Mention struct btf_ext_info_sec rather than non-existent btf_sec_func_info in BTF.ext struct documentation.

Signed-off-by: Tony Ambardar tony.ambardar@gmail.com --- tools/lib/bpf/libbpf_internal.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 408df59e0771..8cda511a1982 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -448,11 +448,11 @@ struct btf_ext_info { * * The func_info subsection layout: * record size for struct bpf_func_info in the func_info subsection - * struct btf_sec_func_info for section #1 + * struct btf_ext_info_sec for section #1 * a list of bpf_func_info records for section #1 * where struct bpf_func_info mimics one in include/uapi/linux/bpf.h * but may not be identical - * struct btf_sec_func_info for section #2 + * struct btf_ext_info_sec for section #2 * a list of bpf_func_info records for section #2 * ...... *

Support for handling BTF data of either endianness was added in [1], but did not include BTF.ext data for lack of use cases. Later, support for static linking [2] provided a use case, but this feature and later ones were restricted to native-endian usage.

Add support for BTF.ext handling in either endianness. Convert BTF.ext data to native endianness when read into memory for further processing, and support raw data access that restores the original byte-order for output. Add internal header functions for byte-swapping func, line, and core info records.

Add new API functions btf_ext__endianness() and btf_ext__set_endianness() for query and setting byte-order, as already exist for BTF data.

[1] 3289959b97ca ("libbpf: Support BTF loading and raw data output in both endianness") [2] 8fd27bf69b86 ("libbpf: Add BPF static linker BTF and BTF.ext support")

Signed-off-by: Tony Ambardar tony.ambardar@gmail.com --- tools/lib/bpf/btf.c | 280 +++++++++++++++++++++++++------- tools/lib/bpf/btf.h | 3 + tools/lib/bpf/libbpf.map | 2 + tools/lib/bpf/libbpf_internal.h | 30 ++++ 4 files changed, 258 insertions(+), 57 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index e1d4cbd83729..c04f37b87f25 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -2885,22 +2885,29 @@ int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id, return btf_commit_type(btf, sz); }

-struct btf_ext_sec_setup_param { +struct btf_ext_sec_info_param { __u32 off; __u32 len; __u32 min_rec_size; + __u32 rec_size; struct btf_ext_info *ext_info; const char *desc; };

-static int btf_ext_setup_info(struct btf_ext *btf_ext, - struct btf_ext_sec_setup_param *ext_sec) +/* + * Parse a single info subsection of the BTF.ext info data: + * - validate subsection structure and elements + * - save info subsection start and sizing details in struct btf_ext + * - endian-independent operation, for calling before byte-swapping + */ +static int btf_ext_parse_sec_info(struct btf_ext *btf_ext, + struct btf_ext_sec_info_param *ext_sec, + bool is_native) { const struct btf_ext_info_sec *sinfo; struct btf_ext_info *ext_info; __u32 info_left, record_size; size_t sec_cnt = 0; - /* The start of the info sec (including the __u32 record_size). */ void *info;

if (ext_sec->len == 0) @@ -2912,6 +2919,7 @@ static int btf_ext_setup_info(struct btf_ext *btf_ext, return -EINVAL; }

+ /* The start of the info sec (including the __u32 record_size). */ info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off; info_left = ext_sec->len;

@@ -2927,9 +2935,13 @@ static int btf_ext_setup_info(struct btf_ext *btf_ext, return -EINVAL; }

- /* The record size needs to meet the minimum standard */ - record_size = *(__u32 *)info; + /* The record size needs to meet either the minimum standard or, when + * handling non-native endianness data, the exact standard so as + * to allow safe byte-swapping. + */ + record_size = is_native ? *(__u32 *)info : bswap_32(*(__u32 *)info); if (record_size < ext_sec->min_rec_size || + (!is_native && record_size != ext_sec->rec_size) || record_size & 0x03) { pr_debug("%s section in .BTF.ext has invalid record size %u\n", ext_sec->desc, record_size); @@ -2956,7 +2968,7 @@ static int btf_ext_setup_info(struct btf_ext *btf_ext, return -EINVAL; }

- num_records = sinfo->num_info; + num_records = is_native ? sinfo->num_info : bswap_32(sinfo->num_info); if (num_records == 0) { pr_debug("%s section has incorrect num_records in .BTF.ext\n", ext_sec->desc); @@ -2984,64 +2996,160 @@ static int btf_ext_setup_info(struct btf_ext *btf_ext, return 0; }

