From 8f2951559127ffb93c3e36d5fc9d870768826ae9 Mon Sep 17 00:00:00 2001 From: Jerome Marchand Date: Thu, 24 Mar 2022 16:08:17 +0100 Subject: [PATCH 2/2] RHEL: libbpf version fixes Revert "bcc: Replace deprecated libbpf APIs" since the libbpf version provided in RHEL 8 doesn't provide the new APIs. Remove BPF_MAP_TYPE_BLOOM_FILTER from bps since the libbpf version in RHEL 8, doesn't provide bloom filter map. Rename btf__load_vmlinux_btf into libbpf_find_kernel_btf. The function has been renamed upstream for naming consistency, but RHEL 8 libbpf still uses the old name. Add definition of struct bpf_core_relo. --- introspection/bps.c | 1 - libbpf-tools/ksnoop.c | 2 +- src/cc/bcc_btf.cc | 73 ++++++++++++++++++++++++++++++++++++- src/cc/libbpf.c | 84 +++++++------------------------------------ 4 files changed, 85 insertions(+), 75 deletions(-) diff --git a/introspection/bps.c b/introspection/bps.c index 232b23d4..6ec02e6c 100644 --- a/introspection/bps.c +++ b/introspection/bps.c @@ -80,7 +80,6 @@ static const char * const map_type_strings[] = { [BPF_MAP_TYPE_RINGBUF] = "ringbuf", [BPF_MAP_TYPE_INODE_STORAGE] = "inode_storage", [BPF_MAP_TYPE_TASK_STORAGE] = "task_storage", - [BPF_MAP_TYPE_BLOOM_FILTER] = "bloom_filter", }; #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x))) diff --git a/libbpf-tools/ksnoop.c b/libbpf-tools/ksnoop.c index 69c58403..a6ea6107 100644 --- a/libbpf-tools/ksnoop.c +++ b/libbpf-tools/ksnoop.c @@ -347,7 +347,7 @@ static struct btf *get_btf(const char *name) name && strlen(name) > 0 ? name : "vmlinux"); if (!vmlinux_btf) { - vmlinux_btf = btf__load_vmlinux_btf(); + vmlinux_btf = libbpf_find_kernel_btf(); if (!vmlinux_btf) { err = -errno; p_err("No BTF, cannot determine type info: %s", strerror(-err)); diff --git a/src/cc/bcc_btf.cc b/src/cc/bcc_btf.cc index 7f551ae8..c78ba823 100644 --- a/src/cc/bcc_btf.cc +++ b/src/cc/bcc_btf.cc @@ -170,6 +170,77 @@ static int btf_ext_setup_line_info(struct btf_ext *btf_ext) return btf_ext_setup_info(btf_ext, ¶m); } +/* bpf_core_relo_kind encodes which aspect of captured field/type/enum value + * has to be adjusted by relocations. + */ +enum bpf_core_relo_kind { + BPF_FIELD_BYTE_OFFSET = 0, /* field byte offset */ + BPF_FIELD_BYTE_SIZE = 1, /* field size in bytes */ + BPF_FIELD_EXISTS = 2, /* field existence in target kernel */ + BPF_FIELD_SIGNED = 3, /* field signedness (0 - unsigned, 1 - signed) */ + BPF_FIELD_LSHIFT_U64 = 4, /* bitfield-specific left bitshift */ + BPF_FIELD_RSHIFT_U64 = 5, /* bitfield-specific right bitshift */ + BPF_TYPE_ID_LOCAL = 6, /* type ID in local BPF object */ + BPF_TYPE_ID_TARGET = 7, /* type ID in target kernel */ + BPF_TYPE_EXISTS = 8, /* type existence in target kernel */ + BPF_TYPE_SIZE = 9, /* type size in bytes */ + BPF_ENUMVAL_EXISTS = 10, /* enum value existence in target kernel */ + BPF_ENUMVAL_VALUE = 11, /* enum value integer value */ +}; + +/* The minimum bpf_core_relo checked by the loader + * + * CO-RE relocation captures the following data: + * - insn_off - instruction offset (in bytes) within a BPF program that needs + * its insn->imm field to be relocated with actual field info; + * - type_id - BTF type ID of the "root" (containing) entity of a relocatable + * type or field; + * - access_str_off - offset into corresponding .BTF string section. String + * interpretation depends on specific relocation kind: + * - for field-based relocations, string encodes an accessed field using + * a sequence of field and array indices, separated by colon (:). It's + * conceptually very close to LLVM's getelementptr ([0]) instruction's + * arguments for identifying offset to a field. + * - for type-based relocations, strings is expected to be just "0"; + * - for enum value-based relocations, string contains an index of enum + * value within its enum type; + * + * Example to provide a better feel. + * + * struct