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Commit: Add note merging to strip, and add merging of stack size notes
- From: Nick Clifton <nickc at redhat dot com>
- To: binutils at sourceware dot org
- Date: Thu, 13 Apr 2017 14:50:40 +0100
- Subject: Commit: Add note merging to strip, and add merging of stack size notes
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Hi Guys,
I am applying the attached patch to add the note merging ability to
the strip program, and to enhance the merging by adding support for
combining stack size notes.
Cheers
Nick
binutils/ChangeLog
2017-04-13 Nick Clifton <nickc@redhat.com>
* objcopy.c: Add --no-merge-notes option to disable note merging.
Add --[no-]merge-notes option to strip, and enable it by default.
(num_bytes): New function.
(merge_gnu_build_notes): Add code to merge stack size notes.
* binutils.texi: Update strip and objcopy documentation.
* readelf.c (print_gnu_build_attribute_name): Use defined
constants for note types.
diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi
index da4ed52..23d8685 100644
--- a/binutils/doc/binutils.texi
+++ b/binutils/doc/binutils.texi
@@ -1191,6 +1191,7 @@ objcopy [@option{-F} @var{bfdname}|@option{--target=}@var{bfdname}]
[@option{--decompress-debug-sections}]
[@option{--elf-stt-common=@var{val}}]
[@option{--merge-notes}]
+ [@option{--no-merge-notes}]
[@option{-v}|@option{--verbose}]
[@option{-V}|@option{--version}]
[@option{--help}] [@option{--info}]
@@ -2008,8 +2009,9 @@ converted to the @code{STT_COMMON} or @code{STT_OBJECT} type.
type to @code{STT_OBJECT}.
@item --merge-notes
-For ELF files, attempt to reduce the size of any SHT_NOTE type
-sections by removing duplicate notes.
+@itemx --no-merge-notes
+For ELF files, attempt (or do not attempt) to reduce the size of any
+SHT_NOTE type sections by removing duplicate notes.
@item -V
@itemx --version
@@ -3114,7 +3116,8 @@ strip [@option{-F} @var{bfdname} |@option{--target=}@var{bfdname}]
[@option{-s}|@option{--strip-all}]
[@option{-S}|@option{-g}|@option{-d}|@option{--strip-debug}]
[@option{--strip-dwo}]
- [@option{-K} @var{symbolname} |@option{--keep-symbol=}@var{symbolname}]
+ [@option{-K} @var{symbolname}|@option{--keep-symbol=}@var{symbolname}]
+ [@option{-M}|@option{--merge-notes}][@option{--no-merge-notes}]
[@option{-N} @var{symbolname} |@option{--strip-symbol=}@var{symbolname}]
[@option{-w}|@option{--wildcard}]
[@option{-x}|@option{--discard-all}] [@option{-X} |@option{--discard-locals}]
@@ -3241,6 +3244,13 @@ Remove all symbols that are not needed for relocation processing.
When stripping symbols, keep symbol @var{symbolname} even if it would
normally be stripped. This option may be given more than once.
+@item -M
+@itemx --merge-notes
+@itemx --no-merge-notes
+For ELF files, attempt (or do not attempt) to reduce the size of any
+SHT_NOTE type sections by removing duplicate notes. The default is to
+attempt this reduction.
