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2025-06-27bpftool: Fix cgroup command to only show cgroup bpf programsMartin KaFai Lau
commit b69d4413aa1961930fbf9ffad8376d577378daf9 upstream. The netkit program is not a cgroup bpf program and should not be shown in the output of the "bpftool cgroup show" command. However, if the netkit device happens to have ifindex 3, the "bpftool cgroup show" command will output the netkit bpf program as well: > ip -d link show dev nk1 3: nk1@if2: ... link/ether ... netkit mode ... > bpftool net show tc: nk1(3) netkit/peer tw_ns_nk2phy prog_id 469447 > bpftool cgroup show /sys/fs/cgroup/... ID AttachType AttachFlags Name ... ... ... 469447 netkit_peer tw_ns_nk2phy The reason is that the target_fd (which is the cgroup_fd here) and the target_ifindex are in a union in the uapi/linux/bpf.h. The bpftool iterates all values in "enum bpf_attach_type" which includes non cgroup attach types like netkit. The cgroup_fd is usually 3 here, so the bug is triggered when the netkit ifindex just happens to be 3 as well. The bpftool's cgroup.c already has a list of cgroup-only attach type defined in "cgroup_attach_types[]". This patch fixes it by iterating over "cgroup_attach_types[]" instead of "__MAX_BPF_ATTACH_TYPE". Cc: Quentin Monnet <qmo@kernel.org> Reported-by: Takshak Chahande <ctakshak@meta.com> Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20250507203232.1420762-1-martin.lau@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-06-19bpftool: Fix regression of "bpftool cgroup tree" EINVAL on older kernelsYiFei Zhu
[ Upstream commit 43745d11bfd9683abdf08ad7a5cc403d6a9ffd15 ] If cgroup_has_attached_progs queries an attach type not supported by the running kernel, due to the kernel being older than the bpftool build, it would encounter an -EINVAL from BPF_PROG_QUERY syscall. Prior to commit 98b303c9bf05 ("bpftool: Query only cgroup-related attach types"), this EINVAL would be ignored by the function, allowing the function to only consider supported attach types. The commit changed so that, instead of querying all attach types, only attach types from the array `cgroup_attach_types` is queried. The assumption is that because these are only cgroup attach types, they should all be supported. Unfortunately this assumption may be false when the kernel is older than the bpftool build, where the attach types queried by bpftool is not yet implemented in the kernel. This would result in errors such as: $ bpftool cgroup tree CgroupPath ID AttachType AttachFlags Name Error: can't query bpf programs attached to /sys/fs/cgroup: Invalid argument This patch restores the logic of ignoring EINVAL from prior to that patch. Fixes: 98b303c9bf05 ("bpftool: Query only cgroup-related attach types") Reported-by: Sagarika Sharma <sharmasagarika@google.com> Reported-by: Minh-Anh Nguyen <minhanhdn@google.com> Signed-off-by: YiFei Zhu <zhuyifei@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20250428211536.1651456-1-zhuyifei@google.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-05-29bpftool: Fix readlink usage in get_fd_typeViktor Malik
[ Upstream commit 0053f7d39d491b6138d7c526876d13885cbb65f1 ] The `readlink(path, buf, sizeof(buf))` call reads at most sizeof(buf) bytes and *does not* append null-terminator to buf. With respect to that, fix two pieces in get_fd_type: 1. Change the truncation check to contain sizeof(buf) rather than sizeof(path). 2. Append null-terminator to buf. Reported by Coverity. Signed-off-by: Viktor Malik <vmalik@redhat.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20250129071857.75182-1-vmalik@redhat.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-05-02bpf: bpftool: Setting error code in do_loader()Sewon Nam
[ Upstream commit 02a4694107b4c830d4bd6d194e98b3ac0bc86f29 ] We are missing setting error code in do_loader() when bpf_object__open_file() fails. This means the command's exit status code will be successful, even though the operation failed. So make sure to return the correct error code. To maintain consistency with other locations where bpf_object__open_file() is called, return -1. [0] Closes: https://github.com/libbpf/bpftool/issues/156 Reported-by: Dan Carpenter <dan.carpenter@linaro.org> Signed-off-by: Sewon Nam <swnam0729@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Quentin Monnet <qmo@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/d3b5b4b4-19bb-4619-b4dd-86c958c4a367@stanley.mountain/t/#u Link: https://lore.kernel.org/bpf/20250311031238.14865-1-swnam0729@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-12-14bpftool: fix potential NULL pointer dereferencing in prog_dump()Amir Mohammadi
[ Upstream commit ef3ba8c258ee368a5343fa9329df85b4bcb9e8b5 ] A NULL pointer dereference could occur if ksyms is not properly checked before usage in the prog_dump() function. Fixes: b053b439b72a ("bpf: libbpf: bpftool: Print bpf_line_info during prog dump") Signed-off-by: Amir Mohammadi <amiremohamadi@yahoo.com> Reviewed-by: Quentin Monnet <qmo@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/r/20241121083413.7214-1-amiremohamadi@yahoo.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-12-05bpf, bpftool: Fix incorrect disasm pcLeon Hwang
