]> git.ipfire.org Git - thirdparty/kernel/linux.git/commitdiff
selftests/bpf: Support array presets in veristat
authorMykyta Yatsenko <yatsenko@meta.com>
Wed, 25 Jun 2025 16:59:03 +0000 (17:59 +0100)
committerAndrii Nakryiko <andrii@kernel.org>
Thu, 26 Jun 2025 17:28:50 +0000 (10:28 -0700)
Implement support for presetting values for array elements in veristat.
For example:
```
sudo ./veristat set_global_vars.bpf.o -G "arr[3] = 1"
```
Arrays of structures and structure of arrays work, but each individual
scalar value has to be set separately: `foo[1].bar[2] = value`.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20250625165904.87820-3-mykyta.yatsenko5@gmail.com
tools/testing/selftests/bpf/veristat.c

index 4049d4dda97ae25094708585da5bb0e78b4d3031..1e9f61f9fd0adc08cfc7773af5bfe57a54b53b66 100644 (file)
@@ -165,7 +165,11 @@ struct rvalue {
 };
 
 struct field_access {
-       char *name;
+       enum { FIELD_NAME, ARRAY_INDEX } type;
+       union {
+               char *name;
+               struct rvalue index;
+       };
 };
 
 struct var_preset {
@@ -1630,28 +1634,60 @@ static int process_prog(const char *filename, struct bpf_object *obj, struct bpf
                free(buf);
 
        return 0;
-};
+}
+
+static int append_preset_atom(struct var_preset *preset, char *value, bool is_index)
+{
+       struct field_access *tmp;
+       int i = preset->atom_count;
+       int err;
+
+       tmp = reallocarray(preset->atoms, i + 1, sizeof(*preset->atoms));
+       if (!tmp)
+               return -ENOMEM;
+
+       preset->atoms = tmp;
+       preset->atom_count++;
+
+       if (is_index) {
+               preset->atoms[i].type = ARRAY_INDEX;
+               err = parse_rvalue(value, &preset->atoms[i].index);
+               if (err)
+                       return err;
+       } else {
+               preset->atoms[i].type = FIELD_NAME;
+               preset->atoms[i].name = strdup(value);
+               if (!preset->atoms[i].name)
+                       return -ENOMEM;
+       }
+       return 0;
+}
 
 static int parse_var_atoms(const char *full_var, struct var_preset *preset)
 {
-       char expr[256], *name, *saveptr;
+       char expr[256], var[256], *name, *saveptr;
+       int n, len, off;
 
        snprintf(expr, sizeof(expr), "%s", full_var);
        preset->atom_count = 0;
        while ((name = strtok_r(preset->atom_count ? NULL : expr, ".", &saveptr))) {
-               struct field_access *tmp;
-               int i = preset->atom_count;
-
-               tmp = reallocarray(preset->atoms, i + 1, sizeof(*preset->atoms));
-               if (!tmp)
-                       return -ENOMEM;
-
-               preset->atoms = tmp;
-               preset->atom_count++;
+               len = strlen(name);
+               /* parse variable name */
+               if (sscanf(name, "%[a-zA-Z0-9_] %n", var, &off) != 1) {
+                       fprintf(stderr, "Can't parse %s\n", name);
+                       return -EINVAL;
+               }
+               append_preset_atom(preset, var, false);
 
-               preset->atoms[i].name = strdup(name);
-               if (!preset->atoms[i].name)
-                       return -ENOMEM;
+               /* parse optional array indexes */
+               while (off < len) {
+                       if (sscanf(name + off, " [ %[a-zA-Z0-9_] ] %n", var, &n) != 1) {
+                               fprintf(stderr, "Can't parse %s as index\n", name + off);
+                               return -EINVAL;
+                       }
+                       append_preset_atom(preset, var, true);
+                       off += n;
+               }
        }
        return 0;
 }
@@ -1661,7 +1697,7 @@ static int append_var_preset(struct var_preset **presets, int *cnt, const char *
        void *tmp;
        struct var_preset *cur;
        char var[256], val[256];
-       int n, err;
+       int n, err, i;
 
        tmp = realloc(*presets, (*cnt + 1) * sizeof(**presets));
        if (!tmp)
@@ -1671,10 +1707,16 @@ static int append_var_preset(struct var_preset **presets, int *cnt, const char *
        memset(cur, 0, sizeof(*cur));
        (*cnt)++;
 