+
@item -N @var{symbolname}
@itemx --strip-symbol=@var{symbolname}
Remove symbol @var{symbolname} from the source file. This option may be
diff --git a/binutils/objcopy.c b/binutils/objcopy.c
index f9fe06b..9bad4b7 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -321,6 +321,7 @@ enum command_line_switch
OPTION_LOCALIZE_SYMBOLS,
OPTION_LONG_SECTION_NAMES,
OPTION_MERGE_NOTES,
+ OPTION_NO_MERGE_NOTES,
OPTION_NO_CHANGE_WARNINGS,
OPTION_ONLY_KEEP_DEBUG,
OPTION_PAD_TO,
@@ -368,6 +369,8 @@ static struct option strip_options[] =
{"input-target", required_argument, 0, 'I'},
{"keep-file-symbols", no_argument, 0, OPTION_KEEP_FILE_SYMBOLS},
{"keep-symbol", required_argument, 0, 'K'},
+ {"merge-notes", no_argument, 0, 'M'},
+ {"no-merge-notes", no_argument, 0, OPTION_NO_MERGE_NOTES},
{"only-keep-debug", no_argument, 0, OPTION_ONLY_KEEP_DEBUG},
{"output-file", required_argument, 0, 'o'},
{"output-format", required_argument, 0, 'O'}, /* Obsolete */
@@ -443,6 +446,7 @@ static struct option copy_options[] =
{"localize-symbols", required_argument, 0, OPTION_LOCALIZE_SYMBOLS},
{"long-section-names", required_argument, 0, OPTION_LONG_SECTION_NAMES},
{"merge-notes", no_argument, 0, 'M'},
+ {"no-merge-notes", no_argument, 0, OPTION_NO_MERGE_NOTES},
{"no-adjust-warnings", no_argument, 0, OPTION_NO_CHANGE_WARNINGS},
{"no-change-warnings", no_argument, 0, OPTION_NO_CHANGE_WARNINGS},
{"only-keep-debug", no_argument, 0, OPTION_ONLY_KEEP_DEBUG},
@@ -642,6 +646,7 @@ copy_usage (FILE *stream, int exit_status)
--elf-stt-common=[yes|no] Generate ELF common symbols with STT_COMMON\n\
type\n\
-M --merge-notes Remove redundant entries in note sections\n\
+ --no-merge-notes Do not attempt to remove redundant notes (default)\n\
-v --verbose List all object files modified\n\
@<file> Read options from <file>\n\
-V --version Display this program's version number\n\
@@ -686,6 +691,8 @@ strip_usage (FILE *stream, int exit_status)
--strip-dwo Remove all DWO sections\n\
--strip-unneeded Remove all symbols not needed by relocations\n\
--only-keep-debug Strip everything but the debug information\n\
+ -M --merge-notes Remove redundant entries in note sections (default)\n\
+ --no-merge-notes Do not attempt to remove redundant notes\n\
-N --strip-symbol=<name> Do not copy symbol <name>\n\
-K --keep-symbol=<name> Do not strip symbol <name>\n\
--keep-file-symbols Do not strip file symbol(s)\n\
@@ -1882,6 +1889,22 @@ copy_unknown_object (bfd *ibfd, bfd *obfd)
return TRUE;
}
+/* Returns the number of bytes needed to store VAL. */
+
+static inline unsigned int
+num_bytes (unsigned long val)
+{
+ unsigned int count = 0;
+
+ /* FIXME: There must be a faster way to do this. */
+ while (val)
+ {
+ count ++;
+ val >>= 8;
+ }
+ return count;
+}
+
/* Merge the notes on SEC, removing redundant entries.
Returns the new, smaller size of the section upon success. */
@@ -1899,7 +1922,7 @@ merge_gnu_build_notes (bfd * abfd, asection * sec, bfd_size_type size, bfd_byte
/* Make a copy of the notes.
Minimum size of a note is 12 bytes. */
- pnote = pnotes = (Elf_Internal_Note *) xmalloc ((size / 12) * sizeof (Elf_Internal_Note));
+ pnote = pnotes = (Elf_Internal_Note *) xcalloc ((size / 12), sizeof (Elf_Internal_Note));
while (remain >= 12)
{
pnote->namesz = (bfd_get_32 (abfd, in ) + 3) & ~3;
@@ -1939,6 +1962,12 @@ merge_gnu_build_notes (bfd * abfd, asection * sec, bfd_size_type size, bfd_byte
remain -= 12 + pnote->namesz + pnote->descsz;
in += 12 + pnote->namesz + pnote->descsz;
+ if (pnote->namedata[pnote->namesz - 1] != 0)
+ {
+ err = _("corrupt GNU build attribute note: name not NUL terminated");
+ goto done;
+ }
+
if (pnote->namesz > 1 && pnote->namedata[1] == GNU_BUILD_ATTRIBUTE_VERSION)
++ version_notes_seen;
pnote ++;
@@ -1983,7 +2012,9 @@ merge_gnu_build_notes (bfd * abfd, asection * sec, bfd_size_type size, bfd_byte
3. Eliminate any NT_GNU_BUILD_ATTRIBUTE_OPEN notes that have the same
full name field as the immediately preceeding note with the same type
of name.
