From cd7e9e8a2fc2464fb67fd4d786ff6097a3941739 Mon Sep 17 00:00:00 2001 From: Eugene Syromiatnikov Date: Sun, 5 Feb 2023 01:26:01 +0100 Subject: [PATCH] find-provides.ksyms, find-requires.ksyms: rewrite indirect CRC parsing Linux commit v5.19-rc1~139^2~2 ("kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS") has broken the assumption aobut the placement of non-absolute CRC symbols in .rodata (and also affects the architectures that used to have these symbols as absolute); rewrite the parsing by utilising "objdump -t" output to figure out the section(s) where the __crc_* symbols are stored and process it instead of the hard-coded ".rodata" section. The change also speeds up the processing a bit, around 33% on synthetic tests: $ time sh -c 'find ./lib/modules/5.14.0-258.el9.ppc64le -name "*.ko.xz" | find-provides.ksyms.old > /dev/null 2> /dev/null' sh -c 10.36s user 5.58s system 137% cpu 11.613 total $ time sh -c 'find ./lib/modules/5.14.0-258.el9.ppc64le -name "*.ko.xz" | find-provides.ksyms.new > /dev/null 2> /dev/null' sh -c 7.82s user 4.59s system 142% cpu 8.686 total $ time sh -c 'find ./lib/modules/5.14.0-258.el9.ppc64le -name "*.ko.xz" -exec sh -c "echo {} | find-provides.ksyms.old" \; > /dev/null 2> /dev/null' sh -c 11.85s user 6.76s system 129% cpu 14.318 total $ time sh -c 'find ./lib/modules/5.14.0-258.el9.ppc64le -name "*.ko.xz" -exec sh -c "echo {} | find-provides.ksyms.new" \; > /dev/null 2> /dev/null' sh -c 8.91s user 5.51s system 135% cpu 10.647 total * find-provides.ksyms: Process "objdump -t" output to get the list of sections where __crc_* symbol contents are placed; retrieve each one with "readelf -R" and supply it to an awk script that cuts the required part of it for each __crc_* symbol in that section. * find-requires.ksyms (all_provides): Likewise. Signed-off-by: Eugene Syromiatnikov Resolves: #2135047 --- find-provides.ksyms | 35 +++++++++++++++++++---------------- find-requires.ksyms | 37 ++++++++++++++++++++----------------- 2 files changed, 39 insertions(+), 33 deletions(-) diff --git a/find-provides.ksyms b/find-provides.ksyms index 9402623..aa656e1 100755 --- a/find-provides.ksyms +++ b/find-provides.ksyms @@ -42,23 +42,26 @@ for module in $(grep -E '/lib/modules/.+\.ko(\.gz|\.bz2|\.xz|\.zst)?$') "$@"; do 'match($0, /^([0-9a-f]+) A __crc_(.+)/, a) { printf("%s(%s) = 0x%08x\n", dep_pfx, a[2], strtonum("0x" a[1])) }' \ | sort -u else - ELFRODATA=$(readelf -R .rodata $module | awk '/0x/{printf $2$3$4$5}') - if [[ -n $(readelf -h $module | grep "little endian") ]]; then - RODATA=$(echo $ELFRODATA | sed 's/\(..\)\(..\)\(..\)\(..\)/\4\3\2\1/g') - else - RODATA=$ELFRODATA - fi - # Commit binutils-2_33~1385[1] has changed (and binutils-2_35~1768[2] - # has not reverted it) the calculated type for symbols in read-write - # .rodata section from 'R' to 'D', since, apparently, many kernel - # modules have it indeed read-write. - # - # [1] https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=a288c270991d - # [2] https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=49d9fd42acef - for sym in $(nm $module | sed -r -ne 's:^0*([0-9a-f]+) [DR] __crc_(.