bpf: libbpf: Add btf_line_info support to libbpf

This patch adds bpf_line_info support to libbpf:
1) Parsing the line_info sec from ".BTF.ext"
2) Relocating the line_info.  If the main prog *_info relocation
   fails, it will ignore the remaining subprog line_info and continue.
   If the subprog *_info relocation fails, it will bail out.
3) BPF_PROG_LOAD a prog with line_info

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

5 files changed, 239 insertions, 89 deletions

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 9fbbc0ed5952..3caaa3428774 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -173,11 +173,36 @@ int bpf_create_map_in_map(enum bpf_map_type map_type, const char *name,
                                           -1);
 }
 
+static void *
+alloc_zero_tailing_info(const void *orecord, __u32 cnt,
+                        __u32 actual_rec_size, __u32 expected_rec_size)
+{
+        __u64 info_len = actual_rec_size * cnt;
+        void *info, *nrecord;
+        int i;
+
+        info = malloc(info_len);
+        if (!info)
+                return NULL;
+
+        /* zero out bytes kernel does not understand */
+        nrecord = info;
+        for (i = 0; i < cnt; i++) {
+                memcpy(nrecord, orecord, expected_rec_size);
+                memset(nrecord + expected_rec_size, 0,
+                       actual_rec_size - expected_rec_size);
+                orecord += actual_rec_size;
+                nrecord += actual_rec_size;
+        }
+
+        return info;
+}
+
 int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
                            char *log_buf, size_t log_buf_sz)
 {
+        void *finfo = NULL, *linfo = NULL;
         union bpf_attr attr;
-        void *finfo = NULL;
         __u32 name_len;
         int fd;
 
@@ -201,6 +226,9 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
         attr.func_info_rec_size = load_attr->func_info_rec_size;
         attr.func_info_cnt = load_attr->func_info_cnt;
         attr.func_info = ptr_to_u64(load_attr->func_info);
+        attr.line_info_rec_size = load_attr->line_info_rec_size;
+        attr.line_info_cnt = load_attr->line_info_cnt;
+        attr.line_info = ptr_to_u64(load_attr->line_info);
         memcpy(attr.prog_name, load_attr->name,
                min(name_len, BPF_OBJ_NAME_LEN - 1));
 
@@ -212,36 +240,35 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
          * to give user space a hint how to deal with loading failure.
          * Check to see whether we can make some changes and load again.
          */
-        if (errno == E2BIG && attr.func_info_cnt &&
-            attr.func_info_rec_size < load_attr->func_info_rec_size) {
-                __u32 actual_rec_size = load_attr->func_info_rec_size;
-                __u32 expected_rec_size = attr.func_info_rec_size;
-                __u32 finfo_cnt = load_attr->func_info_cnt;
-                __u64 finfo_len = actual_rec_size * finfo_cnt;
-                const void *orecord;
-                void *nrecord;
-                int i;
-
-                finfo = malloc(finfo_len);
-                if (!finfo)
-                        /* further try with log buffer won't help */
-                        return fd;
-
-                /* zero out bytes kernel does not understand */
-                orecord = load_attr->func_info;
-                nrecord = finfo;
-                for (i = 0; i < load_attr->func_info_cnt; i++) {
-                        memcpy(nrecord, orecord, expected_rec_size);
-                        memset(nrecord + expected_rec_size, 0,
-                               actual_rec_size - expected_rec_size);
-                        orecord += actual_rec_size;
-                        nrecord += actual_rec_size;
+        while (errno == E2BIG && (!finfo || !linfo)) {
+                if (!finfo && attr.func_info_cnt &&
+                    attr.func_info_rec_size < load_attr->func_info_rec_size) {
+                        /* try with corrected func info records */
+                        finfo = alloc_zero_tailing_info(load_attr->func_info,
+                                                        load_attr->func_info_cnt,
+                                                        load_attr->func_info_rec_size,
+                                                        attr.func_info_rec_size);
+                        if (!finfo)
+                                goto done;
+
+                        attr.func_info = ptr_to_u64(finfo);
+                        attr.func_info_rec_size = load_attr->func_info_rec_size;
+                } else if (!linfo && attr.line_info_cnt &&
+                           attr.line_info_rec_size <
+                           load_attr->line_info_rec_size) {
+                        linfo = alloc_zero_tailing_info(load_attr->line_info,
+                                                        load_attr->line_info_cnt,
+                                                        load_attr->line_info_rec_size,
+                                                        attr.line_info_rec_size);
+                        if (!linfo)
+                                goto done;
+
+                        attr.line_info = ptr_to_u64(linfo);
+                        attr.line_info_rec_size = load_attr->line_info_rec_size;
+                } else {
+                        break;
                 }
 
