| Message ID | 20231112124834.388735-11-alan.maguire@oracle.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | Add kind layout, CRCs to BTF | expand |
2023-11-12 12:49 UTC+0000 ~ Alan Maguire <alan.maguire@oracle.com> > Provide a way to dump BTF metadata info via bpftool; this > consists of BTF size, header fields and kind layout info > (if available); for example > > $ bpftool btf dump file vmlinux format meta > size 5161076 > magic 0xeb9f > version 1 > flags 0x1 > hdr_len 40 > type_len 3036368 > type_off 0 > str_len 2124588 > str_off 3036368 > kind_layout_len 80 > kind_layout_off 5160956 > crc 0x64af901b > base_crc 0x0 > kind 0 UNKNOWN flags 0x0 info_sz 0 elem_sz 0 > kind 1 INT flags 0x0 info_sz 0 elem_sz 0 > kind 2 PTR flags 0x0 info_sz 0 elem_sz 0 > kind 3 ARRAY flags 0x0 info_sz 0 elem_sz 0 > kind 4 STRUCT flags 0x35 info_sz 0 elem_sz 0 > ... > > JSON output is also supported: > > $ bpftool -j btf dump file vmlinux format meta > {"size":5161076,"header":{"magic":60319,"version":1,"flags":1,"hdr_len":40,"type_len":3036368,"type_off":0,"str_len":2124588,"str_off":3036368,"kind_layout_len":80,"kind_layout_offset":5160956,"crc":1689227291,"base_crc":0},"kind_layouts":[{"kind":0,"name":"UNKNOWN","flags":0,"info_sz":0,"elem_sz":0},{"kind":1,"name":"INT","flags":0,"info_sz":0,"elem_sz":0},{"kind":2,"name":"PTR","flags":0,"info_sz":0,"elem_sz":0},{"kind":3,"name":"ARRAY","flags":0,"info_sz":0,"elem_sz":0},{"kind":4,"name":"STRUCT","flags":53,"info_sz":0,"elem_sz":0},{"kind":5,"name":"UNION","flags":0,"info_sz":0,"elem_sz":0},{"kind":6,"name":"ENUM","flags":60319,"info_sz":1,"elem_sz":1},{"kind":7,"name":"FWD","flags":40,"info_sz":0,"elem_sz":0},{"kind":8,"name":"TYPEDEF","flags":0,"info_sz":0,"elem_sz":0},{"kind":9,"name":"VOLATILE","flags":0,"info_sz":0,"elem_sz":0},{"kind":10,"name":"CONST","flags":0,"info_sz":0,"elem_sz":0},{"kind":11,"name":"RESTRICT","flags":1,"info_sz":0,"elem_sz":0},{"kind":12,"name":"FUNC","flags":0,"info_sz":0,"elem_sz":0},{"kind":13,"name":"FUNC_PROTO","flags":80,"info_sz":0,"elem_sz":0},{"kind":14,"name":"VAR","flags":0,"info_sz":0,"elem_sz":0},{"kind":15,"name":"DATASEC","flags":0,"info_sz":0,"elem_sz":0},{"kind":16,"name":"FLOAT","flags":53,"info_sz":0,"elem_sz":0},{"kind":17,"name":"DECL_TAG","flags":0,"info_sz":0,"elem_sz":0},{"kind":18,"name":"TYPE_TAG","flags":11441,"info_sz":3,"elem_sz":0},{"kind":19,"name":"ENUM64","flags":0,"info_sz":0,"elem_sz":0}]} > > Signed-off-by: Alan Maguire <alan.maguire@oracle.com> > --- > tools/bpf/bpftool/bash-completion/bpftool | 2 +- > tools/bpf/bpftool/btf.c | 91 ++++++++++++++++++++++- > 2 files changed, 90 insertions(+), 3 deletions(-) > > diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool > index 6e4f7ce6bc01..157c3afd8247 100644 > --- a/tools/bpf/bpftool/bash-completion/bpftool > +++ b/tools/bpf/bpftool/bash-completion/bpftool > @@ -937,7 +937,7 @@ _bpftool() > return 0 > ;; > format) > - COMPREPLY=( $( compgen -W "c raw" -- "$cur" ) ) > + COMPREPLY=( $( compgen -W "c raw meta" -- "$cur" ) ) > ;; > *) > # emit extra options > diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c > index 91fcb75babe3..208f3a587534 100644 > --- a/tools/bpf/bpftool/btf.c > +++ b/tools/bpf/bpftool/btf.c > @@ -504,6 +504,88 @@ static int dump_btf_c(const struct btf *btf, > return err; > } > > +static int dump_btf_meta(const struct btf *btf) > +{ > + const struct btf_header *hdr; > + const struct btf_kind_layout *k; > + __u8 i, nr_kinds = 0; > + const void *data; > + __u32 data_sz; > + > + data = btf__raw_data(btf, &data_sz); > + if (!data) > + return -ENOMEM; > + hdr = data; > + if (json_output) { > + jsonw_start_object(json_wtr); /* btf metadata object */ Nit: Please make sure to be consistent when aligning these comments: there are several occurrences with spaces (here three spaces), several ones with tabs. For these, I'd prefer tabs to align the start and end comments for a given object/array, although I don't really using a single space as well as long as we keep it consistent. > + jsonw_uint_field(json_wtr, "size", data_sz); > + jsonw_name(json_wtr, "header"); > + jsonw_start_object(json_wtr); /* btf header object */ > + jsonw_uint_field(json_wtr, "magic", hdr->magic); > + jsonw_uint_field(json_wtr, "version", hdr->version); > + jsonw_uint_field(json_wtr, "flags", hdr->flags); > + jsonw_uint_field(json_wtr, "hdr_len", hdr->hdr_len); > + jsonw_uint_field(json_wtr, "type_len", hdr->type_len); > + jsonw_uint_field(json_wtr, "type_off", hdr->type_off); > + jsonw_uint_field(json_wtr, "str_len", hdr->str_len); > + jsonw_uint_field(json_wtr, "str_off", hdr->str_off); > + } else { > + printf("size %-10d\n", data_sz); > + printf("magic 0x%-10x\nversion %-10d\nflags 0x%-10x\nhdr_len %-10d\n", > + hdr->magic, hdr->version, hdr->flags, hdr->hdr_len); > + printf("type_len %-10d\ntype_off %-10d\n", hdr->type_len, hdr->type_off); > + printf("str_len %-10d\nstr_off %-10d\n", hdr->str_len, hdr->str_off); > + } > + > + if (hdr->hdr_len < sizeof(struct btf_header)) { > + if (json_output) { > + jsonw_end_object(json_wtr); /* header object */ > + jsonw_end_object(json_wtr); /* metadata object */ Similarly, can you please keep consistent comment strings? "metadata object" here vs. "end metadata" below. > + } > + return 0; > + } > + if (hdr->kind_layout_len > 0 && hdr->kind_layout_off > 0) { > + k = (void *)hdr + hdr->hdr_len + hdr->kind_layout_off; > + nr_kinds = hdr->kind_layout_len / sizeof(*k); > + } > + if (json_output) { > + jsonw_uint_field(json_wtr, "kind_layout_len", hdr->kind_layout_len); > + jsonw_uint_field(json_wtr, "kind_layout_offset", hdr->kind_layout_off); > + jsonw_uint_field(json_wtr, "crc", hdr->crc); > + jsonw_uint_field(json_wtr, "base_crc", hdr->base_crc); > + jsonw_end_object(json_wtr); /* end header object */ > + > + if (nr_kinds > 0) { > + jsonw_name(json_wtr, "kind_layouts"); > + jsonw_start_array(json_wtr); > + for (i = 0; i < nr_kinds; i++) { > + jsonw_start_object(json_wtr); > + jsonw_uint_field(json_wtr, "kind", i); > + if (i < NR_BTF_KINDS) > + jsonw_string_field(json_wtr, "name", btf_kind_str[i]); I prefer to avoid conditional fields in JSON, especially in an array it's easier to process the JSON if all items have the same structure. Would it make sense to keep the "name" field, but use jsonw_null() (or "UNKNOWN") for the value when there's no name to print? Thanks, Quentin
On 14/11/2023 05:10, Quentin Monnet wrote: > 2023-11-12 12:49 UTC+0000 ~ Alan Maguire <alan.maguire@oracle.com> >> Provide a way to dump BTF metadata info via bpftool; this >> consists of BTF size, header fields and kind layout info >> (if available); for example >> >> $ bpftool btf dump file vmlinux format meta >> size 5161076 >> magic 0xeb9f >> version 1 >> flags 0x1 >> hdr_len 40 >> type_len 3036368 >> type_off 0 >> str_len 2124588 >> str_off 3036368 >> kind_layout_len 80 >> kind_layout_off 5160956 >> crc 0x64af901b >> base_crc 0x0 >> kind 0 UNKNOWN flags 0x0 info_sz 0 elem_sz 0 >> kind 1 INT flags 0x0 info_sz 0 elem_sz 0 >> kind 2 PTR flags 0x0 info_sz 0 elem_sz 0 >> kind 3 ARRAY flags 0x0 info_sz 0 elem_sz 0 >> kind 4 STRUCT flags 0x35 info_sz 0 elem_sz 0 >> ... >> >> JSON output is also supported: >> >> $ bpftool -j btf dump file vmlinux format meta >> {"size":5161076,"header":{"magic":60319,"version":1,"flags":1,"hdr_len":40,"type_len":3036368,"type_off":0,"str_len":2124588,"str_off":3036368,"kind_layout_len":80,"kind_layout_offset":5160956,"crc":1689227291,"base_crc":0},"kind_layouts":[{"kind":0,"name":"UNKNOWN","flags":0,"info_sz":0,"elem_sz":0},{"kind":1,"name":"INT","flags":0,"info_sz":0,"elem_sz":0},{"kind":2,"name":"PTR","flags":0,"info_sz":0,"elem_sz":0},{"kind":3,"name":"ARRAY","flags":0,"info_sz":0,"elem_sz":0},{"kind":4,"name":"STRUCT","flags":53,"info_sz":0,"elem_sz":0},{"kind":5,"name":"UNION","flags":0,"info_sz":0,"elem_sz":0},{"kind":6,"name":"ENUM","flags":60319,"info_sz":1,"elem_sz":1},{"kind":7,"name":"FWD","flags":40,"info_sz":0,"elem_sz":0},{"kind":8,"name":"TYPEDEF","flags":0,"info_sz":0,"elem_sz":0},{"kind":9,"name":"VOLATILE","flags":0,"info_sz":0,"elem_sz":0},{"kind":10,"name":"CONST","flags":0,"info_sz":0,"elem_sz":0},{"kind":11,"name":"RESTRICT","flags":1,"info_sz":0,"elem_sz":0},{"kind":12,"name":"FUNC","flags":0,"info_sz":0,"elem_sz":0},{"kind":13,"name":"FUNC_PROTO","flags":80,"info_sz":0,"elem_sz":0},{"kind":14,"name":"VAR","flags":0,"info_sz":0,"elem_sz":0},{"kind":15,"name":"DATASEC","flags":0,"info_sz":0,"elem_sz":0},{"kind":16,"name":"FLOAT","flags":53,"info_sz":0,"elem_sz":0},{"kind":17,"name":"DECL_TAG","flags":0,"info_sz":0,"elem_sz":0},{"kind":18,"name":"TYPE_TAG","flags":11441,"info_sz":3,"elem_sz":0},{"kind":19,"name":"ENUM64","flags":0,"info_sz":0,"elem_sz":0}]} >> >> Signed-off-by: Alan Maguire <alan.maguire@oracle.com> >> --- >> tools/bpf/bpftool/bash-completion/bpftool | 2 +- >> tools/bpf/bpftool/btf.c | 91 ++++++++++++++++++++++- >> 2 files changed, 90 insertions(+), 3 deletions(-) >> >> diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool >> index 6e4f7ce6bc01..157c3afd8247 100644 >> --- a/tools/bpf/bpftool/bash-completion/bpftool >> +++ b/tools/bpf/bpftool/bash-completion/bpftool >> @@ -937,7 +937,7 @@ _bpftool() >> return 0 >> ;; >> format) >> - COMPREPLY=( $( compgen -W "c raw" -- "$cur" ) ) >> + COMPREPLY=( $( compgen -W "c raw meta" -- "$cur" ) ) >> ;; >> *) >> # emit extra options >> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c >> index 91fcb75babe3..208f3a587534 100644 >> --- a/tools/bpf/bpftool/btf.c >> +++ b/tools/bpf/bpftool/btf.c >> @@ -504,6 +504,88 @@ static int dump_btf_c(const struct btf *btf, >> return err; >> } >> >> +static int dump_btf_meta(const struct btf *btf) >> +{ >> + const struct btf_header *hdr; >> + const struct btf_kind_layout *k; >> + __u8 i, nr_kinds = 0; >> + const void *data; >> + __u32 data_sz; >> + >> + data = btf__raw_data(btf, &data_sz); >> + if (!data) >> + return -ENOMEM; >> + hdr = data; >> + if (json_output) { >> + jsonw_start_object(json_wtr); /* btf metadata object */ > > Nit: Please make sure to be consistent when aligning these comments: > there are several occurrences with spaces (here three spaces), several > ones with tabs. For these, I'd prefer tabs to align the start and end > comments for a given object/array, although I don't really using a > single space as well as long as we keep it consistent. > >> + jsonw_uint_field(json_wtr, "size", data_sz); >> + jsonw_name(json_wtr, "header"); >> + jsonw_start_object(json_wtr); /* btf header object */ >> + jsonw_uint_field(json_wtr, "magic", hdr->magic); >> + jsonw_uint_field(json_wtr, "version", hdr->version); >> + jsonw_uint_field(json_wtr, "flags", hdr->flags); >> + jsonw_uint_field(json_wtr, "hdr_len", hdr->hdr_len); >> + jsonw_uint_field(json_wtr, "type_len", hdr->type_len); >> + jsonw_uint_field(json_wtr, "type_off", hdr->type_off); >> + jsonw_uint_field(json_wtr, "str_len", hdr->str_len); >> + jsonw_uint_field(json_wtr, "str_off", hdr->str_off); >> + } else { >> + printf("size %-10d\n", data_sz); >> + printf("magic 0x%-10x\nversion %-10d\nflags 0x%-10x\nhdr_len %-10d\n", >> + hdr->magic, hdr->version, hdr->flags, hdr->hdr_len); >> + printf("type_len %-10d\ntype_off %-10d\n", hdr->type_len, hdr->type_off); >> + printf("str_len %-10d\nstr_off %-10d\n", hdr->str_len, hdr->str_off); >> + } >> + >> + if (hdr->hdr_len < sizeof(struct btf_header)) { >> + if (json_output) { >> + jsonw_end_object(json_wtr); /* header object */ >> + jsonw_end_object(json_wtr); /* metadata object */ > > Similarly, can you please keep consistent comment strings? "metadata > object" here vs. "end metadata" below. > Sure, I'll fix indent consistency/naming and the docs issue in the next revision. Thanks! >> + } >> + return 0; >> + } >> + if (hdr->kind_layout_len > 0 && hdr->kind_layout_off > 0) { >> + k = (void *)hdr + hdr->hdr_len + hdr->kind_layout_off; >> + nr_kinds = hdr->kind_layout_len / sizeof(*k); >> + } >> + if (json_output) { >> + jsonw_uint_field(json_wtr, "kind_layout_len", hdr->kind_layout_len); >> + jsonw_uint_field(json_wtr, "kind_layout_offset", hdr->kind_layout_off); >> + jsonw_uint_field(json_wtr, "crc", hdr->crc); >> + jsonw_uint_field(json_wtr, "base_crc", hdr->base_crc); >> + jsonw_end_object(json_wtr); /* end header object */ >> + >> + if (nr_kinds > 0) { >> + jsonw_name(json_wtr, "kind_layouts"); >> + jsonw_start_array(json_wtr); >> + for (i = 0; i < nr_kinds; i++) { >> + jsonw_start_object(json_wtr); >> + jsonw_uint_field(json_wtr, "kind", i); >> + if (i < NR_BTF_KINDS) >> + jsonw_string_field(json_wtr, "name", btf_kind_str[i]); > > I prefer to avoid conditional fields in JSON, especially in an array > it's easier to process the JSON if all items have the same structure. > Would it make sense to keep the "name" field, but use jsonw_null() (or > "UNKNOWN") for the value when there's no name to print? > The only thing about UNKNOWN is that there is a BTF_KIND_UNKN that is displayed as UNKNOWN; what about "?" to be consistent with the non-json output (or if there's another option of course, we could use that for both)? Thanks! Alan
