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Thu, 19 Jun 2025 00:34:15 -0700 (PDT) Message-ID: <9bb199046f0b55ea4952ee028fc242db7a56bcc3.camel@gmail.com> Subject: Re: [PATCH bpf-next v4 2/3] selftests/bpf: support array presets in veristat From: Eduard Zingerman To: Mykyta Yatsenko , bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, kafai@meta.com, kernel-team@meta.com Cc: Mykyta Yatsenko Date: Thu, 19 Jun 2025 00:34:13 -0700 In-Reply-To: <20250618203903.539270-3-mykyta.yatsenko5@gmail.com> References: <20250618203903.539270-1-mykyta.yatsenko5@gmail.com> <20250618203903.539270-3-mykyta.yatsenko5@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.54.3 (3.54.3-1.fc41) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, 2025-06-18 at 21:39 +0100, Mykyta Yatsenko wrote: > From: Mykyta Yatsenko >=20 > Implement support for presetting values for array elements in veristat. > For example: > ``` > sudo ./veristat set_global_vars.bpf.o -G "arr[3] =3D 1" > ``` > Arrays of structures and structure of arrays work, but each individual > scalar value has to be set separately: `foo[1].bar[2] =3D value`. >=20 > Signed-off-by: Mykyta Yatsenko > --- > tools/testing/selftests/bpf/veristat.c | 226 ++++++++++++++++++++----- > 1 file changed, 180 insertions(+), 46 deletions(-) >=20 > diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selft= ests/bpf/veristat.c > index 483442c08ecf..9942adbda411 100644 > --- a/tools/testing/selftests/bpf/veristat.c > +++ b/tools/testing/selftests/bpf/veristat.c Acked-by: Eduard Zingerman [...] > @@ -1670,7 +1706,7 @@ static int append_var_preset(struct var_preset **pr= esets, int *cnt, const char * > memset(cur, 0, sizeof(*cur)); > (*cnt)++; > =20 > - if (sscanf(expr, "%s =3D %s %n", var, val, &n) !=3D 2 || n !=3D strlen(= expr)) { > + if (sscanf(expr, "%[][a-zA-Z0-9_.] =3D %s %n", var, val, &n) !=3D 2 || = n !=3D strlen(expr)) { Out of curiosity, won't match if the pattern would remain "%s =3D %s %n"? > fprintf(stderr, "Failed to parse expression '%s'\n", expr); > return -EINVAL; > } > @@ -1763,17 +1799,103 @@ static bool is_preset_supported(const struct btf= _type *t) > return btf_is_int(t) || btf_is_enum(t) || btf_is_enum64(t); > } > =20 > +static int find_enum_value(const struct btf *btf, const char *name, long= long *value) > +{ > + const struct btf_type *t; > + int cnt, i; > + long long lvalue; > + > + cnt =3D btf__type_cnt(btf); > + for (i =3D 1; i !=3D cnt; ++i) { > + t =3D btf__type_by_id(btf, i); > + > + if (!btf_is_any_enum(t)) > + continue; > + > + if (enum_value_from_name(btf, t, name, &lvalue) =3D=3D 0) { > + *value =3D lvalue; > + return 0; > + } > + } > + return -ESRCH; > +} > + [...] > @@ -1815,26 +1938,29 @@ const int btf_find_member(const struct btf *btf, > static int adjust_var_secinfo(struct btf *btf, const struct btf_type *t, > struct btf_var_secinfo *sinfo, struct var_preset *preset) > { > - const struct btf_type *base_type, *member_type; > - int err, member_tid, i; > - __u32 member_offset =3D 0; > - > - base_type =3D btf__type_by_id(btf, btf__resolve_type(btf, t->type)); > - > - for (i =3D 1; i < preset->atom_count; ++i) { > - err =3D btf_find_member(btf, base_type, 0, preset->atoms[i].name, > - &member_tid, &member_offset); > - if (err) { > - fprintf(stderr, "Could not find member %s for variable %s\n", > - preset->atoms[i].name, preset->atoms[i - 1].name); > - return err; > + const struct btf_type *base_type; > + int err, i =3D 1, n; > + int tid; > + > + tid =3D btf__resolve_type(btf, t->type); > + base_type =3D btf__type_by_id(btf, tid); > + > + while (i < preset->atom_count) { > + if (preset->atoms[i].type =3D=3D ARRAY_INDEX) { > + n =3D adjust_var_secinfo_array(btf, tid, preset, i, sinfo); > + if (n < 0) > + return n; > + i +=3D n; Having a nested loop to consume all indices looks annoying. On the other hand, there is not much one can do w/o some kind of btf__type_physical_size. > + } else { > + err =3D btf_find_member(btf, base_type, 0, preset->atoms[i].name, sin= fo); > + if (err) > + return err; > + i++; > } > - member_type =3D btf__type_by_id(btf, member_tid); > - sinfo->offset +=3D member_offset / 8; > - sinfo->size =3D member_type->size; > - sinfo->type =3D member_tid; > - base_type =3D member_type; > + base_type =3D btf__type_by_id(btf, sinfo->type); > + tid =3D sinfo->type; > } > + > return 0; > } > =20 [...]