-                /* try with corrected func info records */
-                attr.func_info = ptr_to_u64(finfo);
-                attr.func_info_rec_size = load_attr->func_info_rec_size;
-
                 fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
 
                 if (fd >= 0)
@@ -259,6 +286,7 @@ int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
         fd = sys_bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
 done:
         free(finfo);
+        free(linfo);
         return fd;
 }
 
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 098e6f793b76..8f09de482839 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -82,6 +82,9 @@ struct bpf_load_program_attr {
         __u32 func_info_rec_size;
         const void *func_info;
         __u32 func_info_cnt;
+        __u32 line_info_rec_size;
+        const void *line_info;
+        __u32 line_info_cnt;
 };
 
 /* Flags to direct loading requirements */
diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index aa4fa02b13fc..d682d3b8f7b9 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -37,16 +37,26 @@ struct btf {
         int fd;
 };
 
+struct btf_ext_info {
+        /*
+         * info points to a deep copy of the individual info section
+         * (e.g. func_info and line_info) from the .BTF.ext.
+         * It does not include the __u32 rec_size.
+         */
+        void *info;
+        __u32 rec_size;
+        __u32 len;
+};
+
 struct btf_ext {
-        void *func_info;
-        __u32 func_info_rec_size;
-        __u32 func_info_len;
+        struct btf_ext_info func_info;
+        struct btf_ext_info line_info;
 };
 
-struct btf_sec_func_info {
+struct btf_ext_info_sec {
         __u32   sec_name_off;
-        __u32   num_func_info;
-        /* Followed by num_func_info number of bpf func_info records */
+        __u32   num_info;
+        /* Followed by num_info * record_size number of bytes */
         __u8    data[0];
 };
 
@@ -56,6 +66,14 @@ struct bpf_func_info_min {
         __u32   type_id;
 };
 
+/* The minimum bpf_line_info checked by the loader */
+struct bpf_line_info_min {
+        __u32   insn_off;
+        __u32   file_name_off;
+        __u32   line_off;
+        __u32   line_col;
+};
+
 static inline __u64 ptr_to_u64(const void *ptr)
 {
         return (__u64) (unsigned long) ptr;
@@ -486,12 +504,22 @@ exit_free:
         return err;
 }
 
-static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
-                                  __u8 *data, __u32 data_size,
-                                  btf_print_fn_t err_log)
+struct btf_ext_sec_copy_param {
+        __u32 off;
+        __u32 len;
+        __u32 min_rec_size;
+        struct btf_ext_info *ext_info;
+        const char *desc;
+};
+
+static int btf_ext_copy_info(struct btf_ext *btf_ext,
+                             __u8 *data, __u32 data_size,
+                             struct btf_ext_sec_copy_param *ext_sec,
+                             btf_print_fn_t err_log)
 {
         const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
-        const struct btf_sec_func_info *sinfo;
+        const struct btf_ext_info_sec *sinfo;
+        struct btf_ext_info *ext_info;
         __u32 info_left, record_size;
         /* The start of the info sec (including the __u32 record_size). */
         const void *info;
@@ -500,66 +528,69 @@ static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
         data = data + hdr->hdr_len;
         data_size -= hdr->hdr_len;
 
-        if (hdr->func_info_off & 0x03) {
-                elog("BTF.ext func_info section is not aligned to 4 bytes\n");
+        if (ext_sec->off & 0x03) {
+                elog(".BTF.ext %s section is not aligned to 4 bytes\n",
+                     ext_sec->desc);
                 return -EINVAL;
         }
 