[ Upstream commit 4d99e509c161f8610de125202c648fa4acd00541 ] This patch addresses the bpftool issue "Wrong callq address displayed"[0]. The issue stemmed from an incorrect program counter (PC) value used during disassembly with LLVM or libbfd. For LLVM: The PC argument must represent the actual address in the kernel to compute the correct relative address. For libbfd: The relative address can be adjusted by adding func_ksym within the custom info->print_address_func to yield the correct address. Links: [0] https://github.com/libbpf/bpftool/issues/109 Changes: v2 -> v3: * Address comment from Quentin: * Remove the typedef. v1 -> v2: * Fix the broken libbfd disassembler. Fixes: e1947c750ffe ("bpftool: Refactor disassembler for JIT-ed programs") Signed-off-by: Leon Hwang <leon.hwang@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Quentin Monnet <qmo@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/bpf/20241031152844.68817-1-leon.hwang@linux.dev Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-09-10bpftool: Fix undefined behavior in qsort(NULL, 0, ...)Kuan-Wei Chiu
When netfilter has no entry to display, qsort is called with qsort(NULL, 0, ...). This results in undefined behavior, as UBSan reports: net.c:827:2: runtime error: null pointer passed as argument 1, which is declared to never be null Although the C standard does not explicitly state whether calling qsort with a NULL pointer when the size is 0 constitutes undefined behavior, Section 7.1.4 of the C standard (Use of library functions) mentions: "Each of the following statements applies unless explicitly stated otherwise in the detailed descriptions that follow: If an argument to a function has an invalid value (such as a value outside the domain of the function, or a pointer outside the address space of the program, or a null pointer, or a pointer to non-modifiable storage when the corresponding parameter is not const-qualified) or a type (after promotion) not expected by a function with variable number of arguments, the behavior is undefined." To avoid this, add an early return when nf_link_info is NULL to prevent calling qsort with a NULL pointer. Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240910150207.3179306-1-visitorckw@gmail.com
2024-09-09bpftool: Fix typosAndrew Kreimer
Fix typos in documentation. Reported-by: Matthew Wilcox <willy@infradead.org> Reported-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Andrew Kreimer <algonell@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240909092452.4293-1-algonell@gmail.com
2024-09-09bpftool: Fix undefined behavior caused by shifting into the sign bitKuan-Wei Chiu
Replace shifts of '1' with '1U' in bitwise operations within __show_dev_tc_bpf() to prevent undefined behavior caused by shifting into the sign bit of a signed integer. By using '1U', the operations are explicitly performed on unsigned integers, avoiding potential integer overflow or sign-related issues. Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240908140009.3149781-1-visitorckw@gmail.com
2024-09-06bpftool: Improve btf c dump sorting stabilityMykyta Yatsenko
Existing algorithm for BTF C dump sorting uses only types and names of the structs and unions for ordering. As dump contains structs with the same names but different contents, relative to each other ordering of those structs will be accidental. This patch addresses this problem by introducing a new sorting field that contains hash of the struct/union field names and types to disambiguate comparison of the non-unique named structs. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240906132453.146085-1-mykyta.yatsenko5@gmail.com
2024-09-05bpftool: fix some typos in bpftoolLin Yikai
Hi, fix some spelling errors in bpftool, the details are as follows: -in file "bpftool-gen.rst" libppf->libbpf -in the code comments: ouptut->output Signed-off-by: Lin Yikai <yikai.lin@vivo.com> Link: https://lore.kernel.org/r/20240905110354.3274546-2-yikai.lin@vivo.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-09-02bpftool: Fix handling enum64 in btf dump sortingMykyta Yatsenko
Wrong function is used to access the first enum64 element. Substituting btf_enum(t) with btf_enum64(t) for BTF_KIND_ENUM64. Fixes: 94133cf24bb3 ("bpftool: Introduce btf c dump sorting") Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240902171721.105253-1-mykyta.yatsenko5@gmail.com
2024-09-02bpftool: Add missing blank lines in bpftool-net doc exampleQuentin Monnet
In bpftool-net documentation, two blank lines are missing in a recently added example, causing docutils to complain: $ cd tools/bpf/bpftool $ make doc DESCEND Documentation GEN bpftool-btf.8 GEN bpftool-cgroup.8 GEN bpftool-feature.8 GEN bpftool-gen.8 GEN bpftool-iter.8 GEN bpftool-link.8 GEN bpftool-map.8 GEN bpftool-net.8 <stdin>:189: (INFO/1) Possible incomplete section title. Treating the overline as ordinary text because it's so short. <stdin>:192: (INFO/1) Blank line missing before literal block (after the "::")? Interpreted as a definition list item. <stdin>:199: (INFO/1) Possible incomplete section title. Treating the overline as ordinary text because it's so short. <stdin>:201: (INFO/1) Blank line missing before literal block (after the "::")? Interpreted as a definition list item. GEN bpftool-perf.8 GEN bpftool-prog.8 GEN bpftool.8 GEN bpftool-struct_ops.8 Add the missing blank lines. Fixes: 0d7c06125cea ("bpftool: Add document for net attach/detach on tcx subcommand") Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240901210742.25758-1-qmo@kernel.org
2024-07-30tools/bpf: Fix the wrong format specifierZhu Jun
The format specifier of "unsigned int" in printf() should be "%u", not "%d". Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240724111120.11625-1-zhujun2@cmss.chinamobile.com
2024-07-29bpftool: Add document for net attach/detach on tcx subcommandTao Chen
This commit adds sample output for net attach/detach on tcx subcommand. Signed-off-by: Tao Chen <chen.dylane@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240721144252.96264-1-chen.dylane@gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-07-29bpftool: Add bash-completion for tcx subcommandTao Chen
