On 10/15/21 2:08 PM, Arnaldo Carvalho de Melo wrote:
Em Thu, Oct 14, 2021 at 12:48:49PM +0100, Douglas RAILLARD escreveu:From: Douglas Raillard <douglas.raillard@xxxxxxx> This code: struct X { struct { } __attribute__((foo)) x __attribute__((bar)); } Was wrongly printed as: struct X { struct { } x __attribute__((foo)) __attribute__((bar)); } This unfortunately matters a lot, since "bar" is suppose to apply to "x", but "foo" to typeof(x). In the wrong form, both apply to "x", leading to e.g. incorrect layout for __aligned__ attribute.I couldn't quickly find a change in behaviour with a random vmlinux I have for testing: ⬢[acme@toolbox pahole]$ build/pahole.old -F dwarf vmlinux > before ⬢[acme@toolbox pahole]$ build/pahole -F dwarf vmlinux > after ⬢[acme@toolbox pahole]$ diff -u before after ⬢[acme@toolbox pahole]$ grep "__attribute__.*__attribute__" before | wc -l 40
That's strange, I get plenty of diff such as this one from struct cfs_rq: - } removed __attribute__((__aligned__(64))) __attribute__((__aligned__(64))); /* 192 128 */ + } __attribute__((__aligned__(64))) removed __attribute__((__aligned__(64))); /* 192 128 */
⬢[acme@toolbox pahole]$ btdiff is happy tho:
Same on my side
⬢[acme@toolbox pahole]$ btfdiff vmlinux
⬢[acme@toolbox pahole]$ cat btfdiff
#!/bin/bash
# SPDX-License-Identifier: GPL-2.0-only
# Copyright © 2019 Red Hat Inc, Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
# Use pahole to produce output from BTF and from DWARF, then do a diff
# Use --flat_arrays with DWARF as BTF, like CTF, flattens arrays.
# Use --show_private_classes as BTF shows all structs, while pahole knows
# if some struct is defined only inside another struct/class or in a function,
# this information is not available when loading from BTF.
if [ $# -eq 0 ] ; then
echo "Usage: btfdiff <filename_with_DWARF_and_maybe_BTF_info> [<filename_with_BTF_info>]"
exit 1
fi
dwarf_input=$1
btf_input=$dwarf_input
if [ $# -eq 2 ] ; then
btf_input=$2
fi
btf_output=$(mktemp /tmp/btfdiff.btf.XXXXXX)
dwarf_output=$(mktemp /tmp/btfdiff.dwarf.XXXXXX)
pahole_bin=${PAHOLE-"pahole"}
${pahole_bin} -F dwarf \
--flat_arrays \
--sort \
--jobs \
--suppress_aligned_attribute \
--suppress_force_paddings \
--suppress_packed \
--show_private_classes $dwarf_input > $dwarf_output
${pahole_bin} -F btf \
--sort \
--suppress_packed \
$btf_input > $btf_output
diff -up $dwarf_output $btf_output
rm -f $btf_output $dwarf_output
exit 0
⬢[acme@toolbox pahole]$
As is fullcircle:
I tried fullcircle on the whole vmlinux and got a bunch of: readelf: Error: LEB value too large but beyond that it seems happy.
⬢[acme@toolbox pahole]$ fullcircle tcp.o ⬢[acme@toolbox pahole]$ cat fullcircle #!/bin/bash # SPDX-License-Identifier: GPL-2.0-only # Copyright © 2019 Red Hat Inc, Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> # Use pfunct to produce compilable output from a object, then do a codiff -s # To see if the type information generated from source code generated # from type information in a file compiled from the original source code matches. if [ $# -eq 0 ] ; then echo "Usage: fullcircle <filename_with_type_info>" exit 1 fi file=$1 nr_cus=$(readelf -wi ${file} | grep DW_TAG_compile_unit | wc -l) if [ $nr_cus -gt 1 ]; then exit 0 fi c_output=$(mktemp /tmp/fullcircle.XXXXXX.c) o_output=$(mktemp /tmp/fullcircle.XXXXXX.o) pfunct_bin=${PFUNCT-"pfunct"} codiff_bin=${CODIFF-"codiff"} # See how your DW_AT_producer looks like and find the # right regexp to get after the GCC version string, this one # seems good enough for Red Hat/Fedora/CentOS that look like: # # DW_AT_producer : (indirect string, offset: 0x3583): GNU C89 8.2.1 20181215 (Red Hat 8.2.1-6) -mno-sse -mno-mmx # # So we need from -mno-sse onwards CFLAGS=$(readelf -wi $file | grep -w DW_AT_producer | sed -r 's/.*\)( -[[:alnum:]]+.*)+/\1/g') # Check if we managed to do the sed or if this is something like GNU AS [ "${CFLAGS/DW_AT_producer/}" != "${CFLAGS}" ] && exit ${pfunct_bin} --compile $file > $c_output gcc $CFLAGS -c -g $c_output -o $o_output ${codiff_bin} -q -s $file $o_output rm -f $c_output $o_output exit 0 ⬢[acme@toolbox pahole]$ - ArnaldoSigned-off-by: Douglas Raillard <douglas.raillard@xxxxxxx> --- dwarves_fprintf.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/dwarves_fprintf.c b/dwarves_fprintf.c index c35868a..1c1d949 100644 --- a/dwarves_fprintf.c +++ b/dwarves_fprintf.c @@ -787,7 +787,7 @@ print_default: (type->tag == DW_TAG_class_type && !tconf.classes_as_structs) ? "class" : "struct", tconf.type_spacing - 7, - type__name(ctype), name); + type__name(ctype), name ?: ""); } else { struct class *cclass = tag__class(type);@@ -802,7 +802,7 @@ print_default:ctype = tag__type(type);if (type__name(ctype) != NULL && !expand_types) {- printed += fprintf(fp, "union %-*s %s", tconf.type_spacing - 6, type__name(ctype), name); + printed += fprintf(fp, "union %-*s %s", tconf.type_spacing - 6, type__name(ctype), name ?: ""); } else { tconf.type_spacing -= 8; printed += union__fprintf(ctype, cu, &tconf, fp); @@ -812,7 +812,7 @@ print_default: ctype = tag__type(type);if (type__name(ctype) != NULL)- printed += fprintf(fp, "enum %-*s %s", tconf.type_spacing - 5, type__name(ctype), name); + printed += fprintf(fp, "enum %-*s %s", tconf.type_spacing - 5, type__name(ctype), name ?: ""); else printed += enumeration__fprintf(type, &tconf, fp); break; @@ -863,7 +863,21 @@ static size_t class_member__fprintf(struct class_member *member, bool union_memb if (member->is_static) printed += fprintf(fp, "static ");- printed += type__fprintf(type, cu, name, &sconf, fp);+ /* For struct-like constructs, the name of the member cannot be + * conflated with the name of its type, otherwise __attribute__ are + * printed in the wrong order. + */ + if (tag__is_union(type) || tag__is_struct(type) || + tag__is_enumeration(type)) { + printed += type__fprintf(type, cu, NULL, &sconf, fp); + if (name) { + if (!type__name(tag__type(type))) + printed += fprintf(fp, " "); + printed += fprintf(fp, "%s", name); + } + } else { + printed += type__fprintf(type, cu, name, &sconf, fp); + }if (member->is_static) {if (member->const_value != 0) -- 2.25.1