-        if (data_size < hdr->func_info_off ||
-            hdr->func_info_len > data_size - hdr->func_info_off) {
-                elog("func_info section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
-                     hdr->func_info_off, hdr->func_info_len);
+        if (data_size < ext_sec->off ||
+            ext_sec->len > data_size - ext_sec->off) {
+                elog("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
+                     ext_sec->desc, ext_sec->off, ext_sec->len);
                 return -EINVAL;
         }
 
-        info = data + hdr->func_info_off;
-        info_left = hdr->func_info_len;
+        info = data + ext_sec->off;
+        info_left = ext_sec->len;
 
-        /* At least a func_info record size */
+        /* At least a record size */
         if (info_left < sizeof(__u32)) {
-                elog("BTF.ext func_info record size not found");
+                elog(".BTF.ext %s record size not found\n", ext_sec->desc);
                 return -EINVAL;
         }
 
         /* The record size needs to meet the minimum standard */
         record_size = *(__u32 *)info;
-        if (record_size < sizeof(struct bpf_func_info_min) ||
+        if (record_size < ext_sec->min_rec_size ||
             record_size & 0x03) {
-                elog("BTF.ext func_info invalid record size");
+                elog("%s section in .BTF.ext has invalid record size %u\n",
+                     ext_sec->desc, record_size);
                 return -EINVAL;
         }
 
         sinfo = info + sizeof(__u32);
         info_left -= sizeof(__u32);
 
-        /* If no func_info records, return failure now so .BTF.ext
-         * won't be used.
-         */
+        /* If no records, return failure now so .BTF.ext won't be used. */
         if (!info_left) {
-                elog("BTF.ext no func info records");
+                elog("%s section in .BTF.ext has no records", ext_sec->desc);
                 return -EINVAL;
         }
 
         while (info_left) {
-                unsigned int sec_hdrlen = sizeof(struct btf_sec_func_info);
+                unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
                 __u64 total_record_size;
                 __u32 num_records;
 
                 if (info_left < sec_hdrlen) {
-                        elog("BTF.ext func_info header not found");
+                        elog("%s section header is not found in .BTF.ext\n",
+                             ext_sec->desc);
                         return -EINVAL;
                 }
 
-                num_records = sinfo->num_func_info;
+                num_records = sinfo->num_info;
                 if (num_records == 0) {
-                        elog("incorrect BTF.ext num_func_info");
+                        elog("%s section has incorrect num_records in .BTF.ext\n",
+                             ext_sec->desc);
                         return -EINVAL;
                 }
 
                 total_record_size = sec_hdrlen +
                                     (__u64)num_records * record_size;
                 if (info_left < total_record_size) {
-                        elog("incorrect BTF.ext num_func_info");
+                        elog("%s section has incorrect num_records in .BTF.ext\n",
+                             ext_sec->desc);
                         return -EINVAL;
                 }
 
@@ -567,17 +598,49 @@ static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
                 sinfo = (void *)sinfo + total_record_size;
         }
 
-        btf_ext->func_info_len = hdr->func_info_len - sizeof(__u32);
-        btf_ext->func_info_rec_size = record_size;
-        btf_ext->func_info = malloc(btf_ext->func_info_len);
-        if (!btf_ext->func_info)
+        ext_info = ext_sec->ext_info;
+        ext_info->len = ext_sec->len - sizeof(__u32);
+        ext_info->rec_size = record_size;
+        ext_info->info = malloc(ext_info->len);
+        if (!ext_info->info)
                 return -ENOMEM;
-        memcpy(btf_ext->func_info, info + sizeof(__u32),
-               btf_ext->func_info_len);
+        memcpy(ext_info->info, info + sizeof(__u32), ext_info->len);
 
