On Fri, 2012-05-25 at 10:10 +0300, Panu Matilainen wrote:
> On 05/25/2012 09:26 AM, Alexander Larsson wrote:
> > On Thu, 2012-05-24 at 13:20 -0400, Casey Dahlin wrote:
> >> On Thu, May 24, 2012 at 09:28:16AM +0200, Alexander Larsson wrote:
> >>> I'm at a loss to how to proceed with the MiniDebugInfo work. I have
> >>> patches to rpmbuild that creates the compressed minidebuginfo putting
> >>> them in the main binaries, and I have patches to gdb that reads the
> >>> compressed debuginfo on demand.
> >>>
> >>> However, the whole thing is useless unless we agree that we want to
> >>> enable this by default. It seems some people like the idea, whereas
> >>> others disagree that its worth the increased binary size. It doesn't
> >>> look like either side is gonna be able to convince the other side, so
> >>> how do we get to a decision here?
> >>>
> >>
> >> Just go do it. See who actually shows up to stop you.
> >
> > To actually get the debuginfo in the builds all I need is a minor patch
> > to the find-debuginfo.sh script in rpm-build. However, since the effect
> > of it is global it seems to me that its a wider decision than just the
> > maintainer of rpm-build.
>
> As long as the behavior is optional and configurable, just send the
> patch to rpm-maint and we'll see. Fedora isn't the only consumer of rpm,
> and somebody else might find it useful regardless of whether Fedora
> wants to enable the thing or not.
Ok, here goes:
* rpm-minidebuginfo.patch
Patches find-debuginfo.sh and adds new _include_minidebuginfo option
defaulting to off
* redhat-rpm-config-minidebug.patch
Example patch that enables building minidebuginfo by default on Fedora
* 0001-configure.ac-Look-for-and-use-libzma-on-ELF-systems.patch
* 0002-Support-lzma-compressed-.gnu_debugdata-sections.patch
Gdb patches enabling on-demand lzma decompression of
the .gnu_debugdata section looking for separate debuginfo there.
With these patches all applied any rpm you build (that doesn't
explicitly disable debuginfo generation) will get xz compresses minimal
debug info that gdb will find automatically (unless the real debuginfo
is installed, then that will be used).
diff -up rpm-4.9.1.3/macros.in.minidebug rpm-4.9.1.3/macros.in
--- rpm-4.9.1.3/macros.in.minidebug 2012-06-11 11:16:21.216952339 +0200
+++ rpm-4.9.1.3/macros.in 2012-06-11 11:16:23.686912455 +0200
@@ -175,7 +175,7 @@
# the script. See the script for details.
#
%__debug_install_post \
- %{_rpmconfigdir}/find-debuginfo.sh %{?_missing_build_ids_terminate_build:--strict-build-id} %{?_find_debuginfo_opts} "%{_builddir}/%{?buildsubdir}"\
+ %{_rpmconfigdir}/find-debuginfo.sh %{?_missing_build_ids_terminate_build:--strict-build-id} %{?_include_minidebuginfo:-m} %{?_find_debuginfo_opts} "%{_builddir}/%{?buildsubdir}"\
%{nil}
# Template for debug information sub-package.
@@ -418,6 +418,12 @@ package or when debugging this package.\
#%_missing_build_ids_terminate_build 1
#
+# Include minimal debug information in build binaries.
+# Requires _enable_debug_packages.
+#
+#%_include_minidebuginfo 1
+
+#
# Use internal dependency generator rather than external helpers?
%_use_internal_dependency_generator 1
diff -up rpm-4.9.1.3/scripts/find-debuginfo.sh.minidebug rpm-4.9.1.3/scripts/find-debuginfo.sh
--- rpm-4.9.1.3/scripts/find-debuginfo.sh.minidebug 2012-06-11 11:16:09.698138273 +0200
+++ rpm-4.9.1.3/scripts/find-debuginfo.sh 2012-06-11 11:16:13.399078526 +0200
@@ -2,7 +2,7 @@
#find-debuginfo.sh - automagically generate debug info and file list
#for inclusion in an rpm spec file.
