selftests/bpf: Support struct/union presets in veristat

Extend commit e3c9abd0d14b ("selftests/bpf: Implement setting global
variables in veristat") to support applying presets to members of
the global structs or unions in veristat.
For example:
```
./veristat set_global_vars.bpf.o  -G "union1.struct3.var_u8_h = 0xBB"
```

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250408104544.140317-1-mykyta.yatsenko5@gmail.com

diff --git a/tools/testing/selftests/bpf/prog_tests/test_veristat.c b/tools/testing/selftests/bpf/prog_tests/test_veristat.c
index a95b42bf744a2e12c60cf434067cd8b7a798f4bb..47b56c258f3f43d3a706b06b10deb012ec1158f8 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/test_veristat.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_veristat.c
@@ -63,6 +63,9 @@ static void test_set_global_vars_succeeds(void)
            " -G \"var_eb = EB2\" "\
            " -G \"var_ec = EC2\" "\
            " -G \"var_b = 1\" "\
+           " -G \"struct1.struct2.u.var_u8 = 170\" "\
+           " -G \"union1.struct3.var_u8_l = 0xaa\" "\
+           " -G \"union1.struct3.var_u8_h = 0xaa\" "\
            "-vl2 > %s", fix->veristat, fix->tmpfile);
 
        read(fix->fd, fix->output, fix->sz);
@@ -78,6 +81,8 @@ static void test_set_global_vars_succeeds(void)
        __CHECK_STR("_w=12 ", "var_eb = EB2");
        __CHECK_STR("_w=13 ", "var_ec = EC2");
        __CHECK_STR("_w=1 ", "var_b = 1");
+       __CHECK_STR("_w=170 ", "struct1.struct2.u.var_u8 = 170");
+       __CHECK_STR("_w=0xaaaa ", "union1.var_u16 = 0xaaaa");
 
 out:
        teardown_fixture(fix);

diff --git a/tools/testing/selftests/bpf/progs/prepare.c b/tools/testing/selftests/bpf/progs/prepare.c
index 1f1dd547e4ee240b59ee71db39ae3ea530275573..cfc1f48e0d28dd7caa58889ac8e2b9c6d2cfec9b 100644 (file)
--- a/tools/testing/selftests/bpf/progs/prepare.c
+++ b/tools/testing/selftests/bpf/progs/prepare.c
@@ -2,7 +2,6 @@
 /* Copyright (c) 2025 Meta */
 #include <vmlinux.h>
 #include <bpf/bpf_helpers.h>
-//#include <bpf/bpf_tracing.h>
 
 char _license[] SEC("license") = "GPL";
 

diff --git a/tools/testing/selftests/bpf/progs/set_global_vars.c b/tools/testing/selftests/bpf/progs/set_global_vars.c
index 9adb5ba4cd4d701b18f275bc394cd169bc8b7672..90f5656c3991142df7d15d85160b4093bc10b40d 100644 (file)
--- a/tools/testing/selftests/bpf/progs/set_global_vars.c
+++ b/tools/testing/selftests/bpf/progs/set_global_vars.c
@@ -24,6 +24,44 @@ const volatile enum Enumu64 var_eb = EB1;
 const volatile enum Enums64 var_ec = EC1;
 const volatile bool var_b = false;
 
+struct Struct {
+       int:16;
+       __u16 filler;
+       struct {
+               const __u16 filler2;
+       };
+       struct Struct2 {
+               __u16 filler;
+               volatile struct {
+                       const int:1;
+                       union {
+                               const volatile __u8 var_u8;
+                               const volatile __s16 filler3;
+                               const int:1;
+                       } u;
+               };
+       } struct2;
+};
+
+const volatile __u32 stru = 0; /* same prefix as below */
+const volatile struct Struct struct1 = {.struct2 = {.u = {.var_u8 = 1}}};
+
+union Union {
+       __u16 var_u16;
+       struct Struct3 {
+               struct {
+                       __u8 var_u8_l;
+               };
+               struct {
+                       struct {
+                               __u8 var_u8_h;
+                       };
+               };
+       } struct3;
+};
+
+const volatile union Union union1 = {.var_u16 = -1};
+
 char arr[4] = {0};
 
 SEC("socket")
@@ -43,5 +81,8 @@ int test_set_globals(void *ctx)
        a = var_eb;
        a = var_ec;
        a = var_b;
+       a = struct1.struct2.u.var_u8;
+       a = union1.var_u16;
+
        return a;
 }

diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c
index a18972ffdeb6f2291613af2b0561e05b7015f7a7..b2bb20b009524d66bfc7758d39c0e5534a54ebae 100644 (file)
--- a/tools/testing/selftests/bpf/veristat.c
+++ b/tools/testing/selftests/bpf/veristat.c
@@ -1486,7 +1486,84 @@ static bool is_preset_supported(const struct btf_type *t)
        return btf_is_int(t) || btf_is_enum(t) || btf_is_enum64(t);
 }
 
