summaryrefslogtreecommitdiffstats
path: root/tools
diff options
context:
space:
mode:
Diffstat (limited to 'tools')
-rw-r--r--tools/lib/bpf/bpf_helpers.h1
-rw-r--r--tools/lib/bpf/btf.h5
-rw-r--r--tools/lib/bpf/libbpf.c144
3 files changed, 144 insertions, 6 deletions
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index f67dce2af802..a510d8ed716f 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -75,5 +75,6 @@ enum libbpf_tristate {
};
#define __kconfig __attribute__((section(".kconfig")))
+#define __ksym __attribute__((section(".ksyms")))
#endif
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 70c1b7ec2bd0..06cd1731c154 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -168,6 +168,11 @@ static inline bool btf_kflag(const struct btf_type *t)
return BTF_INFO_KFLAG(t->info);
}
+static inline bool btf_is_void(const struct btf_type *t)
+{
+ return btf_kind(t) == BTF_KIND_UNKN;
+}
+
static inline bool btf_is_int(const struct btf_type *t)
{
return btf_kind(t) == BTF_KIND_INT;
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ffccb5af32a5..18461deb1b19 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -285,6 +285,7 @@ struct bpf_struct_ops {
#define BSS_SEC ".bss"
#define RODATA_SEC ".rodata"
#define KCONFIG_SEC ".kconfig"
+#define KSYMS_SEC ".ksyms"
#define STRUCT_OPS_SEC ".struct_ops"
enum libbpf_map_type {
@@ -331,6 +332,7 @@ struct bpf_map {
enum extern_type {
EXT_UNKNOWN,
EXT_KCFG,
+ EXT_KSYM,
};
enum kcfg_type {
@@ -358,6 +360,9 @@ struct extern_desc {
int data_off;
bool is_signed;
} kcfg;
+ struct {
+ unsigned long long addr;
+ } ksym;
};
};
@@ -2817,9 +2822,25 @@ static int cmp_externs(const void *_a, const void *_b)
return strcmp(a->name, b->name);
}
+static int find_int_btf_id(const struct btf *btf)
+{
+ const struct btf_type *t;
+ int i, n;
+
+ n = btf__get_nr_types(btf);
+ for (i = 1; i <= n; i++) {
+ t = btf__type_by_id(btf, i);
+
+ if (btf_is_int(t) && btf_int_bits(t) == 32)
+ return i;
+ }
+
+ return 0;
+}
+
static int bpf_object__collect_externs(struct bpf_object *obj)
{
- struct btf_type *sec, *kcfg_sec = NULL;
+ struct btf_type *sec, *kcfg_sec = NULL, *ksym_sec = NULL;
const struct btf_type *t;
struct extern_desc *ext;
int i, n, off;
@@ -2900,6 +2921,17 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
pr_warn("extern (kcfg) '%s' type is unsupported\n", ext_name);
return -ENOTSUP;
}
+ } else if (strcmp(sec_name, KSYMS_SEC) == 0) {
+ const struct btf_type *vt;
+
+ ksym_sec = sec;
+ ext->type = EXT_KSYM;
+
+ vt = skip_mods_and_typedefs(obj->btf, t->type, NULL);
+ if (!btf_is_void(vt)) {
+ pr_warn("extern (ksym) '%s' is not typeless (void)\n", ext_name);
+ return -ENOTSUP;
+ }
} else {
pr_warn("unrecognized extern section '%s'\n", sec_name);
return -ENOTSUP;
@@ -2913,6 +2945,46 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
/* sort externs by type, for kcfg ones also by (align, size, name) */
qsort(obj->externs, obj->nr_extern, sizeof(*ext), cmp_externs);
+ /* for .ksyms section, we need to turn all externs into allocated
+ * variables in BTF to pass kernel verification; we do this by
+ * pretending that each extern is a 8-byte variable
+ */
+ if (ksym_sec) {
+ /* find existing 4-byte integer type in BTF to use for fake
+ * extern variables in DATASEC
+ */
+ int int_btf_id = find_int_btf_id(obj->btf);
+
+ for (i = 0; i < obj->nr_extern; i++) {
+ ext = &obj->externs[i];
+ if (ext->type != EXT_KSYM)
+ continue;
+ pr_debug("extern (ksym) #%d: symbol %d, name %s\n",
+ i, ext->sym_idx, ext->name);
+ }
+
+ sec = ksym_sec;
+ n = btf_vlen(sec);
+ for (i = 0, off = 0; i < n; i++, off += sizeof(int)) {
