https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93608
Bug ID: 93608
Summary: [libbacktrace] Add support for .gnu_debugdata section
(aka MiniDebugInfo)
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: libbacktrace
Assignee: unassigned at gcc dot gnu.org
Reporter: vries at gcc dot gnu.org
CC: ian at gcc dot gnu.org
Target Milestone: ---
The find-debuginfo.sh script in the rpm software package has an ability to
generate a .gnu_debugdata section (originally developed at
https://fedoraproject.org/wiki/Features/MiniDebugInfo):
...
add_minidebug()
{
local debuginfo="$1"
local binary="$2"
local dynsyms=`mktemp`
local funcsyms=`mktemp`
local keep_symbols=`mktemp`
local mini_debuginfo=`mktemp`
# In the minisymtab we don't need the .debug_ sections (already removed
# by -S) but also not other non-allocated PROGBITS, NOTE or NOBITS sections.
# List and remove them explicitly. We do want to keep the allocated,
# symbol and NOBITS sections so cannot use --keep-only because that is
# too aggressive. Field $2 is the section name, $3 is the section type
# and $8 are the section flags.
local remove_sections=`readelf -W -S "$debuginfo" \
| awk '{ if (index($2,".debug_") != 1 \
&& ($3 == "PROGBITS" || $3 == "NOTE" || $3 == "NOBITS") \
&& index($8,"A") == 0) \
printf "--remove-section "$2" " }'`
# Extract the dynamic symbols from the main binary, there is no need to also
have these
# in the normal symbol table
nm -D "$binary" --format=posix --defined-only | awk '{ print $1 }' | sort >
"$dynsyms"
# Extract all the text (i.e. function) symbols from the debuginfo
# Use format sysv to make sure we can match against the actual ELF FUNC
# symbol type. The binutils nm posix format symbol type chars are
# ambigous for architectures that might use function descriptors.
nm "$debuginfo" --format=sysv --defined-only | awk -F \| '{ if ($4 ~ "FUNC")
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 $remove_sections --keep-symbols="$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"
}...
It would be nice if libbacktrace could use this information.