#
-# Usage: find-debuginfo.sh [--strict-build-id] [-g] [-r]
+# Usage: find-debuginfo.sh [--strict-build-id] [-g] [-r] [-m]
# [-o debugfiles.list]
# [[-l filelist]... [-p 'pattern'] -o debuginfo.list]
# [builddir]
@@ -29,6 +29,9 @@ strip_g=false
# with -r arg, pass --reloc-debug-sections to eu-strip.
strip_r=false
+# with -m arg, add minimal debuginfo to binary.
+include_minidebug=false
+
# Barf on missing build IDs.
strict=false
@@ -43,6 +46,9 @@ while [ $# -gt 0 ]; do
-g)
strip_g=true
;;
+ -m)
+ include_minidebug=true
+ ;;
-o)
if [ -z "${lists[$nout]}" -a -z "${ptns[$nout]}" ]; then
out=$2
@@ -105,6 +111,32 @@ strip_to_debug()
chmod 444 "$1" || exit
}
+add_minidebug()
+{
+ local debuginfo="$1"
+ local binary="$2"
+
+ local dynsyms=`mktemp`
+ local funcsyms=`mktemp`
+ local keep_symbols=`mktemp`
+ local mini_debuginfo=`mktemp`
+
+ # Extract the dynamic symbols from the main binary, there is no need to also have these
+ # in the normal symbol table
+ nm -D "$binary" --format=posix --defined-only | awk '{ print $1 }' | sort > "$dynsyms"
+ # Extract all the text (i.e. function) symbols from the debuginfo
+ nm "$debuginfo" --format=posix --defined-only | awk '{ if ($2 == "T" || $2 == "t") print $1 }' | sort > "$funcsyms"
+ # Keep all the function symbols not already in the dynamic symbol table
+ comm -13 "$dynsyms" "$funcsyms" > "$keep_symbols"
+ # Copy the full debuginfo, keeping only a minumal set of symbols and removing some unnecessary sections
+ objcopy -S --remove-section .gdb_index --remove-section .comment --keep-symbols="$keep_symbols" "$debuginfo" "$mini_debuginfo" &> /dev/null
+ #Inject the compressed data into the .gnu_debugdata section of the original binary
+ xz "$mini_debuginfo"
+ mini_debuginfo="${mini_debuginfo}.xz"
+ objcopy --add-section .gnu_debugdata="$mini_debuginfo" "$binary"
+ rm -f "$dynsyms" "$funcsyms" "$keep_symbols" "$mini_debuginfo"
+}
+
# Make a relative symlink to $1 called $3$2
shopt -s extglob
link_relative()
@@ -260,6 +292,9 @@ while read nlinks inum f; do
chmod u-w "$f"
fi
+ $include_minidebug && add_minidebug "${debugfn}" "$f"
+
+
if [ -n "$id" ]; then
make_id_link "$id" "$dn/$(basename $f)"
make_id_link "$id" "/usr/lib/debug$dn/$bn" .debug
diff -up redhat-rpm-config-9.1.0/macros.minidebug redhat-rpm-config-9.1.0/macros
--- redhat-rpm-config-9.1.0/macros.minidebug 2012-06-11 11:48:58.144578684 +0200
+++ redhat-rpm-config-9.1.0/macros 2012-06-11 11:49:18.444255286 +0200
@@ -22,6 +22,7 @@
%_fmoddir %{_libdir}/gfortran/modules
%_enable_debug_packages 1
+%_include_minidebuginfo 1
#==============================================================================
# ---- configure and makeinstall.
>From 8cf60203e72033724cea813ad516809662995c57 Mon Sep 17 00:00:00 2001
From: Alexander Larsson <al...@redhat.com>
Date: Fri, 27 Apr 2012 15:01:47 +0200
Subject: [PATCH 1/2] configure.ac: Look for and use libzma on ELF systems
This will be used for compressed debug info
---
gdb/Makefile.in | 5 ++++-
gdb/configure.ac | 19 +++++++++++++++++++
2 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 0e87eeb..06965d2 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -151,6 +151,9 @@ READLINE_CFLAGS = @READLINE_CFLAGS@
# Where is expat? This will be empty if expat was not available.
LIBEXPAT = @LIBEXPAT@
+# Where is lzma? This will be empty if lzma was not available.
