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2020-02-18libbpf: Sanitise internal map names so they are not rejected by the kernelToke Høiland-Jørgensen1-1/+7
The kernel only accepts map names with alphanumeric characters, underscores and periods in their name. However, the auto-generated internal map names used by libbpf takes their prefix from the user-supplied BPF object name, which has no such restriction. This can lead to "Invalid argument" errors when trying to load a BPF program using global variables. Fix this by sanitising the map names, replacing any non-allowed characters with underscores. Fixes: d859900c4c56 ("bpf, libbpf: support global data/bss/rodata sections") Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200217171701.215215-1-toke@redhat.com
2020-01-24libbpf: Fix realloc usage in bpf_core_find_candsAndrii Nakryiko1-1/+3
Fix bug requesting invalid size of reallocated array when constructing CO-RE relocation candidate list. This can cause problems if there are many potential candidates and a very fine-grained memory allocator bucket sizes are used. Fixes: ddc7c3042614 ("libbpf: implement BPF CO-RE offset relocation algorithm") Reported-by: William Smith <williampsmith@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200124201847.212528-1-andriin@fb.com
2020-01-24libbpf: Improve handling of failed CO-RE relocationsAndrii Nakryiko2-40/+61
Previously, if libbpf failed to resolve CO-RE relocation for some instructions, it would either return error immediately, or, if .relaxed_core_relocs option was set, would replace relocatable offset/imm part of an instruction with a bogus value (-1). Neither approach is good, because there are many possible scenarios where relocation is expected to fail (e.g., when some field knowingly can be missing on specific kernel versions). On the other hand, replacing offset with invalid one can hide programmer errors, if this relocation failue wasn't anticipated. This patch deprecates .relaxed_core_relocs option and changes the approach to always replacing instruction, for which relocation failed, with invalid BPF helper call instruction. For cases where this is expected, BPF program should already ensure that that instruction is unreachable, in which case this invalid instruction is going to be silently ignored. But if instruction wasn't guarded, BPF program will be rejected at verification step with verifier log pointing precisely to the place in assembly where the problem is. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200124053837.2434679-1-andriin@fb.com
2020-01-22libbpf: Add support for program extensionsAlexei Starovoitov5-4/+17
Add minimal support for program extensions. bpf_object_open_opts() needs to be called with attach_prog_fd = target_prog_fd and BPF program extension needs to have in .c file section definition like SEC("freplace/func_to_be_replaced"). libbpf will search for "func_to_be_replaced" in the target_prog_fd's BTF and will pass it in attach_btf_id to the kernel. This approach works for tests, but more compex use case may need to request function name (and attach_btf_id that kernel sees) to be more dynamic. Such API will be added in future patches. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20200121005348.2769920-3-ast@kernel.org
2020-01-17libbpf: Load btf_vmlinux only once per object.KP Singh1-52/+101
As more programs (TRACING, STRUCT_OPS, and upcoming LSM) use vmlinux BTF information, loading the BTF vmlinux information for every program in an object is sub-optimal. The fix was originally proposed in: https://lore.kernel.org/bpf/CAEf4BzZodr3LKJuM7QwD38BiEH02Cc1UbtnGpVkCJ00Mf+V_Qg@mail.gmail.com/ The btf_vmlinux is populated in the object if any of the programs in the object requires it just before the programs are loaded and freed after the programs finish loading. Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com> Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Brendan Jackman <jackmanb@chromium.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200117212825.11755-1-kpsingh@chromium.org
2020-01-17libbpf: Fix potential multiplication overflow in mmap() size calculationAndrii Nakryiko1-1/+1
Prevent potential overflow performed in 32-bit integers, before assigning result to size_t. Reported by LGTM static analysis. Fixes: eba9c5f498a1 ("libbpf: Refactor global data map initialization") Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200117060801.1311525-4-andriin@fb.com