This commit adds bash-completion for attaching tcx program on interface. Signed-off-by: Tao Chen <chen.dylane@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240721144238.96246-1-chen.dylane@gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-07-29bpftool: Add net attach/detach command to tcx progTao Chen
Now, attach/detach tcx prog supported in libbpf, so we can add new command 'bpftool attach/detach tcx' to attach tcx prog with bpftool for user. # bpftool prog load tc_prog.bpf.o /sys/fs/bpf/tc_prog # bpftool prog show ... 192: sched_cls name tc_prog tag 187aeb611ad00cfc gpl loaded_at 2024-07-11T15:58:16+0800 uid 0 xlated 152B jited 97B memlock 4096B map_ids 100,99,97 btf_id 260 # bpftool net attach tcx_ingress name tc_prog dev lo # bpftool net ... tc: lo(1) tcx/ingress tc_prog prog_id 29 # bpftool net detach tcx_ingress dev lo # bpftool net ... tc: # bpftool net attach tcx_ingress name tc_prog dev lo # bpftool net tc: lo(1) tcx/ingress tc_prog prog_id 29 Test environment: ubuntu_22_04, 6.7.0-060700-generic Signed-off-by: Tao Chen <chen.dylane@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240721144221.96228-1-chen.dylane@gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-07-29bpftool: Refactor xdp attach/detach type judgmentTao Chen
This commit no logical changed, just increases code readability and facilitates TCX prog expansion, which will be implemented in the next patch. Signed-off-by: Tao Chen <chen.dylane@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240721143353.95980-2-chen.dylane@gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-07-17bpftool: Fix typo in usage helpDonald Hunter
The usage help for "bpftool prog help" contains a ° instead of the _ symbol for cgroup/sendmsg_unix. Fix the typo. Fixes: 8b3cba987e6d ("bpftool: Add support for cgroup unix socket address hooks") Signed-off-by: Donald Hunter <donald.hunter@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240717134508.77488-1-donald.hunter@gmail.com
2024-07-09bpftool: improve skeleton backwards compat with old buggy libbpfsAndrii Nakryiko
Old versions of libbpf don't handle varying sizes of bpf_map_skeleton struct correctly. As such, BPF skeleton generated by newest bpftool might not be compatible with older libbpf (though only when libbpf is used as a shared library), even though it, by design, should. Going forward libbpf will be fixed, plus we'll release bug fixed versions of relevant old libbpfs, but meanwhile try to mitigate from bpftool side by conservatively assuming older and smaller definition of bpf_map_skeleton, if possible. Meaning, if there are no struct_ops maps. If there are struct_ops, then presumably user would like to have auto-attaching logic and struct_ops map link placeholders, so use the full bpf_map_skeleton definition in that case. Acked-by: Quentin Monnet <qmo@kernel.org> Co-developed-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240708204540.4188946-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-07-02bpftool: Mount bpffs when pinmaps path not under the bpffsTao Chen
As Quentin said [0], BPF map pinning will fail if the pinmaps path is not under the bpffs, like: libbpf: specified path /home/ubuntu/test/sock_ops_map is not on BPF FS Error: failed to pin all maps [0] https://github.com/libbpf/bpftool/issues/146 Fixes: 3767a94b3253 ("bpftool: add pinmaps argument to the load/loadall") Signed-off-by: Tao Chen <chen.dylane@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Quentin Monnet <qmo@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240702131150.15622-1-chen.dylane@gmail.com
2024-06-21bpftool: Allow compile-time checks of BPF map auto-attach support in skeletonAndrii Nakryiko
New versions of bpftool now emit additional link placeholders for BPF maps (struct_ops maps are the only maps right now that support attachment), and set up BPF skeleton in such a way that libbpf will auto-attach BPF maps automatically, assumming libbpf is recent enough (v1.5+). Old libbpf will do nothing with those links and won't attempt to auto-attach maps. This allows user code to handle both pre-v1.5 and v1.5+ versions of libbpf at runtime, if necessary. But if users don't have (or don't want to) control bpftool version that generates skeleton, then they can't just assume that skeleton will have link placeholders. To make this detection possible and easy, let's add the following to generated skeleton header file: #define BPF_SKEL_SUPPORTS_MAP_AUTO_ATTACH 1 This can be used during compilation time to guard code that accesses skel->links.<map> slots. Note, if auto-attachment is undesirable, libbpf allows to disable this through bpf_map__set_autoattach(map, false). This is necessary only on libbpf v1.5+, older libbpf doesn't support map auto-attach anyways. Libbpf version can be detected at compilation time using LIBBPF_MAJOR_VERSION and LIBBPF_MINOR_VERSION macros, or at runtime with libbpf_major_version() and libbpf_minor_version() APIs. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240618183832.2535876-1-andrii@kernel.org
2024-06-12bpftool: Support dumping kfunc prototypes from BTFDaniel Xu
