From 2ce8450ef5a381e5ffeb4682c0093a3ab5d07008 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 4 Oct 2019 15:40:35 -0700 Subject: libbpf: add bpf_object__open_{file, mem} w/ extensible opts Add new set of bpf_object__open APIs using new approach to optional parameters extensibility allowing simpler ABI compatibility approach. This patch demonstrates an approach to implementing libbpf APIs that makes it easy to extend existing APIs with extra optional parameters in such a way, that ABI compatibility is preserved without having to do symbol versioning and generating lots of boilerplate code to handle it. To facilitate succinct code for working with options, add OPTS_VALID, OPTS_HAS, and OPTS_GET macros that hide all the NULL, size, and zero checks. Additionally, newly added libbpf APIs are encouraged to follow similar pattern of having all mandatory parameters as formal function parameters and always have optional (NULL-able) xxx_opts struct, which should always have real struct size as a first field and the rest would be optional parameters added over time, which tune the behavior of existing API, if specified by user. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov --- tools/lib/bpf/libbpf_internal.h | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'tools/lib/bpf/libbpf_internal.h') diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 2e83a34f8c79..f51444fc7eb7 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -47,6 +47,38 @@ do { \ #define pr_info(fmt, ...) __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__) #define pr_debug(fmt, ...) __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__) +static inline bool libbpf_validate_opts(const char *opts, + size_t opts_sz, size_t user_sz, + const char *type_name) +{ + if (user_sz < sizeof(size_t)) { + pr_warning("%s size (%zu) is too small\n", type_name, user_sz); + return false; + } + if (user_sz > opts_sz) { + size_t i; + + for (i = opts_sz; i < user_sz; i++) { + if (opts[i]) { + pr_warning("%s has non-zero extra bytes", + type_name); + return false; + } + } + } + return true; +} + +#define OPTS_VALID(opts, type) \ + (!(opts) || libbpf_validate_opts((const char *)opts, \ + offsetofend(struct type, \ + type##__last_field), \ + (opts)->sz, #type)) +#define OPTS_HAS(opts, field) \ + ((opts) && opts->sz >= offsetofend(typeof(*(opts)), field)) +#define OPTS_GET(opts, field, fallback_value) \ + (OPTS_HAS(opts, field) ? (opts)->field : fallback_value) + int libbpf__load_raw_btf(const char *raw_types, size_t types_len, const char *str_sec, size_t str_len); -- cgit From 511bb0085c6fe48353c35cd3d25f4f8720579a6d Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Tue, 15 Oct 2019 11:28:45 -0700 Subject: libbpf: Update BTF reloc support to latest Clang format BTF offset reloc was generalized in recent Clang into field relocation, capturing extra u32 field, specifying what aspect of captured field needs to be relocated. This changes .BTF.ext's record size for this relocation from 12 bytes to 16 bytes. Given these format changes happened in Clang before official released version, it's ok to not support outdated 12-byte record size w/o breaking ABI. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20191015182849.3922287-2-andriin@fb.com --- tools/lib/bpf/libbpf_internal.h | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) (limited to 'tools/lib/bpf/libbpf_internal.h') diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index f51444fc7eb7..5bfe85d4f8aa 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -110,7 +110,7 @@ struct btf_ext { }; struct btf_ext_info func_info; struct btf_ext_info line_info; - struct btf_ext_info offset_reloc_info; + struct btf_ext_info field_reloc_info; __u32 data_size; }; @@ -135,13 +135,23 @@ struct bpf_line_info_min { __u32 line_col; }; -/* The minimum bpf_offset_reloc checked by the loader +/* bpf_field_info_kind encodes which aspect of captured field has to be + * adjusted by relocations. Currently supported values are: + * - BPF_FIELD_BYTE_OFFSET: field offset (in bytes); + * - BPF_FIELD_EXISTS: field existence (1, if field exists; 0, otherwise); + */ +enum bpf_field_info_kind { + BPF_FIELD_BYTE_OFFSET = 0, /* field byte offset */ + BPF_FIELD_EXISTS = 2, /* field existence in target kernel */ +}; + +/* The minimum bpf_field_reloc checked by the loader * - * Offset relocation captures the following data: + * Field 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 offset; + * its insn->imm field to be relocated with actual field info; * - type_id - BTF type ID of the "root" (containing) entity of a relocatable - * offset; + * field; * - access_str_off - offset into corresponding .BTF string section. String * itself encodes an accessed field using a sequence of field and array * indicies, separated by colon (:). It's conceptually very close to LLVM's @@ -172,15 +182,16 @@ struct bpf_line_info_min { * bpf_probe_read(&dst, sizeof(dst), * __builtin_preserve_access_index(&src->a.b.c)); * - * In this case Clang will emit offset relocation recording necessary data to + * 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_offset_reloc { +struct bpf_field_reloc { __u32 insn_off; __u32 type_id; __u32 access_str_off; + enum bpf_field_info_kind kind; }; #endif /* __LIBBPF_LIBBPF_INTERNAL_H */ -- cgit From be18010ea2d83c184cc32afdc895410a1cf2cbd5 Mon Sep 17 00:00:00 2001 From: Kefeng Wang Date: Mon, 21 Oct 2019 13:55:32 +0800 Subject: tools, bpf: Rename pr_warning to pr_warn to align with kernel logging For kernel logging macros, pr_warning() is completely removed and replaced by pr_warn(). By using pr_warn() in tools/lib/bpf/ for symmetry to kernel logging macros, we could eventually drop the use of pr_warning() in the whole kernel tree. Signed-off-by: Kefeng Wang Signed-off-by: Daniel Borkmann Reviewed-by: Sergey Senozhatsky Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20191021055532.185245-1-wangkefeng.wang@huawei.com --- tools/lib/bpf/libbpf_internal.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'tools/lib/bpf/libbpf_internal.h') diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index 5bfe85d4f8aa..b2880766e6b9 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -43,7 +43,7 @@ do { \ libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \ } while (0) -#define pr_warning(fmt, ...) __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__) +#define pr_warn(fmt, ...) __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__) #define pr_info(fmt, ...) __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__) #define pr_debug(fmt, ...) __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__) @@ -52,7 +52,7 @@ static inline bool libbpf_validate_opts(const char *opts, const char *type_name) { if (user_sz < sizeof(size_t)) { - pr_warning("%s size (%zu) is too small\n", type_name, user_sz); + pr_warn("%s size (%zu) is too small\n", type_name, user_sz); return false; } if (user_sz > opts_sz) { @@ -60,8 +60,8 @@ static inline bool libbpf_validate_opts(const char *opts, for (i = opts_sz; i < user_sz; i++) { if (opts[i]) { - pr_warning("%s has non-zero extra bytes", - type_name); + pr_warn("%s has non-zero extra bytes", + type_name); return false; } } -- cgit From ee26dade0e3bcd8a34ae7520e373fb69365fce7a Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Fri, 1 Nov 2019 15:28:07 -0700 Subject: libbpf: Add support for relocatable bitfields Add support for the new field relocation kinds, necessary to support relocatable bitfield reads. Provide macro for abstracting necessary code doing full relocatable bitfield extraction into u64 value. Two separate macros are provided: - BPF_CORE_READ_BITFIELD macro for direct memory read-enabled BPF programs (e.g., typed raw tracepoints). It uses direct memory dereference to extract bitfield backing integer value. - BPF_CORE_READ_BITFIELD_PROBED macro for cases where bpf_probe_read() needs to be used to extract same backing integer value. Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20191101222810.1246166-3-andriin@fb.com --- tools/lib/bpf/libbpf_internal.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'tools/lib/bpf/libbpf_internal.h') diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h index bd6f48ea407b..97ac17a64a58 100644 --- a/tools/lib/bpf/libbpf_internal.h +++ b/tools/lib/bpf/libbpf_internal.h @@ -158,7 +158,11 @@ struct bpf_line_info_min { */ enum bpf_field_info_kind { BPF_FIELD_BYTE_OFFSET = 0, /* field byte offset */ + BPF_FIELD_BYTE_SIZE = 1, BPF_FIELD_EXISTS = 2, /* field existence in target kernel */ + BPF_FIELD_SIGNED = 3, + BPF_FIELD_LSHIFT_U64 = 4, + BPF_FIELD_RSHIFT_U64 = 5, }; /* The minimum bpf_field_reloc checked by the loader -- cgit