-       if (sscanf(expr, "%s = %s %n", var, val, &n) != 2 || n != strlen(expr)) {
+       if (sscanf(expr, " %[][a-zA-Z0-9_. ] = %s %n", var, val, &n) != 2 || n != strlen(expr)) {
                fprintf(stderr, "Failed to parse expression '%s'\n", expr);
                return -EINVAL;
        }
+       /* Remove trailing spaces from var, as scanf may add those */
+       for (i = strlen(var) - 1; i > 0; --i) {
+               if (!isspace(var[i]))
+                       break;
+               var[i] = '\0';
+       }
 
        err = parse_rvalue(val, &cur->value);
        if (err)
@@ -1764,22 +1806,96 @@ static bool is_preset_supported(const struct btf_type *t)
        return btf_is_int(t) || btf_is_enum(t) || btf_is_enum64(t);
 }
 
-const int btf_find_member(const struct btf *btf,
-                         const struct btf_type *parent_type,
-                         __u32 parent_offset,
-                         const char *member_name,
-                         int *member_tid,
-                         __u32 *member_offset)
+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 = btf__type_cnt(btf);
+       for (i = 1; i != cnt; ++i) {
+               t = btf__type_by_id(btf, i);
+
+               if (!btf_is_any_enum(t))
+                       continue;
+
+               if (enum_value_from_name(btf, t, name, &lvalue) == 0) {
+                       *value = lvalue;
+                       return 0;
+               }
+       }
+       return -ESRCH;
+}
+
+static int resolve_rvalue(struct btf *btf, const struct rvalue *rvalue, long long *result)
+{
+       int err = 0;
+
+       switch (rvalue->type) {
+       case INTEGRAL:
+               *result = rvalue->ivalue;
+               return 0;
+       case ENUMERATOR:
+               err = find_enum_value(btf, rvalue->svalue, result);
+               if (err) {
+                       fprintf(stderr, "Can't resolve enum value %s\n", rvalue->svalue);
+                       return err;
+               }
+               return 0;
+       default:
+               fprintf(stderr, "Unknown rvalue type\n");
+               return -EOPNOTSUPP;
+       }
+       return 0;
+}
+
+static int adjust_var_secinfo_array(struct btf *btf, int tid, struct field_access *atom,
+                                   const char *array_name, struct btf_var_secinfo *sinfo)
+{
+       const struct btf_type *t;
+       struct btf_array *barr;
+       long long idx;
+       int err;
+
+       tid = btf__resolve_type(btf, tid);
+       t = btf__type_by_id(btf, tid);
+       if (!btf_is_array(t)) {
+               fprintf(stderr, "Array index is not expected for %s\n",
+                       array_name);
+               return -EINVAL;
+       }
+       barr = btf_array(t);
+       err = resolve_rvalue(btf, &atom->index, &idx);
+       if (err)
+               return err;
+       if (idx < 0 || idx >= barr->nelems) {
+               fprintf(stderr, "Array index %lld is out of bounds [0, %u]: %s\n",
+                       idx, barr->nelems, array_name);
+               return -EINVAL;
+       }
+       sinfo->size = btf__resolve_size(btf, barr->type);
+       sinfo->offset += sinfo->size * idx;
+       sinfo->type = btf__resolve_type(btf, barr->type);
+       return 0;
+}
+
+static int adjust_var_secinfo_member(const struct btf *btf,
+                                    const struct btf_type *parent_type,
+                                    __u32 parent_offset,
+                                    const char *member_name,
+                                    struct btf_var_secinfo *sinfo)
 {
        int i;
 
-       if (!btf_is_composite(parent_type))
+       if (!btf_is_composite(parent_type)) {
+               fprintf(stderr, "Can't resolve field %s for non-composite type\n", member_name);
                return -EINVAL;
+       }
 
        for (i = 0; i < btf_vlen(parent_type); ++i) {
                const struct btf_member *member;
                const struct btf_type *member_type;
-               int tid;
+               int tid, off;
 
                member = btf_members(parent_type) + i;
                tid =  btf__resolve_type(btf, member->type);
@@ -1787,6 +1903,7 @@ const int btf_find_member(const struct btf *btf,
                        return -EINVAL;
 
                member_type = btf__type_by_id(btf, tid);
+               off = parent_offset + member->offset;
                if (member->name_off) {
                        const char *name = btf__name_by_offset(btf, member->name_off);
 