2020-01-17libbpf: Simplify BTF initialization logicAndrii Nakryiko1-13/+6
Current implementation of bpf_object's BTF initialization is very convoluted and thus prone to errors. It doesn't have to be like that. This patch simplifies it significantly. This code also triggered static analysis issues over logically dead code due to redundant error checks. This simplification should fix that as well. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200117060801.1311525-3-andriin@fb.com
2020-01-17libbpf: Fix error handling bug in btf_dump__newAndrii Nakryiko1-0/+1
Fix missing jump to error handling in btf_dump__new, found by Coverity static code analysis. Fixes: 9f81654eebe8 ("libbpf: Expose BTF-to-C type declaration emitting API") Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200117060801.1311525-2-andriin@fb.com
2020-01-16libbpf: Revert bpf_helper_defs.h inclusion regressionAndrii Nakryiko1-1/+1
Revert bpf_helpers.h's change to include auto-generated bpf_helper_defs.h through <> instead of "", which causes it to be searched in include path. This can break existing applications that don't have their include path pointing directly to where libbpf installs its headers. There is ongoing work to make all (not just bpf_helper_defs.h) includes more consistent across libbpf and its consumers, but this unbreaks user code as is right now without any regressions. Selftests still behave sub-optimally (taking bpf_helper_defs.h from libbpf's source directory, if it's present there), which will be fixed in subsequent patches. Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir") Reported-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200117004103.148068-1-andriin@fb.com
2020-01-16libbpf: Fix unneeded extra initialization in bpf_map_batch_commonBrian Vazquez1-1/+1
bpf_attr doesn't required to be declared with '= {}' as memset is used in the code. Fixes: 2ab3d86ea1859 ("libbpf: Add libbpf support to batch ops") Reported-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Brian Vazquez <brianvv@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200116045918.75597-1-brianvv@google.com
2020-01-15libbpf: Expose bpf_find_kernel_btf as a LIBBPF_APIMartin KaFai Lau4-96/+102
This patch exposes bpf_find_kernel_btf() as a LIBBPF_API. It will be used in 'bpftool map dump' in a following patch to dump a map with btf_vmlinux_value_type_id set. bpf_find_kernel_btf() is renamed to libbpf_find_kernel_btf() and moved to btf.c. As <linux/kernel.h> is included, some of the max/min type casting needs to be fixed. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200115230031.1102305-1-kafai@fb.com
2020-01-15libbpf: Add libbpf support to batch opsYonghong Song3-0/+84
Added four libbpf API functions to support map batch operations: . int bpf_map_delete_batch( ... ) . int bpf_map_lookup_batch( ... ) . int bpf_map_lookup_and_delete_batch( ... ) . int bpf_map_update_batch( ... ) Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200115184308.162644-8-brianvv@google.com
2020-01-15libbpf: Support .text sub-calls relocationsAndrii Nakryiko1-7/+22
The LLVM patch https://reviews.llvm.org/D72197 makes LLVM emit function call relocations within the same section. This includes a default .text section, which contains any BPF sub-programs. This wasn't the case before and so libbpf was able to get a way with slightly simpler handling of subprogram call relocations. This patch adds support for .text section relocations. It needs to ensure correct order of relocations, so does two passes: - first, relocate .text instructions, if there are any relocations in it; - then process all the other programs and copy over patched .text instructions for all sub-program calls. v1->v2: - break early once .text program is processed. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Cc: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200115190856.2391325-1-andriin@fb.com
2020-01-13libbpf: Clean up bpf_helper_defs.h generation outputAndrii Nakryiko1-1/+1
bpf_helpers_doc.py script, used to generate bpf_helper_defs.h, unconditionally emits one informational message to stderr. Remove it and preserve stderr to contain only relevant errors. Also make sure script invocations command is muted by default in libbpf's Makefile. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200113073143.1779940-3-andriin@fb.com
2020-01-10libbpf: Poison kernel-only integer typesAndrii Nakryiko12-1/+37
