summaryrefslogtreecommitdiff
path: root/tools/lib
diff options
context:
space:
mode:
Diffstat (limited to 'tools/lib')
-rw-r--r--tools/lib/bpf/libbpf.c124
-rw-r--r--tools/lib/bpf/libbpf.h22
-rw-r--r--tools/lib/bpf/libbpf.map4
3 files changed, 133 insertions, 17 deletions
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 47284586836a..63c0f412266c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -357,6 +357,7 @@ enum libbpf_map_type {
};
struct bpf_map {
+ struct bpf_object *obj;
char *name;
/* real_name is defined for special internal maps (.rodata*,
* .data*, .bss, .kconfig) and preserves their original ELF section
@@ -386,7 +387,7 @@ struct bpf_map {
char *pin_path;
bool pinned;
bool reused;
- bool skipped;
+ bool autocreate;
__u64 map_extra;
};
@@ -1442,8 +1443,10 @@ static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
return ERR_PTR(err);
map = &obj->maps[obj->nr_maps++];
+ map->obj = obj;
map->fd = -1;
map->inner_map_fd = -1;
+ map->autocreate = true;
return map;
}
@@ -4307,6 +4310,20 @@ static int bpf_get_map_info_from_fdinfo(int fd, struct bpf_map_info *info)
return 0;
}
+bool bpf_map__autocreate(const struct bpf_map *map)
+{
+ return map->autocreate;
+}
+
+int bpf_map__set_autocreate(struct bpf_map *map, bool autocreate)
+{
+ if (map->obj->loaded)
+ return libbpf_err(-EBUSY);
+
+ map->autocreate = autocreate;
+ return 0;
+}
+
int bpf_map__reuse_fd(struct bpf_map *map, int fd)
{
struct bpf_map_info info = {};
@@ -5163,9 +5180,11 @@ bpf_object__create_maps(struct bpf_object *obj)
* bpf_object loading will succeed just fine even on old
* kernels.
*/
- if (bpf_map__is_internal(map) &&
- !kernel_supports(obj, FEAT_GLOBAL_DATA)) {
- map->skipped = true;
+ if (bpf_map__is_internal(map) && !kernel_supports(obj, FEAT_GLOBAL_DATA))
+ map->autocreate = false;
+
+ if (!map->autocreate) {
+ pr_debug("map '%s': skipped auto-creating...\n", map->name);
continue;
}
@@ -5788,6 +5807,36 @@ out:
return err;
}
+/* base map load ldimm64 special constant, used also for log fixup logic */
+#define MAP_LDIMM64_POISON_BASE 2001000000
+#define MAP_LDIMM64_POISON_PFX "200100"
+
+static void poison_map_ldimm64(struct bpf_program *prog, int relo_idx,
+ int insn_idx, struct bpf_insn *insn,
+ int map_idx, const struct bpf_map *map)
+{
+ int i;
+
+ pr_debug("prog '%s': relo #%d: poisoning insn #%d that loads map #%d '%s'\n",
+ prog->name, relo_idx, insn_idx, map_idx, map->name);
+
+ /* we turn single ldimm64 into two identical invalid calls */
+ for (i = 0; i < 2; i++) {
+ insn->code = BPF_JMP | BPF_CALL;
+ insn->dst_reg = 0;
+ insn->src_reg = 0;
+ insn->off = 0;
+ /* if this instruction is reachable (not a dead code),
+ * verifier will complain with something like:
+ * invalid func unknown#2001000123
+ * where lower 123 is map index into obj->maps[] array
+ */
+ insn->imm = MAP_LDIMM64_POISON_BASE + map_idx;
+
+ insn++;
+ }
+}
+
/* Relocate data references within program code:
* - map references;
* - global variable references;
@@ -5801,33 +5850,35 @@ bpf_object__relocate_data(struct bpf_object *obj, struct bpf_program *prog)
for (i = 0; i < prog->nr_reloc; i++) {
struct reloc_desc *relo = &prog->reloc_desc[i];
struct bpf_insn *insn = &prog->insns[relo->insn_idx];
+ const struct bpf_map *map;
struct extern_desc *ext;
switch (relo->type) {
case RELO_LD64:
+ map = &obj->maps[relo->map_idx];
if (obj->gen_loader) {
insn[0].src_reg = BPF_PSEUDO_MAP_IDX;
insn[0].imm = relo->map_idx;
- } else {
+ } else if (map->autocreate) {
insn[0].src_reg = BPF_PSEUDO_MAP_FD;
- insn[0].imm = obj->maps[relo->map_idx].fd;
+ insn[0].imm = map->fd;
+ } else {
+ poison_map_ldimm64(prog, i, relo->insn_idx, insn,
+ relo->map_idx, map);
}
break;
case RELO_DATA:
+ map = &obj->maps[relo->map_idx];
insn[1].imm = insn[0].imm + relo->sym_off;
if (obj->gen_loader) {
insn[0].src_reg = BPF_PSEUDO_MAP_IDX_VALUE;
insn[0].imm = relo->map_idx;
- } else {
- const struct bpf_map *map = &obj->maps[relo->map_idx];
-
- if (map->skipped) {
- pr_warn("prog '%s': relo #%d: kernel doesn't support global data\n",
- prog->name, i);
- return -ENOTSUP;
- }
+ } else if (map->autocreate) {
insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
- insn[0].imm = obj->maps[relo->map_idx].fd;
+ insn[0].imm = map->fd;
+ } else {
+ poison_map_ldimm64(prog, i, relo->insn_idx, insn,
+ relo->map_idx, map);
}
break;
case RELO_EXTERN_VAR:
@@ -6967,6 +7018,39 @@ static void fixup_log_failed_core_relo(struct bpf_program *prog,
patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
}
+static void fixup_log_missing_map_load(struct bpf_program *prog,
+ char *buf, size_t buf_sz, size_t log_sz,
+ char *line1, char *line2, char *line3)
+{
+ /* Expected log for failed and not properly guarded CO-RE relocation:
+ * line1 -> 123: (85) call unknown#2001000345
+ * line2 -> invalid func unknown#2001000345
+ * line3 -> <anything else or end of buffer>
+ *
+ * "123" is the index of the instruction that was poisoned.