-static int btf_ext_setup_func_info(struct btf_ext *btf_ext) +/* Parse all info secs in the BTF.ext info data */ +static int btf_ext_parse_info(struct btf_ext *btf_ext, bool is_native) { - struct btf_ext_sec_setup_param param = { + struct btf_ext_sec_info_param func_info = { .off = btf_ext->hdr->func_info_off, .len = btf_ext->hdr->func_info_len, .min_rec_size = sizeof(struct bpf_func_info_min), + .rec_size = sizeof(struct bpf_func_info), .ext_info = &btf_ext->func_info, .desc = "func_info" }; - - return btf_ext_setup_info(btf_ext, &param); -} - -static int btf_ext_setup_line_info(struct btf_ext *btf_ext) -{ - struct btf_ext_sec_setup_param param = { + struct btf_ext_sec_info_param line_info = { .off = btf_ext->hdr->line_info_off, .len = btf_ext->hdr->line_info_len, .min_rec_size = sizeof(struct bpf_line_info_min), + .rec_size = sizeof(struct bpf_line_info), .ext_info = &btf_ext->line_info, .desc = "line_info", }; - - return btf_ext_setup_info(btf_ext, &param); -} - -static int btf_ext_setup_core_relos(struct btf_ext *btf_ext) -{ - struct btf_ext_sec_setup_param param = { + struct btf_ext_sec_info_param core_relo = { .off = btf_ext->hdr->core_relo_off, .len = btf_ext->hdr->core_relo_len, .min_rec_size = sizeof(struct bpf_core_relo), + .rec_size = sizeof(struct bpf_core_relo), .ext_info = &btf_ext->core_relo_info, .desc = "core_relo", }; + int err; + + err = btf_ext_parse_sec_info(btf_ext, &func_info, is_native); + if (err) + return err; + + err = btf_ext_parse_sec_info(btf_ext, &line_info, is_native); + if (err) + return err; + + if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len)) + return 0; /* skip core relos parsing */

- return btf_ext_setup_info(btf_ext, &param); + err = btf_ext_parse_sec_info(btf_ext, &core_relo, is_native); + if (err) + return err; + + return 0; }

-static int btf_ext_parse_hdr(__u8 *data, __u32 data_size) +/* Swap byte-order of BTF.ext header with any endianness */ +static void btf_ext_bswap_hdr(struct btf_ext_header *h) { - const struct btf_ext_header *hdr = (struct btf_ext_header *)data; + bool is_native = h->magic == BTF_MAGIC; + __u32 hdr_len;

- if (data_size < offsetofend(struct btf_ext_header, hdr_len) || - data_size < hdr->hdr_len) { - pr_debug("BTF.ext header not found\n"); + hdr_len = is_native ? h->hdr_len : bswap_32(h->hdr_len); + + h->magic = bswap_16(h->magic); + h->hdr_len = bswap_32(h->hdr_len); + h->func_info_off = bswap_32(h->func_info_off); + h->func_info_len = bswap_32(h->func_info_len); + h->line_info_off = bswap_32(h->line_info_off); + h->line_info_len = bswap_32(h->line_info_len); + + if (hdr_len < offsetofend(struct btf_ext_header, core_relo_len)) + return; + + h->core_relo_off = bswap_32(h->core_relo_off); + h->core_relo_len = bswap_32(h->core_relo_len); +} + +/* Swap byte-order of generic info subsection */ +static void btf_ext_bswap_info_sec(void *info, __u32 len, bool is_native, + info_rec_bswap_fn bswap_fn) +{ + struct btf_ext_info_sec *sec; + __u32 info_left, rec_size, *rs; + + if (len == 0) + return; + + rs = info; /* info record size */ + rec_size = is_native ? *rs : bswap_32(*rs); + *rs = bswap_32(*rs); + + sec = info + sizeof(__u32); /* info sec #1 */ + info_left = len - sizeof(__u32); + while (info_left) { + unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec); + __u32 i, num_recs; + void *p; + + num_recs = is_native ? sec->num_info : bswap_32(sec->num_info); + sec->sec_name_off = bswap_32(sec->sec_name_off); + sec->num_info = bswap_32(sec->num_info); + p = sec->data; /* info rec #1 */ + for (i = 0; i < num_recs; i++, p += rec_size) + bswap_fn(p); + sec = p; + info_left -= sec_hdrlen + (__u64)rec_size * num_recs; + } +} + +/* + * Swap byte-order of all info data in a BTF.ext section + * - requires BTF.ext hdr in native endianness + */ +static void btf_ext_bswap_info(struct btf_ext *btf_ext, void *data) +{ + const bool is_native = btf_ext->swapped_endian; + const struct btf_ext_header *h = data; + void *info; + + /* Swap func_info subsection byte-order */ + info = data + h->hdr_len + h->func_info_off; + btf_ext_bswap_info_sec(info, h->func_info_len, is_native, + (info_rec_bswap_fn)bpf_func_info_bswap); + + /* Swap line_info subsection byte-order */ + info = data + h->hdr_len + h->line_info_off; + btf_ext_bswap_info_sec(info, h->line_info_len, is_native, + (info_rec_bswap_fn)bpf_line_info_bswap); + + /* Swap core_relo subsection byte-order (if present) */ + if (h->hdr_len < offsetofend(struct btf_ext_header, core_relo_len)) + return; + + info = data + h->hdr_len + h->core_relo_off; + btf_ext_bswap_info_sec(info, h->core_relo_len, is_native, + (info_rec_bswap_fn)bpf_core_relo_bswap); +} + +/* Parse hdr data and info sections: check and convert to native endianness */ +static int btf_ext_parse(struct btf_ext *btf_ext) +{ + __u32 hdr_len, data_size = btf_ext->data_size; + struct btf_ext_header *hdr = btf_ext->hdr; + bool swapped_endian = false; + int err; + + if (data_size < offsetofend(struct btf_ext_header, hdr_len)) { + pr_debug("BTF.ext header too short\n"); return -EINVAL; }