On 15 November 2023 03:45:41 GMT-05:00, Alan Maguire <alan.maguire@oracle.com> wrote: >On 14/11/2023 05:10, Quentin Monnet wrote: >> 2023-11-12 12:49 UTC+0000 ~ Alan Maguire <alan.maguire@oracle.com> >>> Provide a way to dump BTF metadata info via bpftool; this >>> consists of BTF size, header fields and kind layout info >>> (if available); for example >>> >>> $ bpftool btf dump file vmlinux format meta >>> size 5161076 >>> magic 0xeb9f >>> version 1 >>> flags 0x1 >>> hdr_len 40 >>> type_len 3036368 >>> type_off 0 >>> str_len 2124588 >>> str_off 3036368 >>> kind_layout_len 80 >>> kind_layout_off 5160956 >>> crc 0x64af901b >>> base_crc 0x0 >>> kind 0 UNKNOWN flags 0x0 info_sz 0 elem_sz 0 >>> kind 1 INT flags 0x0 info_sz 0 elem_sz 0 >>> kind 2 PTR flags 0x0 info_sz 0 elem_sz 0 >>> kind 3 ARRAY flags 0x0 info_sz 0 elem_sz 0 >>> kind 4 STRUCT flags 0x35 info_sz 0 elem_sz 0 >>> ... >>> >>> JSON output is also supported: >>> >>> $ bpftool -j btf dump file vmlinux format meta >>> {"size":5161076,"header":{"magic":60319,"version":1,"flags":1,"hdr_len":40,"type_len":3036368,"type_off":0,"str_len":2124588,"str_off":3036368,"kind_layout_len":80,"kind_layout_offset":5160956,"crc":1689227291,"base_crc":0},"kind_layouts":[{"kind":0,"name":"UNKNOWN","flags":0,"info_sz":0,"elem_sz":0},{"kind":1,"name":"INT","flags":0,"info_sz":0,"elem_sz":0},{"kind":2,"name":"PTR","flags":0,"info_sz":0,"elem_sz":0},{"kind":3,"name":"ARRAY","flags":0,"info_sz":0,"elem_sz":0},{"kind":4,"name":"STRUCT","flags":53,"info_sz":0,"elem_sz":0},{"kind":5,"name":"UNION","flags":0,"info_sz":0,"elem_sz":0},{"kind":6,"name":"ENUM","flags":60319,"info_sz":1,"elem_sz":1},{"kind":7,"name":"FWD","flags":40,"info_sz":0,"elem_sz":0},{"kind":8,"name":"TYPEDEF","flags":0,"info_sz":0,"elem_sz":0},{"kind":9,"name":"VOLATILE","flags":0,"info_sz":0,"elem_sz":0},{"kind":10,"name":"CONST","flags":0,"info_sz":0,"elem_sz":0},{"kind":11,"name":"RESTRICT","flags":1,"info_sz":0,"elem_sz":0},{"kind":12,"name":"FUNC","flags":0,"info_sz":0,"elem_sz":0},{"kind":13,"name":"FUNC_PROTO","flags":80,"info_sz":0,"elem_sz":0},{"kind":14,"name":"VAR","flags":0,"info_sz":0,"elem_sz":0},{"kind":15,"name":"DATASEC","flags":0,"info_sz":0,"elem_sz":0},{"kind":16,"name":"FLOAT","flags":53,"info_sz":0,"elem_sz":0},{"kind":17,"name":"DECL_TAG","flags":0,"info_sz":0,"elem_sz":0},{"kind":18,"name":"TYPE_TAG","flags":11441,"info_sz":3,"elem_sz":0},{"kind":19,"name":"ENUM64","flags":0,"info_sz":0,"elem_sz":0}]} >>> >>> Signed-off-by: Alan Maguire <alan.maguire@oracle.com> >>> --- >>> tools/bpf/bpftool/bash-completion/bpftool | 2 +- >>> tools/bpf/bpftool/btf.c | 91 ++++++++++++++++++++++- >>> 2 files changed, 90 insertions(+), 3 deletions(-) >>> >>> diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool >>> index 6e4f7ce6bc01..157c3afd8247 100644 >>> --- a/tools/bpf/bpftool/bash-completion/bpftool >>> +++ b/tools/bpf/bpftool/bash-completion/bpftool >>> @@ -937,7 +937,7 @@ _bpftool() >>> return 0 >>> ;; >>> format) >>> - COMPREPLY=( $( compgen -W "c raw" -- "$cur" ) ) >>> + COMPREPLY=( $( compgen -W "c raw meta" -- "$cur" ) ) >>> ;; >>> *) >>> # emit extra options >>> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c >>> index 91fcb75babe3..208f3a587534 100644 >>> --- a/tools/bpf/bpftool/btf.c >>> +++ b/tools/bpf/bpftool/btf.c >>> @@ -504,6 +504,88 @@ static int dump_btf_c(const struct btf *btf, >>> return err; >>> } >>> >>> +static int dump_btf_meta(const struct btf *btf) >>> +{ >>> + const struct btf_header *hdr; >>> + const struct btf_kind_layout *k; >>> + __u8 i, nr_kinds = 0; >>> + const void *data; >>> + __u32 data_sz; >>> + >>> + data = btf__raw_data(btf, &data_sz); >>> + if (!data) >>> + return -ENOMEM; >>> + hdr = data; >>> + if (json_output) { >>> + jsonw_start_object(json_wtr); /* btf metadata object */ >> >> Nit: Please make sure to be consistent when aligning these comments: >> there are several occurrences with spaces (here three spaces), several >> ones with tabs. For these, I'd prefer tabs to align the start and end >> comments for a given object/array, although I don't really using a >> single space as well as long as we keep it consistent. >> >>> + jsonw_uint_field(json_wtr, "size", data_sz); >>> + jsonw_name(json_wtr, "header"); >>> + jsonw_start_object(json_wtr); /* btf header object */ >>> + jsonw_uint_field(json_wtr, "magic", hdr->magic); >>> + jsonw_uint_field(json_wtr, "version", hdr->version); >>> + jsonw_uint_field(json_wtr, "flags", hdr->flags); >>> + jsonw_uint_field(json_wtr, "hdr_len", hdr->hdr_len); >>> + jsonw_uint_field(json_wtr, "type_len", hdr->type_len); >>> + jsonw_uint_field(json_wtr, "type_off", hdr->type_off); >>> + jsonw_uint_field(json_wtr, "str_len", hdr->str_len); >>> + jsonw_uint_field(json_wtr, "str_off", hdr->str_off); >>> + } else { >>> + printf("size %-10d\n", data_sz); >>> + printf("magic 0x%-10x\nversion %-10d\nflags 0x%-10x\nhdr_len %-10d\n", >>> + hdr->magic, hdr->version, hdr->flags, hdr->hdr_len); >>> + printf("type_len %-10d\ntype_off %-10d\n", hdr->type_len, hdr->type_off); >>> + printf("str_len %-10d\nstr_off %-10d\n", hdr->str_len, hdr->str_off); >>> + } >>> + >>> + if (hdr->hdr_len < sizeof(struct btf_header)) { >>> + if (json_output) { >>> + jsonw_end_object(json_wtr); /* header object */ >>> + jsonw_end_object(json_wtr); /* metadata object */ >> >> Similarly, can you please keep consistent comment strings? "metadata >> object" here vs. "end metadata" below. >> > >Sure, I'll fix indent consistency/naming and the docs issue in the >next revision. Thanks! > >>> + } >>> + return 0; >>> + } >>> + if (hdr->kind_layout_len > 0 && hdr->kind_layout_off > 0) { >>> + k = (void *)hdr + hdr->hdr_len + hdr->kind_layout_off; >>> + nr_kinds = hdr->kind_layout_len / sizeof(*k); >>> + } >>> + if (json_output) { >>> + jsonw_uint_field(json_wtr, "kind_layout_len", hdr->kind_layout_len); >>> + jsonw_uint_field(json_wtr, "kind_layout_offset", hdr->kind_layout_off); >>> + jsonw_uint_field(json_wtr, "crc", hdr->crc); >>> + jsonw_uint_field(json_wtr, "base_crc", hdr->base_crc); >>> + jsonw_end_object(json_wtr); /* end header object */ >>> + >>> + if (nr_kinds > 0) { >>> + jsonw_name(json_wtr, "kind_layouts"); >>> + jsonw_start_array(json_wtr); >>> + for (i = 0; i < nr_kinds; i++) { >>> + jsonw_start_object(json_wtr); >>> + jsonw_uint_field(json_wtr, "kind", i); >>> + if (i < NR_BTF_KINDS) >>> + jsonw_string_field(json_wtr, "name", btf_kind_str[i]); >> >> I prefer to avoid conditional fields in JSON, especially in an array >> it's easier to process the JSON if all items have the same structure. >> Would it make sense to keep the "name" field, but use jsonw_null() (or >> "UNKNOWN") for the value when there's no name to print? >> > >The only thing about UNKNOWN is that there is a BTF_KIND_UNKN that >is displayed as UNKNOWN; what about "?" to be consistent with the >non-json output (or if there's another option of course, we could >use that for both)? Thanks! Right, sorry, I realised just after sending my message. In that case we could just use a 'null' value in JSON with jsonw_null()? The object '{"name": null}' is valid. The question mark is another possibility but requires comparing strings when parsing the JSON. Thanks, Quentin
On 15/11/2023 14:51, Quentin Monnet wrote: > > > On 15 November 2023 03:45:41 GMT-05:00, Alan Maguire <alan.maguire@oracle.com> wrote: >> On 14/11/2023 05:10, Quentin Monnet wrote: >>> 2023-11-12 12:49 UTC+0000 ~ Alan Maguire <alan.maguire@oracle.com> >>>> Provide a way to dump BTF metadata info via bpftool; this >>>> consists of BTF size, header fields and kind layout info >>>> (if available); for example >>>> >>>> $ bpftool btf dump file vmlinux format meta >>>> size 5161076 >>>> magic 0xeb9f >>>> version 1 >>>> flags 0x1 >>>> hdr_len 40 >>>> type_len 3036368 >>>> type_off 0 >>>> str_len 2124588 >>>> str_off 3036368 >>>> kind_layout_len 80 >>>> kind_layout_off 5160956 >>>> crc 0x64af901b >>>> base_crc 0x0 >>>> kind 0 UNKNOWN flags 0x0 info_sz 0 elem_sz 0 >>>> kind 1 INT flags 0x0 info_sz 0 elem_sz 0 >>>> kind 2 PTR flags 0x0 info_sz 0 elem_sz 0 >>>> kind 3 ARRAY flags 0x0 info_sz 0 elem_sz 0 >>>> kind 4 STRUCT flags 0x35 info_sz 0 elem_sz 0 >>>> ... >>>> >>>> JSON output is also supported: >>>> >>>> $ bpftool -j btf dump file vmlinux format meta >>>> {"size":5161076,"header":{"magic":60319,"version":1,"flags":1,"hdr_len":40,"type_len":3036368,"type_off":0,"str_len":2124588,"str_off":3036368,"kind_layout_len":80,"kind_layout_offset":5160956,"crc":1689227291,"base_crc":0},"kind_layouts":[{"kind":0,"name":"UNKNOWN","flags":0,"info_sz":0,"elem_sz":0},{"kind":1,"name":"INT","flags":0,"info_sz":0,"elem_sz":0},{"kind":2,"name":"PTR","flags":0,"info_sz":0,"elem_sz":0},{"kind":3,"name":"ARRAY","flags":0,"info_sz":0,"elem_sz":0},{"kind":4,"name":"STRUCT","flags":53,"info_sz":0,"elem_sz":0},{"kind":5,"name":"UNION","flags":0,"info_sz":0,"elem_sz":0},{"kind":6,"name":"ENUM","flags":60319,"info_sz":1,"elem_sz":1},{"kind":7,"name":"FWD","flags":40,"info_sz":0,"elem_sz":0},{"kind":8,"name":"TYPEDEF","flags":0,"info_sz":0,"elem_sz":0},{"kind":9,"name":"VOLATILE","flags":0,"info_sz":0,"elem_sz":0},{"kind":10,"name":"CONST","flags":0,"info_sz":0,"elem_sz":0},{"kind":11,"name":"RESTRICT","flags":1,"info_sz":0,"elem_sz":0},{"kind":12,"name":"FUNC","flags":0,"info_sz":0,"elem_sz":0},{"kind":13,"name":"FUNC_PROTO","flags":80,"info_sz":0,"elem_sz":0},{"kind":14,"name":"VAR","flags":0,"info_sz":0,"elem_sz":0},{"kind":15,"name":"DATASEC","flags":0,"info_sz":0,"elem_sz":0},{"kind":16,"name":"FLOAT","flags":53,"info_sz":0,"elem_sz":0},{"kind":17,"name":"DECL_TAG","flags":0,"info_sz":0,"elem_sz":0},{"kind":18,"name":"TYPE_TAG","flags":11441,"info_sz":3,"elem_sz":0},{"kind":19,"name":"ENUM64","flags":0,"info_sz":0,"elem_sz":0}]} >>>> >>>> Signed-off-by: Alan Maguire <alan.maguire@oracle.com> >>>> --- >>>> tools/bpf/bpftool/bash-completion/bpftool | 2 +- >>>> tools/bpf/bpftool/btf.c | 91 ++++++++++++++++++++++- >>>> 2 files changed, 90 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool >>>> index 6e4f7ce6bc01..157c3afd8247 100644 >>>> --- a/tools/bpf/bpftool/bash-completion/bpftool >>>> +++ b/tools/bpf/bpftool/bash-completion/bpftool >>>> @@ -937,7 +937,7 @@ _bpftool() >>>> return 0 >>>> ;; >>>> format) >>>> - COMPREPLY=( $( compgen -W "c raw" -- "$cur" ) ) >>>> + COMPREPLY=( $( compgen -W "c raw meta" -- "$cur" ) ) >>>> ;; >>>> *) >>>> # emit extra options >>>> diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c >>>> index 91fcb75babe3..208f3a587534 100644 >>>> --- a/tools/bpf/bpftool/btf.c >>>> +++ b/tools/bpf/bpftool/btf.c >>>> @@ -504,6 +504,88 @@ static int dump_btf_c(const struct btf *btf, >>>> return err; >>>> } >>>> >>>> +static int dump_btf_meta(const struct btf *btf) >>>> +{ >>>> + const struct btf_header *hdr; >>>> + const struct btf_kind_layout *k; >>>> + __u8 i, nr_kinds = 0; >>>> + const void *data; >>>> + __u32 data_sz; >>>> + >>>> + data = btf__raw_data(btf, &data_sz); >>>> + if (!data) >>>> + return -ENOMEM; >>>> + hdr = data; >>>> + if (json_output) { >>>> + jsonw_start_object(json_wtr); /* btf metadata object */ >>> >>> Nit: Please make sure to be consistent when aligning these comments: >>> there are several occurrences with spaces (here three spaces), several >>> ones with tabs. For these, I'd prefer tabs to align the start and end >>> comments for a given object/array, although I don't really using a >>> single space as well as long as we keep it consistent. >>> >>>> + jsonw_uint_field(json_wtr, "size", data_sz); >>>> + jsonw_name(json_wtr, "header"); >>>> + jsonw_start_object(json_wtr); /* btf header object */ >>>> + jsonw_uint_field(json_wtr, "magic", hdr->magic); >>>> + jsonw_uint_field(json_wtr, "version", hdr->version); >>>> + jsonw_uint_field(json_wtr, "flags", hdr->flags); >>>> + jsonw_uint_field(json_wtr, "hdr_len", hdr->hdr_len); >>>> + jsonw_uint_field(json_wtr, "type_len", hdr->type_len); >>>> + jsonw_uint_field(json_wtr, "type_off", hdr->type_off); >>>> + jsonw_uint_field(json_wtr, "str_len", hdr->str_len); >>>> + jsonw_uint_field(json_wtr, "str_off", hdr->str_off); >>>> + } else { >>>> + printf("size %-10d\n", data_sz); >>>> + printf("magic 0x%-10x\nversion %-10d\nflags 0x%-10x\nhdr_len %-10d\n", >>>> + hdr->magic, hdr->version, hdr->flags, hdr->hdr_len); >>>> + printf("type_len %-10d\ntype_off %-10d\n", hdr->type_len, hdr->type_off); >>>> + printf("str_len %-10d\nstr_off %-10d\n", hdr->str_len, hdr->str_off); >>>> + } >>>> + >>>> + if (hdr->hdr_len < sizeof(struct btf_header)) { >>>> + if (json_output) { >>>> + jsonw_end_object(json_wtr); /* header object */ >>>> + jsonw_end_object(json_wtr); /* metadata object */ >>> >>> Similarly, can you please keep consistent comment strings? "metadata >>> object" here vs. "end metadata" below. >>> >> >> Sure, I'll fix indent consistency/naming and the docs issue in the >> next revision. Thanks! >> >>>> + } >>>> + return 0; >>>> + } >>>> + if (hdr->kind_layout_len > 0 && hdr->kind_layout_off > 0) { >>>> + k = (void *)hdr + hdr->hdr_len + hdr->kind_layout_off; >>>> + nr_kinds = hdr->kind_layout_len / sizeof(*k); >>>> + } >>>> + if (json_output) { >>>> + jsonw_uint_field(json_wtr, "kind_layout_len", hdr->kind_layout_len); >>>> + jsonw_uint_field(json_wtr, "kind_layout_offset", hdr->kind_layout_off); >>>> + jsonw_uint_field(json_wtr, "crc", hdr->crc); >>>> + jsonw_uint_field(json_wtr, "base_crc", hdr->base_crc); >>>> + jsonw_end_object(json_wtr); /* end