Messages in this thread | | | Date | Tue, 10 Jul 2018 16:05:14 +0100 | From | Okash Khawaja <> | Subject | Re: [PATCH bpf-next v3 2/3] bpf: btf: add btf print functionality |
| |
On Mon, Jul 09, 2018 at 08:56:12PM -0700, Jakub Kicinski wrote: > On Sun, 8 Jul 2018 13:30:04 -0700, Okash Khawaja wrote: > > This consumes functionality exported in the previous patch. It does the > > main job of printing with BTF data. This is used in the following patch > > to provide a more readable output of a map's dump. It relies on > > json_writer to do json printing. Below is sample output where map keys > > are ints and values are of type struct A: > > > > typedef int int_type; > > enum E { > > E0, > > E1, > > }; > > > > struct B { > > int x; > > int y; > > }; > > > > struct A { > > int m; > > unsigned long long n; > > char o; > > int p[8]; > > int q[4][8]; > > enum E r; > > void *s; > > struct B t; > > const int u; > > int_type v; > > unsigned int w1: 3; > > unsigned int w2: 3; > > }; > > > > $ sudo bpftool map dump id 14 > > [{ > > "key": 0, > > "value": { > > "m": 1, > > "n": 2, > > "o": "c", > > "p": [15,16,17,18,15,16,17,18 > > ], > > "q": [[25,26,27,28,25,26,27,28 > > ],[35,36,37,38,35,36,37,38 > > ],[45,46,47,48,45,46,47,48 > > ],[55,56,57,58,55,56,57,58 > > ] > > ], > > "r": 1, > > "s": 0x7ffd80531cf8, > > "t": { > > "x": 5, > > "y": 10 > > }, > > "u": 100, > > "v": 20, > > "w1": 0x7, > > "w2": 0x3 > > } > > } > > ] > > > > This patch uses json's {} and [] to imply struct/union and array. More > > explicit information can be added later. For example, a command line > > option can be introduced to print whether a key or value is struct > > or union, name of a struct etc. This will however come at the expense > > of duplicating info when, for example, printing an array of structs. > > enums are printed as ints without their names. > > > > Signed-off-by: Okash Khawaja <osk@fb.com> > > Acked-by: Martin KaFai Lau <kafai@fb.com> > > > > --- > > tools/bpf/bpftool/btf_dumper.c | 253 +++++++++++++++++++++++++++++++++++++++++ > > tools/bpf/bpftool/main.h | 15 ++ > > 2 files changed, 268 insertions(+) > > > > --- /dev/null > > +++ b/tools/bpf/bpftool/btf_dumper.c > > @@ -0,0 +1,253 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* Copyright (c) 2018 Facebook */ > > + > > +#include <linux/btf.h> > > +#include <linux/err.h> > > +#include <stdio.h> /* for (FILE *) used by json_writer */ > > +#include <linux/bitops.h> > > +#include <string.h> > > +#include <ctype.h> > > fwiw: the preferred ordering would have been: > > #include <ctype.h> > #include <stdio.h> /* for (FILE *) used by json_writer */ > #include <string.h> > #include <linux/bitops.h> > #include <linux/btf.h> > #include <linux/err.h> > > > +#include "btf.h" > > +#include "json_writer.h" > > +#include "main.h" > > + > > +#define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1) > > +#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK) > > +#define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3) > > +#define BITS_ROUNDUP_BYTES(bits) \ > > + (BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits)) > > +const int one = 1; > > +#define is_big_endian() ((*(char *)&one) == 0) > > Could we try to do this at compilation time? Without the variable? :( > > #include <asm/byteorder.h> > > #if defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN) > return true; > #else > return false; > #endif > > We could also just include endian.h, but since it's a non-standard > extension perhaps using kernel header is a safer bet. > > > +static int btf_dumper_do_type(const struct btf_dumper *d, __u32 type_id, > > + __u8 bit_offset, const void *data); > > + > > +static void btf_dumper_ptr(const void *data, json_writer_t *jw, > > + bool is_plain_text) > > +{ > > + if (is_plain_text) > > + jsonw_printf(jw, "%p", *((unsigned long *)data)); > > + else > > + jsonw_printf(jw, "%u", *((unsigned long *)data)); > > nit: I think you missed these parenthesis > > > +} > > + > > > +static void btf_dumper_int_bits(__u32 int_type, __u8 bit_offset, > > + const void *data, json_writer_t *jw, > > + bool is_plain_text) > > +{ > > + int left_shift_bits, right_shift_bits; > > + int nr_bits = BTF_INT_BITS(int_type); > > + int total_bits_offset; > > + int bytes_to_copy; > > + int bits_to_copy; > > + __u64 print_num; > > + > > + total_bits_offset = bit_offset + BTF_INT_OFFSET(int_type); > > + data += BITS_ROUNDDOWN_BYTES(total_bits_offset); > > + bit_offset = BITS_PER_BYTE_MASKED(total_bits_offset); > > + bits_to_copy = bit_offset + nr_bits; > > + bytes_to_copy = BITS_ROUNDUP_BYTES(bits_to_copy); > > + > > + print_num = 0; > > + memcpy(&print_num, data, bytes_to_copy); > > + if (is_big_endian()) { > > + left_shift_bits = bit_offset; > > + right_shift_bits = 64 - nr_bits; > > + } else { > > + left_shift_bits = 64 - bits_to_copy; > > + right_shift_bits = 64 - nr_bits; > > + } > > Or you can just put the #if here, since it's the only use. > > > + print_num <<= left_shift_bits; > > + print_num >>= right_shift_bits; > > + if (is_plain_text) > > + jsonw_printf(jw, "0x%llx", print_num); > > + else > > + jsonw_printf(jw, "%llu", print_num); > > +} > > + > > +static int btf_dumper_int(const struct btf_type *t, __u8 bit_offset, > > + const void *data, json_writer_t *jw, > > + bool is_plain_text) > > +{ > > + __u32 *int_type; > > + __u32 nr_bits; > > + > > + int_type = (__u32 *)(t + 1); > > + nr_bits = BTF_INT_BITS(*int_type); > > + /* if this is bit field */ > > + if (bit_offset || BTF_INT_OFFSET(*int_type) || > > + BITS_PER_BYTE_MASKED(nr_bits)) { > > + btf_dumper_int_bits(*int_type, bit_offset, data, jw, > > + is_plain_text); > > + return 0; > > + } > > + > > + switch (BTF_INT_ENCODING(*int_type)) { > > + case 0: > > + if (BTF_INT_BITS(*int_type) == 64) > > + jsonw_printf(jw, "%lu", *((__u64 *)data)); > > nit: more parenthesis here > > > + else if (BTF_INT_BITS(*int_type) == 32) > > + jsonw_printf(jw, "%u", *((__u32 *)data)); > > + else if (BTF_INT_BITS(*int_type) == 16) > > + jsonw_printf(jw, "%hu", *((__u16 *)data)); > > + else if (BTF_INT_BITS(*int_type) == 8) > > + jsonw_printf(jw, "%hhu", *((__u8 *)data)); > > + else > > + btf_dumper_int_bits(*int_type, bit_offset, data, jw, > > + is_plain_text); > > + break; > > + case BTF_INT_SIGNED: > > + if (BTF_INT_BITS(*int_type) == 64) > > + jsonw_printf(jw, "%ld", *((long long *)data)); > > + else if (BTF_INT_BITS(*int_type) == 32) > > + jsonw_printf(jw, "%d", *((int *)data)); > > + else if (BTF_INT_BITS(*int_type) == 16) > > + jsonw_printf(jw, "%hd", *((short *)data)); > > + else if (BTF_INT_BITS(*int_type) == 8) > > + jsonw_printf(jw, "%hhd", *((char *)data)); > > + else > > + btf_dumper_int_bits(*int_type, bit_offset, data, jw, > > + is_plain_text); > > + break; > > + case BTF_INT_CHAR: > > + if (*((char *)data) == '\0') > > nit: here too, etc.. > > > + jsonw_null(jw); > > I don't think the null is good. I thought I mentioned that? yes! i intended but missed doing that amongst the several other changes :)
> Look for > example at Python: > > >>> import json > >>> thing = json.loads('{"a": [97, 98, 99, 100]}') > >>> bytearray(thing["str"]).decode('utf-8') > 'abcd' > >>> "".join(map(chr, thing["str"])) > 'abcd' > >>> thing = json.loads('{"str": [97, 98, 99, 100, null]}') > >>> bytearray(thing["str"]).decode('utf-8') > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > TypeError: an integer is required > >>> "".join(map(chr, thing["str"])) > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > TypeError: an integer is required (got type NoneType) > > If you start putting nulls into the array the conversion to a string > will become more difficult, won't it? Do you have a use case where > this helps? Maybe my Python-foo is not strong enough? > > > + else if (isprint(*((char *)data))) > > + jsonw_printf(jw, "\"%c\"", *((char *)data)); > > + else > > + if (is_plain_text) > > + jsonw_printf(jw, "0x%hhx", *((char *)data)); > > + else > > + jsonw_printf(jw, "\"\\u00%02hhx\"", > > + *((char *)data)); > > + break; > > + case BTF_INT_BOOL: > > + jsonw_bool(jw, *((int *)data)); > > + break; > > + default: > > + /* shouldn't happen */ > > + return -EINVAL; > > + } > > + > > + return 0; > > +} > > + > > +static int btf_dumper_struct(const struct btf_dumper *d, __u32 type_id, > > + const void *data) > > +{ > > + const struct btf_type *t; > > + struct btf_member *m; > > + int ret = 0; > > + int i, vlen; > > + > > + t = btf__type_by_id(d->btf, type_id); > > + if (!t) > > + return -EINVAL; > > + > > + vlen = BTF_INFO_VLEN(t->info); > > + jsonw_start_object(d->jw); > > + m = (struct btf_member *)(t + 1); > > + > > + for (i = 0; i < vlen; i++) { > > + const void *data_off = data + > > + BITS_ROUNDDOWN_BYTES(m[i].offset); > > nit: empty line between variable declaration and code, perhaps also > don't init inline since it doesn't fit that way? > > > + jsonw_name(d->jw, btf__name_by_offset(d->btf, m[i].name_off)); > > + ret = btf_dumper_do_type(d, m[i].type, > > + BITS_PER_BYTE_MASKED(m[i].offset), > > + data_off); > > + if (ret) > > + break; > > + } > > + > > + jsonw_end_object(d->jw); > > + > > + return ret; > > +} > > Thanks for all the changes you've made so far!
| |