+ hdr_len = hdr->hdr_len; if (hdr->magic == bswap_16(BTF_MAGIC)) { - pr_warn("BTF.ext in non-native endianness is not supported\n"); - return -ENOTSUP; + swapped_endian = true; + hdr_len = bswap_32(hdr_len); } else if (hdr->magic != BTF_MAGIC) { pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic); return -EINVAL; }

- if (hdr->version != BTF_VERSION) { + /* Ensure known version of structs, current BTF_VERSION == 1 */ + if (hdr->version != 1) { pr_debug("Unsupported BTF.ext version:%u\n", hdr->version); return -ENOTSUP; } @@ -3051,11 +3159,39 @@ static int btf_ext_parse_hdr(__u8 *data, __u32 data_size) return -ENOTSUP; }

- if (data_size == hdr->hdr_len) { + if (data_size < hdr_len) { + pr_debug("BTF.ext header not found\n"); + return -EINVAL; + } else if (data_size == hdr_len) { pr_debug("BTF.ext has no data\n"); return -EINVAL; }

+ /* Verify mandatory hdr info details present */ + if (hdr_len < offsetofend(struct btf_ext_header, line_info_len)) { + pr_warn("BTF.ext header missing func_info, line_info\n"); + return -EINVAL; + } + + /* Keep hdr native byte-order in memory for introspection */ + if (swapped_endian) + btf_ext_bswap_hdr(btf_ext->hdr); + + /* Validate info subsections and cache key metadata */ + err = btf_ext_parse_info(btf_ext, !swapped_endian); + if (err) + return err; + + /* Keep infos native byte-order in memory for introspection */ + if (swapped_endian) + btf_ext_bswap_info(btf_ext, btf_ext->data); + + /* + * Set btf_ext->swapped_endian only after all header and info data has + * been swapped, helping bswap functions determine if their data are + * in native byte-order when called. + */ + btf_ext->swapped_endian = swapped_endian; return 0; }

@@ -3067,6 +3203,7 @@ void btf_ext__free(struct btf_ext *btf_ext) free(btf_ext->line_info.sec_idxs); free(btf_ext->core_relo_info.sec_idxs); free(btf_ext->data); + free(btf_ext->data_swapped); free(btf_ext); }

@@ -3087,29 +3224,7 @@ struct btf_ext *btf_ext__new(const __u8 *data, __u32 size) } memcpy(btf_ext->data, data, size);

- err = btf_ext_parse_hdr(btf_ext->data, size); - if (err) - goto done; - - if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, line_info_len)) { - err = -EINVAL; - goto done; - } - - err = btf_ext_setup_func_info(btf_ext); - if (err) - goto done; - - err = btf_ext_setup_line_info(btf_ext); - if (err) - goto done; - - if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len)) - goto done; /* skip core relos parsing */ - - err = btf_ext_setup_core_relos(btf_ext); - if (err) - goto done; + err = btf_ext_parse(btf_ext);

done: if (err) { @@ -3120,15 +3235,66 @@ struct btf_ext *btf_ext__new(const __u8 *data, __u32 size) return btf_ext; }

+static void *btf_ext_raw_data(const struct btf_ext *btf_ext_ro, bool swap_endian) +{ + struct btf_ext *btf_ext = (struct btf_ext *)btf_ext_ro; + const __u32 data_sz = btf_ext->data_size; + void *data; + + /* Return native data (always present) or swapped data if present */ + if (!swap_endian) + return btf_ext->data; + else if (btf_ext->data_swapped) + return btf_ext->data_swapped; + + /* Recreate missing swapped data, then cache and return */ + data = calloc(1, data_sz); + if (!data) + return NULL; + memcpy(data, btf_ext->data, data_sz); + + btf_ext_bswap_info(btf_ext, data); + btf_ext_bswap_hdr(data); + btf_ext->data_swapped = data; + return data; +} + const void *btf_ext__raw_data(const struct btf_ext *btf_ext, __u32 *size) { + void *data; + + data = btf_ext_raw_data(btf_ext, btf_ext->swapped_endian); + if (!data) + return errno = ENOMEM, NULL; + *size = btf_ext->data_size; - return btf_ext->data; + return data; }

__attribute__((alias("btf_ext__raw_data"))) const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size);

+enum btf_endianness btf_ext__endianness(const struct btf_ext *btf_ext) +{ + if (is_host_big_endian()) + return btf_ext->swapped_endian ? BTF_LITTLE_ENDIAN : BTF_BIG_ENDIAN; + else + return btf_ext->swapped_endian ? BTF_BIG_ENDIAN : BTF_LITTLE_ENDIAN; +} + +int btf_ext__set_endianness(struct btf_ext *btf_ext, enum btf_endianness endian) +{ + if (endian != BTF_LITTLE_ENDIAN && endian != BTF_BIG_ENDIAN) + return libbpf_err(-EINVAL); + + btf_ext->swapped_endian = is_host_big_endian() != (endian == BTF_BIG_ENDIAN); + + if (!btf_ext->swapped_endian) { + free(btf_ext->data_swapped); + btf_ext->data_swapped = NULL; + } + return 0; +}

struct btf_dedup;

diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index 4e349ad79ee6..47ee8f6ac489 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -167,6 +167,9 @@ LIBBPF_API const char *btf__str_by_offset(const struct btf *btf, __u32 offset); LIBBPF_API struct btf_ext *btf_ext__new(const __u8 *data, __u32 size); LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext); LIBBPF_API const void *btf_ext__raw_data(const struct btf_ext *btf_ext, __u32 *size); +LIBBPF_API enum btf_endianness btf_ext__endianness(const struct btf_ext *btf_ext); +LIBBPF_API int btf_ext__set_endianness(struct btf_ext *btf_ext, + enum btf_endianness endian);