This patch enables dumping kfunc prototypes from bpftool. This is useful b/c with this patch, end users will no longer have to manually define kfunc prototypes. For the kernel tree, this also means we can optionally drop kfunc prototypes from: tools/testing/selftests/bpf/bpf_kfuncs.h tools/testing/selftests/bpf/bpf_experimental.h Example usage: $ make PAHOLE=/home/dxu/dev/pahole/build/pahole -j30 vmlinux $ ./tools/bpf/bpftool/bpftool btf dump file ./vmlinux format c | rg "__ksym;" | head -3 extern void cgroup_rstat_updated(struct cgroup *cgrp, int cpu) __weak __ksym; extern void cgroup_rstat_flush(struct cgroup *cgrp) __weak __ksym; extern struct bpf_key *bpf_lookup_user_key(u32 serial, u64 flags) __weak __ksym; Signed-off-by: Daniel Xu <dxu@dxuuu.xyz> Link: https://lore.kernel.org/r/bf6c08f9263c4bd9d10a717de95199d766a13f61.1718207789.git.dxu@dxuuu.xyz Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-11bpftool: Query only cgroup-related attach typesKenta Tada
When CONFIG_NETKIT=y, bpftool-cgroup shows error even if the cgroup's path is correct: $ bpftool cgroup tree /sys/fs/cgroup CgroupPath ID AttachType AttachFlags Name Error: can't query bpf programs attached to /sys/fs/cgroup: No such device or address >From strace and kernel tracing, I found netkit returned ENXIO and this command failed. I think this AttachType(BPF_NETKIT_PRIMARY) is not relevant to cgroup. bpftool-cgroup should query just only cgroup-related attach types. v2->v3: - removed an unnecessary check v1->v2: - used an array of cgroup attach types Signed-off-by: Kenta Tada <tadakentaso@gmail.com> Reviewed-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20240607111704.6716-1-tadakentaso@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-06libbpf: Auto-attach struct_ops BPF maps in BPF skeletonMykyta Yatsenko
Similarly to `bpf_program`, support `bpf_map` automatic attachment in `bpf_object__attach_skeleton`. Currently only struct_ops maps could be attached. On bpftool side, code-generate links in skeleton struct for struct_ops maps. Similarly to `bpf_program_skeleton`, set links in `bpf_map_skeleton`. On libbpf side, extend `bpf_map` with new `autoattach` field to support enabling or disabling autoattach functionality, introducing getter/setter for this field. `bpf_object__(attach|detach)_skeleton` is extended with attaching/detaching struct_ops maps logic. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240605175135.117127-1-yatsenko@meta.com
2024-06-05bpftool: Use BTF field iterator in btfgenAndrii Nakryiko
Switch bpftool's code which is using libbpf-internal btf_type_visit_type_ids() helper to new btf_field_iter functionality. This makes bpftool code simpler, but also unblocks removing libbpf's btf_type_visit_type_ids() helper completely. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Alan Maguire <alan.maguire@oracle.com> Reviewed-by: Quentin Monnet <qmo@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/bpf/20240605001629.4061937-5-andrii@kernel.org
2024-06-03bpftool: Fix typo in MAX_NUM_METRICS macro nameSwan Beaujard
Correct typo in bpftool profiler and change all instances of 'MATRICS' to 'METRICS' in the profiler.bpf.c file. Signed-off-by: Swan Beaujard <beaujardswan@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240602225812.81171-1-beaujardswan@gmail.com
2024-05-30bpftool: Change pid_iter.bpf.c to comply with the change of bpf_link_fops.Kui-Feng Lee
To support epoll, a new instance of file_operations, bpf_link_fops_poll, has been added for links that support epoll. The pid_iter.bpf.c checks f_ops for links and other BPF objects. The check should fail for struct_ops links without this patch. Acked-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com> Link: https://lore.kernel.org/r/20240530065946.979330-9-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2024-05-21bpftool: Un-const bpf_func_info to fix it for llvm 17 and newerIvan Babrou
LLVM 17 started treating const structs as constants: * https://github.com/llvm/llvm-project/commit/0b2d5b967d98 Combined with pointer laundering via ptr_to_u64, which takes a const ptr, but in reality treats the underlying memory as mutable, this makes clang always pass zero to btf__type_by_id, which breaks full name resolution. Disassembly before (LLVM 16) and after (LLVM 17): - 8b 75 cc mov -0x34(%rbp),%esi - e8 47 8d 02 00 call 3f5b0 <btf__type_by_id> + 31 f6 xor %esi,%esi + e8 a9 8c 02 00 call 3f510 <btf__type_by_id> It's a bigger project to fix this properly (and a question whether LLVM itself should detect this), but for right now let's just fix bpftool. For more information, see this thread in bpf mailing list: * https://lore.kernel.org/bpf/CABWYdi0ymezpYsQsPv7qzpx2fWuTkoD1-wG1eT-9x-TSREFrQg@mail.gmail.com/T/ Fixes: b662000aff84 ("bpftool: Adding support for BTF program names") Signed-off-by: Ivan Babrou <ivan@cloudflare.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Nick Desaulniers <ndesaulniers@google.com> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/bpf/20240520225149.5517-1-ivan@cloudflare.com
2024-05-18bpftool: Fix make dependencies for vmlinux.hArtem Savkov
With pre-generated vmlinux.h there is no dependency on neither vmlinux nor bootstrap bpftool. Define dependencies separately for both modes. This avoids needless rebuilds in some corner cases. Suggested-by: Jan Stancek <jstancek@redhat.com> Signed-off-by: Artem Savkov <asavkov@redhat.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240513112658.43691-1-asavkov@redhat.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-05-18bpftool: Introduce btf c dump sortingMykyta Yatsenko