+LIBLZMA = @LIBLZMA@
+
WARN_CFLAGS = @WARN_CFLAGS@
WERROR_CFLAGS = @WERROR_CFLAGS@
GDB_WARN_CFLAGS = $(WARN_CFLAGS)
@@ -467,7 +470,7 @@ INTERNAL_LDFLAGS = $(CFLAGS) $(GLOBAL_CFLAGS) $(MH_LDFLAGS) $(LDFLAGS) $(CONFIG_
# LIBIBERTY appears twice on purpose.
CLIBS = $(SIM) $(READLINE) $(OPCODES) $(BFD) $(INTL) $(LIBIBERTY) $(LIBDECNUMBER) \
$(XM_CLIBS) $(NAT_CLIBS) $(GDBTKLIBS) @LIBS@ @PYTHON_LIBS@ \
- $(LIBEXPAT) \
+ $(LIBEXPAT) $(LIBLZMA) \
$(LIBIBERTY) $(WIN32LIBS) $(LIBGNU)
CDEPS = $(XM_CDEPS) $(NAT_CDEPS) $(SIM) $(BFD) $(READLINE_DEPS) \
$(OPCODES) $(INTL_DEPS) $(LIBIBERTY) $(CONFIG_DEPS) $(LIBGNU)
diff --git a/gdb/configure.ac b/gdb/configure.ac
index a40c2e5..84282a9 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -1962,6 +1962,25 @@ LIBS=$OLD_LIBS
# Add any host-specific objects to GDB.
CONFIG_OBS="${CONFIG_OBS} ${gdb_host_obs}"
+# If building on ELF, look for lzma support for embedded compressed debug info.
+if test $gdb_cv_var_elf = yes; then
+ AC_ARG_WITH(lzma,
+ AS_HELP_STRING([--with-lzma], [support lzma compression (auto/yes/no)]),
+ [], [with_lzma=auto])
+ AC_MSG_CHECKING([whether to use lzma])
+ AC_MSG_RESULT([$with_lzma])
+
+ if test "${with_lzma}" != no; then
+ AC_LIB_HAVE_LINKFLAGS([lzma], [], [#include "lzma.h"],
+ [lzma_mf_is_supported (LZMA_MF_HC3);])
+ if test "$HAVE_LIBLZMA" != yes; then
+ if test "$with_lzma" = yes; then
+ AC_MSG_ERROR([missing liblzma for --with-lzma])
+ fi
+ fi
+ fi
+fi
+
LIBGUI="../libgui/src/libgui.a"
GUI_CFLAGS_X="-I${srcdir}/../libgui/src"
AC_SUBST(LIBGUI)
--
1.7.10
>From 36de94adffc71b6b88b8be04e170071952013800 Mon Sep 17 00:00:00 2001
From: Alexander Larsson <al...@redhat.com>
Date: Fri, 27 Apr 2012 11:31:52 +0200
Subject: [PATCH 2/2] Support lzma compressed .gnu_debugdata sections
In addition to normal separate debuginfo as an external file we also allow
putting a xz compressed debuginfo file into the .gnu_debugdata section of
the ELF file.
This allows us to e.g. have a minimized debuginfo file (say one with
only a subset of the symbols) efficiently stored in the executable file.
