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authorDan Callaghan <dan.callaghan@opengear.com>2020-04-19 18:16:03 +1000
committerRichard Purdie <richard.purdie@linuxfoundation.org>2020-04-26 13:58:45 +0100
commit4df992ce50c2d12e356b6d9fe7b23a6320c8b4df (patch)
tree16aed7b00e8502db421ffe37e69b81a43b82c543
parent7b3cdc74773fce29ef4fec4f60b719f46c3e7f30 (diff)
downloadopenembedded-core-contrib-4df992ce50c2d12e356b6d9fe7b23a6320c8b4df.tar.gz
package.bbclass: inject "minidebuginfo" into packaged binaries
"Mini debuginfo" is a special section in ELF executables containing minimal compressed debuginfo for non-exported symbols: https://sourceware.org/gdb/onlinedocs/gdb/MiniDebugInfo.html It lets debugging tools produce better stack traces, including local function names, without incurring the space overhead of full debuginfo. The feature was originally developed for Fedora: https://fedoraproject.org/wiki/Features/MiniDebugInfo but nowadays it is widely supported in the ecosystem, including in gdb and elfutils (and therefore also in tools which use elfutils, such as systemd-coredump). This patch adds an optional extra step in package.bbclass to inject minidebuginfo while stripping and splitting out debuginfo. It can be enabled by setting PACKAGE_MINIDEBUGINFO=1. In my testing, this increases the size of resulting binaries by roughly 5%. The code for producing and re-injecting the minidebuginfo is my own Python implementation but corresponds directly to the shell implementation that RPM uses for doing the same: https://github.com/rpm-software-management/rpm/blob/rpm-4.15.1-release/scripts/find-debuginfo.sh#L261 Signed-off-by: Dan Callaghan <dan.callaghan@opengear.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
-rw-r--r--meta/classes/package.bbclass84
1 files changed, 84 insertions, 0 deletions
diff --git a/meta/classes/package.bbclass b/meta/classes/package.bbclass
index d4c6a90e84..648297ad25 100644
--- a/meta/classes/package.bbclass
+++ b/meta/classes/package.bbclass
@@ -245,6 +245,8 @@ python () {
deps = ""
for dep in (d.getVar('PACKAGE_DEPENDS') or "").split():
deps += " %s:do_populate_sysroot" % dep
+ if d.getVar('PACKAGE_MINIDEBUGINFO') == '1':
+ deps += ' xz-native:do_populate_sysroot'
d.appendVarFlag('do_package', 'depends', deps)
# shlibs requires any DEPENDS to have already packaged for the *.list files
@@ -459,6 +461,83 @@ def splitstaticdebuginfo(file, dvar, debugstaticdir, debugstaticlibdir, debugsta
return (file, sources)
+def inject_minidebuginfo(file, dvar, debugdir, debuglibdir, debugappend, debugsrcdir, d):
+ # Extract just the symbols from debuginfo into minidebuginfo,
+ # compress it with xz and inject it back into the binary in a .gnu_debugdata section.
+ # https://sourceware.org/gdb/onlinedocs/gdb/MiniDebugInfo.html
+
+ import subprocess
+
+ readelf = d.getVar('READELF')
+ nm = d.getVar('NM')
+ objcopy = d.getVar('OBJCOPY')
+
+ minidebuginfodir = d.expand('${WORKDIR}/minidebuginfo')
+
+ src = file[len(dvar):]
+ dest = debuglibdir + os.path.dirname(src) + debugdir + "/" + os.path.basename(src) + debugappend
+ debugfile = dvar + dest
+ minidebugfile = minidebuginfodir + src + '.minidebug'
+ bb.utils.mkdirhier(os.path.dirname(minidebugfile))
+
+ # If we didn't produce debuginfo for any reason, we can't produce minidebuginfo either
+ # so skip it.
+ if not os.path.exists(debugfile):
+ bb.debug(1, 'ELF file {} has no debuginfo, skipping minidebuginfo injection'.format(file))
+ return
+
+ # Find non-allocated PROGBITS, NOTE, and NOBITS sections in the debuginfo.
+ # We will exclude all of these from minidebuginfo to save space.
+ remove_section_names = []
+ for line in subprocess.check_output([readelf, '-W', '-S', debugfile], universal_newlines=True).splitlines():
+ fields = line.split()
+ if len(fields) < 8:
+ continue
+ name = fields[0]
+ type = fields[1]
+ flags = fields[7]
+ # .debug_ sections will be removed by objcopy -S so no need to explicitly remove them
+ if name.startswith('.debug_'):
+ continue
+ if 'A' not in flags and type in ['PROGBITS', 'NOTE', 'NOBITS']:
+ remove_section_names.append(name)
+
+ # List dynamic symbols in the binary. We can exclude these from minidebuginfo
+ # because they are always present in the binary.
+ dynsyms = set()
+ for line in subprocess.check_output([nm, '-D', file, '--format=posix', '--defined-only'], universal_newlines=True).splitlines():
+ dynsyms.add(line.split()[0])
+
+ # Find all function symbols from debuginfo which aren't in the dynamic symbols table.
+ # These are the ones we want to keep in minidebuginfo.
+ keep_symbols_file = minidebugfile + '.symlist'
+ found_any_symbols = False
+ with open(keep_symbols_file, 'w') as f:
+ for line in subprocess.check_output([nm, debugfile, '--format=sysv', '--defined-only'], universal_newlines=True).splitlines():
+ fields = line.split('|')
+ if len(fields) < 7:
+ continue
+ name = fields[0].strip()
+ type = fields[3].strip()
+ if type == 'FUNC' and name not in dynsyms:
+ f.write('{}\n'.format(name))
+ found_any_symbols = True
+
+ if not found_any_symbols:
+ bb.debug(1, 'ELF file {} contains no symbols, skipping minidebuginfo injection'.format(file))
+ return
+
+ bb.utils.remove(minidebugfile)
+ bb.utils.remove(minidebugfile + '.xz')
+
+ subprocess.check_call([objcopy, '-S'] +
+ ['--remove-section={}'.format(s) for s in remove_section_names] +
+ ['--keep-symbols={}'.format(keep_symbols_file), debugfile, minidebugfile])
+
+ subprocess.check_call(['xz', '--keep', minidebugfile])
+
+ subprocess.check_call([objcopy, '--add-section', '.gnu_debugdata={}.xz'.format(minidebugfile), file])
+
def copydebugsources(debugsrcdir, sources, d):
# The debug src information written out to sourcefile is further processed
# and copied to the destination here.
@@ -1185,6 +1264,11 @@ python split_and_strip_files () {
oe.utils.multiprocess_launch(oe.package.runstrip, sfiles, d)
+ # Build "minidebuginfo" and reinject it back into the stripped binaries
+ if d.getVar('PACKAGE_MINIDEBUGINFO') == '1':
+ oe.utils.multiprocess_launch(inject_minidebuginfo, list(elffiles), d,
+ extraargs=(dvar, debugdir, debuglibdir, debugappend, debugsrcdir, d))
+
#
# End of strip
#