header object */ >>>> + >>>> + if (nr_kinds > 0) { >>>> + jsonw_name(json_wtr, "kind_layouts"); >>>> + jsonw_start_array(json_wtr); >>>> + for (i = 0; i < nr_kinds; i++) { >>>> + jsonw_start_object(json_wtr); >>>> + jsonw_uint_field(json_wtr, "kind", i); >>>> + if (i < NR_BTF_KINDS) >>>> + jsonw_string_field(json_wtr, "name", btf_kind_str[i]); >>> >>> I prefer to avoid conditional fields in JSON, especially in an array >>> it's easier to process the JSON if all items have the same structure. >>> Would it make sense to keep the "name" field, but use jsonw_null() (or >>> "UNKNOWN") for the value when there's no name to print? >>> >> >> The only thing about UNKNOWN is that there is a BTF_KIND_UNKN that >> is displayed as UNKNOWN; what about "?" to be consistent with the >> non-json output (or if there's another option of course, we could >> use that for both)? Thanks! > > Right, sorry, I realised just after sending my message. > In that case we could just use a 'null' value in JSON with jsonw_null()? The object '{"name": null}' is valid. The question mark is another possibility but requires comparing strings when parsing the JSON. > Great idea! I'll use jsonw_null() for the next version. I think given the fact we're not sure about the way forward on CRCs and standalone BTF I'll probably just separate out the kind layout stuff + bpftool dump meta parts since I _think_ at this point those pieces are relatively uncontroversial. Thanks again for the reviews Quentin! Alan > Thanks, > Quentin
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool index 6e4f7ce6bc01..157c3afd8247 100644 --- a/tools/bpf/bpftool/bash-completion/bpftool +++ b/tools/bpf/bpftool/bash-completion/bpftool @@ -937,7 +937,7 @@ _bpftool() return 0 ;; format) - COMPREPLY=( $( compgen -W "c raw" -- "$cur" ) ) + COMPREPLY=( $( compgen -W "c raw meta" -- "$cur" ) ) ;; *) # emit extra options diff --git a/tools/bpf/bpftool/btf.c b/tools/bpf/bpftool/btf.c index 91fcb75babe3..208f3a587534 100644 --- a/tools/bpf/bpftool/btf.c +++ b/tools/bpf/bpftool/btf.c @@ -504,6 +504,88 @@ static int dump_btf_c(const struct btf *btf, return err; } +static int dump_btf_meta(const struct btf *btf) +{ + const struct btf_header *hdr; + const struct btf_kind_layout *k; + __u8 i, nr_kinds = 0; + const void *data; + __u32 data_sz; + + data = btf__raw_data(btf, &data_sz); + if (!data) + return -ENOMEM; + hdr = data; + if (json_output) { + jsonw_start_object(json_wtr); /* btf metadata object */ + jsonw_uint_field(json_wtr, "size", data_sz); + jsonw_name(json_wtr, "header"); + jsonw_start_object(json_wtr); /* btf header object */ + jsonw_uint_field(json_wtr, "magic", hdr->magic); + jsonw_uint_field(json_wtr, "version", hdr->version); + jsonw_uint_field(json_wtr, "flags", hdr->flags); + jsonw_uint_field(json_wtr, "hdr_len", hdr->hdr_len); + jsonw_uint_field(json_wtr, "type_len", hdr->type_len); + jsonw_uint_field(json_wtr, "type_off", hdr->type_off); + jsonw_uint_field(json_wtr, "str_len", hdr->str_len); + jsonw_uint_field(json_wtr, "str_off", hdr->str_off); + } else { + printf("size %-10d\n", data_sz); + printf("magic 0x%-10x\nversion %-10d\nflags 0x%-10x\nhdr_len %-10d\n", + hdr->magic, hdr->version, hdr->flags, hdr->hdr_len); + printf("type_len %-10d\ntype_off %-10d\n", hdr->type_len, hdr->type_off); + printf("str_len %-10d\nstr_off %-10d\n", hdr->str_len, hdr->str_off); + } + + if (hdr->hdr_len < sizeof(struct btf_header)) { + if (json_output) { + jsonw_end_object(json_wtr); /* header object */ + jsonw_end_object(json_wtr); /* metadata object */ + } + return 0; + } + if (hdr->kind_layout_len > 0 && hdr->kind_layout_off > 0) { + k = (void *)hdr + hdr->hdr_len + hdr->kind_layout_off; + nr_kinds = hdr->kind_layout_len / sizeof(*k); + } + if (json_output) { + jsonw_uint_field(json_wtr, "kind_layout_len", hdr->kind_layout_len); + jsonw_uint_field(json_wtr, "kind_layout_offset", hdr->kind_layout_off); + jsonw_uint_field(json_wtr, "crc", hdr->crc); + jsonw_uint_field(json_wtr, "base_crc", hdr->base_crc); + jsonw_end_object(json_wtr); /* end header object */ + + if (nr_kinds > 0) { + jsonw_name(json_wtr, "kind_layouts"); + jsonw_start_array(json_wtr); + for (i = 0; i < nr_kinds; i++) { + jsonw_start_object(json_wtr); + jsonw_uint_field(json_wtr, "kind", i); + if (i < NR_BTF_KINDS) + jsonw_string_field(json_wtr, "name", btf_kind_str[i]); + jsonw_uint_field(json_wtr, "flags", k[i].flags); + jsonw_uint_field(json_wtr, "info_sz", k[i].info_sz); + jsonw_uint_field(json_wtr, "elem_sz", k[i].elem_sz); + jsonw_end_object(json_wtr); + } + jsonw_end_array(json_wtr); + } + jsonw_end_object(json_wtr); /* end metadata */ + } else { + printf("kind_layout_len %-10d\nkind_layout_off %-10d\n", + hdr->kind_layout_len, hdr->kind_layout_off); + printf("crc 0x%-10x\nbase_crc 0x%-10x\n", + hdr->crc, hdr->base_crc); + for (i = 0; i < nr_kinds; i++) { + printf("kind %-4d %-10s flags 0x%-4x info_sz %-4d elem_sz %-4d\n", + i, i < NR_BTF_KINDS ? btf_kind_str[i] : "?", + k[i].flags, k[i].info_sz, k[i].elem_sz); + } + } + + return 0; +} + static const char sysfs_vmlinux[] = "/sys/kernel/btf/vmlinux"; static struct btf *get_vmlinux_btf_from_sysfs(void) @@ -553,6 +635,7 @@ static int do_dump(int argc, char **argv) __u32 root_type_ids[2]; int root_type_cnt = 0; bool dump_c = false; + bool dump_meta = false; __u32 btf_id = -1; const char *src; int fd = -1; @@ -654,10 +737,12 @@ static int do_dump(int argc, char **argv) } if (strcmp(*argv, "c") == 0) { dump_c = true; + } else if (is_prefix(*argv, "meta")) { + dump_meta = true; } else if (strcmp(*argv, "raw") == 0) { dump_c = false; } else { - p_err("unrecognized format specifier: '%s', possible values: raw, c", + p_err("unrecognized format specifier: '%s', possible values: raw, c, meta", *argv); err = -EINVAL; goto done; @@ -692,6 +777,8 @@ static int do_dump(int argc, char **argv) goto done; } err = dump_btf_c(btf, root_type_ids, root_type_cnt); + } else if (dump_meta) { + err = dump_btf_meta(btf); } else { err = dump_btf_raw(btf, root_type_ids, root_type_cnt); } @@ -1063,7 +1150,7 @@ static int do_help(int argc, char **argv) " %1$s %2$s help\n" "\n" " BTF_SRC := { id BTF_ID | prog PROG | map MAP [{key | value | kv | all}] | file FILE }\n" - " FORMAT := { raw | c }\n" + " FORMAT := { raw | c | meta }\n" " " HELP_SPEC_MAP "\n" " " HELP_SPEC_PROGRAM "\n" " " HELP_SPEC_OPTIONS " |\n"
Provide a way to dump BTF metadata info via bpftool; this consists of BTF size, header fields and kind layout info (if available); for example $ bpftool btf dump file vmlinux format meta size 5161076 magic 0xeb9f version 1 flags 0x1 hdr_len 40 type_len 3036368 type_off 0 str_len 2124588 str_off 3036368 kind_layout_len 80 kind_layout_off 5160956 crc 0x64af901b base_crc 0x0 kind 0 UNKNOWN flags 0x0 info_sz 0 elem_sz 0 kind 1 INT flags 0x0 info_sz 0 elem_sz 0 kind 2 PTR flags 0x0 info_sz 0 elem_sz 0 kind 3 ARRAY flags 0x0 info_sz 0 elem_sz 0 kind 4 STRUCT flags 0x35 info_sz 0 elem_sz 0 ... JSON output is also supported: $ bpftool -j btf dump file vmlinux format meta {"size":5161076,"header":{"magic":60319,"version":1,"flags":1,"hdr_len":40,"type_len":3036368,"type_off":0,"str_len":2124588,"str_off":3036368,"kind_layout_len":80,"kind_layout_offset":5160956,"crc":1689227291,"base_crc":0},"kind_layouts":[{"kind":0,"name":"UNKNOWN","flags":0,"info_sz":0,"elem_sz":0},{"kind":1,"name":"INT","flags":0,"info_sz":0,"elem_sz":0},{"kind":2,"name":"PTR","flags":0,"info_sz":0,"elem_sz":0},{"kind":3,"name":"ARRAY","flags":0,"info_sz":0,"elem_sz":0},{"kind":4,"name":"STRUCT","flags":53,"info_sz":0,"elem_sz":0},{"kind":5,"name":"UNION","flags":0,"info_sz":0,"elem_sz":0},{"kind":6,"name":"ENUM","flags":60319,"info_sz":1,"elem_sz":1},{"kind":7,"name":"FWD","flags":40,"info_sz":0,"elem_sz":0},{"kind":8,"name":"TYPEDEF","flags":0,"info_sz":0,"elem_sz":0},{"kind":9,"name":"VOLATILE","flags":0,"info_sz":0,"elem_sz":0},{"kind":10,"name":"CONST","flags":0,"info_sz":0,"elem_sz":0},{"kind":11,"name":"RESTRICT","flags":1,"info_sz":0,"elem_sz":0},{"kind":12,"name":"FUNC","flags":0,"info_sz":0,"elem_sz":0},{"kind":13,"name":"FUNC_PROTO","flags":80,"info_sz":0,"elem_sz":0},{"kind":14,"name":"VAR","flags":0,"info_sz":0,"elem_sz":0},{"kind":15,"name":"DATASEC","flags":0,"info_sz":0,"elem_sz":0},{"kind":16,"name":"FLOAT","flags":53,"info_sz":0,"elem_sz":0},{"kind":17,"name":"DECL_TAG","flags":0,"info_sz":0,"elem_sz":0},{"kind":18,"name":"TYPE_TAG","flags":11441,"info_sz":3,"elem_sz":0},{"kind":19,"name":"ENUM64","flags":0,"info_sz":0,"elem_sz":0}]} Signed-off-by: Alan Maguire <alan.maguire@oracle.com> --- tools/bpf/bpftool/bash-completion/bpftool | 2 +- tools/bpf/bpftool/btf.c | 91 ++++++++++++++++++++++- 2 files changed, 90 insertions(+), 3 deletions(-)