From 63fe3fd393dc4e7ea3948e79947362ffbb0fd616 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Mon, 10 Aug 2020 20:08:52 -0700 Subject: libbpf: Do not use __builtin_offsetof for offsetof Commit 5fbc220862fc ("tools/libpf: Add offsetof/container_of macro in bpf_helpers.h") added a macro offsetof() to get the offset of a structure member: #define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER) In certain use cases, size_t type may not be available so Commit da7a35062bcc ("libbpf bpf_helpers: Use __builtin_offsetof for offsetof") changed to use __builtin_offsetof which removed the dependency on type size_t, which I suggested. But using __builtin_offsetof will prevent CO-RE relocation generation in case that, e.g., TYPE is annotated with "preserve_access_info" where a relocation is desirable in case the member offset is changed in a different kernel version. So this patch reverted back to the original macro but using "unsigned long" instead of "site_t". Fixes: da7a35062bcc ("libbpf bpf_helpers: Use __builtin_offsetof for offsetof") Signed-off-by: Yonghong Song Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: Ian Rogers Link: https://lore.kernel.org/bpf/20200811030852.3396929-1-yhs@fb.com --- tools/lib/bpf/bpf_helpers.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools/lib') diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h index bc14db706b88..e9a4ecddb7a5 100644 --- a/tools/lib/bpf/bpf_helpers.h +++ b/tools/lib/bpf/bpf_helpers.h @@ -40,7 +40,7 @@ * Helper macro to manipulate data structures */ #ifndef offsetof -#define offsetof(TYPE, MEMBER) __builtin_offsetof(TYPE, MEMBER) +#define offsetof(TYPE, MEMBER) ((unsigned long)&((TYPE *)0)->MEMBER) #endif #ifndef container_of #define container_of(ptr, type, member) \ -- cgit v1.2.3 From 702eddc77a905782083b14ccd05b23840675fd18 Mon Sep 17 00:00:00 2001 From: Jean-Philippe Brucker Date: Wed, 12 Aug 2020 16:39:10 +0200 Subject: libbpf: Handle GCC built-in types for Arm NEON When building Arm NEON (SIMD) code from lib/raid6/neon.uc, GCC emits DWARF information using a base type "__Poly8_t", which is internal to GCC and not recognized by Clang. This causes build failures when building with Clang a vmlinux.h generated from an arm64 kernel that was built with GCC. vmlinux.h:47284:9: error: unknown type name '__Poly8_t' typedef __Poly8_t poly8x16_t[16]; ^~~~~~~~~ The polyX_t types are defined as unsigned integers in the "Arm C Language Extension" document (101028_Q220_00_en). Emit typedefs based on standard integer types for the GCC internal types, similar to those emitted by Clang. Including linux/kernel.h to use ARRAY_SIZE() incidentally redefined max(), causing a build bug due to different types, hence the seemingly unrelated change. Reported-by: Jakov Petrina Signed-off-by: Jean-Philippe Brucker Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200812143909.3293280-1-jean-philippe@linaro.org --- tools/lib/bpf/btf_dump.c | 35 ++++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) (limited to 'tools/lib') diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c index cf711168d34a..ac81f3f8957a 100644 --- a/tools/lib/bpf/btf_dump.c +++ b/tools/lib/bpf/btf_dump.c @@ -13,6 +13,7 @@ #include #include #include +#include #include "btf.h" #include "hashmap.h" #include "libbpf.h" @@ -549,6 +550,9 @@ static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr) } } +static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id, + const struct btf_type *t); + static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id, const struct btf_type *t); static void btf_dump_emit_struct_def(struct btf_dump *d, __u32 id, @@ -671,6 +675,9 @@ static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id) switch (kind) { case BTF_KIND_INT: + /* Emit type alias definitions if necessary */ + btf_dump_emit_missing_aliases(d, id, t); + tstate->emit_state = EMITTED; break; case BTF_KIND_ENUM: @@ -870,7 +877,7 @@ static void btf_dump_emit_struct_def(struct btf_dump *d, btf_dump_printf(d, ": %d", m_sz); off = m_off + m_sz; } else { - m_sz = max(0, btf__resolve_size(d->btf, m->type)); + m_sz = max(0LL, btf__resolve_size(d->btf, m->type)); off = m_off + m_sz * 8; } btf_dump_printf(d, ";"); @@ -890,6 +897,32 @@ static void btf_dump_emit_struct_def(struct btf_dump *d, btf_dump_printf(d, " __attribute__((packed))"); } +static const char *missing_base_types[][2] = { + /* + * GCC emits typedefs to its internal __PolyX_t types when compiling Arm + * SIMD intrinsics. Alias them to standard base types. + */ + { "__Poly8_t", "unsigned char" }, + { "__Poly16_t", "unsigned short" }, + { "__Poly64_t", "unsigned long long" }, + { "__Poly128_t", "unsigned __int128" }, +}; + +static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id, + const struct btf_type *t) +{ + const char *name = btf_dump_type_name(d, id); + int i; + + for (i = 0; i < ARRAY_SIZE(missing_base_types); i++) { + if (strcmp(name, missing_base_types[i][0]) == 0) { + btf_dump_printf(d, "typedef %s %s;\n\n", + missing_base_types[i][1], name); + break; + } + } +} + static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id, const struct btf_type *t) { -- cgit v1.2.3 From 23ab656be263813acc3c20623757d3cd1496d9e1 Mon Sep 17 00:00:00 2001 From: Toke Høiland-Jørgensen Date: Thu, 13 Aug 2020 16:29:05 +0200 Subject: libbpf: Prevent overriding errno when logging errors MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Turns out there were a few more instances where libbpf didn't save the errno before writing an error message, causing errno to be overridden by the printf() return and the error disappearing if logging is enabled. Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200813142905.160381-1-toke@redhat.com --- tools/lib/bpf/libbpf.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'tools/lib') diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 0a06124f7999..0d48c18d5030 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -3478,10 +3478,11 @@ bpf_object__probe_global_data(struct bpf_object *obj) map = bpf_create_map_xattr(&map_attr); if (map < 0) { - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); + ret = -errno; + cp = libbpf_strerror_r(ret, errmsg, sizeof(errmsg)); pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n", - __func__, cp, errno); - return -errno; + __func__, cp, -ret); + return ret; } insns[0].imm = map; @@ -6012,9 +6013,10 @@ int bpf_program__pin_instance(struct bpf_program *prog, const char *path, } if (bpf_obj_pin(prog->instances.fds[instance], path)) { - cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); + err = -errno; + cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg)); pr_warn("failed to pin program: %s\n", cp); - return -errno; + return err; } pr_debug("pinned program '%s'\n", path); -- cgit v1.2.3 From 15728ad3e71c120278105f20fa65b3735e715e0f Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 13 Aug 2020 13:49:39 -0700 Subject: libbpf: Fix BTF-defined map-in-map initialization on 32-bit host arches Libbpf built in 32-bit mode should be careful about not conflating 64-bit BPF pointers in BPF ELF file and host architecture pointers. This patch fixes issue of incorrect initializating of map-in-map inner map slots due to such difference. Fixes: 646f02ffdd49 ("libbpf: Add BTF-defined map-in-map support") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200813204945.1020225-4-andriin@fb.com --- tools/lib/bpf/libbpf.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'tools/lib') diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 0d48c18d5030..6accddaaedab 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -5195,7 +5195,8 @@ static int bpf_object__collect_st_ops_relos(struct bpf_object *obj, static int bpf_object__collect_map_relos(struct bpf_object *obj, GElf_Shdr *shdr, Elf_Data *data) { - int i, j, nrels, new_sz, ptr_sz = sizeof(void *); + const int bpf_ptr_sz = 8, host_ptr_sz = sizeof(void *); + int i, j, nrels, new_sz; const struct btf_var_secinfo *vi = NULL; const struct btf_type *sec, *var, *def; const struct btf_member *member; @@ -5244,7 +5245,7 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj, vi = btf_var_secinfos(sec) + map->btf_var_idx; if (vi->offset <= rel.r_offset && - rel.r_offset + sizeof(void *) <= vi->offset + vi->size) + rel.r_offset + bpf_ptr_sz <= vi->offset + vi->size) break; } if (j == obj->nr_maps) { @@ -5280,17 +5281,20 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj, return -EINVAL; moff = rel.r_offset - vi->offset - moff; - if (moff % ptr_sz) + /* here we use BPF pointer size, which is always 64 