+ * "345" in "2001000345" are map index in obj->maps to fetch map name.
+ */
+ struct bpf_object *obj = prog->obj;
+ const struct bpf_map *map;
+ int insn_idx, map_idx;
+ char patch[128];
+
+ if (sscanf(line1, "%d: (%*d) call unknown#%d\n", &insn_idx, &map_idx) != 2)
+ return;
+
+ map_idx -= MAP_LDIMM64_POISON_BASE;
+ if (map_idx < 0 || map_idx >= obj->nr_maps)
+ return;
+ map = &obj->maps[map_idx];
+
+ snprintf(patch, sizeof(patch),
+ "%d: <invalid BPF map reference>\n"
+ "BPF map '%s' is referenced but wasn't created\n",
+ insn_idx, map->name);
+
+ patch_log(buf, buf_sz, log_sz, line1, line3 - line1, patch);
+}
+
static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_sz)
{
/* look for familiar error patterns in last N lines of the log */
@@ -6995,6 +7079,14 @@ static void fixup_verifier_log(struct bpf_program *prog, char *buf, size_t buf_s
fixup_log_failed_core_relo(prog, buf, buf_sz, log_sz,
prev_line, cur_line, next_line);
return;
+ } else if (str_has_pfx(cur_line, "invalid func unknown#"MAP_LDIMM64_POISON_PFX)) {
+ prev_line = find_prev_line(buf, cur_line);
+ if (!prev_line)
+ continue;
+
+ fixup_log_missing_map_load(prog, buf, buf_sz, log_sz,
+ prev_line, cur_line, next_line);
+ return;
}
}
}
@@ -8183,7 +8275,7 @@ int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
char *pin_path = NULL;
char buf[PATH_MAX];
- if (map->skipped)
+ if (!map->autocreate)
continue;
if (path) {
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index cdbfee60ea3e..114b1f6f73a5 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -867,6 +867,28 @@ LIBBPF_API struct bpf_map *
bpf_object__prev_map(const struct bpf_object *obj, const struct bpf_map *map);
/**
+ * @brief **bpf_map__set_autocreate()** sets whether libbpf has to auto-create
+ * BPF map during BPF object load phase.
+ * @param map the BPF map instance
+ * @param autocreate whether to create BPF map during BPF object load
+ * @return 0 on success; -EBUSY if BPF object was already loaded
+ *
+ * **bpf_map__set_autocreate()** allows to opt-out from libbpf auto-creating
+ * BPF map. By default, libbpf will attempt to create every single BPF map
+ * defined in BPF object file using BPF_MAP_CREATE command of bpf() syscall
+ * and fill in map FD in BPF instructions.
+ *
+ * This API allows to opt-out of this process for specific map instance. This
+ * can be useful if host kernel doesn't support such BPF map type or used
+ * combination of flags and user application wants to avoid creating such
+ * a map in the first place. User is still responsible to make sure that their
+ * BPF-side code that expects to use such missing BPF map is recognized by BPF
+ * verifier as dead code, otherwise BPF verifier will reject such BPF program.
+ */
+LIBBPF_API int bpf_map__set_autocreate(struct bpf_map *map, bool autocreate);
+LIBBPF_API bool bpf_map__autocreate(const struct bpf_map *map);
+
+/**
* @brief **bpf_map__fd()** gets the file descriptor of the passed
* BPF map
* @param map the BPF map instance
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 82f6d62176dd..b5bc84039407 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -442,10 +442,12 @@ LIBBPF_0.7.0 {
LIBBPF_0.8.0 {
global:
+ bpf_map__autocreate;
+ bpf_map__set_autocreate;
bpf_object__destroy_subskeleton;
bpf_object__open_subskeleton;
+ bpf_program__attach_kprobe_multi_opts;
bpf_program__attach_usdt;
libbpf_register_prog_handler;
libbpf_unregister_prog_handler;
- bpf_program__attach_kprobe_multi_opts;
} LIBBPF_0.7.0;
generated by cgit v1.2.3 (git 2.39.0) at 2025-01-19 22:06:24 +0300