LIBBPF_API int btf__find_str(struct btf *btf, const char *s); LIBBPF_API int btf__add_str(struct btf *btf, const char *s); diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 0096e483f7eb..f40ccc2946e7 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -421,6 +421,8 @@ LIBBPF_1.5.0 { global: btf__distill_base; btf__relocate; + btf_ext__endianness; + btf_ext__set_endianness; bpf_map__autoattach; bpf_map__set_autoattach; bpf_object__token_fd; diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 8cda511a1982..1307753b49b3 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -484,6 +484,8 @@ struct btf_ext { struct btf_ext_header *hdr; void *data; }; + void *data_swapped; + bool swapped_endian; struct btf_ext_info func_info; struct btf_ext_info line_info; struct btf_ext_info core_relo_info; @@ -511,6 +513,34 @@ struct bpf_line_info_min { __u32 line_col; };

+/* Functions to byte-swap info records */ + +typedef void (*info_rec_bswap_fn)(void *); + +static inline void bpf_func_info_bswap(struct bpf_func_info *i) +{ + i->insn_off = bswap_32(i->insn_off); + i->type_id = bswap_32(i->type_id); +} + +static inline void bpf_line_info_bswap(struct bpf_line_info *i) +{ + i->insn_off = bswap_32(i->insn_off); + i->file_name_off = bswap_32(i->file_name_off); + i->line_off = bswap_32(i->line_off); + i->line_col = bswap_32(i->line_col); +} + +static inline void bpf_core_relo_bswap(struct bpf_core_relo *i) +{ + _Static_assert(sizeof(i->kind) == sizeof(__u32), + "enum bpf_core_relo_kind is not 32-bit\n"); + i->insn_off = bswap_32(i->insn_off); + i->type_id = bswap_32(i->type_id); + i->access_str_off = bswap_32(i->access_str_off); + i->kind = bswap_32(i->kind); +} + enum btf_field_iter_kind { BTF_FIELD_ITER_IDS, BTF_FIELD_ITER_STRS,

Allow bpf_object__open() to access files of either endianness, and convert included BPF programs to native byte-order in-memory for introspection. Loading BPF objects of non-native byte-order is still disallowed however.

Signed-off-by: Tony Ambardar tony.ambardar@gmail.com --- tools/lib/bpf/libbpf.c | 51 +++++++++++++++++++++++++++------ tools/lib/bpf/libbpf_internal.h | 11 +++++++ 2 files changed, 53 insertions(+), 9 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 60b69c6aaf53..0540d2331535 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -694,6 +694,8 @@ struct bpf_object { /* Information when doing ELF related work. Only valid if efile.elf is not NULL */ struct elf_state efile;

+ unsigned char byteorder; + struct btf *btf; struct btf_ext *btf_ext;

@@ -940,6 +942,20 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data, return 0; }

+static void bpf_object_bswap_progs(struct bpf_object *obj) +{ + struct bpf_program *prog = obj->programs; + struct bpf_insn *insn; + int p, i; + + for (p = 0; p < obj->nr_programs; p++, prog++) { + insn = prog->insns; + for (i = 0; i < prog->insns_cnt; i++, insn++) + bpf_insn_bswap(insn); + } + pr_debug("converted %zu BPF programs to native byte order\n", obj->nr_programs); +} + static const struct btf_member * find_member_by_offset(const struct btf_type *t, __u32 bit_offset) { @@ -1506,6 +1522,7 @@ static void bpf_object__elf_finish(struct bpf_object *obj)

elf_end(obj->efile.elf); obj->efile.elf = NULL; + obj->efile.ehdr = NULL; obj->efile.symbols = NULL; obj->efile.arena_data = NULL;

@@ -1571,6 +1588,16 @@ static int bpf_object__elf_init(struct bpf_object *obj) goto errout; }

+ /* Validate ELF object endianness... */ + if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB && + ehdr->e_ident[EI_DATA] != ELFDATA2MSB) { + err = -LIBBPF_ERRNO__ENDIAN; + pr_warn("elf: '%s' has unknown byte order\n", obj->path); + goto errout; + } + /* and save after bpf_object_open() frees ELF data */ + obj->byteorder = ehdr->e_ident[EI_DATA]; + if (elf_getshdrstrndx(elf, &obj->efile.shstrndx)) { pr_warn("elf: failed to get section names section index for %s: %s\n", obj->path, elf_errmsg(-1)); @@ -1599,19 +1626,15 @@ static int bpf_object__elf_init(struct bpf_object *obj) return err; }