bit, as we + * are parsing ELF that was built for BPF target + */ + if (moff % bpf_ptr_sz) return -EINVAL; - moff /= ptr_sz; + moff /= bpf_ptr_sz; if (moff >= map->init_slots_sz) { new_sz = moff + 1; - tmp = realloc(map->init_slots, new_sz * ptr_sz); + tmp = realloc(map->init_slots, new_sz * host_ptr_sz); if (!tmp) return -ENOMEM; map->init_slots = tmp; memset(map->init_slots + map->init_slots_sz, 0, - (new_sz - map->init_slots_sz) * ptr_sz); + (new_sz - map->init_slots_sz) * host_ptr_sz); map->init_slots_sz = new_sz; } map->init_slots[moff] = targ_map; -- cgit v1.2.3 From 44ad23dfbccbcd26d6ca504eba1ac55755864969 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 13 Aug 2020 13:49:40 -0700 Subject: libbpf: Handle BTF pointer sizes more carefully With libbpf and BTF it is pretty common to have libbpf built for one architecture, while BTF information was generated for a different architecture (typically, but not always, BPF). In such case, the size of a pointer might differ betweem architectures. libbpf previously was always making an assumption that pointer size for BTF is the same as native architecture pointer size, but that breaks for cases where libbpf is built as 32-bit library, while BTF is for 64-bit architecture. To solve this, add heuristic to determine pointer size by searching for `long` or `unsigned long` integer type and using its size as a pointer size. Also, allow to override the pointer size with a new API btf__set_pointer_size(), for cases where application knows which pointer size should be used. User application can check what libbpf "guessed" by looking at the result of btf__pointer_size(). If it's not 0, then libbpf successfully determined a pointer size, otherwise native arch pointer size will be used. For cases where BTF is parsed from ELF file, use ELF's class (32-bit or 64-bit) to determine pointer size. Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf") Fixes: 351131b51c7a ("libbpf: add btf_dump API for BTF-to-C conversion") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200813204945.1020225-5-andriin@fb.com --- tools/lib/bpf/btf.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++-- tools/lib/bpf/btf.h | 2 ++ tools/lib/bpf/btf_dump.c | 4 ++- tools/lib/bpf/libbpf.map | 2 ++ 4 files changed, 87 insertions(+), 4 deletions(-) (limited to 'tools/lib') diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c index 4843e44916f7..7dfca7016aaa 100644 --- a/tools/lib/bpf/btf.c +++ b/tools/lib/bpf/btf.c @@ -41,6 +41,7 @@ struct btf { __u32 types_size; __u32 data_size; int fd; + int ptr_sz; }; static inline __u64 ptr_to_u64(const void *ptr) @@ -221,6 +222,70 @@ const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id) return btf->types[type_id]; } +static int determine_ptr_size(const struct btf *btf) +{ + const struct btf_type *t; + const char *name; + int i; + + for (i = 1; i <= btf->nr_types; i++) { + t = btf__type_by_id(btf, i); + if (!btf_is_int(t)) + continue; + + name = btf__name_by_offset(btf, t->name_off); + if (!name) + continue; + + if (strcmp(name, "long int") == 0 || + strcmp(name, "long unsigned int") == 0) { + if (t->size != 4 && t->size != 8) + continue; + return t->size; + } + } + + return -1; +} + +static size_t btf_ptr_sz(const struct btf *btf) +{ + if (!btf->ptr_sz) + ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf); + return btf->ptr_sz < 0 ? sizeof(void *) : btf->ptr_sz; +} + +/* Return pointer size this BTF instance assumes. The size is heuristically + * determined by looking for 'long' or 'unsigned long' integer type and + * recording its size in bytes. If BTF type information doesn't have any such + * type, this function returns 0. In the latter case, native architecture's + * pointer size is assumed, so will be either 4 or 8, depending on + * architecture that libbpf was compiled for. It's possible to override + * guessed value by using btf__set_pointer_size() API. + */ +size_t btf__pointer_size(const struct btf *btf) +{ + if (!btf->ptr_sz) + ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf); + + if (btf->ptr_sz < 0) + /* not enough BTF type info to guess */ + return 0; + + return btf->ptr_sz; +} + +/* Override or set pointer size in bytes. Only values of 4 and 8 are + * supported. + */ +int btf__set_pointer_size(struct btf *btf, size_t ptr_sz) +{ + if (ptr_sz != 4 && ptr_sz != 8) + return -EINVAL; + btf->ptr_sz = ptr_sz; + return 0; +} + static bool btf_type_is_void(const struct btf_type *t) { return t == &btf_void || btf_is_fwd(t); @@ -253,7 +318,7 @@ __s64 btf__resolve_size(const struct btf *btf, __u32 type_id) size = t->size; goto done; case BTF_KIND_PTR: - size = sizeof(void *); + size = btf_ptr_sz(btf); goto done; case BTF_KIND_TYPEDEF: case BTF_KIND_VOLATILE: @@ -293,9 +358,9 @@ int btf__align_of(const struct btf *btf, __u32 id) switch (kind) { case BTF_KIND_INT: case BTF_KIND_ENUM: - return min(sizeof(void *), (size_t)t->size); + return min(btf_ptr_sz(btf), (size_t)t->size); case BTF_KIND_PTR: - return sizeof(void *); + return btf_ptr_sz(btf); case BTF_KIND_TYPEDEF: case BTF_KIND_VOLATILE: case BTF_KIND_CONST: @@ -533,6 +598,18 @@ struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext) if (IS_ERR(btf)) goto done; + switch (gelf_getclass(elf)) { + case ELFCLASS32: + btf__set_pointer_size(btf, 4); + break; + case ELFCLASS64: + btf__set_pointer_size(btf, 8); + break; + default: + pr_warn("failed to get ELF class (bitness) for %s\n", path); + break; + } + if (btf_ext && btf_ext_data) { *btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size); diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h index f4a1a1d2b9a3..1ca14448df4c 100644 --- a/tools/lib/bpf/btf.h +++ b/tools/lib/bpf/btf.h @@ -76,6 +76,8 @@ LIBBPF_API __s32 btf__find_by_name_kind(const struct btf *btf, LIBBPF_API __u32 btf__get_nr_types(const struct btf *btf); LIBBPF_API const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 id); +LIBBPF_API size_t btf__pointer_size(const struct btf *btf); +LIBBPF_API int btf__set_pointer_size(struct btf *btf, size_t ptr_sz); LIBBPF_API __s64 btf__resolve_size(const struct btf *btf, __u32 type_id); LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id); LIBBPF_API int btf__align_of(const struct btf *btf, __u32 id); diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c index ac81f3f8957a..fe39bd774697 100644 --- a/tools/lib/bpf/btf_dump.c +++ b/tools/lib/bpf/btf_dump.c @@ -61,6 +61,7 @@ struct btf_dump { const struct btf_ext *btf_ext; btf_dump_printf_fn_t printf_fn; struct btf_dump_opts opts; + int ptr_sz; bool strip_mods; /* per-type auxiliary state */ @@ -139,6 +140,7 @@ struct btf_dump *btf_dump__new(const struct btf *btf, d->btf_ext = btf_ext; d->printf_fn = printf_fn; d->opts.ctx = opts ? opts->ctx : NULL; + d->ptr_sz = btf__pointer_size(btf) ? : sizeof(void *); d->type_names = hashmap__new(str_hash_fn, str_equal_fn, NULL); if (IS_ERR(d->type_names)) { @@ -804,7 +806,7 @@ static void btf_dump_emit_bit_padding(const struct btf_dump *d, int align, int lvl) { int off_diff = m_off - cur_off; - int ptr_bits = sizeof(void *) * 8; + int ptr_bits = d->ptr_sz * 8; if (off_diff <= 0) /* no gap */ diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 0c4722bfdd0a..e35bd6cdbdbf 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -295,5 +295,7 @@ LIBBPF_0.1.0 { bpf_program__set_sk_lookup; btf__parse; btf__parse_raw; + btf__pointer_size; btf__set_fd; + btf__set_pointer_size; } LIBBPF_0.0.9; -- cgit v1.2.3 From 4c01925f583eaa7d9d003dc87a4b75b8140b4ff6 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 13 Aug 2020 13:49:42 -0700 Subject: libbpf: Enforce 64-bitness of BTF for BPF object files BPF object files are always targeting 64-bit BPF target architecture, so enforce that at BTF level as well. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200813204945.1020225-7-andriin@fb.com --- tools/lib/bpf/libbpf.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'tools/lib') diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 6accddaaedab..5d20b2da4427 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -2434,6 +2434,8 @@ static int bpf_object__init_btf(struct bpf_object *obj, BTF_ELF_SEC, err); goto out; } + /* enforce 8-byte pointers for BPF-targeted BTFs */ + btf__set_pointer_size(obj->btf, 8); err = 0; } if (btf_ext_data) { @@ -2542,6 +2544,8 @@ static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj) if (IS_ERR(kern_btf)) return PTR_ERR(kern_btf); + /* enforce 8-byte pointers for BPF-targeted BTFs */ + btf__set_pointer_size(obj->btf, 8); bpf_object__sanitize_btf(obj, kern_btf); } -- cgit v1.2.3