It's been a recurring issue with types like u32 slipping into libbpf source code accidentally. This is not detected during builds inside kernel source tree, but becomes a compilation error in libbpf's Github repo. Libbpf is supposed to use only __{s,u}{8,16,32,64} typedefs, so poison {s,u}{8,16,32,64} explicitly in every .c file. Doing that in a bit more centralized way, e.g., inside libbpf_internal.h breaks selftests, which are both using kernel u32 and libbpf_internal.h. This patch also fixes a new u32 occurence in libbpf.c, added recently. Fixes: 590a00888250 ("bpf: libbpf: Add STRUCT_OPS support") Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200110181916.271446-1-andriin@fb.com
2020-01-10libbpf: Sanitize global functionsAlexei Starovoitov1-1/+34
In case the kernel doesn't support BTF_FUNC_GLOBAL sanitize BTF produced by the compiler for global functions. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200110064124.1760511-2-ast@kernel.org
2020-01-09selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dirAndrii Nakryiko1-1/+1
Reorder includes search path to ensure $(OUTPUT) and $(CURDIR) go before libbpf's directory. Also fix bpf_helpers.h to include bpf_helper_defs.h in such a way as to leverage includes search path. This allows selftests to not use libbpf's local and potentially stale bpf_helper_defs.h. It's important because selftests/bpf's Makefile only re-generates bpf_helper_defs.h in seltests' output directory, not the one in libbpf's directory. Also force regeneration of bpf_helper_defs.h when libbpf.a is updated to reduce staleness. Fixes: fa633a0f8919 ("libbpf: Fix build on read-only filesystems") Reported-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200110051716.1591485-3-andriin@fb.com
2020-01-09libbpf,selftests/bpf: Fix clean targetsAndrii Nakryiko1-4/+5
Libbpf's clean target should clean out generated files in $(OUTPUT) directory and not make assumption that $(OUTPUT) directory is current working directory. Selftest's Makefile should delegate cleaning of libbpf-generated files to libbpf's Makefile. This ensures more robust clean up. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200110051716.1591485-2-andriin@fb.com
2020-01-09libbpf: Make bpf_map order and indices stableAndrii Nakryiko1-14/+0
Currently, libbpf re-sorts bpf_map structs after all the maps are added and initialized, which might change their relative order and invalidate any bpf_map pointer or index taken before that. This is inconvenient and error-prone. For instance, it can cause .kconfig map index to point to a wrong map. Furthermore, libbpf itself doesn't rely on any specific ordering of bpf_maps, so it's just an unnecessary complication right now. This patch drops sorting of maps and makes their relative positions fixed. If efficient index is ever needed, it's better to have a separate array of pointers as a search index, instead of reordering bpf_map struct in-place. This will be less error-prone and will allow multiple independent orderings, if necessary (e.g., either by section index or by name). Fixes: 166750bc1dd2 ("libbpf: Support libbpf-provided extern variables") Reported-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200110034247.1220142-1-andriin@fb.com
2020-01-09bpf: libbpf: Add STRUCT_OPS supportMartin KaFai Lau6-13/+661
This patch adds BPF STRUCT_OPS support to libbpf. The only sec_name convention is SEC(".struct_ops") to identify the struct_ops implemented in BPF, e.g. To implement a tcp_congestion_ops: SEC(".struct_ops") struct tcp_congestion_ops dctcp = { .init = (void *)dctcp_init, /* <-- a bpf_prog */ /* ... some more func prts ... */ .name = "bpf_dctcp", }; Each struct_ops is defined as a global variable under SEC(".struct_ops") as above. libbpf creates a map for each variable and the variable name is the map's name. Multiple struct_ops is supported under SEC(".struct_ops"). In the bpf_object__open phase, libbpf will look for the SEC(".struct_ops") section and find out what is the btf-type the struct_ops is implementing. Note that the btf-type here is referring to a type in the bpf_prog.o's btf. A "struct bpf_map" is added by bpf_object__add_map() as other maps do. It will then collect (through SHT_REL) where are the bpf progs that the func ptrs are referring to. No btf_vmlinux is needed in the open phase. In the bpf_object__load phase, the map-fields, which depend on the btf_vmlinux, are initialized (in bpf_map__init_kern_struct_ops()). It