-static int bpf_object__check_endianness(struct bpf_object *obj) +static bool is_native_endianness(struct bpf_object *obj) { #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ - if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2LSB) - return 0; + return obj->byteorder == ELFDATA2LSB; #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ - if (obj->efile.ehdr->e_ident[EI_DATA] == ELFDATA2MSB) - return 0; + return obj->byteorder == ELFDATA2MSB; #else # error "Unrecognized __BYTE_ORDER__" #endif - pr_warn("elf: endianness mismatch in %s.\n", obj->path); - return -LIBBPF_ERRNO__ENDIAN; }

static int @@ -3953,6 +3976,10 @@ static int bpf_object__elf_collect(struct bpf_object *obj) return -LIBBPF_ERRNO__FORMAT; }

+ /* change BPF program insns to native endianness for introspection */ + if (!is_native_endianness(obj)) + bpf_object_bswap_progs(obj); + /* sort BPF programs by section name and in-section instruction offset * for faster search */ @@ -7992,7 +8019,6 @@ static struct bpf_object *bpf_object_open(const char *path, const void *obj_buf, }

err = bpf_object__elf_init(obj); - err = err ? : bpf_object__check_endianness(obj); err = err ? : bpf_object__elf_collect(obj); err = err ? : bpf_object__collect_externs(obj); err = err ? : bpf_object_fixup_btf(obj); @@ -8498,8 +8524,15 @@ static int bpf_object_load(struct bpf_object *obj, int extra_log_level, const ch return libbpf_err(-EINVAL); }

- if (obj->gen_loader) + /* Disallow kernel loading programs of non-native endianness but + * permit cross-endian creation of "light skeleton". + */ + if (obj->gen_loader) { bpf_gen__init(obj->gen_loader, extra_log_level, obj->nr_programs, obj->nr_maps); + } else if (!is_native_endianness(obj)) { + pr_warn("object '%s': loading non-native endianness is unsupported\n", obj->name); + return libbpf_err(-LIBBPF_ERRNO__ENDIAN); + }

err = bpf_object_prepare_token(obj); err = err ? : bpf_object__probe_loading(obj); diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 1307753b49b3..37477387fb5b 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -11,6 +11,7 @@

#include <stdlib.h> #include <limits.h> +#include <byteswap.h> #include <errno.h> #include <linux/err.h> #include <fcntl.h> @@ -618,6 +619,16 @@ static inline bool is_ldimm64_insn(struct bpf_insn *insn) return insn->code == (BPF_LD | BPF_IMM | BPF_DW); }

+static inline void bpf_insn_bswap(struct bpf_insn *insn) +{ + __u8 tmp_reg = insn->dst_reg; + + insn->dst_reg = insn->src_reg; + insn->src_reg = tmp_reg; + insn->off = bswap_16(insn->off); + insn->imm = bswap_32(insn->imm); +} + /* Unconditionally dup FD, ensuring it doesn't use [0, 2] range. * Original FD is not closed or altered in any other way. * Preserves original FD value, if it's invalid (negative).

Track target endianness in 'struct bpf_gen' and process in-memory data in native byte-order, but on finalization convert the embedded loader BPF insns to target endianness.

The light skeleton also includes a target-accessed data blob which is heterogeneous and thus difficult to convert to target byte-order on finalization. Add support functions to convert data to target endianness as it is added to the blob.

Also add additional debug logging for data blob structure details and skeleton loading.

Acked-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Tony Ambardar tony.ambardar@gmail.com --- tools/lib/bpf/bpf_gen_internal.h | 1 + tools/lib/bpf/gen_loader.c | 187 ++++++++++++++++++++++--------- tools/lib/bpf/libbpf.c | 1 + tools/lib/bpf/skel_internal.h | 3 +- 4 files changed, 139 insertions(+), 53 deletions(-)

diff --git a/tools/lib/bpf/bpf_gen_internal.h b/tools/lib/bpf/bpf_gen_internal.h index fdf44403ff36..6ff963a491d9 100644 --- a/tools/lib/bpf/bpf_gen_internal.h +++ b/tools/lib/bpf/bpf_gen_internal.h @@ -34,6 +34,7 @@ struct bpf_gen { void *data_cur; void *insn_start; void *insn_cur; + bool swapped_endian; ssize_t cleanup_label; __u32 nr_progs; __u32 nr_maps; diff --git a/tools/lib/bpf/gen_loader.c b/tools/lib/bpf/gen_loader.c index cf3323fd47b8..8a2b0f62d91d 100644 --- a/tools/lib/bpf/gen_loader.c +++ b/tools/lib/bpf/gen_loader.c @@ -401,6 +401,15 @@ int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps) opts->insns_sz = gen->insn_cur - gen->insn_start; opts->data = gen->data_start; opts->data_sz = gen->data_cur - gen->data_start; + + /* use target endianness for embedded loader */ + if (gen->swapped_endian) { + struct bpf_insn *insn = (struct bpf_insn *)opts->insns; + int insn_cnt = opts->insns_sz / sizeof(struct bpf_insn); + + for (i = 0; i < insn_cnt; i++) + bpf_insn_bswap(insn++); + } } return gen->error; } @@ -414,6 +423,28 @@ void bpf_gen__free(struct bpf_gen *gen) free(gen); }

