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-rw-r--r--tools/lib/bpf/libbpf.c130
-rw-r--r--tools/lib/bpf/libbpf_internal.h27
-rw-r--r--tools/lib/bpf/libbpf_probes.c73
3 files changed, 197 insertions, 33 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 11a65db4b93f..7e3b79d7c25f 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -44,6 +44,7 @@
#include "btf.h"
#include "str_error.h"
#include "libbpf_util.h"
+#include "libbpf_internal.h"
#ifndef EM_BPF
#define EM_BPF 247
@@ -128,6 +129,10 @@ struct bpf_capabilities {
__u32 name:1;
/* v5.2: kernel support for global data sections. */
__u32 global_data:1;
+ /* BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO support */
+ __u32 btf_func:1;
+ /* BTF_KIND_VAR and BTF_KIND_DATASEC support */
+ __u32 btf_datasec:1;
};
/*
@@ -1021,6 +1026,74 @@ static bool section_have_execinstr(struct bpf_object *obj, int idx)
return false;
}
+static void bpf_object__sanitize_btf(struct bpf_object *obj)
+{
+ bool has_datasec = obj->caps.btf_datasec;
+ bool has_func = obj->caps.btf_func;
+ struct btf *btf = obj->btf;
+ struct btf_type *t;
+ int i, j, vlen;
+ __u16 kind;
+
+ if (!obj->btf || (has_func && has_datasec))
+ return;
+
+ for (i = 1; i <= btf__get_nr_types(btf); i++) {
+ t = (struct btf_type *)btf__type_by_id(btf, i);
+ kind = BTF_INFO_KIND(t->info);
+
+ if (!has_datasec && kind == BTF_KIND_VAR) {
+ /* replace VAR with INT */
+ t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
+ t->size = sizeof(int);
+ *(int *)(t+1) = BTF_INT_ENC(0, 0, 32);
+ } else if (!has_datasec && kind == BTF_KIND_DATASEC) {
+ /* replace DATASEC with STRUCT */
+ struct btf_var_secinfo *v = (void *)(t + 1);
+ struct btf_member *m = (void *)(t + 1);
+ struct btf_type *vt;
+ char *name;
+
+ name = (char *)btf__name_by_offset(btf, t->name_off);
+ while (*name) {
+ if (*name == '.')
+ *name = '_';
+ name++;
+ }
+
+ vlen = BTF_INFO_VLEN(t->info);
+ t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, vlen);
+ for (j = 0; j < vlen; j++, v++, m++) {
+ /* order of field assignments is important */
+ m->offset = v->offset * 8;
+ m->type = v->type;
+ /* preserve variable name as member name */
+ vt = (void *)btf__type_by_id(btf, v->type);
+ m->name_off = vt->name_off;
+ }
+ } else if (!has_func && kind == BTF_KIND_FUNC_PROTO) {
+ /* replace FUNC_PROTO with ENUM */
+ vlen = BTF_INFO_VLEN(t->info);
+ t->info = BTF_INFO_ENC(BTF_KIND_ENUM, 0, vlen);
+ t->size = sizeof(__u32); /* kernel enforced */
+ } else if (!has_func && kind == BTF_KIND_FUNC) {
+ /* replace FUNC with TYPEDEF */
+ t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0);
+ }
+ }
+}
+
+static void bpf_object__sanitize_btf_ext(struct bpf_object *obj)
+{
+ if (!obj->btf_ext)
+ return;
+
+ if (!obj->caps.btf_func) {
+ btf_ext__free(obj->btf_ext);
+ obj->btf_ext = NULL;
+ }
+}
+
static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
{
Elf *elf = obj->efile.elf;
@@ -1164,8 +1237,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
obj->btf = NULL;
} else {
err = btf__finalize_data(obj, obj->btf);
- if (!err)
+ if (!err) {
+ bpf_object__sanitize_btf(obj);
err = btf__load(obj->btf);
+ }
if (err) {
pr_warning("Error finalizing and loading %s into kernel: %d. Ignored and continue.\n",
BTF_ELF_SEC, err);
@@ -1187,6 +1262,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj, int flags)
BTF_EXT_ELF_SEC,
PTR_ERR(obj->btf_ext));
obj->btf_ext = NULL;
+ } else {
+ bpf_object__sanitize_btf_ext(obj);
}
}
}
@@ -1556,12 +1633,63 @@ bpf_object__probe_global_data(struct bpf_object *obj)
return 0;
}
+static int bpf_object__probe_btf_func(struct bpf_object *obj)
+{
+ const char strs[] = "\0int\0x\0a";
+ /* void x(int a) {} */
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
+ /* FUNC_PROTO */ /* [2] */
+ BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
+ BTF_PARAM_ENC(7, 1),
+ /* FUNC x */ /* [3] */
+ BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2),
+ };
+ int res;
+
+ res = libbpf__probe_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs));
+ if (res < 0)
+ return res;
+ if (res > 0)
+ obj->caps.btf_func = 1;
+ return 0;
+}
+
+static int bpf_object__probe_btf_datasec(struct bpf_object *obj)
+{
+ const char strs[] = "\0x\0.data";
+ /* static int a; */
+ __u32 types[] = {
+ /* int */
+ BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
+ /* VAR x */ /* [2] */
+ BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
+ BTF_VAR_STATIC,
+ /* DATASEC val */ /* [3] */
+ BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
+ BTF_VAR_SECINFO_ENC(2, 0, 4),
+ };
+ int res;
+
+ res = libbpf__probe_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs));
+ if (res < 0)
+ return res;
+ if (res > 0)
+ obj->caps.btf_datasec = 1;
+ return 0;