will also set the prog->type, prog->attach_btf_id, and prog->expected_attach_type. Thus, the prog's properties do not rely on its section name. [ Currently, the bpf_prog's btf-type ==> btf_vmlinux's btf-type matching process is as simple as: member-name match + btf-kind match + size match. If these matching conditions fail, libbpf will reject. The current targeting support is "struct tcp_congestion_ops" which most of its members are function pointers. The member ordering of the bpf_prog's btf-type can be different from the btf_vmlinux's btf-type. ] Then, all obj->maps are created as usual (in bpf_object__create_maps()). Once the maps are created and prog's properties are all set, the libbpf will proceed to load all the progs. bpf_map__attach_struct_ops() is added to register a struct_ops map to a kernel subsystem. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200109003514.3856730-1-kafai@fb.com
2020-01-08libbpf: Add probe for large INSN limitMichal Rostecki3-0/+23
Introduce a new probe which checks whether kernel has large maximum program size which was increased in the following commit: c04c0d2b968a ("bpf: increase complexity limit and maximum program size") Based on the similar check in Cilium[0], authored by Daniel Borkmann. [0] https://github.com/cilium/cilium/commit/657d0f585afd26232cfa5d4e70b6f64d2ea91596 Co-authored-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Michal Rostecki <mrostecki@opensuse.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com> Link: https://lore.kernel.org/bpf/20200108162428.25014-2-mrostecki@opensuse.org
2019-12-26libbpf: Support CO-RE relocations for LDX/ST/STX instructionsAndrii Nakryiko1-3/+28
Clang patch [0] enables emitting relocatable generic ALU/ALU64 instructions (i.e, shifts and arithmetic operations), as well as generic load/store instructions. The former ones are already supported by libbpf as is. This patch adds further support for load/store instructions. Relocatable field offset is encoded in BPF instruction's 16-bit offset section and are adjusted by libbpf based on target kernel BTF. These Clang changes and corresponding libbpf changes allow for more succinct generated BPF code by encoding relocatable field reads as a single ST/LDX/STX instruction. It also enables relocatable access to BPF context. Previously, if context struct (e.g., __sk_buff) was accessed with CO-RE relocations (e.g., due to preserve_access_index attribute), it would be rejected by BPF verifier due to modified context pointer dereference. With Clang patch, such context accesses are both relocatable and have a fixed offset from the point of view of BPF verifier. [0] https://reviews.llvm.org/D71790 Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20191223180305.86417-1-andriin@fb.com
2019-12-23libbpf: Fix build on read-only filesystemsNamhyung Kim1-7/+8
I got the following error when I tried to build perf on a read-only filesystem with O=dir option. $ cd /some/where/ro/linux/tools/perf $ make O=$HOME/build/perf ... CC /home/namhyung/build/perf/lib.o /bin/sh: bpf_helper_defs.h: Read-only file system make[3]: *** [Makefile:184: bpf_helper_defs.h] Error 1 make[2]: *** [Makefile.perf:778: /home/namhyung/build/perf/libbpf.a] Error 2 make[2]: *** Waiting for unfinished jobs.... LD /home/namhyung/build/perf/libperf-in.o AR /home/namhyung/build/perf/libperf.a PERF_VERSION = 5.4.0 make[1]: *** [Makefile.perf:225: sub-make] Error 2 make: *** [Makefile:70: all] Error 2 It was becaused bpf_helper_defs.h was generated in current directory. Move it to OUTPUT directory. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20191223061326.843366-1-namhyung@kernel.org
2019-12-19libbpf: Introduce bpf_prog_attach_xattrAndrey Ignatov3-1/+28
Introduce a new bpf_prog_attach_xattr function that, in addition to program fd, target fd and attach type, accepts an extendable struct bpf_prog_attach_opts. bpf_prog_attach_opts relies on DECLARE_LIBBPF_OPTS macro to maintain backward and forward compatibility and has the following "optional" attach attributes: * existing attach_flags, since it's not required when attaching in NONE mode. Even though it's quite often used in MULTI and OVERRIDE mode it seems to be a good idea to reduce number of arguments to bpf_prog_attach_xattr; * newly introduced attribute of BPF_PROG_ATTACH command: replace_prog_fd that is fd of previously attached cgroup-bpf program to replace if BPF_F_REPLACE flag is used. The new function is named to be consistent with other xattr-functions (bpf_prog_test_run_xattr, bpf_create_map_xattr, bpf_load_program_xattr). The struct bpf_prog_attach_opts is supposed to be used with DECLARE_LIBBPF_OPTS macro. Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/bd6e0732303eb14e4b79cb128268d9e9ad6db208.1576741281.git.rdna@fb.com