         return 0;
 }
 
+static int btf_ext_copy_func_info(struct btf_ext *btf_ext,
+                                  __u8 *data, __u32 data_size,
+                                  btf_print_fn_t err_log)
+{
+        const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
+        struct btf_ext_sec_copy_param param = {
+                .off = hdr->func_info_off,
+                .len = hdr->func_info_len,
+                .min_rec_size = sizeof(struct bpf_func_info_min),
+                .ext_info = &btf_ext->func_info,
+                .desc = "func_info"
+        };
+
+        return btf_ext_copy_info(btf_ext, data, data_size, &param, err_log);
+}
+
+static int btf_ext_copy_line_info(struct btf_ext *btf_ext,
+                                  __u8 *data, __u32 data_size,
+                                  btf_print_fn_t err_log)
+{
+        const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
+        struct btf_ext_sec_copy_param param = {
+                .off = hdr->line_info_off,
+                .len = hdr->line_info_len,
+                .min_rec_size = sizeof(struct bpf_line_info_min),
+                .ext_info = &btf_ext->line_info,
+                .desc = "line_info",
+        };
+
+        return btf_ext_copy_info(btf_ext, data, data_size, &param, err_log);
+}
+
 static int btf_ext_parse_hdr(__u8 *data, __u32 data_size,
                              btf_print_fn_t err_log)
 {
@@ -617,7 +680,8 @@ void btf_ext__free(struct btf_ext *btf_ext)
         if (!btf_ext)
                 return;
 
-        free(btf_ext->func_info);
+        free(btf_ext->func_info.info);
+        free(btf_ext->line_info.info);
         free(btf_ext);
 }
 
@@ -640,25 +704,32 @@ struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log)
                 return ERR_PTR(err);
         }
 
+        err = btf_ext_copy_line_info(btf_ext, data, size, err_log);
+        if (err) {
+                btf_ext__free(btf_ext);
+                return ERR_PTR(err);
+        }
+
         return btf_ext;
 }
 
-int btf_ext__reloc_func_info(struct btf *btf, struct btf_ext *btf_ext,
-                             const char *sec_name, __u32 insns_cnt,
-                             void **func_info, __u32 *cnt)
+static int btf_ext_reloc_info(const struct btf *btf,
+                              const struct btf_ext_info *ext_info,
+                              const char *sec_name, __u32 insns_cnt,
+                              void **info, __u32 *cnt)
 {
-        __u32 sec_hdrlen = sizeof(struct btf_sec_func_info);
-        __u32 i, record_size, existing_flen, records_len;
-        struct btf_sec_func_info *sinfo;
+        __u32 sec_hdrlen = sizeof(struct btf_ext_info_sec);
+        __u32 i, record_size, existing_len, records_len;
+        struct btf_ext_info_sec *sinfo;
         const char *info_sec_name;
         __u64 remain_len;
         void *data;
 
-        record_size = btf_ext->func_info_rec_size;
-        sinfo = btf_ext->func_info;
-        remain_len = btf_ext->func_info_len;
+        record_size = ext_info->rec_size;
+        sinfo = ext_info->info;
+        remain_len = ext_info->len;
         while (remain_len > 0) {
-                records_len = sinfo->num_func_info * record_size;
+                records_len = sinfo->num_info * record_size;
                 info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off);
                 if (strcmp(info_sec_name, sec_name)) {
                         remain_len -= sec_hdrlen + records_len;
@@ -666,32 +737,52 @@ int btf_ext__reloc_func_info(struct btf *btf, struct btf_ext *btf_ext,
                         continue;
                 }
 
-                existing_flen = (*cnt) * record_size;
-                data = realloc(*func_info, existing_flen + records_len);
+                existing_len = (*cnt) * record_size;
+                data = realloc(*info, existing_len + records_len);
                 if (!data)
                         return -ENOMEM;
 
-                memcpy(data + existing_flen, sinfo->data, records_len);
+                memcpy(data + existing_len, sinfo->data, records_len);
                 /* adjust insn_off only, the rest data will be passed
                  * to the kernel.
                  */
-                for (i = 0; i < sinfo->num_func_info; i++) {
-                        struct bpf_func_info_min *record;
+                for (i = 0; i < sinfo->num_info; i++) {
+                        __u32 *insn_off;
 