+/* + * Fields of bpf_attr are set to values in native byte-order before being + * written to the target-bound data blob, and may need endian conversion. + * This macro allows providing the correct value in situ more simply than + * writing a separate converter for *all fields* of *all records* included + * in union bpf_attr. Note that sizeof(rval) should match the assignment + * target to avoid runtime problems. + */ +#define tgt_endian(rval) ({ \ + typeof(rval) _val = (rval); \ + if (gen->swapped_endian) { \ + switch (sizeof(_val)) { \ + case 1: break; \ + case 2: _val = bswap_16(_val); break; \ + case 4: _val = bswap_32(_val); break; \ + case 8: _val = bswap_64(_val); break; \ + default: pr_warn("unsupported bswap size!\n"); \ + } \ + } \ + _val; \ +}) + void bpf_gen__load_btf(struct bpf_gen *gen, const void *btf_raw_data, __u32 btf_raw_size) { @@ -422,11 +453,12 @@ void bpf_gen__load_btf(struct bpf_gen *gen, const void *btf_raw_data, union bpf_attr attr;

memset(&attr, 0, attr_size); - pr_debug("gen: load_btf: size %d\n", btf_raw_size); btf_data = add_data(gen, btf_raw_data, btf_raw_size);

- attr.btf_size = btf_raw_size; + attr.btf_size = tgt_endian(btf_raw_size); btf_load_attr = add_data(gen, &attr, attr_size); + pr_debug("gen: load_btf: off %d size %d, attr: off %d size %d\n", + btf_data, btf_raw_size, btf_load_attr, attr_size);

/* populate union bpf_attr with user provided log details */ move_ctx2blob(gen, attr_field(btf_load_attr, btf_log_level), 4, @@ -457,28 +489,29 @@ void bpf_gen__map_create(struct bpf_gen *gen, union bpf_attr attr;

memset(&attr, 0, attr_size); - attr.map_type = map_type; - attr.key_size = key_size; - attr.value_size = value_size; - attr.map_flags = map_attr->map_flags; - attr.map_extra = map_attr->map_extra; + attr.map_type = tgt_endian(map_type); + attr.key_size = tgt_endian(key_size); + attr.value_size = tgt_endian(value_size); + attr.map_flags = tgt_endian(map_attr->map_flags); + attr.map_extra = tgt_endian(map_attr->map_extra); if (map_name) libbpf_strlcpy(attr.map_name, map_name, sizeof(attr.map_name)); - attr.numa_node = map_attr->numa_node; - attr.map_ifindex = map_attr->map_ifindex; - attr.max_entries = max_entries; - attr.btf_key_type_id = map_attr->btf_key_type_id; - attr.btf_value_type_id = map_attr->btf_value_type_id; - - pr_debug("gen: map_create: %s idx %d type %d value_type_id %d\n", - attr.map_name, map_idx, map_type, attr.btf_value_type_id); + attr.numa_node = tgt_endian(map_attr->numa_node); + attr.map_ifindex = tgt_endian(map_attr->map_ifindex); + attr.max_entries = tgt_endian(max_entries); + attr.btf_key_type_id = tgt_endian(map_attr->btf_key_type_id); + attr.btf_value_type_id = tgt_endian(map_attr->btf_value_type_id);

map_create_attr = add_data(gen, &attr, attr_size); - if (attr.btf_value_type_id) + pr_debug("gen: map_create: %s idx %d type %d value_type_id %d, attr: off %d size %d\n", + map_name, map_idx, map_type, map_attr->btf_value_type_id, + map_create_attr, attr_size); + + if (map_attr->btf_value_type_id) /* populate union bpf_attr with btf_fd saved in the stack earlier */ move_stack2blob(gen, attr_field(map_create_attr, btf_fd), 4, stack_off(btf_fd)); - switch (attr.map_type) { + switch (map_type) { case BPF_MAP_TYPE_ARRAY_OF_MAPS: case BPF_MAP_TYPE_HASH_OF_MAPS: move_stack2blob(gen, attr_field(map_create_attr, inner_map_fd), 4, @@ -498,8 +531,8 @@ void bpf_gen__map_create(struct bpf_gen *gen, /* emit MAP_CREATE command */ emit_sys_bpf(gen, BPF_MAP_CREATE, map_create_attr, attr_size); debug_ret(gen, "map_create %s idx %d type %d value_size %d value_btf_id %d", - attr.map_name, map_idx, map_type, value_size, - attr.btf_value_type_id); + map_name, map_idx, map_type, value_size, + map_attr->btf_value_type_id); emit_check_err(gen); /* remember map_fd in the stack, if successful */ if (map_idx < 0) { @@ -784,12 +817,12 @@ static void emit_relo_ksym_typeless(struct bpf_gen *gen, emit_ksym_relo_log(gen, relo, kdesc->ref); }