2019-12-19libbpf: Fix another __u64 printf warningAndrii Nakryiko1-2/+2
Fix yet another printf warning for %llu specifier on ppc64le. This time size_t casting won't work, so cast to verbose `unsigned long long`. Fixes: 166750bc1dd2 ("libbpf: Support libbpf-provided extern variables") Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20191219052103.3515-1-andriin@fb.com
2019-12-19libbpf: Fix printing of ulimit valueToke Høiland-Jørgensen1-1/+1
Naresh pointed out that libbpf builds fail on 32-bit architectures because rlimit.rlim_cur is defined as 'unsigned long long' on those architectures. Fix this by using %zu in printf and casting to size_t. Fixes: dc3a2d254782 ("libbpf: Print hint about ulimit when getting permission denied error") Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20191219090236.905059-1-toke@redhat.com
2019-12-19libbpf: Add missing newline in opts validation macroToke Høiland-Jørgensen1-1/+1
The error log output in the opts validation macro was missing a newline. Fixes: 2ce8450ef5a3 ("libbpf: add bpf_object__open_{file, mem} w/ extensible opts") Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20191219120714.928380-1-toke@redhat.com
2019-12-18libbpf: BTF is required when externs are presentAndrii Nakryiko1-1/+2
BTF is required to get type information about extern variables. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191219002837.3074619-4-andriin@fb.com
2019-12-18libbpf: Allow to augment system Kconfig through extra optional configAndrii Nakryiko2-84/+128
Instead of all or nothing approach of overriding Kconfig file location, allow to extend it with extra values and override chosen subset of values though optional user-provided extra config, passed as a string through open options' .kconfig option. If same config key is present in both user-supplied config and Kconfig, user-supplied one wins. This allows applications to more easily test various conditions despite host kernel's real configuration. If all of BPF object's __kconfig externs are satisfied from user-supplied config, system Kconfig won't be read at all. Simplify selftests by not needing to create temporary Kconfig files. Suggested-by: Alexei Starovoitov <ast@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191219002837.3074619-3-andriin@fb.com
2019-12-18libbpf: Put Kconfig externs into .kconfig sectionAndrii Nakryiko2-23/+37
Move Kconfig-provided externs into custom .kconfig section. Add __kconfig into bpf_helpers.h for user convenience. Update selftests accordingly. Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191219002837.3074619-2-andriin@fb.com
2019-12-18libbpf: Add bpf_link__disconnect() API to preserve underlying BPF resourceAndrii Nakryiko3-10/+32
There are cases in which BPF resource (program, map, etc) has to outlive userspace program that "installed" it in the system in the first place. When BPF program is attached, libbpf returns bpf_link object, which is supposed to be destroyed after no longer necessary through bpf_link__destroy() API. Currently, bpf_link destruction causes both automatic detachment and frees up any resources allocated to for bpf_link in-memory representation. This is inconvenient for the case described above because of coupling of detachment and resource freeing. This patch introduces bpf_link__disconnect() API call, which marks bpf_link as disconnected from its underlying BPF resouces. This means that when bpf_link is destroyed later, all its memory resources will be freed, but BPF resource itself won't be detached. This design allows to follow strict and resource-leak-free design by default, while giving easy and straightforward way for user code to opt for keeping BPF resource attached beyond lifetime of a bpf_link. For some BPF programs (i.e., FS-based tracepoints, kprobes, raw tracepoint, etc), user has to make sure to pin BPF program to prevent kernel to automatically detach it on process exit. This should typically be achived by pinning BPF program (or map in some cases) in BPF FS. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20191218225039.2668205-1-andriin@fb.com