-                        record = data + existing_flen + i * record_size;
-                        record->insn_off =
-                                record->insn_off / sizeof(struct bpf_insn) +
+                        insn_off = data + existing_len + (i * record_size);
+                        *insn_off = *insn_off / sizeof(struct bpf_insn) +
                                 insns_cnt;
                 }
-                *func_info = data;
-                *cnt += sinfo->num_func_info;
+                *info = data;
+                *cnt += sinfo->num_info;
                 return 0;
         }
 
         return -ENOENT;
 }
 
+int btf_ext__reloc_func_info(const struct btf *btf, const struct btf_ext *btf_ext,
+                             const char *sec_name, __u32 insns_cnt,
+                             void **func_info, __u32 *cnt)
+{
+        return btf_ext_reloc_info(btf, &btf_ext->func_info, sec_name,
+                                  insns_cnt, func_info, cnt);
+}
+
+int btf_ext__reloc_line_info(const struct btf *btf, const struct btf_ext *btf_ext,
+                             const char *sec_name, __u32 insns_cnt,
+                             void **line_info, __u32 *cnt)
+{
+        return btf_ext_reloc_info(btf, &btf_ext->line_info, sec_name,
+                                  insns_cnt, line_info, cnt);
+}
+
 __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext)
 {
-        return btf_ext->func_info_rec_size;
+        return btf_ext->func_info.rec_size;
+}
+
+__u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext)
+{
+        return btf_ext->line_info.rec_size;
 }
diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
index 936177a538cd..b0610dcdae6b 100644
--- a/tools/lib/bpf/btf.h
+++ b/tools/lib/bpf/btf.h
@@ -51,6 +51,8 @@ struct btf_ext_header {
         /* All offsets are in bytes relative to the end of this header */
         __u32   func_info_off;
         __u32   func_info_len;
+        __u32   line_info_off;
+        __u32   line_info_len;
 };
 
 typedef int (*btf_print_fn_t)(const char *, ...)
@@ -70,10 +72,16 @@ LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
 
 struct btf_ext *btf_ext__new(__u8 *data, __u32 size, btf_print_fn_t err_log);
 void btf_ext__free(struct btf_ext *btf_ext);
-int btf_ext__reloc_func_info(struct btf *btf, struct btf_ext *btf_ext,
+int btf_ext__reloc_func_info(const struct btf *btf,
+                             const struct btf_ext *btf_ext,
                              const char *sec_name, __u32 insns_cnt,
                              void **func_info, __u32 *func_info_len);
+int btf_ext__reloc_line_info(const struct btf *btf,
+                             const struct btf_ext *btf_ext,
+                             const char *sec_name, __u32 insns_cnt,
+                             void **line_info, __u32 *cnt);
 __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
+__u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);
 
 #ifdef __cplusplus
 } /* extern "C" */
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 4ea3368bf803..e2bc75ee1614 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -170,6 +170,10 @@ struct bpf_program {
         __u32 func_info_cnt;
 
         struct bpf_capabilities *caps;
+
+        void *line_info;
+        __u32 line_info_rec_size;
+        __u32 line_info_cnt;
 };
 
 struct bpf_map {
@@ -1342,6 +1346,19 @@ bpf_program_reloc_btf_ext(struct bpf_program *prog, struct bpf_object *obj,
                 prog->func_info_rec_size = btf_ext__func_info_rec_size(obj->btf_ext);
         }
 
+        if (!insn_offset || prog->line_info) {
+                err = btf_ext__reloc_line_info(obj->btf, obj->btf_ext,
+                                               section_name, insn_offset,
+                                               &prog->line_info,
+                                               &prog->line_info_cnt);
+                if (err)
+                        return check_btf_ext_reloc_err(prog, err,
+                                                       prog->line_info,
+                                                       "bpf_line_info");
+
+                prog->line_info_rec_size = btf_ext__line_info_rec_size(obj->btf_ext);
+        }
+
         if (!insn_offset)
                 prog->btf_fd = btf__fd(obj->btf);
 
@@ -1526,6 +1543,9 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
         load_attr.func_info = prog->func_info;
         load_attr.func_info_rec_size = prog->func_info_rec_size;
         load_attr.func_info_cnt = prog->func_info_cnt;
+        load_attr.line_info = prog->line_info;
+        load_attr.line_info_rec_size = prog->line_info_rec_size;
+        load_attr.line_info_cnt = prog->line_info_cnt;
         if (!load_attr.insns || !load_attr.insns_cnt)
                 return -EINVAL;