@@ -1796,15 +1913,16 @@ const int btf_find_member(const struct btf *btf,
                                                name);
                                        return -EINVAL;
                                }
-                               *member_offset = parent_offset + member->offset;
-                               *member_tid = tid;
+                               sinfo->offset += off / 8;
+                               sinfo->type = tid;
+                               sinfo->size = member_type->size;
                                return 0;
                        }
                } else if (btf_is_composite(member_type)) {
                        int err;
 
-                       err = btf_find_member(btf, member_type, parent_offset + member->offset,
-                                             member_name, member_tid, member_offset);
+                       err = adjust_var_secinfo_member(btf, member_type, off,
+                                                       member_name, sinfo);
                        if (!err)
                                return 0;
                }
@@ -1816,26 +1934,39 @@ 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 = 0;
+       const struct btf_type *base_type;
+       const char *prev_name;
+       int err, i;
+       int tid;
+
+       assert(preset->atom_count > 0);
+       assert(preset->atoms[0].type == FIELD_NAME);
 
-       base_type = btf__type_by_id(btf, btf__resolve_type(btf, t->type));
+       tid = btf__resolve_type(btf, t->type);
+       base_type = btf__type_by_id(btf, tid);
+       prev_name = preset->atoms[0].name;
 
        for (i = 1; i < preset->atom_count; ++i) {
-               err = 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;
+               struct field_access *atom = preset->atoms + i;
+
+               switch (atom->type) {
+               case ARRAY_INDEX:
+                       err = adjust_var_secinfo_array(btf, tid, atom, prev_name, sinfo);
+                       break;
+               case FIELD_NAME:
+                       err = adjust_var_secinfo_member(btf, base_type, 0, atom->name, sinfo);
+                       prev_name = atom->name;
+                       break;
+               default:
+                       fprintf(stderr, "Unknown field_access type\n");
+                       return -EOPNOTSUPP;
                }
-               member_type = btf__type_by_id(btf, member_tid);
-               sinfo->offset += member_offset / 8;
-               sinfo->size = member_type->size;
-               sinfo->type = member_tid;
-               base_type = member_type;
+               if (err)
+                       return err;
+               base_type = btf__type_by_id(btf, sinfo->type);
+               tid = sinfo->type;
        }
+
        return 0;
 }
 
@@ -1854,8 +1985,8 @@ static int set_global_var(struct bpf_object *obj, struct btf *btf,
                return -EINVAL;
        }
        if (!is_preset_supported(base_type)) {
-               fprintf(stderr, "Setting value for type %s is not supported\n",
-                       btf__name_by_offset(btf, base_type->name_off));
+               fprintf(stderr, "Can't set %s. Only ints and enums are supported\n",
+                       preset->full_name);
                return -EINVAL;
        }
 
@@ -1972,6 +2103,7 @@ static int set_global_vars(struct bpf_object *obj, struct var_preset *presets, i
                if (!presets[i].applied) {
                        fprintf(stderr, "Global variable preset %s has not been applied\n",
                                presets[i].full_name);
+                       err = -EINVAL;
                }
                presets[i].applied = false;
        }
@@ -3165,11 +3297,18 @@ int main(int argc, char **argv)
        free(env.deny_filters);
        for (i = 0; i < env.npresets; ++i) {
                free(env.presets[i].full_name);
-               for (j = 0; j < env.presets[i].atom_count; ++j)
-                       free(env.presets[i].atoms[j].name);
+               for (j = 0; j < env.presets[i].atom_count; ++j) {
+                       switch (env.presets[i].atoms[j].type) {
+                       case FIELD_NAME:
+                               free(env.presets[i].atoms[j].name);
+                               break;
+                       case ARRAY_INDEX:
+                               if (env.presets[i].atoms[j].index.type == ENUMERATOR)
+                                       free(env.presets[i].atoms[j].index.svalue);
+                               break;
+                       }
+               }
                free(env.presets[i].atoms);
-               if (env.presets[i].value.type == ENUMERATOR)
-                       free(env.presets[i].value.svalue);
        }
        free(env.presets);
        return -err;