sample { + * int a; + * struct { + * int b[10]; + * }; + * }; + * + * struct sample *s = ...; + * int x = &s->a; // encoded as "0:0" (a is field #0) + * int y = &s->b[5]; // encoded as "0:1:0:5" (anon struct is field #1, + * // b is field #0 inside anon struct, accessing elem #5) + * int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array) + * + * type_id for all relocs in this example will capture BTF type id of + * `struct sample`. + * + * Such relocation is emitted when using __builtin_preserve_access_index() + * Clang built-in, passing expression that captures field address, e.g.: + * + * bpf_probe_read(&dst, sizeof(dst), + * __builtin_preserve_access_index(&src->a.b.c)); + * + * In this case Clang will emit field relocation recording necessary data to + * be able to find offset of embedded `a.b.c` field within `src` struct. + * + * [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction + */ +struct bpf_core_relo { + __u32 insn_off; + __u32 type_id; + __u32 access_str_off; + enum bpf_core_relo_kind kind; +}; + static int btf_ext_setup_core_relos(struct btf_ext *btf_ext) { struct btf_ext_sec_setup_param param = { @@ -597,7 +668,7 @@ int BTF::load(uint8_t *btf_sec, uintptr_t btf_sec_size, return -1; } - if (btf__load_into_kernel(btf)) { + if (btf__load(btf)) { btf__free(btf); warning("Loading .BTF section failed\n"); return -1; diff --git a/src/cc/libbpf.c b/src/cc/libbpf.c index e6403299..7410ae1a 100644 --- a/src/cc/libbpf.c +++ b/src/cc/libbpf.c @@ -297,25 +297,6 @@ static uint64_t ptr_to_u64(void *ptr) return (uint64_t) (unsigned long) ptr; } -static int libbpf_bpf_map_create(struct bpf_create_map_attr *create_attr) -{ - LIBBPF_OPTS(bpf_map_create_opts, p); - - p.map_flags = create_attr->map_flags; - p.numa_node = create_attr->numa_node; - p.btf_fd = create_attr->btf_fd; - p.btf_key_type_id = create_attr->btf_key_type_id; - p.btf_value_type_id = create_attr->btf_value_type_id; - p.map_ifindex = create_attr->map_ifindex; - if (create_attr->map_type == BPF_MAP_TYPE_STRUCT_OPS) - p.btf_vmlinux_value_type_id = create_attr->btf_vmlinux_value_type_id; - else - p.inner_map_fd = create_attr->inner_map_fd; - - return bpf_map_create(create_attr->map_type, create_attr->name, create_attr->key_size, - create_attr->value_size, create_attr->max_entries, &p); -} - int bcc_create_map_xattr(struct bpf_create_map_attr *attr, bool allow_rlimit) { unsigned name_len = attr->name ? strlen(attr->name) : 0; @@ -323,7 +304,7 @@ int bcc_create_map_xattr(struct bpf_create_map_attr *attr, bool allow_rlimit) memcpy(map_name, attr->name, min(name_len, BPF_OBJ_NAME_LEN - 1)); attr->name = map_name; - int ret = libbpf_bpf_map_create(attr); + int ret = bpf_create_map_xattr(attr); if (ret < 0 && errno == EPERM) { if (!allow_rlimit) @@ -335,7 +316,7 @@ int bcc_create_map_xattr(struct bpf_create_map_attr *attr, bool allow_rlimit) rl.rlim_max = RLIM_INFINITY; rl.rlim_cur = rl.rlim_max; if (setrlimit(RLIMIT_MEMLOCK, &rl) == 0) - ret = libbpf_bpf_map_create(attr); + ret = bpf_create_map_xattr(attr); } } @@ -345,12 +326,12 @@ int bcc_create_map_xattr(struct bpf_create_map_attr *attr, bool allow_rlimit) attr->btf_fd = 0; attr->btf_key_type_id = 0; attr->btf_value_type_id = 0; - ret = libbpf_bpf_map_create(attr); + ret = bpf_create_map_xattr(attr); } if (ret < 0 && name_len && (errno == E2BIG || errno == EINVAL)) { map_name[0] = '\0'; - ret = libbpf_bpf_map_create(attr); + ret = bpf_create_map_xattr(attr); } if (ret < 0 && errno == EPERM) { @@ -363,7 +344,7 @@ int bcc_create_map_xattr(struct bpf_create_map_attr *attr, bool allow_rlimit) rl.rlim_max = RLIM_INFINITY; rl.rlim_cur = rl.rlim_max; if (setrlimit(RLIMIT_MEMLOCK, &rl) == 0) - ret = libbpf_bpf_map_create(attr); + ret = bpf_create_map_xattr(attr); } } return ret; @@ -627,47 +608,6 @@ int bpf_prog_get_tag(int fd, unsigned long long *ptag) return 0; } -static int