+ struct btf_var_secinfo *vs = btf_var_secinfos(sec) + i;
+ struct btf_type *vt;
+
+ vt = (void *)btf__type_by_id(obj->btf, vs->type);
+ ext_name = btf__name_by_offset(obj->btf, vt->name_off);
+ ext = find_extern_by_name(obj, ext_name);
+ if (!ext) {
+ pr_warn("failed to find extern definition for BTF var '%s'\n",
+ ext_name);
+ return -ESRCH;
+ }
+ btf_var(vt)->linkage = BTF_VAR_GLOBAL_ALLOCATED;
+ vt->type = int_btf_id;
+ vs->offset = off;
+ vs->size = sizeof(int);
+ }
+ sec->size = off;
+ }
+
if (kcfg_sec) {
sec = kcfg_sec;
/* for kcfg externs calculate their offsets within a .kconfig map */
@@ -2924,7 +2996,7 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
ext->kcfg.data_off = roundup(off, ext->kcfg.align);
off = ext->kcfg.data_off + ext->kcfg.sz;
- pr_debug("extern #%d (kcfg): symbol %d, off %u, name %s\n",
+ pr_debug("extern (kcfg) #%d: symbol %d, off %u, name %s\n",
i, ext->sym_idx, ext->kcfg.data_off, ext->name);
}
sec->size = off;
@@ -5022,9 +5094,14 @@ bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
break;
case RELO_EXTERN:
ext = &obj->externs[relo->sym_off];
- insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
- insn[0].imm = obj->maps[obj->kconfig_map_idx].fd;
- insn[1].imm = ext->kcfg.data_off;
+ if (ext->type == EXT_KCFG) {
+ insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+ insn[0].imm = obj->maps[obj->kconfig_map_idx].fd;
+ insn[1].imm = ext->kcfg.data_off;
+ } else /* EXT_KSYM */ {
+ insn[0].imm = (__u32)ext->ksym.addr;
+ insn[1].imm = ext->ksym.addr >> 32;
+ }
break;
case RELO_CALL:
err = bpf_program__reloc_text(prog, obj, relo);
@@ -5643,10 +5720,58 @@ static int bpf_object__sanitize_maps(struct bpf_object *obj)
return 0;
}
+static int bpf_object__read_kallsyms_file(struct bpf_object *obj)
+{
+ char sym_type, sym_name[500];
+ unsigned long long sym_addr;
+ struct extern_desc *ext;
+ int ret, err = 0;
+ FILE *f;
+
+ f = fopen("/proc/kallsyms", "r");
+ if (!f) {
+ err = -errno;
+ pr_warn("failed to open /proc/kallsyms: %d\n", err);
+ return err;
+ }
+
+ while (true) {
+ ret = fscanf(f, "%llx %c %499s%*[^\n]\n",
+ &sym_addr, &sym_type, sym_name);
+ if (ret == EOF && feof(f))
+ break;
+ if (ret != 3) {
+ pr_warn("failed to read kallasyms entry: %d\n", ret);
+ err = -EINVAL;
+ goto out;
+ }
+
+ ext = find_extern_by_name(obj, sym_name);
+ if (!ext || ext->type != EXT_KSYM)
+ continue;
+
+ if (ext->is_set && ext->ksym.addr != sym_addr) {
+ pr_warn("extern (ksym) '%s' resolution is ambiguous: 0x%llx or 0x%llx\n",
+ sym_name, ext->ksym.addr, sym_addr);
+ err = -EINVAL;
+ goto out;
+ }
+ if (!ext->is_set) {
+ ext->is_set = true;
+ ext->ksym.addr = sym_addr;
+ pr_debug("extern (ksym) %s=0x%llx\n", sym_name, sym_addr);
+ }
+ }
+
+out:
+ fclose(f);
+ return err;
+}
+
static int bpf_object__resolve_externs(struct bpf_object *obj,
const char *extra_kconfig)
{
- bool need_config = false;
+ bool need_config = false, need_kallsyms = false;
struct extern_desc *ext;
void *kcfg_data = NULL;
int err, i;
@@ -5676,6 +5801,8 @@ static int bpf_object__resolve_externs(struct bpf_object *obj,
} else if (ext->type == EXT_KCFG &&
strncmp(ext->name, "CONFIG_", 7) == 0) {
need_config = true;
+ } else if (ext->type == EXT_KSYM) {
+ need_kallsyms = true;
} else {
pr_warn("unrecognized extern '%s'\n", ext->name);
return -EINVAL;
@@ -5699,6 +5826,11 @@ static int bpf_object__resolve_externs(struct bpf_object *obj,
if (err)
return -EINVAL;
}
+ if (need_kallsyms) {
+ err = bpf_object__read_kallsyms_file(obj);
+ if (err)
+ return -EINVAL;
+ }
for (i = 0; i < obj->nr_extern; i++) {
ext = &obj->externs[i];
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-28 08:20:03 +0000