
/* Discard the symbols we don't want to print.
It's OK to do this in place; we'll free the storage anyway
(after printing). */
diff --git a/gold/layout.h b/gold/layout.h
index bfd44e1307..b9b75816e8 100644
--- a/gold/layout.h
+++ b/gold/layout.h
@@ -593,6 +593,14 @@ class Layout
set_unique_segment_for_sections_specified()
{ this->unique_segment_for_sections_specified_ = true; }
+ bool
+ is_lto_slim_object () const
+ { return this->lto_slim_object_; }
+
+ void
+ set_lto_slim_object ()
+ { this->lto_slim_object_ = true; }
+
// For incremental updates, allocate a block of memory from the
// free list. Find a block starting at or after MINOFF.
off_t
@@ -1480,6 +1488,8 @@ class Layout
Incremental_inputs* incremental_inputs_;
// Whether we record output section data created in script
bool record_output_section_data_from_script_;
+ // Set if this is a slim LTO object not loaded with a compiler plugin
+ bool lto_slim_object_;
// List of output data that needs to be removed at relaxation clean up.
Output_section_data_list script_output_section_data_list_;
// Structure to save segment states before entering the relaxation loop.
diff --git a/gold/object.cc b/gold/object.cc
index 689448f50c..86c519acf7 100644
--- a/gold/object.cc
+++ b/gold/object.cc
@@ -1380,6 +1380,18 @@ Sized_relobj_file<size, big_endian>::layout_gnu_property_section(
}
}
+// This a copy of lto_section defined in GCC (lto-streamer.h)
+
+struct lto_section
+{
+ int16_t major_version;
+ int16_t minor_version;
+ unsigned char slim_object;
+
+ /* Flags is a private field that is not defined publicly. */
+ uint16_t flags;
+};
+
// Lay out the input sections. We walk through the sections and check
// whether they should be included in the link. If they should, we
// pass them to the Layout object, which will return an output section
@@ -1865,6 +1877,19 @@ Sized_relobj_file<size, big_endian>::do_layout(Symbol_table* symtab,
debug_types_sections.push_back(i);
}
}
+
+ /* GCC uses .gnu.lto_.lto.<some_hash> as a LTO bytecode information
+ section. */
+ const char *lto_section_name = ".gnu.lto_.lto.";
+ if (strncmp (name, lto_section_name, strlen (lto_section_name)) == 0)
+ {
+ section_size_type contents_len;
+ const unsigned char* pcontents = this->section_contents(i, &contents_len, false);
+ struct lto_section lsection = *(const lto_section*)pcontents;
+ if (lsection.slim_object)
+ gold_info(_("%s: plugin needed to handle lto object"),
+ this->name().c_str());
+ }
}
if (!is_pass_two)
@@ -2083,7 +2108,7 @@ template<int size, bool big_endian>
void
Sized_relobj_file<size, big_endian>::do_add_symbols(Symbol_table* symtab,
Read_symbols_data* sd,
- Layout*)
+ Layout* layout)
{
if (sd->symbols == NULL)
{
@@ -2102,6 +2127,10 @@ Sized_relobj_file<size, big_endian>::do_add_symbols(Symbol_table* symtab,
this->symbols_.resize(symcount);
+ if (layout->is_lto_slim_object ())
+ gold_info(_("%s: plugin needed to handle lto object"),
+ this->name().c_str());
+
const char* sym_names =
reinterpret_cast<const char*>(sd->symbol_names->data());
symtab->add_from_relobj(this,