2019-12-17libbpf: Remove BPF_EMBED_OBJ macro from libbpf.hAndrii Nakryiko1-35/+0
Drop BPF_EMBED_OBJ and struct bpf_embed_data now that skeleton automatically embeds contents of its source object file. While BPF_EMBED_OBJ is useful independently of skeleton, we are currently don't have any use cases utilizing it, so let's remove them until/if we need it. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20191218052552.2915188-3-andriin@fb.com
2019-12-17libbpf: Reduce log level for custom section namesAndrii Nakryiko1-3/+3
Libbpf is trying to recognize BPF program type based on its section name during bpf_object__open() phase. This is not strictly enforced and user code has ability to specify/override correct BPF program type after open. But if BPF program is using custom section name, libbpf will still emit warnings, which can be quite annoying to users. This patch reduces log level of information messages emitted by libbpf if section name is not canonical. User can still get a list of all supported section names as debug-level message. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191217234228.1739308-1-andriin@fb.com
2019-12-18libbpf: Fix libbpf_common.h when installing libbpf through 'make install'Toke Høiland-Jørgensen2-0/+3
This fixes two issues with the newly introduced libbpf_common.h file: - The header failed to include <string.h> for the definition of memset() - The new file was not included in the install_headers rule in the Makefile Both of these issues cause breakage when installing libbpf with 'make install' and trying to use it in applications. Fixes: 544402d4b493 ("libbpf: Extract common user-facing helpers") Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20191217112810.768078-1-toke@redhat.com
2019-12-16libbpf: Add zlib as a dependency in pkg-config templateAndrii Nakryiko1-1/+1
List zlib as another dependency of libbpf in pkg-config template. Verified it is correctly resolved to proper -lz flag: $ make DESTDIR=/tmp/libbpf-install install $ pkg-config --libs /tmp/libbpf-install/usr/local/lib64/pkgconfig/libbpf.pc -L/usr/local/lib64 -lbpf $ pkg-config --libs --static /tmp/libbpf-install/usr/local/lib64/pkgconfig/libbpf.pc -L/usr/local/lib64 -lbpf -lelf -lz Fixes: 166750bc1dd2 ("libbpf: Support libbpf-provided extern variables") Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Cc: Luca Boccassi <bluca@debian.org> Link: https://lore.kernel.org/bpf/20191216183830.3972964-1-andriin@fb.com
2019-12-16libbpf: Print hint about ulimit when getting permission denied errorToke Høiland-Jørgensen1-0/+29
Probably the single most common error newcomers to XDP are stumped by is the 'permission denied' error they get when trying to load their program and 'ulimit -l' is set too low. For examples, see [0], [1]. Since the error code is UAPI, we can't change that. Instead, this patch adds a few heuristics in libbpf and outputs an additional hint if they are met: If an EPERM is returned on map create or program load, and geteuid() shows we are root, and the current RLIMIT_MEMLOCK is not infinity, we output a hint about raising 'ulimit -l' as an additional log line. [0] https://marc.info/?l=xdp-newbies&m=157043612505624&w=2 [1] https://github.com/xdp-project/xdp-tutorial/issues/86 Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20191216181204.724953-1-toke@redhat.com
2019-12-16libbpf: Fix build by renaming variablesPrashant Bhole1-6/+6
In btf__align_of() variable name 't' is shadowed by inner block declaration of another variable with same name. Patch renames variables in order to fix it. CC sharedobjs/btf.o btf.c: In function ‘btf__align_of’: btf.c:303:21: error: declaration of ‘t’ shadows a previous local [-Werror=shadow] 303 | int i, align = 1, t; | ^ btf.c:283:25: note: shadowed declaration is here 283 | const struct btf_type *t = btf__type_by_id(btf, id); | Fixes: 3d208f4ca111 ("libbpf: Expose btf__align_of() API") Signed-off-by: Prashant Bhole <prashantbhole.linux@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20191216082738.28421-1-prashantbhole.linux@gmail.com
2019-12-15libbpf: Support flexible arrays in CO-REAndrii Nakryiko1-5/+29
Some data stuctures in kernel are defined with either zero-sized array or flexible (dimensionless) array at the end of a struct. Actual data of such array follows in memory immediately after the end of that struct, forming its variable-sized "body" of elements. Support such access pattern in CO-RE relocation handling. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191215070844.1014385-2-andriin@fb.com