Sort bpftool c dump output; aiming to simplify vmlinux.h diffing and forcing more natural type definitions ordering. Definitions are sorted first by their BTF kind ranks, then by their base type name and by their own name. Type ranks Assign ranks to btf kinds (defined in function btf_type_rank) to set next order: 1. Anonymous enums/enums64 2. Named enums/enums64 3. Trivial types typedefs (ints, then floats) 4. Structs/Unions 5. Function prototypes 6. Forward declarations Type rank is set to maximum for unnamed reference types, structs and unions to avoid emitting those types early. They will be emitted as part of the type chain starting with named type. Lexicographical ordering Each type is assigned a sort_name and own_name. sort_name is the resolved name of the final base type for reference types (typedef, pointer, array etc). Sorting by sort_name allows to group typedefs of the same base type. sort_name for non-reference type is the same as own_name. own_name is a direct name of particular type, is used as final sorting step. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <qmo@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240514131221.20585-1-yatsenko@meta.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-05-06bpftool, selftests/hid/bpf: Fix 29 clang warningsJohn Hubbard
When building either tools/bpf/bpftool, or tools/testing/selftests/hid, (the same Makefile is used for these), clang generates many instances of the following: "clang: warning: -lLLVM-17: 'linker' input unused" Quentin points out that the LLVM version is only required in $(LIBS), not in $(CFLAGS), so the fix is to remove it from CFLAGS. Suggested-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240505230054.13813-1-jhubbard@nvidia.com
2024-04-16bpftool: Address minor issues in bash completionQuentin Monnet
This commit contains a series of clean-ups and fixes for bpftool's bash completion file: - Make sure all local variables are declared as such. - Make sure variables are initialised before being read. - Update ELF section ("maps" -> ".maps") for looking up map names in object files. - Fix call to _init_completion. - Move definition for MAP_TYPE and PROG_TYPE higher up in the scope to avoid defining them multiple times, reuse MAP_TYPE where relevant. - Simplify completion for "duration" keyword in "bpftool prog profile". - Fix completion for "bpftool struct_ops register" and "bpftool link (pin|detach)" where we would repeatedly suggest file names instead of suggesting just one name. - Fix completion for "bpftool iter pin ... map MAP" to account for the "map" keyword. - Add missing "detach" suggestion for "bpftool link". Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240413011427.14402-3-qmo@kernel.org
2024-04-16bpftool: Update documentation where progs/maps can be passed by nameQuentin Monnet
When using references to BPF programs, bpftool supports passing programs by name on the command line. The manual pages for "bpftool prog" and "bpftool map" (for prog_array updates) mention it, but we have a few additional subcommands that support referencing programs by name but do not mention it in their documentation. Let's update the pages for subcommands "btf", "cgroup", and "net". Similarly, we can reference maps by name when passing them to "bpftool prog load", so we update the page for "bpftool prog" as well. Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240413011427.14402-2-qmo@kernel.org
2024-04-12bpftool: Fix typo in error messageThorsten Blum
s/at at/at a/ Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240411164258.533063-3-thorsten.blum@toblux.com
2024-04-10bpftool: Add link dump support for BPF_LINK_TYPE_SOCKMAPYonghong Song
An example output looks like: $ bpftool link 1776: sk_skb prog 49730 map_id 0 attach_type sk_skb_verdict pids test_progs(8424) 1777: sk_skb prog 49755 map_id 0 attach_type sk_skb_stream_verdict pids test_progs(8424) 1778: sk_msg prog 49770 map_id 8208 attach_type sk_msg_verdict pids test_progs(8424) Reviewed-by: John Fastabend <john.fastabend@gmail.com> Reviewed-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20240410043537.3737928-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-04-04bpftool: Mount bpffs on provided dir instead of parent dirSahil Siddiq
When pinning programs/objects under PATH (eg: during "bpftool prog loadall") the bpffs is mounted on the parent dir of PATH in the following situations: - the given dir exists but it is not bpffs. - the given dir doesn't exist and the parent dir is not bpffs. Mounting on the parent dir can also have the unintentional side- effect of hiding other files located under the parent dir. If the given dir exists but is not bpffs, then the bpffs should be mounted on the given dir and not its parent dir. Similarly, if the given dir doesn't exist and its parent dir is not bpffs, then the given dir should be created and the bpffs should be mounted on this new dir. Fixes: 2a36c26fe3b8 ("bpftool: Support bpffs mountpoint as pin path for prog loadall") Signed-off-by: Sahil Siddiq <icegambit91@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/2da44d24-74ae-a564-1764-afccf395eeec@isovalent.com/T/#t Link: https://lore.kernel.org/bpf/20240404192219.52373-1-icegambit91@gmail.com Closes: https://github.com/libbpf/bpftool/issues/100 Changes since v1: - Split "mount_bpffs_for_pin" into two functions. This is done to improve maintainability and readability. Changes since v2: - mount_bpffs_for_pin: rename to "create_and_mount_bpffs_dir". - mount_bpffs_given_file: rename to "mount_bpffs_given_file". - create_and_mount_bpffs_dir: - introduce "dir_exists" boolean. - remove new dir if "mnt_fs" fails. - improve error handling and error messages. Changes since v3: - Rectify function name. - Improve error messages and formatting. - mount_bpffs_for_file: - Check if dir exists before block_mount check. Changes since v4: - Use strdup instead of strcpy. - create_and_mount_bpffs_dir: - Use S_IRWXU instead of 0700. - Improve error handling and formatting.