---
gdb/elfread.c | 246 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 243 insertions(+), 3 deletions(-)
diff --git a/gdb/elfread.c b/gdb/elfread.c
index 117e674..063efee 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -42,6 +42,10 @@
#include "gdbthread.h"
#include "regcache.h"
#include "bcache.h"
+#include "gdbcore.h"
+#ifdef HAVE_LIBLZMA
+# include <lzma.h>
+#endif
extern void _initialize_elfread (void);
@@ -1202,6 +1206,236 @@ find_separate_debug_file_by_buildid (struct objfile *objfile)
return NULL;
}
+#ifdef HAVE_LIBLZMA
+
+/* Custom allocator for the lzma functions so they use the gdb ones. */
+
+static void *
+alloc_lzma (void *opaque, size_t nmemb, size_t size)
+{
+ return xmalloc (nmemb * size);
+}
+
+static void
+free_lzma (void *opaque, void *ptr)
+{
+ xfree (ptr);
+}
+
+static lzma_allocator gdb_lzma_allocator = { alloc_lzma, free_lzma, NULL};
+
+/* Custom bfd_openr_iovec implementation to read compressed data from a
+ section. This keeps only the last decompressed block in memory to
+ allow larger data without using to much memory. */
+
+struct lzma_stream
+{
+ asection *section;
+ lzma_index *index;
+
+ /* Currently decoded block. */
+ bfd_size_type data_start;
+ bfd_size_type data_end;
+ gdb_byte *data;
+};
+
+static void *
+lzma_open (struct bfd *nbfd,
+ void *open_closure)
+{
+ asection *section;
+ bfd_size_type size, offset;
+ lzma_stream_flags options;
+ gdb_byte footer[LZMA_STREAM_HEADER_SIZE];
+ gdb_byte *indexdata;
+ lzma_index *index;
+ int ret;
+ uint64_t memlimit = UINT64_MAX;
+ struct lzma_stream *lstream;
+ size_t pos;
+
+ section = open_closure;
+
+ size = bfd_get_section_size (section);
+ offset = section->filepos + size - LZMA_STREAM_HEADER_SIZE;
+ if (bfd_seek (section->owner, offset, SEEK_SET) != 0
+ || !bfd_bread (footer, (bfd_size_type) LZMA_STREAM_HEADER_SIZE,
+ section->owner)
+ || lzma_stream_footer_decode (&options, (uint8_t *)footer))
+ {
+ bfd_set_error (bfd_error_wrong_format);
+ return NULL;
+ }
+
+ offset -= options.backward_size;
+ indexdata = xmalloc (options.backward_size);
+ index = NULL;
+ pos = 0;
+ if (bfd_seek (section->owner, offset, SEEK_SET) != 0
+ || !bfd_bread (indexdata, (bfd_size_type) options.backward_size,
+ section->owner)
+ || lzma_index_buffer_decode (&index, &memlimit, &gdb_lzma_allocator,
+ indexdata, &pos, options.backward_size)
+ || lzma_index_size (index) != options.backward_size)
+ {
+ xfree (indexdata);
+ bfd_set_error (bfd_error_wrong_format);
+ return NULL;
+ }
+ xfree (indexdata);
+
+ lstream = xcalloc (1, sizeof (struct lzma_stream));
+ lstream->section = section;
+ lstream->index = index;
+
+ return lstream;
+}
+
+static file_ptr
+lzma_pread (struct bfd *nbfd,
+ void *stream,
+ void *buf,
+ file_ptr nbytes,
+ file_ptr offset)
+{
+ struct lzma_stream *lstream = stream;
+ bfd_size_type chunk_size;
+ lzma_index_iter iter;
+ gdb_byte *compressed, *uncompressed;
+ file_ptr block_offset;
+ lzma_filter filters[LZMA_FILTERS_MAX + 1];
+ lzma_block block;
+ size_t compressed_pos, uncompressed_pos;
+ file_ptr res;
+
+ res = 0;
+ while (nbytes > 0)
+ {
+ if (lstream->data == NULL
+ || lstream->data_start > offset || offset >= lstream->data_end)
+ {
+ asection *section = lstream->section;
+
+ lzma_index_iter_init (&iter, lstream->index);
+ if (lzma_index_iter_locate (&iter, offset))
+ break;
+
+ compressed = xmalloc (iter.block.total_size);
+ block_offset = section->filepos + iter.block.compressed_file_offset;
