linux/tools/lib/bpf, branch v5.10

libbpf: Fix ring_buffer__poll() to return number of consumed samples

2020-12-02T04:21:45Z

Fix ring_buffer__poll() to return the number of non-discarded records consumed, just like its documentation states. It's also consistent with ring_buffer__consume() return. Fix up selftests with wrong expected results. Fixes: bf99c936f947 ("libbpf: Add BPF ring buffer support") Fixes: cb1c9ddd5525 ("selftests/bpf: Add BPF ringbuf selftests") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201130223336.904192-1-andrii@kernel.org

libbpf: Fix VERSIONED_SYM_COUNT number parsing

2020-11-19T16:45:12Z

We remove "other info" from "readelf -s --wide" output when parsing GLOBAL_SYM_COUNT variable, which was added in [1]. But we don't do that for VERSIONED_SYM_COUNT and it's failing the check_abi target on powerpc Fedora 33. The extra "other info" wasn't problem for VERSIONED_SYM_COUNT parsing until commit [2] added awk in the pipe, which assumes that the last column is symbol, but it can be "other info". Adding "other info" removal for VERSIONED_SYM_COUNT the same way as we did for GLOBAL_SYM_COUNT parsing. [1] aa915931ac3e ("libbpf: Fix readelf output parsing for Fedora") [2] 746f534a4809 ("tools/libbpf: Avoid counting local symbols in ABI check") Fixes: 746f534a4809 ("tools/libbpf: Avoid counting local symbols in ABI check") Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20201118211350.1493421-1-jolsa@kernel.org

libbpf: Don't attempt to load unused subprog as an entry-point BPF program

2020-11-09T21:15:23Z

If BPF code contains unused BPF subprogram and there are no other subprogram calls (which can realistically happen in real-world applications given sufficiently smart Clang code optimizations), libbpf will erroneously assume that subprograms are entry-point programs and will attempt to load them with UNSPEC program type. Fix by not relying on subcall instructions and rather detect it based on the structure of BPF object's sections. Fixes: 9a94f277c4fb ("tools: libbpf: restore the ability to load programs from .text section") Reported-by: Dmitrii Banshchikov Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20201107000251.256821-1-andrii@kernel.org

libbpf: Fix possible use after free in xsk_socket__delete

2020-11-04T20:37:29Z

Fix a possible use after free in xsk_socket__delete that will happen if xsk_put_ctx() frees the ctx. To fix, save the umem reference taken from the context and just use that instead. Fixes: 2f6324a3937f ("libbpf: Support shared umems between queues and devices") Signed-off-by: Magnus Karlsson Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/1604396490-12129-3-git-send-email-magnus.karlsson@gmail.com

libbpf: Fix null dereference in xsk_socket__delete

2020-11-04T20:37:28Z

Fix a possible null pointer dereference in xsk_socket__delete that will occur if a null pointer is fed into the function. Fixes: 2f6324a3937f ("libbpf: Support shared umems between queues and devices") Reported-by: Andrii Nakryiko Signed-off-by: Magnus Karlsson Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/1604396490-12129-2-git-send-email-magnus.karlsson@gmail.com

libbpf, hashmap: Fix undefined behavior in hash_bits

2020-11-02T22:33:51Z

If bits is 0, the case when the map is empty, then the >> is the size of the register which is undefined behavior - on x86 it is the same as a shift by 0. Fix by handling the 0 case explicitly and guarding calls to hash_bits for empty maps in hashmap__for_each_key_entry and hashmap__for_each_entry_safe. Fixes: e3b924224028 ("libbpf: add resizable non-thread safe internal hashmap") Suggested-by: Andrii Nakryiko , Signed-off-by: Ian Rogers Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20201029223707.494059-1-irogers@google.com