libbpf_bpf_prog_load(const struct bpf_load_program_attr *load_attr, - char *log_buf, size_t log_buf_sz) -{ - LIBBPF_OPTS(bpf_prog_load_opts, p); - - if (!load_attr || !log_buf != !log_buf_sz) { - errno = EINVAL; - return -EINVAL; - } - - p.expected_attach_type = load_attr->expected_attach_type; - switch (load_attr->prog_type) { - case BPF_PROG_TYPE_STRUCT_OPS: - case BPF_PROG_TYPE_LSM: - p.attach_btf_id = load_attr->attach_btf_id; - break; - case BPF_PROG_TYPE_TRACING: - case BPF_PROG_TYPE_EXT: - p.attach_btf_id = load_attr->attach_btf_id; - p.attach_prog_fd = load_attr->attach_prog_fd; - break; - default: - p.prog_ifindex = load_attr->prog_ifindex; - p.kern_version = load_attr->kern_version; - } - p.log_level = load_attr->log_level; - p.log_buf = log_buf; - p.log_size = log_buf_sz; - p.prog_btf_fd = load_attr->prog_btf_fd; - p.func_info_rec_size = load_attr->func_info_rec_size; - p.func_info_cnt = load_attr->func_info_cnt; - p.func_info = load_attr->func_info; - p.line_info_rec_size = load_attr->line_info_rec_size; - p.line_info_cnt = load_attr->line_info_cnt; - p.line_info = load_attr->line_info; - p.prog_flags = load_attr->prog_flags; - - return bpf_prog_load(load_attr->prog_type, load_attr->name, load_attr->license, - load_attr->insns, load_attr->insns_cnt, &p); -} - int bcc_prog_load_xattr(struct bpf_load_program_attr *attr, int prog_len, char *log_buf, unsigned log_buf_size, bool allow_rlimit) { @@ -750,7 +690,7 @@ int bcc_prog_load_xattr(struct bpf_load_program_attr *attr, int prog_len, attr->name = prog_name; } - ret = libbpf_bpf_prog_load(attr, attr_log_buf, attr_log_buf_size); + ret = bpf_load_program_xattr(attr, attr_log_buf, attr_log_buf_size); // func_info/line_info may not be supported in old kernels. if (ret < 0 && attr->func_info && errno == EINVAL) { @@ -761,14 +701,14 @@ int bcc_prog_load_xattr(struct bpf_load_program_attr *attr, int prog_len, attr->line_info = NULL; attr->line_info_cnt = 0; attr->line_info_rec_size = 0; - ret = libbpf_bpf_prog_load(attr, attr_log_buf, attr_log_buf_size); + ret = bpf_load_program_xattr(attr, attr_log_buf, attr_log_buf_size); } // BPF object name is not supported on older Kernels. // If we failed due to this, clear the name and try again. if (ret < 0 && name_len && (errno == E2BIG || errno == EINVAL)) { prog_name[0] = '\0'; - ret = libbpf_bpf_prog_load(attr, attr_log_buf, attr_log_buf_size); + ret = bpf_load_program_xattr(attr, attr_log_buf, attr_log_buf_size); } if (ret < 0 && errno == EPERM) { @@ -787,7 +727,7 @@ int bcc_prog_load_xattr(struct bpf_load_program_attr *attr, int prog_len, rl.rlim_max = RLIM_INFINITY; rl.rlim_cur = rl.rlim_max; if (setrlimit(RLIMIT_MEMLOCK, &rl) == 0) - ret = libbpf_bpf_prog_load(attr, attr_log_buf, attr_log_buf_size); + ret = bpf_load_program_xattr(attr, attr_log_buf, attr_log_buf_size); } } @@ -805,7 +745,7 @@ int bcc_prog_load_xattr(struct bpf_load_program_attr *attr, int prog_len, // If logging is not already enabled, enable it and do the syscall again. if (attr->log_level == 0) { attr->log_level = 1; - ret = libbpf_bpf_prog_load(attr, log_buf, log_buf_size); + ret = bpf_load_program_xattr(attr, log_buf, log_buf_size); } // Print the log message and return. bpf_print_hints(ret, log_buf); @@ -829,7 +769,7 @@ int bcc_prog_load_xattr(struct bpf_load_program_attr *attr, int prog_len, goto return_result; } tmp_log_buf[0] = 0; - ret = libbpf_bpf_prog_load(attr, tmp_log_buf, tmp_log_buf_size); + ret = bpf_load_program_xattr(attr, tmp_log_buf, tmp_log_buf_size); if (ret < 0 && errno == ENOSPC) { // Temporary buffer size is not enough. Double it and try again. free(tmp_log_buf); @@ -1369,7 +1309,7 @@ int kernel_struct_has_field(const char *struct_name, const char *field_name) struct btf *btf; int i, ret, btf_id; - btf = btf__load_vmlinux_btf(); + btf = libbpf_find_kernel_btf(); ret = libbpf_get_error(btf); if (ret) return -1; -- 2.35.3