+ if (bfd_seek (section->owner, block_offset, SEEK_SET) != 0
+ || !bfd_bread (compressed, (bfd_size_type) iter.block.total_size,
+ section->owner))
+ {
+ xfree (compressed);
+ break;
+ }
+
+ uncompressed = xmalloc (iter.block.uncompressed_size);
+
+ memset (&block, 0, sizeof (block));
+ block.filters = filters;
+ block.header_size = lzma_block_header_size_decode(compressed[0]);
+ if (lzma_block_header_decode (&block, &gdb_lzma_allocator,
+ compressed))
+ {
+ xfree (compressed);
+ xfree (uncompressed);
+ break;
+ }
+
+ compressed_pos = block.header_size;
+ uncompressed_pos = 0;
+ if (lzma_block_buffer_decode (&block, &gdb_lzma_allocator,
+ compressed, &compressed_pos,
+ iter.block.total_size,
+ uncompressed, &uncompressed_pos,
+ iter.block.uncompressed_size))
+ {
+ xfree (compressed);
+ xfree (uncompressed);
+ break;
+ }
+
+ xfree (compressed);
+
+ xfree (lstream->data);
+ lstream->data = uncompressed;
+ lstream->data_start = iter.block.uncompressed_file_offset;
+ lstream->data_end =
+ iter.block.uncompressed_file_offset + iter.block.uncompressed_size;
+ }
+
+ chunk_size = min (nbytes, lstream->data_end - offset);
+ memcpy (buf, lstream->data + offset - lstream->data_start, chunk_size);
+ buf = (void *)((gdb_byte *)buf + chunk_size);
+ offset += chunk_size;
+ nbytes -= chunk_size;
+ res += chunk_size;
+ }
+
+ return res;
+}
+
+static int
+lzma_close (struct bfd *nbfd,
+ void *stream)
+{
+ struct lzma_stream *lstream = stream;
+
+ lzma_index_end (lstream->index, &gdb_lzma_allocator);
+ xfree (lstream->data);
+ xfree (lstream);
+ return 0;
+}
+
+static int
+lzma_stat (struct bfd *abfd,
+ void *stream,
+ struct stat *sb)
+{
+ struct lzma_stream *lstream = stream;
+
+ sb->st_size = lzma_index_uncompressed_size (lstream->index);
+ return 0;
+}
+
+/* This looks for a xz compressed separate debug info object file embedded
+ in a section called .gnu_debugdata. If we find one we create a iovec
+ based bfd that decompresses the object data on demand. */
+
+static bfd *
+find_separate_debug_file_in_section (struct objfile *objfile)
+{
+ asection *section;
+ bfd *abfd;
+
+ section = bfd_get_section_by_name (objfile->obfd, ".gnu_debugdata");
+ if (section == NULL)
+ return NULL;
+
+ abfd = bfd_openr_iovec (objfile->name, gnutarget,
+ lzma_open, section,
+ lzma_pread, lzma_close, lzma_stat);
+
+ if (!bfd_check_format (abfd, bfd_object))
+ {
+ bfd_close (abfd);
+ return NULL;
+ }
+
+ return abfd;
+}
+
+#else
+
+static bfd *
+find_separate_debug_file_in_section (struct objfile *objfile)
+{
+ return NULL;
+}
+
+#endif
+
/* Scan and build partial symbols for a symbol file.
We have been initialized by a call to elf_symfile_init, which
currently does nothing.
@@ -1417,6 +1651,7 @@ elf_symfile_read (struct objfile *objfile, int symfile_flags)
`.note.gnu.build-id'. */
else if (!objfile_has_partial_symbols (objfile))
{
+ bfd *abfd = NULL;
char *debugfile;
debugfile = find_separate_debug_file_by_buildid (objfile);
@@ -1426,11 +1661,16 @@ elf_symfile_read (struct objfile *objfile, int symfile_flags)
if (debugfile)
{
- bfd *abfd = symfile_bfd_open (debugfile);
-
- symbol_file_add_separate (abfd, symfile_flags, objfile);
+ abfd = symfile_bfd_open (debugfile);
xfree (debugfile);
}
+
+ if (abfd == NULL)
+ abfd = find_separate_debug_file_in_section (objfile);
+
+ if (abfd != NULL)
+ symbol_file_add_separate (abfd, symfile_flags, objfile);
+
}
}
--
1.7.10
--
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