bpf, libbpf: Guard bpf inline asm from bpf_tail_call_static

2020-10-21T23:46:52Z

Yaniv reported a compilation error after pulling latest libbpf: [...] ../libbpf/src/root/usr/include/bpf/bpf_helpers.h:99:10: error: unknown register name 'r0' in asm : "r0", "r1", "r2", "r3", "r4", "r5"); [...] The issue got triggered given Yaniv was compiling tracing programs with native target (e.g. x86) instead of BPF target, hence no BTF generated vmlinux.h nor CO-RE used, and later llc with -march=bpf was invoked to compile from LLVM IR to BPF object file. Given that clang was expecting x86 inline asm and not BPF one the error complained that these regs don't exist on the former. Guard bpf_tail_call_static() with defined(__bpf__) where BPF inline asm is valid to use. BPF tracing programs on more modern kernels use BPF target anyway and thus the bpf_tail_call_static() function will be available for them. BPF inline asm is supported since clang 7 (clang <= 6 otherwise throws same above error), and __bpf_unreachable() since clang 8, therefore include the latter condition in order to prevent compilation errors for older clang versions. Given even an old Ubuntu 18.04 LTS has official LLVM packages all the way up to llvm-10, I did not bother to special case the __bpf_unreachable() inside bpf_tail_call_static() further. Also, undo the sockex3_kern's use of bpf_tail_call_static() sample given they still have the old hacky way to even compile networking progs with native instead of BPF target so bpf_tail_call_static() won't be defined there anymore. Fixes: 0e9f6841f664 ("bpf, libbpf: Add bpf_tail_call_static helper for bpf programs") Reported-by: Yaniv Agman Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: Yonghong Song Tested-by: Yaniv Agman Link: https://lore.kernel.org/bpf/CAMy7=ZUk08w5Gc2Z-EKi4JFtuUCaZYmE4yzhJjrExXpYKR4L8w@mail.gmail.com Link: https://lore.kernel.org/bpf/20201021203257.26223-1-daniel@iogearbox.net

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2020-10-12T23:16:50Z

Alexei Starovoitov says: ==================== pull-request: bpf-next 2020-10-12 The main changes are: 1) The BPF verifier improvements to track register allocation pattern, from Alexei and Yonghong. 2) libbpf relocation support for different size load/store, from Andrii. 3) bpf_redirect_peer() helper and support for inner map array with different max_entries, from Daniel. 4) BPF support for per-cpu variables, form Hao. 5) sockmap improvements, from John. ==================== Signed-off-by: Jakub Kicinski

libbpf: Allow specifying both ELF and raw BTF for CO-RE BTF override

2020-10-08T01:50:27Z

Use generalized BTF parsing logic, making it possible to parse BTF both from ELF file, as well as a raw BTF dump. This makes it easier to write custom tests with manually generated BTFs. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201008001025.292064-4-andrii@kernel.org

libbpf: Support safe subset of load/store instruction resizing with CO-RE

2020-10-08T01:50:27Z

Add support for patching instructions of the following form: - rX = *(T *)(rY + ); - *(T *)(rX + ) = rY; - *(T *)(rX + ) = , where T is one of {u8, u16, u32, u64}. For such instructions, if the actual kernel field recorded in CO-RE relocation has a different size than the one recorded locally (e.g., from vmlinux.h), then libbpf will adjust T to an appropriate 1-, 2-, 4-, or 8-byte loads. In general, such transformation is not always correct and could lead to invalid final value being loaded or stored. But two classes of cases are always safe: - if both local and target (kernel) types are unsigned integers, but of different sizes, then it's OK to adjust load/store instruction according to the necessary memory size. Zero-extending nature of such instructions and unsignedness make sure that the final value is always correct; - pointer size mismatch between BPF target architecture (which is always 64-bit) and 32-bit host kernel architecture can be similarly resolved automatically, because pointer is essentially an unsigned integer. Loading 32-bit pointer into 64-bit BPF register with zero extension will leave correct pointer in the register. Both cases are necessary to support CO-RE on 32-bit kernels, as `unsigned long` in vmlinux.h generated from 32-bit kernel is 32-bit, but when compiled with BPF program for BPF target it will be treated by compiler as 64-bit integer. Similarly, pointers in vmlinux.h are 32-bit for kernel, but treated as 64-bit values by compiler for BPF target. Both problems are now resolved by libbpf for direct memory reads. But similar transformations are useful in general when kernel fields are "resized" from, e.g., unsigned int to unsigned long (or vice versa). Now, similar transformations for signed integers are not safe to perform as they will result in incorrect sign extension of the value. If such situation is detected, libbpf will emit helpful message and will poison the instruction. Not failing immediately means that it's possible to guard the instruction based on kernel version (or other conditions) and make sure it's not reachable. If there is a need to read signed integers that change sizes between different kernels, it's possible to use BPF_CORE_READ_BITFIELD() macro, which works both with bitfields and non-bitfield integers of any signedness and handles sign-extension properly. Also, bpf_core_read() with proper size and/or use of bpf_core_field_size() relocation could allow to deal with such complicated situations explicitly, if not so conventiently as direct memory reads. Selftests added in a separate patch in progs/test_core_autosize.c demonstrate both direct memory and probed use cases. BPF_CORE_READ() is not changed and it won't deal with such situations as automatically as direct memory reads due to the signedness integer limitations, which are much harder to detect and control with compiler macro magic. So it's encouraged to utilize direct memory reads as much as possible. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201008001025.292064-3-andrii@kernel.org