-static int set_global_var(struct bpf_object *obj, struct btf *btf, const struct btf_type *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)
+{
+       int i;
+
+       if (!btf_is_composite(parent_type))
+               return -EINVAL;
+
+       for (i = 0; i < btf_vlen(parent_type); ++i) {
+               const struct btf_member *member;
+               const struct btf_type *member_type;
+               int tid;
+
+               member = btf_members(parent_type) + i;
+               tid =  btf__resolve_type(btf, member->type);
+               if (tid < 0)
+                       return -EINVAL;
+
+               member_type = btf__type_by_id(btf, tid);
+               if (member->name_off) {
+                       const char *name = btf__name_by_offset(btf, member->name_off);
+
+                       if (strcmp(member_name, name) == 0) {
+                               if (btf_member_bitfield_size(parent_type, i) != 0) {
+                                       fprintf(stderr, "Bitfield presets are not supported %s\n",
+                                               name);
+                                       return -EINVAL;
+                               }
+                               *member_offset = parent_offset + member->offset;
+                               *member_tid = tid;
+                               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);
+                       if (!err)
+                               return 0;
+               }
+       }
+
+       return -EINVAL;
+}
+
+static int adjust_var_secinfo(struct btf *btf, const struct btf_type *t,
+                             struct btf_var_secinfo *sinfo, const char *var)
+{
+       char expr[256], *saveptr;
+       const struct btf_type *base_type, *member_type;
+       int err, member_tid;
+       char *name;
+       __u32 member_offset = 0;
+
+       base_type = btf__type_by_id(btf, btf__resolve_type(btf, t->type));
+       snprintf(expr, sizeof(expr), "%s", var);
+       strtok_r(expr, ".", &saveptr);
+
+       while ((name = strtok_r(NULL, ".", &saveptr))) {
+               err = btf_find_member(btf, base_type, 0, name, &member_tid, &member_offset);
+               if (err) {
+                       fprintf(stderr, "Could not find member %s for variable %s\n", name, var);
+                       return err;
+               }
+               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;
+       }
+       return 0;
+}
+
+static int set_global_var(struct bpf_object *obj, struct btf *btf,
                          struct bpf_map *map, struct btf_var_secinfo *sinfo,
                          struct var_preset *preset)
 {
@@ -1495,9 +1572,9 @@ static int set_global_var(struct bpf_object *obj, struct btf *btf, const struct
        long long value = preset->ivalue;
        size_t size;
 
-       base_type = btf__type_by_id(btf, btf__resolve_type(btf, t->type));
+       base_type = btf__type_by_id(btf, btf__resolve_type(btf, sinfo->type));
        if (!base_type) {
-               fprintf(stderr, "Failed to resolve type %d\n", t->type);
+               fprintf(stderr, "Failed to resolve type %d\n", sinfo->type);
                return -EINVAL;
        }
        if (!is_preset_supported(base_type)) {
@@ -1530,7 +1607,7 @@ static int set_global_var(struct bpf_object *obj, struct btf *btf, const struct
                if (value >= max_val || value < -max_val) {
                        fprintf(stderr,
                                "Variable %s value %lld is out of range [%lld; %lld]\n",
-                               btf__name_by_offset(btf, t->name_off), value,
+                               btf__name_by_offset(btf, base_type->name_off), value,
                                is_signed ? -max_val : 0, max_val - 1);
                        return -EINVAL;
                }
@@ -1583,14 +1660,20 @@ static int set_global_vars(struct bpf_object *obj, struct var_preset *presets, i
                for (j = 0; j < n; ++j, ++sinfo) {
                        const struct btf_type *var_type = btf__type_by_id(btf, sinfo->type);
                        const char *var_name;
+                       int var_len;
 
                        if (!btf_is_var(var_type))
                                continue;
 
                        var_name = btf__name_by_offset(btf, var_type->name_off);
+                       var_len = strlen(var_name);
 
                        for (k = 0; k < npresets; ++k) {
-                               if (strcmp(var_name, presets[k].name) != 0)
+                               struct btf_var_secinfo tmp_sinfo;
+
+                               if (strncmp(var_name, presets[k].name, var_len) != 0 ||
+                                   (presets[k].name[var_len] != '\0' &&
+                                    presets[k].name[var_len] != '.'))
                                        continue;
 
                                if (presets[k].applied) {
@@ -1598,13 +1681,17 @@ static int set_global_vars(struct bpf_object *obj, struct var_preset *presets, i
                                                var_name);
                                        return -EINVAL;
                                }
+                               tmp_sinfo = *sinfo;
+                               err = adjust_var_secinfo(btf, var_type,
+                                                        &tmp_sinfo, presets[k].name);
+                               if (err)
+                                       return err;
 
-                               err = set_global_var(obj, btf, var_type, map, sinfo, presets + k);
+                               err = set_global_var(obj, btf, map, &tmp_sinfo, presets + k);
                                if (err)
                                        return err;
 
                                presets[k].applied = true;
-                               break;
                        }
                }
        }