- 4. If an NT_GNU_BUILD_ATTRIBUTE_OPEN note is going to be preserved and
+ 4. Combine the numeric value of any NT_GNU_BUILD_ATTRIBUTE_OPEN notes
+ of type GNU_BUILD_ATTRIBUTE_STACK_SIZE.
+ 5. If an NT_GNU_BUILD_ATTRIBUTE_OPEN note is going to be preserved and
its description field is empty then the nearest preceeding OPEN note
with a non-empty description field must also be preserved *OR* the
description field of the note must be changed to contain the starting
@@ -2008,6 +2039,54 @@ merge_gnu_build_notes (bfd * abfd, asection * sec, bfd_size_type size, bfd_byte
if (back->type == pnote->type
&& back->namedata[1] == pnote->namedata[1])
{
+ if (back->namedata[1] == GNU_BUILD_ATTRIBUTE_STACK_SIZE)
+ {
+ unsigned char * name;
+ unsigned long note_val;
+ unsigned long back_val;
+ unsigned int shift;
+ unsigned int bytes;
+ unsigned long byte;
+
+ for (shift = 0, note_val = 0, bytes = pnote->namesz - 2, name = (unsigned char *) pnote->namedata + 2;
+ bytes--;)
+ {
+ byte = (* name ++) & 0xff;
+ note_val |= byte << shift;
+ shift += 8;
+ }
+ for (shift = 0, back_val = 0, bytes = back->namesz - 2, name = (unsigned char *) back->namedata + 2;
+ bytes--;)
+ {
+ byte = (* name ++) & 0xff;
+ back_val |= byte << shift;
+ shift += 8;
+ }
+ back_val += note_val;
+ if (num_bytes (back_val) >= back->namesz - 2)
+ {
+ /* We have a problem - the new value requires more bytes of
+ storage in the name field than are available. Currently
+ we have no way of fixing this, so we just preserve both
+ notes. */
+ continue;
+ }
+ /* Write the new val into back. */
+ name = (unsigned char *) back->namedata + 2;
+ while (name < (unsigned char *) back->namedata + back->namesz)
+ {
+ byte = back_val & 0xff;
+ * name ++ = byte;
+ if (back_val == 0)
+ break;
+ back_val >>= 8;
+ }
+
+ duplicate_found = TRUE;
+ pnote->type = 0;
+ break;
+ }
+
if (back->namesz == pnote->namesz
&& memcmp (back->namedata, pnote->namedata, back->namesz) == 0)
{
@@ -2018,10 +2097,11 @@ merge_gnu_build_notes (bfd * abfd, asection * sec, bfd_size_type size, bfd_byte
/* If we have found an attribute match then stop searching backwards. */
if (! ISPRINT (back->namedata[1])
+ /* Names are NUL terminated, so this is safe. */
|| strcmp (back->namedata + 2, pnote->namedata + 2) == 0)
{
/* Since we are keeping this note we must check to see if its
- description refers back to an earlier OPEN note. If so
+ description refers back to an earlier OPEN version note. If so
then we must make sure that version note is also preserved. */
if (pnote->descsz == 0
&& prev_open != NULL
@@ -2821,8 +2901,8 @@ copy_object (bfd *ibfd, bfd *obfd, const bfd_arch_info_type *input_arch)
return FALSE;
}
}
- else
- bfd_nonfatal_message (NULL, obfd, osec, _("ICE: lost merged note section"));
+ else if (! is_strip)
