diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 6f0c13a1fb3c..9e446081fb1c 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -11,8 +11,12 @@ #include #include #include +#include +#include #include #include +#include +#include #include "libbpf.h" @@ -52,3 +56,157 @@ void libbpf_set_print(libbpf_print_fn_t warn, __pr_info = info; __pr_debug = debug; } + +/* Copied from tools/perf/util/util.h */ +#ifndef zfree +# define zfree(ptr) ({ free(*ptr); *ptr = NULL; }) +#endif + +#ifndef zclose +# define zclose(fd) ({ \ + int ___err = 0; \ + if ((fd) >= 0) \ + ___err = close((fd)); \ + fd = -1; \ + ___err; }) +#endif + +#ifdef HAVE_LIBELF_MMAP_SUPPORT +# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP +#else +# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ +#endif + +struct bpf_object { + /* + * Information when doing elf related work. Only valid if fd + * is valid. + */ + struct { + int fd; + Elf *elf; + GElf_Ehdr ehdr; + } efile; + char path[]; +}; +#define obj_elf_valid(o) ((o)->efile.elf) + +static struct bpf_object *bpf_object__new(const char *path) +{ + struct bpf_object *obj; + + obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1); + if (!obj) { + pr_warning("alloc memory failed for %s\n", path); + return NULL; + } + + strcpy(obj->path, path); + obj->efile.fd = -1; + return obj; +} + +static void bpf_object__elf_finish(struct bpf_object *obj) +{ + if (!obj_elf_valid(obj)) + return; + + if (obj->efile.elf) { + elf_end(obj->efile.elf); + obj->efile.elf = NULL; + } + zclose(obj->efile.fd); +} + +static int bpf_object__elf_init(struct bpf_object *obj) +{ + int err = 0; + GElf_Ehdr *ep; + + if (obj_elf_valid(obj)) { + pr_warning("elf init: internal error\n"); + return -EEXIST; + } + + obj->efile.fd = open(obj->path, O_RDONLY); + if (obj->efile.fd < 0) { + pr_warning("failed to open %s: %s\n", obj->path, + strerror(errno)); + return -errno; + } + + obj->efile.elf = elf_begin(obj->efile.fd, + LIBBPF_ELF_C_READ_MMAP, + NULL); + if (!obj->efile.elf) { + pr_warning("failed to open %s as ELF file\n", + obj->path); + err = -EINVAL; + goto errout; + } + + if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) { + pr_warning("failed to get EHDR from %s\n", + obj->path); + err = -EINVAL; + goto errout; + } + ep = &obj->efile.ehdr; + + if ((ep->e_type != ET_REL) || (ep->e_machine != 0)) { + pr_warning("%s is not an eBPF object file\n", + obj->path); + err = -EINVAL; + goto errout; + } + + return 0; +errout: + bpf_object__elf_finish(obj); + return err; +} + +static struct bpf_object * +__bpf_object__open(const char *path) +{ + struct bpf_object *obj; + + if (elf_version(EV_CURRENT) == EV_NONE) { + pr_warning("failed to init libelf for %s\n", path); + return NULL; + } + + obj = bpf_object__new(path); + if (!obj) + return NULL; + + if (bpf_object__elf_init(obj)) + goto out; + + bpf_object__elf_finish(obj); + return obj; +out: + bpf_object__close(obj); + return NULL; +} + +struct bpf_object *bpf_object__open(const char *path) +{ + /* param validation */ + if (!path) + return NULL; + + pr_debug("loading %s\n", path); + + return __bpf_object__open(path); +} + +void bpf_object__close(struct bpf_object *obj) +{ + if (!obj) + return; + + bpf_object__elf_finish(obj); + + free(obj); +} diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 8d1eebafa958..ec3301ceeb85 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -8,6 +8,8 @@ #ifndef __BPF_LIBBPF_H #define __BPF_LIBBPF_H +#include + /* * In include/linux/compiler-gcc.h, __printf is defined. However * it should be better if libbpf.h doesn't depend on Linux header file. @@ -20,4 +22,10 @@ void libbpf_set_print(libbpf_print_fn_t warn, libbpf_print_fn_t info, libbpf_print_fn_t debug); +/* Hide internal to user */ +struct bpf_object; + +struct bpf_object *bpf_object__open(const char *path); +void bpf_object__close(struct bpf_object *object); + #endif