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
⬢[acme@toolbox pahole]$
btdiff is happy tho:
⬢[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:
⬢[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 $o_output
exit 0
⬢[acme@toolbox pahole]$
- Arnaldo
> Signed-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
--
- Arnaldo
