diff options
Diffstat (limited to 'tools/lib/bpf/libbpf.c')
| -rw-r--r-- | tools/lib/bpf/libbpf.c | 130 |
1 files changed, 129 insertions, 1 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; |