2019-12-15bpftool: Generate externs datasec in BPF skeletonAndrii Nakryiko1-5/+5
Add support for generation of mmap()-ed read-only view of libbpf-provided extern variables. As externs are not supposed to be provided by user code (that's what .data, .bss, and .rodata is for), don't mmap() it initially. Only after skeleton load is performed, map .extern contents as read-only memory. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191214014710.3449601-4-andriin@fb.com
2019-12-15libbpf: Support libbpf-provided extern variablesAndrii Nakryiko5-61/+722
Add support for extern variables, provided to BPF program by libbpf. Currently the following extern variables are supported: - LINUX_KERNEL_VERSION; version of a kernel in which BPF program is executing, follows KERNEL_VERSION() macro convention, can be 4- and 8-byte long; - CONFIG_xxx values; a set of values of actual kernel config. Tristate, boolean, strings, and integer values are supported. Set of possible values is determined by declared type of extern variable. Supported types of variables are: - Tristate values. Are represented as `enum libbpf_tristate`. Accepted values are **strictly** 'y', 'n', or 'm', which are represented as TRI_YES, TRI_NO, or TRI_MODULE, respectively. - Boolean values. Are represented as bool (_Bool) types. Accepted values are 'y' and 'n' only, turning into true/false values, respectively. - Single-character values. Can be used both as a substritute for bool/tristate, or as a small-range integer: - 'y'/'n'/'m' are represented as is, as characters 'y', 'n', or 'm'; - integers in a range [-128, 127] or [0, 255] (depending on signedness of char in target architecture) are recognized and represented with respective values of char type. - Strings. String values are declared as fixed-length char arrays. String of up to that length will be accepted and put in first N bytes of char array, with the rest of bytes zeroed out. If config string value is longer than space alloted, it will be truncated and warning message emitted. Char array is always zero terminated. String literals in config have to be enclosed in double quotes, just like C-style string literals. - Integers. 8-, 16-, 32-, and 64-bit integers are supported, both signed and unsigned variants. Libbpf enforces parsed config value to be in the supported range of corresponding integer type. Integers values in config can be: - decimal integers, with optional + and - signs; - hexadecimal integers, prefixed with 0x or 0X; - octal integers, starting with 0. Config file itself is searched in /boot/config-$(uname -r) location with fallback to /proc/config.gz, unless config path is specified explicitly through bpf_object_open_opts' kernel_config_path option. Both gzipped and plain text formats are supported. Libbpf adds explicit dependency on zlib because of this, but this shouldn't be a problem, given libelf already depends on zlib. All detected extern variables, are put into a separate .extern internal map. It, similarly to .rodata map, is marked as read-only from BPF program side, as well as is frozen on load. This allows BPF verifier to track extern values as constants and perform enhanced branch prediction and dead code elimination. This can be relied upon for doing kernel version/feature detection and using potentially unsupported field relocations or BPF helpers in a CO-RE-based BPF program, while still having a single version of BPF program running on old and new kernels. Selftests are validating this explicitly for unexisting BPF helper. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191214014710.3449601-3-andriin@fb.com
2019-12-15libbpf: Extract internal map names into constantsAndrii Nakryiko1-9/+14
Instead of duplicating string literals, keep them in one place and consistent. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191214014710.3449601-2-andriin@fb.com
2019-12-15libbpf: Add BPF object skeleton supportAndrii Nakryiko3-0/+205
Add new set of APIs, allowing to open/load/attach BPF object through BPF object skeleton, generated by bpftool for a specific BPF object file. All the xxx_skeleton() APIs wrap up corresponding bpf_object_xxx() APIs, but additionally also automate map/program lookups by name, global data initialization and mmap()-ing, etc. All this greatly improves and simplifies userspace usability of working with BPF programs. See follow up patches for examples. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20191214014341.3442258-13-andriin@fb.com