+):0x\1 \2:p'); do - echo $sym $RODATA + objdump -t "$module" \ + | sed -n 's/^[0-9a-f][0-9a-f]* g...... \(.*\) [0-9a-f][0-9a-f]* __crc_.*$/\1/p' \ + | sort -u \ + | while read sectname; do + [ -n "$sectname" ] || continue + + ELFSECTDATA=$(readelf -R "$sectname" "$module" | awk '/0x/{printf $2$3$4$5}') + if [[ -n $(readelf -h $module | grep "little endian") ]]; then + SECTDATA=$(echo $ELFSECTDATA | sed 's/\(..\)\(..\)\(..\)\(..\)/\4\3\2\1/g') + else + SECTDATA=$ELFSECTDATA + fi + + objdump -t "$module" \ + | awk \ + -v 'dep_pfx='"$dep_pfx" \ + -v 'sectdata='"$SECTDATA" \ + --non-decimal-data \ + 'match($0, /^([0-9a-f]+) g...... .* [0-9a-f]+ __crc_(.*)$/, a) { printf("%s(%s) = 0x%08s\n", dep_pfx, a[2], substr(sectdata, (strtonum("0x" a[1]) * 2) + 1, 8)) }' done \ - | awk --non-decimal-data '{printf("'"${dep_pfx}"'(%s) = 0x%08s\n", $2, substr($3,($1*2)+1,8))}' \ | sort -u fi diff --git a/find-requires.ksyms b/find-requires.ksyms index dafea97..6e176a4 100755 --- a/find-requires.ksyms +++ b/find-requires.ksyms @@ -42,23 +42,26 @@ all_provides() { --non-decimal-data \ 'match($0, /^([0-9a-f]+) A __crc_(.+)/, a) { printf("%s(%s) = 0x%08x\n", dep_pfx, a[2], strtonum("0x" a[1])) }' else - ELFRODATA=$(readelf -R .rodata "$module" | awk '/0x/{printf $2$3$4$5}') - if [[ -n $(readelf -h "$module" | grep "little endian") ]]; then - RODATA=$(echo $ELFRODATA | sed 's/\(..\)\(..\)\(..\)\(..\)/\4\3\2\1/g') - else - RODATA=$ELFRODATA - fi - # Commit binutils-2_33~1385[1] has changed (and binutils-2_35~1768[2] - # has not reverted it) the calculated type for symbols in read-write - # .rodata section from 'R' to 'D', since, apparently, many kernel - # modules have it indeed read-write. - # - # [1] https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=a288c270991d - # [2] https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=49d9fd42acef - for sym in $(nm "$module" | sed -r -ne 's:^0*([0-9a-f]+) [DR] __crc_(.+):0x\1 \2:p'); do - echo $sym $RODATA - done \ - | awk --non-decimal-data '{printf("%s:0x%08s\n", $2, substr($3,($1*2)+1,8))}' + objdump -t "$module" \ + | sed -n 's/^[0-9a-f][0-9a-f]* g...... \(.*\) [0-9a-f][0-9a-f]* __crc_.*$/\1/p' \ + | sort -u \ + | while read sectname; do + [ -n "$sectname" ] || continue + + ELFSECTDATA=$(readelf -R .rodata "$module" | awk '/0x/{printf $2$3$4$5}') + if [[ -n $(readelf -h "$module" | grep "little endian") ]]; then + SECTDATA=$(echo $ELFSECTDATA | sed 's/\(..\)\(..\)\(..\)\(..\)/\4\3\2\1/g') + else + SECTDATA=$ELFSECTDATA + fi + + objdump -t "$module" \ + | awk \ + -v 'dep_pfx='"$dep_pfx" \ + -v 'sectdata='"$SECTDATA" \ + --non-decimal-data \ + 'match($0, /^([0-9a-f]+) g...... .* [0-9a-f]+ __crc_(.*)$/, a) { printf("%s(%s) = 0x%08s\n", dep_pfx, a[2], substr(sectdata, (strtonum("0x" a[1]) * 2) + 1, 8)) }' + done fi [ -z "$tmpfile" ] || rm -f -- "$tmpfile"