-static __u32 src_reg_mask(void) +static __u32 src_reg_mask(struct bpf_gen *gen) { -#if defined(__LITTLE_ENDIAN_BITFIELD) - return 0x0f; /* src_reg,dst_reg,... */ -#elif defined(__BIG_ENDIAN_BITFIELD) - return 0xf0; /* dst_reg,src_reg,... */ +#if defined(__LITTLE_ENDIAN_BITFIELD) /* src_reg,dst_reg,... */ + return gen->swapped_endian ? 0xf0 : 0x0f; +#elif defined(__BIG_ENDIAN_BITFIELD) /* dst_reg,src_reg,... */ + return gen->swapped_endian ? 0x0f : 0xf0; #else #error "Unsupported bit endianness, cannot proceed" #endif @@ -840,7 +873,7 @@ static void emit_relo_ksym_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0, 3)); clear_src_reg: /* clear bpf_object__relocate_data's src_reg assignment, otherwise we get a verifier failure */ - reg_mask = src_reg_mask(); + reg_mask = src_reg_mask(gen); emit(gen, BPF_LDX_MEM(BPF_B, BPF_REG_9, BPF_REG_8, offsetofend(struct bpf_insn, code))); emit(gen, BPF_ALU32_IMM(BPF_AND, BPF_REG_9, reg_mask)); emit(gen, BPF_STX_MEM(BPF_B, BPF_REG_8, BPF_REG_9, offsetofend(struct bpf_insn, code))); @@ -931,48 +964,94 @@ static void cleanup_relos(struct bpf_gen *gen, int insns) cleanup_core_relo(gen); }

+/* Convert func, line, and core relo info blobs to target endianness */ +static void info_blob_bswap(struct bpf_gen *gen, int func_info, int line_info, + int core_relos, struct bpf_prog_load_opts *load_attr) +{ + struct bpf_func_info *fi = gen->data_start + func_info; + struct bpf_line_info *li = gen->data_start + line_info; + struct bpf_core_relo *cr = gen->data_start + core_relos; + int i; + + for (i = 0; i < load_attr->func_info_cnt; i++) + bpf_func_info_bswap(fi++); + + for (i = 0; i < load_attr->line_info_cnt; i++) + bpf_line_info_bswap(li++); + + for (i = 0; i < gen->core_relo_cnt; i++) + bpf_core_relo_bswap(cr++); +} + void bpf_gen__prog_load(struct bpf_gen *gen, enum bpf_prog_type prog_type, const char *prog_name, const char *license, struct bpf_insn *insns, size_t insn_cnt, struct bpf_prog_load_opts *load_attr, int prog_idx) { + int func_info_tot_sz = load_attr->func_info_cnt * + load_attr->func_info_rec_size; + int line_info_tot_sz = load_attr->line_info_cnt * + load_attr->line_info_rec_size; + int core_relo_tot_sz = gen->core_relo_cnt * + sizeof(struct bpf_core_relo); int prog_load_attr, license_off, insns_off, func_info, line_info, core_relos; int attr_size = offsetofend(union bpf_attr, core_relo_rec_size); union bpf_attr attr;

memset(&attr, 0, attr_size); - pr_debug("gen: prog_load: type %d insns_cnt %zd progi_idx %d\n", - prog_type, insn_cnt, prog_idx); /* add license string to blob of bytes */ license_off = add_data(gen, license, strlen(license) + 1); /* add insns to blob of bytes */ insns_off = add_data(gen, insns, insn_cnt * sizeof(struct bpf_insn)); + pr_debug("gen: prog_load: prog_idx %d type %d insn off %d insns_cnt %zd license off %d\n", + prog_idx, prog_type, insns_off, insn_cnt, license_off);

- attr.prog_type = prog_type; - attr.expected_attach_type = load_attr->expected_attach_type; - attr.attach_btf_id = load_attr->attach_btf_id; - attr.prog_ifindex = load_attr->prog_ifindex; - attr.kern_version = 0; - attr.insn_cnt = (__u32)insn_cnt; - attr.prog_flags = load_attr->prog_flags; - - attr.func_info_rec_size = load_attr->func_info_rec_size; - attr.func_info_cnt = load_attr->func_info_cnt; - func_info = add_data(gen, load_attr->func_info, - attr.func_info_cnt * attr.func_info_rec_size); + /* convert blob insns to target endianness */ + if (gen->swapped_endian) { + struct bpf_insn *insn = gen->data_start + insns_off; + int i;

- attr.line_info_rec_size = load_attr->line_info_rec_size; - attr.line_info_cnt = load_attr->line_info_cnt; - line_info = add_data(gen, load_attr->line_info, - attr.line_info_cnt * attr.line_info_rec_size); + for (i = 0; i < insn_cnt; i++, insn++) + bpf_insn_bswap(insn); + }

- attr.core_relo_rec_size = sizeof(struct bpf_core_relo); - attr.core_relo_cnt = gen->core_relo_cnt; - core_relos = add_data(gen, gen->core_relos, - attr.core_relo_cnt * attr.core_relo_rec_size); + attr.prog_type = tgt_endian(prog_type); + attr.expected_attach_type = tgt_endian(load_attr->expected_attach_type); + attr.attach_btf_id = tgt_endian(load_attr->attach_btf_id); + attr.prog_ifindex = tgt_endian(load_attr->prog_ifindex); + attr.kern_version = 0; + attr.insn_cnt = tgt_endian((__u32)insn_cnt); + attr.prog_flags = tgt_endian(load_attr->prog_flags); + + attr.func_info_rec_size = tgt_endian(load_attr->func_info_rec_size); + attr.func_info_cnt = tgt_endian(load_attr->func_info_cnt); + func_info = add_data(gen, load_attr->func_info, func_info_tot_sz); + pr_debug("gen: prog_load: func_info: off %d cnt %d rec size %d\n", + func_info, load_attr->func_info_cnt, + load_attr->func_info_rec_size); + + attr.line_info_rec_size = tgt_endian(load_attr->line_info_rec_size); + attr.line_info_cnt = tgt_endian(load_attr->line_info_cnt); + line_info = add_data(gen, load_attr->line_info, line_info_tot_sz); + pr_debug("gen: prog_load: line_info: off %d cnt %d rec size %d\n", + line_info, load_attr->line_info_cnt, + load_attr->line_info_rec_size); + + attr.core_relo_rec_size = tgt_endian((__u32)sizeof(struct bpf_core_relo)); + attr.core_relo_cnt = tgt_endian(gen->core_relo_cnt); + core_relos = add_data(gen, gen->core_relos, core_relo_tot_sz); + pr_debug("gen: prog_load: core_relos: off %d cnt %d rec size %zd\n", + core_relos, gen->core_relo_cnt, + sizeof(struct bpf_core_relo)); + + /* convert all info blobs to target endianness */ + if (gen->swapped_endian) + info_blob_bswap(gen, func_info, line_info, core_relos, load_attr);