2019-12-15libbpf: Reduce log level of supported section names dumpAndrii Nakryiko1-1/+1
It's quite spammy. And now that bpf_object__open() is trying to determine program type from its section name, we are getting these verbose messages all the time. Reduce their log level to DEBUG. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20191214014341.3442258-12-andriin@fb.com
2019-12-15libbpf: Postpone BTF ID finding for TRACING programs to load phaseAndrii Nakryiko1-19/+18
Move BTF ID determination for BPF_PROG_TYPE_TRACING programs to a load phase. Performing it at open step is inconvenient, because it prevents BPF skeleton generation on older host kernel, which doesn't contain BTF_KIND_FUNCs information in vmlinux BTF. This is a common set up, though, when, e.g., selftests are compiled on older host kernel, but the test program itself is executed in qemu VM with bleeding edge kernel. Having this BTF searching performed at load time allows to successfully use bpf_object__open() for codegen and inspection of BPF object file. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20191214014341.3442258-11-andriin@fb.com
2019-12-15libbpf: Refactor global data map initializationAndrii Nakryiko1-38/+59
Refactor global data map initialization to use anonymous mmap()-ed memory instead of malloc()-ed one. This allows to do a transparent re-mmap()-ing of already existing memory address to point to BPF map's memory after bpf_object__load() step (done in follow up patch). This choreographed setup allows to have a nice and unsurprising way to pre-initialize read-only (and r/w as well) maps by user and after BPF map creation keep working with mmap()-ed contents of this map. All in a way that doesn't require user code to update any pointers: the illusion of working with memory contents is preserved before and after actual BPF map instantiation. Selftests and runqslower example demonstrate this feature in follow up patches. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20191214014341.3442258-10-andriin@fb.com
2019-12-15libbpf: Expose BPF program's function nameAndrii Nakryiko3-7/+32
Add APIs to get BPF program function name, as opposed to bpf_program__title(), which returns BPF program function's section name. Function name has a benefit of being a valid C identifier and uniquely identifies a specific BPF program, while section name can be duplicated across multiple independent BPF programs. Add also bpf_object__find_program_by_name(), similar to bpf_object__find_program_by_title(), to facilitate looking up BPF programs by their C function names. Convert one of selftests to new API for look up. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20191214014341.3442258-9-andriin@fb.com
2019-12-15libbpf: Expose BTF-to-C type declaration emitting APIAndrii Nakryiko3-26/+65
Expose API that allows to emit type declaration and field/variable definition (if optional field name is specified) in valid C syntax for any provided BTF type. This is going to be used by bpftool when emitting data section layout as a struct. As part of making this API useful in a stand-alone fashion, move initialization of some of the internal btf_dump state to earlier phase. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20191214014341.3442258-8-andriin@fb.com
2019-12-15libbpf: Expose btf__align_of() APIAndrii Nakryiko4-41/+47
Expose BTF API that calculates type alignment requirements. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191214014341.3442258-7-andriin@fb.com
2019-12-15libbpf: Extract common user-facing helpersAndrii Nakryiko4-34/+44
LIBBPF_API and DECLARE_LIBBPF_OPTS are needed in many public libbpf API headers. Extract them into libbpf_common.h to avoid unnecessary interdependency between btf.h, libbpf.h, and bpf.h or code duplication. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191214014341.3442258-6-andriin@fb.com
2019-12-15libbpf: Add BPF_EMBED_OBJ macro for embedding BPF .o filesAndrii Nakryiko1-0/+35
Add a convenience macro BPF_EMBED_OBJ, which allows to embed other files (typically used to embed BPF .o files) into a hosting userspace programs. To C program it is exposed as struct bpf_embed_data, containing a pointer to raw data and its size in bytes. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20191214014341.3442258-5-andriin@fb.com