+ bfd_nonfatal_message (NULL, obfd, osec, _("could not find any mergeable note sections"));
free (merged_notes);
merged_notes = NULL;
merge_notes = FALSE;
@@ -4023,6 +4103,8 @@ strip_main (int argc, char *argv[])
int i;
char *output_file = NULL;
+ merge_notes = TRUE;
+
while ((c = getopt_long (argc, argv, "I:O:F:K:N:R:o:sSpdgxXHhVvwDU",
strip_options, (int *) 0)) != EOF)
{
@@ -4060,6 +4142,12 @@ strip_main (int argc, char *argv[])
case 'K':
add_specific_symbol (optarg, keep_specific_htab);
break;
+ case 'M':
+ merge_notes = TRUE;
+ break;
+ case OPTION_NO_MERGE_NOTES:
+ merge_notes = FALSE;
+ break;
case 'N':
add_specific_symbol (optarg, strip_specific_htab);
break;
@@ -4486,6 +4574,9 @@ copy_main (int argc, char *argv[])
case 'M':
merge_notes = TRUE;
break;
+ case OPTION_NO_MERGE_NOTES:
+ merge_notes = FALSE;
+ break;
case 'N':
add_specific_symbol (optarg, strip_specific_htab);
diff --git a/binutils/readelf.c b/binutils/readelf.c
index d2b8dd4..93b9402 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -16809,9 +16809,12 @@ print_gnu_build_attribute_description (Elf_Internal_Note * pnote,
static bfd_boolean
print_gnu_build_attribute_name (Elf_Internal_Note * pnote)
{
+ static const char string_expected [2] = { GNU_BUILD_ATTRIBUTE_TYPE_STRING, 0 };
+ static const char number_expected [2] = { GNU_BUILD_ATTRIBUTE_TYPE_NUMERIC, 0 };
+ static const char bool_expected [3] = { GNU_BUILD_ATTRIBUTE_TYPE_BOOL_TRUE, GNU_BUILD_ATTRIBUTE_TYPE_BOOL_FALSE, 0 };
char name_type;
char name_attribute;
- char * expected_types;
+ const char * expected_types;
const char * name = pnote->namedata;
const char * text;
int left;
@@ -16845,7 +16848,7 @@ print_gnu_build_attribute_name (Elf_Internal_Note * pnote)
{
case GNU_BUILD_ATTRIBUTE_VERSION:
text = _("<version>");
- expected_types = "$";
+ expected_types = string_expected;
++ name;
break;
case GNU_BUILD_ATTRIBUTE_STACK_PROT:
@@ -16855,17 +16858,17 @@ print_gnu_build_attribute_name (Elf_Internal_Note * pnote)
break;
case GNU_BUILD_ATTRIBUTE_RELRO:
text = _("<relro>");
- expected_types = "!+";
+ expected_types = bool_expected;
++ name;
break;
case GNU_BUILD_ATTRIBUTE_STACK_SIZE:
text = _("<stack size>");
- expected_types = "*";
+ expected_types = number_expected;
++ name;
break;
case GNU_BUILD_ATTRIBUTE_TOOL:
text = _("<tool>");
- expected_types = "$";
+ expected_types = string_expected;
++ name;
break;
case GNU_BUILD_ATTRIBUTE_ABI:
@@ -16875,12 +16878,12 @@ print_gnu_build_attribute_name (Elf_Internal_Note * pnote)
break;
case GNU_BUILD_ATTRIBUTE_PIC:
text = _("<PIC>");
- expected_types = "*";
+ expected_types = number_expected;
++ name;
break;
case GNU_BUILD_ATTRIBUTE_SHORT_ENUM:
text = _("<short enum>");
- expected_types = "!+";
+ expected_types = bool_expected;
++ name;
break;