On Mon, Feb 25, 2019 at 11:00 AM Arnaldo Carvalho de Melo
<arnaldo.melo@xxxxxxxxx> wrote:
>
> Em Mon, Feb 25, 2019 at 01:02:39PM -0300, Arnaldo Carvalho de Melo escreveu:
> > So yeah, the BTF encoder/decoder is working just fine, the problem is in
> > pahole's DWARF code, lemme see...
>
> Please try the patch below, for me btfdiff continues to show no diff for
> all types in my vmlinux and now it also produces the same output for
> when the first element of a bitfield has its bit_size equal to its
> byte_size * 8:
Yes, this fixes all the issues I've seen. btfdiff output is now empty
for my kernel image. Thanks for quick fix!
Reviewed-by: Andrii Nakryiko <andriin@xxxxxx>
>
> [acme@quaco pahole]$ btfdiff vmlinux
> [acme@quaco pahole]$ btfdiff examples/andrii/hsw_tsx_tuning-gcc
> [acme@quaco pahole]$ btfdiff examples/andrii/hsw_tsx_tuning-clang
> [acme@quaco pahole]$ pahole examples/andrii/hsw_tsx_tuning-clang
> union hsw_tsx_tuning {
> struct {
> u32 cycles_last_block; /* 0 4 */
> u32 hle_abort:1; /* 4:31 4 */
> u32 rtm_abort:1; /* 4:30 4 */
> u32 instruction_abort:1; /* 4:29 4 */
> u32 non_instruction_abort:1; /* 4:28 4 */
> u32 retry:1; /* 4:27 4 */
> u32 data_conflict:1; /* 4:26 4 */
> u32 capacity_writes:1; /* 4:25 4 */
> u32 capacity_reads:1; /* 4:24 4 */
> }; /* 0 8 */
> u64 value; /* 0 8 */
> };
> [acme@quaco pahole]$ pahole -F btf examples/andrii/hsw_tsx_tuning-clang
> union hsw_tsx_tuning {
> struct {
> u32 cycles_last_block; /* 0 4 */
> u32 hle_abort:1; /* 4:31 4 */
> u32 rtm_abort:1; /* 4:30 4 */
> u32 instruction_abort:1; /* 4:29 4 */
> u32 non_instruction_abort:1; /* 4:28 4 */
> u32 retry:1; /* 4:27 4 */
> u32 data_conflict:1; /* 4:26 4 */
> u32 capacity_writes:1; /* 4:25 4 */
> u32 capacity_reads:1; /* 4:24 4 */
> }; /* 0 8 */
> u64 value; /* 0 8 */
> };
> [acme@quaco pahole]$
>
> diff --git a/dwarf_loader.c b/dwarf_loader.c
> index adef437109f6..37477fb23be3 100644
> --- a/dwarf_loader.c
> +++ b/dwarf_loader.c
> @@ -607,7 +607,8 @@ static struct variable *variable__new(Dwarf_Die *die, struct cu *cu)
>
> int tag__recode_dwarf_bitfield(struct tag *tag, struct cu *cu, uint16_t bit_size)
> {
> - uint16_t id;
> + int id;
> + uint16_t short_id;
> struct tag *recoded;
> /* in all the cases the name is at the same offset */
> strings_t name = tag__namespace(tag)->name;
> @@ -620,7 +621,7 @@ int tag__recode_dwarf_bitfield(struct tag *tag, struct cu *cu, uint16_t bit_size
> struct tag *type = dtype->tag;
>
> id = tag__recode_dwarf_bitfield(type, cu, bit_size);
> - if (id == tag->type)
> + if (id < 0)
> return id;
>
> struct type *new_typedef = obstack_zalloc(&cu->obstack,
> @@ -660,10 +661,9 @@ int tag__recode_dwarf_bitfield(struct tag *tag, struct cu *cu, uint16_t bit_size
> * the dwarf_cu as in dwarf there are no such things
> * as base_types of less than 8 bits, etc.
> */
> - recoded = cu__find_base_type_by_sname_and_size(cu, name, bit_size, &id);
> + recoded = cu__find_base_type_by_sname_and_size(cu, name, bit_size, &short_id);
> if (recoded != NULL)
> - return id;
> -
> + return short_id;
>
> struct base_type *new_bt = obstack_zalloc(&cu->obstack,
> sizeof(*new_bt));
> @@ -683,10 +683,9 @@ int tag__recode_dwarf_bitfield(struct tag *tag, struct cu *cu, uint16_t bit_size
> * the dwarf_cu as in dwarf there are no such things
> * as enumeration_types of less than 8 bits, etc.
> */
> - recoded = cu__find_enumeration_by_sname_and_size(cu, name,
> - bit_size, &id);
> + recoded = cu__find_enumeration_by_sname_and_size(cu, name, bit_size, &short_id);
> if (recoded != NULL)
> - return id;
> + return short_id;
>
> struct type *alias = tag__type(tag);
> struct type *new_enum = obstack_zalloc(&cu->obstack, sizeof(*new_enum));