2024-04-02bpftool: Use __typeof__() instead of typeof() in BPF skeletonAndrii Nakryiko
When generated BPF skeleton header is included in C++ code base, some compiler setups will emit warning about using language extensions due to typeof() usage, resulting in something like: error: extension used [-Werror,-Wlanguage-extension-token] obj->struct_ops.empty_tcp_ca = (typeof(obj->struct_ops.empty_tcp_ca)) ^ It looks like __typeof__() is a preferred way to do typeof() with better C++ compatibility behavior, so switch to that. With __typeof__() we get no such warning. Fixes: c2a0257c1edf ("bpftool: Cast pointers for shadow types explicitly.") Fixes: 00389c58ffe9 ("bpftool: Add support for subskeletons") Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Kui-Feng Lee <thinker.li@gmail.com> Acked-by: Quentin Monnet <qmo@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20240401170713.2081368-1-andrii@kernel.org
2024-04-02bpftool: Clean-up typos, punctuation, list formatting in docsRameez Rehman
Improve the formatting of the attach flags for cgroup programs in the relevant man page, and fix typos ("can be on of", "an userspace inet socket") when introducing that list. Also fix a couple of other trivial issues in docs. [ Quentin: Fixed trival issues in bpftool-gen.rst and bpftool-iter.rst ] Signed-off-by: Rameez Rehman <rameezrehman408@hotmail.com> Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240331200346.29118-4-qmo@kernel.org
2024-04-02bpftool: Remove useless emphasis on command description in man pagesRameez Rehman
As it turns out, the terms in definition lists in the rST file are already rendered with bold-ish formatting when generating the man pages; all double-star sequences we have in the commands for the command description are unnecessary, and can be removed to make the documentation easier to read. The rST files were automatically processed with: sed -i '/DESCRIPTION/,/OPTIONS/ { /^\*/ s/\*\*//g }' b*.rst Signed-off-by: Rameez Rehman <rameezrehman408@hotmail.com> Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240331200346.29118-3-qmo@kernel.org
2024-04-02bpftool: Use simpler indentation in source rST for documentationRameez Rehman
The rST manual pages for bpftool would use a mix of tabs and spaces for indentation. While this is the norm in C code, this is rather unusual for rST documents, and over time we've seen many contributors use a wrong level of indentation for documentation update. Let's fix bpftool's indentation in docs once and for all: - Let's use spaces, that are more common in rST files. - Remove one level of indentation for the synopsis, the command description, and the "see also" section. As a result, all sections start with the same indentation level in the generated man page. - Rewrap the paragraphs after the changes. There is no content change in this patch, only indentation and rewrapping changes. The wrapping in the generated source files for the manual pages is changed, but the pages displayed with "man" remain the same, apart from the adjusted indentation level on relevant sections. [ Quentin: rebased on bpf-next, removed indent level for command description and options, updated synopsis, command summary, and "see also" sections. ] Signed-off-by: Rameez Rehman <rameezrehman408@hotmail.com> Signed-off-by: Quentin Monnet <qmo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240331200346.29118-2-qmo@kernel.org
2024-03-28bpf: improve error message for unsupported helperMykyta Yatsenko
BPF verifier emits "unknown func" message when given BPF program type does not support BPF helper. This message may be confusing for users, as important context that helper is unknown only to current program type is not provided. This patch changes message to "program of this type cannot use helper " and aligns dependent code in libbpf and tests. Any suggestions on improving/changing this message are welcome. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/r/20240325152210.377548-1-yatsenko@meta.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-03-28Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski
Cross-merge networking fixes after downstream PR. No conflicts, or adjacent changes. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-20bpftool: Clean up HOST_CFLAGS, HOST_LDFLAGS for bootstrap bpftoolQuentin Monnet