+}
+
static int
bpf_object__probe_caps(struct bpf_object *obj)
{
int (*probe_fn[])(struct bpf_object *obj) = {
bpf_object__probe_name,
bpf_object__probe_global_data,
+ bpf_object__probe_btf_func,
+ bpf_object__probe_btf_datasec,
};
int i, ret;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
new file mode 100644
index 000000000000..789e435b5900
--- /dev/null
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Internal libbpf helpers.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+
+#ifndef __LIBBPF_LIBBPF_INTERNAL_H
+#define __LIBBPF_LIBBPF_INTERNAL_H
+
+#define BTF_INFO_ENC(kind, kind_flag, vlen) \
+ ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
+#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
+#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
+ ((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
+#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
+ BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
+ BTF_INT_ENC(encoding, bits_offset, bits)
+#define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
+#define BTF_PARAM_ENC(name, type) (name), (type)
+#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
+
+int libbpf__probe_raw_btf(const char *raw_types, size_t types_len,
+ const char *str_sec, size_t str_len);
+
+#endif /* __LIBBPF_LIBBPF_INTERNAL_H */
diff --git a/tools/lib/bpf/libbpf_probes.c b/tools/lib/bpf/libbpf_probes.c
index a2c64a9ce1a6..5e2aa83f637a 100644
--- a/tools/lib/bpf/libbpf_probes.c
+++ b/tools/lib/bpf/libbpf_probes.c
@@ -15,6 +15,7 @@
#include "bpf.h"
#include "libbpf.h"
+#include "libbpf_internal.h"
static bool grep(const char *buffer, const char *pattern)
{
@@ -132,21 +133,43 @@ bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex)
return errno != EINVAL && errno != EOPNOTSUPP;
}
-static int load_btf(void)
+int libbpf__probe_raw_btf(const char *raw_types, size_t types_len,
+ const char *str_sec, size_t str_len)
{
-#define BTF_INFO_ENC(kind, kind_flag, vlen) \
- ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
-#define BTF_TYPE_ENC(name, info, size_or_type) \
- (name), (info), (size_or_type)
-#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
- ((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
-#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
- BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
- BTF_INT_ENC(encoding, bits_offset, bits)
-#define BTF_MEMBER_ENC(name, type, bits_offset) \
- (name), (type), (bits_offset)
-
- const char btf_str_sec[] = "\0bpf_spin_lock\0val\0cnt\0l";
+ struct btf_header hdr = {
+ .magic = BTF_MAGIC,
+ .version = BTF_VERSION,
+ .hdr_len = sizeof(struct btf_header),
+ .type_len = types_len,
+ .str_off = types_len,
+ .str_len = str_len,
+ };
+ int btf_fd, btf_len;
+ __u8 *raw_btf;
+
+ btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
+ raw_btf = malloc(btf_len);
+ if (!raw_btf)
+ return -ENOMEM;
+
+ memcpy(raw_btf, &hdr, sizeof(hdr));
+ memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
+ memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
+
+ btf_fd = bpf_load_btf(raw_btf, btf_len, NULL, 0, false);
+ if (btf_fd < 0) {
+ free(raw_btf);
+ return 0;
+ }
+
+ close(btf_fd);
+ free(raw_btf);
+ return 1;
+}
+
+static int load_sk_storage_btf(void)
+{
+ const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
/* struct bpf_spin_lock {
* int val;
* };
@@ -155,7 +178,7 @@ static int load_btf(void)
* struct bpf_spin_lock l;
* };
*/
- __u32 btf_raw_types[] = {
+ __u32 types[] = {
/* int */
BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */
/* struct bpf_spin_lock */ /* [2] */
@@ -166,23 +189,9 @@ static int load_btf(void)
BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
};
- struct btf_header btf_hdr = {
- .magic = BTF_MAGIC,
- .version = BTF_VERSION,
- .hdr_len = sizeof(struct btf_header),
- .type_len = sizeof(btf_raw_types),
- .str_off = sizeof(btf_raw_types),
- .str_len = sizeof(btf_str_sec),
- };
- __u8 raw_btf[sizeof(struct btf_header) + sizeof(btf_raw_types) +
- sizeof(btf_str_sec)];
-
- memcpy(raw_btf, &btf_hdr, sizeof(btf_hdr));
- memcpy(raw_btf + sizeof(btf_hdr), btf_raw_types, sizeof(btf_raw_types));
- memcpy(raw_btf + sizeof(btf_hdr) + sizeof(btf_raw_types),
- btf_str_sec, sizeof(btf_str_sec));
- return bpf_load_btf(raw_btf, sizeof(raw_btf), 0, 0, 0);
+ return libbpf__probe_raw_btf((char *)types, sizeof(types),
+ strs, sizeof(strs));
}
bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
@@ -222,7 +231,7 @@ bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
value_size = 8;
max_entries = 0;
map_flags = BPF_F_NO_PREALLOC;
- btf_fd = load_btf();
+ btf_fd = load_sk_storage_btf();
if (btf_fd < 0)
return false;
break;
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.