libbpf_strlcpy(attr.prog_name, prog_name, sizeof(attr.prog_name)); prog_load_attr = add_data(gen, &attr, attr_size); + pr_debug("gen: prog_load: attr: off %d size %d\n", + prog_load_attr, attr_size);

/* populate union bpf_attr with a pointer to license */ emit_rel_store(gen, attr_field(prog_load_attr, license), license_off); @@ -1040,7 +1119,6 @@ void bpf_gen__map_update_elem(struct bpf_gen *gen, int map_idx, void *pvalue, int zero = 0;

memset(&attr, 0, attr_size); - pr_debug("gen: map_update_elem: idx %d\n", map_idx);

value = add_data(gen, pvalue, value_size); key = add_data(gen, &zero, sizeof(zero)); @@ -1068,6 +1146,8 @@ void bpf_gen__map_update_elem(struct bpf_gen *gen, int map_idx, void *pvalue, emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel));

map_update_attr = add_data(gen, &attr, attr_size); + pr_debug("gen: map_update_elem: idx %d, value: off %d size %d, attr: off %d size %d\n", + map_idx, value, value_size, map_update_attr, attr_size); move_blob2blob(gen, attr_field(map_update_attr, map_fd), 4, blob_fd_array_off(gen, map_idx)); emit_rel_store(gen, attr_field(map_update_attr, key), key); @@ -1084,14 +1164,16 @@ void bpf_gen__populate_outer_map(struct bpf_gen *gen, int outer_map_idx, int slo int attr_size = offsetofend(union bpf_attr, flags); int map_update_attr, key; union bpf_attr attr; + int tgt_slot;

memset(&attr, 0, attr_size); - pr_debug("gen: populate_outer_map: outer %d key %d inner %d\n", - outer_map_idx, slot, inner_map_idx);

- key = add_data(gen, &slot, sizeof(slot)); + tgt_slot = tgt_endian(slot); + key = add_data(gen, &tgt_slot, sizeof(tgt_slot));

map_update_attr = add_data(gen, &attr, attr_size); + pr_debug("gen: populate_outer_map: outer %d key %d inner %d, attr: off %d size %d\n", + outer_map_idx, slot, inner_map_idx, map_update_attr, attr_size); move_blob2blob(gen, attr_field(map_update_attr, map_fd), 4, blob_fd_array_off(gen, outer_map_idx)); emit_rel_store(gen, attr_field(map_update_attr, key), key); @@ -1112,8 +1194,9 @@ void bpf_gen__map_freeze(struct bpf_gen *gen, int map_idx) union bpf_attr attr;

memset(&attr, 0, attr_size); - pr_debug("gen: map_freeze: idx %d\n", map_idx); map_freeze_attr = add_data(gen, &attr, attr_size); + pr_debug("gen: map_freeze: idx %d, attr: off %d size %d\n", + map_idx, map_freeze_attr, attr_size); move_blob2blob(gen, attr_field(map_freeze_attr, map_fd), 4, blob_fd_array_off(gen, map_idx)); /* emit MAP_FREEZE command */ diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 0540d2331535..9453a0c01337 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -9129,6 +9129,7 @@ int bpf_object__gen_loader(struct bpf_object *obj, struct gen_loader_opts *opts) if (!gen) return -ENOMEM; gen->opts = opts; + gen->swapped_endian = !is_native_endianness(obj); obj->gen_loader = gen; return 0; } diff --git a/tools/lib/bpf/skel_internal.h b/tools/lib/bpf/skel_internal.h index 0875452521e9..4d5fa079b5d6 100644 --- a/tools/lib/bpf/skel_internal.h +++ b/tools/lib/bpf/skel_internal.h @@ -351,10 +351,11 @@ static inline int bpf_load_and_run(struct bpf_load_and_run_opts *opts) attr.test.ctx_size_in = opts->ctx->sz; err = skel_sys_bpf(BPF_PROG_RUN, &attr, test_run_attr_sz); if (err < 0 || (int)attr.test.retval < 0) { - opts->errstr = "failed to execute loader prog"; if (err < 0) { + opts->errstr = "failed to execute loader prog"; set_err; } else { + opts->errstr = "error returned by loader prog"; err = (int)attr.test.retval; #ifndef __KERNEL__ errno = -err;