Bpftool's Makefile uses $(HOST_CFLAGS) to build the bootstrap version of bpftool, in order to pick the flags for the host (where we run the bootstrap version) and not for the target system (where we plan to run the full bpftool binary). But we pass too much information through this variable. In particular, we set HOST_CFLAGS by copying most of the $(CFLAGS); but we do this after the feature detection for bpftool, which means that $(CFLAGS), hence $(HOST_CFLAGS), contain all macro definitions for using the different optional features. For example, -DHAVE_LLVM_SUPPORT may be passed to the $(HOST_CFLAGS), even though the LLVM disassembler is not used in the bootstrap version, and the related library may even be missing for the host architecture. A similar thing happens with the $(LDFLAGS), that we use unchanged for linking the bootstrap version even though they may contains flags to link against additional libraries. To address the $(HOST_CFLAGS) issue, we move the definition of $(HOST_CFLAGS) earlier in the Makefile, before the $(CFLAGS) update resulting from the feature probing - none of which being relevant to the bootstrap version. To clean up the $(LDFLAGS) for the bootstrap version, we introduce a dedicated $(HOST_LDFLAGS) variable that we base on $(LDFLAGS), before the feature probing as well. On my setup, the following macro and libraries are removed from the compiler invocation to build bpftool after this patch: -DUSE_LIBCAP -DHAVE_LLVM_SUPPORT -I/usr/lib/llvm-17/include -D_GNU_SOURCE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -lLLVM-17 -L/usr/lib/llvm-17/lib Another advantage of cleaning up these flags is that displaying available features with "bpftool version" becomes more accurate for the bootstrap bpftool, and no longer reflects the features detected (and available only) for the final binary. Cc: Jean-Philippe Brucker <jean-philippe@linaro.org> Signed-off-by: Quentin Monnet <qmo@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Message-ID: <20240320014103.45641-1-qmo@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-03-19bpftool: Remove unnecessary source files from bootstrap versionQuentin Monnet
Commit d510296d331a ("bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command.") added new files to the list of objects to compile in order to build the bootstrap version of bpftool. As far as I can tell, these objects are unnecessary and were added by mistake; maybe a draft version intended to add support for loading loader programs from the bootstrap version. Anyway, we can remove these object files from the list to make the bootstrap bpftool binary a tad smaller and faster to build. Fixes: d510296d331a ("bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command.") Signed-off-by: Quentin Monnet <qmo@kernel.org> Message-ID: <20240320013457.44808-1-qmo@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-03-19bpftool: Enable libbpf logs when loading pid_iter in debug modeQuentin Monnet
When trying to load the pid_iter BPF program used to iterate over the PIDs of the processes holding file descriptors to BPF links, we would unconditionally silence libbpf in order to keep the output clean if the kernel does not support iterators and loading fails. Although this is the desirable behaviour in most cases, this may hide bugs in the pid_iter program that prevent it from loading, and it makes it hard to debug such load failures, even in "debug" mode. Instead, it makes more sense to print libbpf's logs when we pass the -d|--debug flag to bpftool, so that users get the logs to investigate failures without having to edit bpftool's source code. Signed-off-by: Quentin Monnet <qmo@kernel.org> Message-ID: <20240320012241.42991-1-qmo@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-03-15libbpf, selftests/bpf: Adjust libbpf, bpftool, selftests to match LLVMAlexei Starovoitov
The selftests use to tell LLVM about special pointers. For LLVM there is nothing "arena" about them. They are simply pointers in a different address space. Hence LLVM diff https://github.com/llvm/llvm-project/pull/85161 renamed: . macro __BPF_FEATURE_ARENA_CAST -> __BPF_FEATURE_ADDR_SPACE_CAST . global variables in __attribute__((address_space(N))) are now placed in section named ".addr_space.N" instead of ".arena.N". Adjust libbpf, bpftool, and selftests to match LLVM. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Stanislav Fomichev <sdf@google.com> Link: https://lore.kernel.org/bpf/20240315021834.62988-3-alexei.starovoitov@gmail.com
2024-03-14bpftool: Fix missing pids during link showYonghong Song
Current 'bpftool link' command does not show pids, e.g., $ tools/build/bpftool/bpftool link ... 4: tracing prog 23 prog_type lsm attach_type lsm_mac target_obj_id 1 target_btf_id 31320 Hack the following change to enable normal libbpf debug output, --- a/tools/bpf/bpftool/pids.c +++ b/tools/bpf/bpftool/pids.c @@ -121,9 +121,9 @@ int build_obj_refs_table(struct hashmap **map, enum bpf_obj_type type) /* we don't want output polluted with libbpf errors if bpf_iter is not * supported */ - default_print = libbpf_set_print(libbpf_print_none); + /* default_print = libbpf_set_print(libbpf_print_none); */ err = pid_iter_bpf__load(skel); - libbpf_set_print(default_print); + /* libbpf_set_print(default_print); */ Rerun the above bpftool command: $ tools/build/bpftool/bpftool link libbpf: prog 'iter': BPF program load failed: Permission denied libbpf: prog 'iter': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; struct task_struct *task = ctx->task; @ pid_iter.bpf.c:69 0: (79) r6 = *(u64 *)(r1 +8) ; R1=ctx() R6_w=ptr_or_null_task_struct(id=1) ; struct file *file = ctx->file; @ pid_iter.bpf.c:68 ... ; struct bpf_link *link = (struct bpf_link *) file->private_data; @ pid_iter.bpf.c:103 80: (79) r3 = *(u64 *)(r8 +432) ; R3_w=scalar() R8=ptr_file() ; if (link->type == bpf_core_enum_value(enum bpf_link_type___local, @ pid_iter.bpf.c:105 81: (61) r1 = *(u32 *)(r3 +12) R3 invalid mem access 'scalar' processed 39 insns (limit 1000000) max_states_per_insn 0 total_states 3 peak_states 3 mark_read 2 -- END PROG LOAD LOG -- libbpf: prog 'iter': failed to load: -13 ... The 'file->private_data' returns a 'void' type and this caused subsequent 'link->type' (insn #81) failed in verification. To fix the issue, restore the previous BPF_CORE_READ so old kernels can also work. With this patch, the 'bpftool link' runs successfully with 'pids'. $ tools/build/bpftool/bpftool link ... 4: tracing prog 23 prog_type lsm attach_type lsm_mac target_obj_id 1 target_btf_id 31320 pids systemd(1) Fixes: 44ba7b30e84f ("bpftool: Use a local copy of BPF_LINK_TYPE_PERF_EVENT in pid_iter.bpf.c") Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Quentin Monnet <quentin@isovalent.com> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240312023249.3776718-1-yonghong.song@linux.dev
2024-03-14bpftool: Cast pointers for shadow types explicitly.Kui-Feng Lee
According to a report, skeletons fail to assign shadow pointers when being compiled with C++ programs. Unlike C doing implicit casting for void pointers, C++ requires an explicit casting. To support C++, we do explicit casting for each shadow pointer. Also add struct_ops_module.skel.h to test_cpp to validate C++ compilation as part of BPF selftests. Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Yonghong Song <yonghong.song@linux.dev> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240312013726.1780720-1-thinker.li@gmail.com
2024-03-11libbpf: Recognize __arena global variables.Andrii Nakryiko
LLVM automatically places __arena variables into ".arena.1" ELF section. In order to use such global variables bpf program must include definition of arena map in ".maps" section, like: struct { __uint(type, BPF_MAP_TYPE_ARENA); __uint(map_flags, BPF_F_MMAPABLE); __uint(max_entries, 1000); /* number of pages */ __ulong(map_extra, 2ull << 44); /* start of mmap() region */ } arena SEC(".maps"); libbpf recognizes both uses of arena and creates single `struct bpf_map *` instance in libbpf APIs. ".arena.1" ELF section data is used as initial data image, which is exposed through skeleton and bpf_map__initial_value() to the user, if they need to tune it before the load phase. During load phase, this initial image is copied over into mmap()'ed region corresponding to arena, and discarded. Few small checks here and there had to be added to make sure this approach works with bpf_map__initial_value(), mostly due to hard-coded assumption that map->mmaped is set up with mmap() syscall and should be munmap()'ed. For arena, .arena.1 can be (much) smaller than maximum arena size, so this smaller data size has to be tracked separately. Given it is enforced that there is only one arena for entire bpf_object instance, we just keep it in a separate field. This can be generalized if necessary later. All global variables from ".arena.1" section are accessible from user space via skel->arena->name_of_var. For bss/data/rodata the skeleton/libbpf perform the following sequence: 1. addr = mmap(MAP_ANONYMOUS) 2. user space optionally modifies global vars 3. map_fd = bpf_create_map() 4. bpf_update_map_elem(map_fd, addr) // to store values into the kernel 5. mmap(addr, MAP_FIXED, map_fd) after step 5 user spaces see the values it wrote at step 2 at the same addresses arena doesn't support update_map_elem. Hence skeleton/libbpf do: 1. addr = malloc(sizeof SEC ".arena.1") 2. user space optionally modifies global vars 3. map_fd = bpf_create_map(MAP_TYPE_ARENA) 4. real_addr = mmap(map->map_extra, MAP_SHARED | MAP_FIXED, map_fd) 5. memcpy(real_addr, addr) // this will fault-in and allocate pages At the end look and feel of global data vs __arena global data is the same from bpf prog pov. Another complication is: struct { __uint(type, BPF_MAP_TYPE_ARENA); } arena SEC(".maps"); int __arena foo; int bar; ptr1 = &foo; // relocation against ".arena.1" section ptr2 = &arena; // relocation against ".maps" section ptr3 = &bar; // relocation against ".bss" section Fo the kernel ptr1 and ptr2 has point to the same arena's map_fd while ptr3 points to a different global array's map_fd. For the verifier: ptr1->type == unknown_scalar ptr2->type == const_ptr_to_map ptr3->type == ptr_to_map_value After verification, from JIT pov all 3 ptr-s are normal ld_imm64 insns. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20240308010812.89848-11-alexei.starovoitov@gmail.com
generated by cgit v1.2.3 (git 2.39.1) at 2025-07-30 10:33:06 +0000