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2024-08-23bpf: Support bpf_kptr_xchg into local kptrDave Marchevsky
Currently, users can only stash kptr into map values with bpf_kptr_xchg(). This patch further supports stashing kptr into local kptr by adding local kptr as a valid destination type. When stashing into local kptr, btf_record in program BTF is used instead of btf_record in map to search for the btf_field of the local kptr. The local kptr specific checks in check_reg_type() only apply when the source argument of bpf_kptr_xchg() is local kptr. Therefore, we make the scope of the check explicit as the destination now can also be local kptr. Acked-by: Martin KaFai Lau <martin.lau@kernel.org> Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com> Signed-off-by: Amery Hung <amery.hung@bytedance.com> Link: https://lore.kernel.org/r/20240813212424.2871455-5-amery.hung@bytedance.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-23bpf: Rename ARG_PTR_TO_KPTR -> ARG_KPTR_XCHG_DESTDave Marchevsky
ARG_PTR_TO_KPTR is currently only used by the bpf_kptr_xchg helper. Although it limits reg types for that helper's first arg to PTR_TO_MAP_VALUE, any arbitrary mapval won't do: further custom verification logic ensures that the mapval reg being xchgd-into is pointing to a kptr field. If this is not the case, it's not safe to xchg into that reg's pointee. Let's rename the bpf_arg_type to more accurately describe the fairly specific expectations that this arg type encodes. This is a nonfunctional change. Acked-by: Martin KaFai Lau <martin.lau@kernel.org> Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com> Signed-off-by: Amery Hung <amery.hung@bytedance.com> Link: https://lore.kernel.org/r/20240813212424.2871455-4-amery.hung@bytedance.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-23bpf: Search for kptrs in prog BTF structsDave Marchevsky
Currently btf_parse_fields is used in two places to create struct btf_record's for structs: when looking at mapval type, and when looking at any struct in program BTF. The former looks for kptr fields while the latter does not. This patch modifies the btf_parse_fields call made when looking at prog BTF struct types to search for kptrs as well. Before this series there was no reason to search for kptrs in non-mapval types: a referenced kptr needs some owner to guarantee resource cleanup, and map values were the only owner that supported this. If a struct with a kptr field were to have some non-kptr-aware owner, the kptr field might not be properly cleaned up and result in resources leaking. Only searching for kptr fields in mapval was a simple way to avoid this problem. In practice, though, searching for BPF_KPTR when populating struct_meta_tab does not expose us to this risk, as struct_meta_tab is only accessed through btf_find_struct_meta helper, and that helper is only called in contexts where recognizing the kptr field is safe: * PTR_TO_BTF_ID reg w/ MEM_ALLOC flag * Such a reg is a local kptr and must be free'd via bpf_obj_drop, which will correctly handle kptr field * When handling specific kfuncs which either expect MEM_ALLOC input or return MEM_ALLOC output (obj_{new,drop}, percpu_obj_{new,drop}, list+rbtree funcs, refcount_acquire) * Will correctly handle kptr field for same reasons as above * When looking at kptr pointee type * Called by functions which implement "correct kptr resource handling" * In btf_check_and_fixup_fields * Helper that ensures no ownership loops for lists and rbtrees, doesn't care about kptr field existence So we should be able to find BPF_KPTR fields in all prog BTF structs without leaking resources. Further patches in the series will build on this change to support kptr_xchg into non-mapval local kptr. Without this change there would be no kptr field found in such a type. Acked-by: Martin KaFai Lau <martin.lau@kernel.org> Acked-by: Hou Tao <houtao1@huawei.com> Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com> Signed-off-by: Amery Hung <amery.hung@bytedance.com> Link: https://lore.kernel.org/r/20240813212424.2871455-3-amery.hung@bytedance.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-23bpf: Let callers of btf_parse_kptr() track life cycle of prog btfAmery Hung
btf_parse_kptr() and btf_record_free() do btf_get() and btf_put() respectively when working on btf_record in program and map if there are kptr fields. If the kptr is from program BTF, since both callers has already tracked the life cycle of program BTF, it is safe to remove the btf_get() and btf_put(). This change prevents memory leak of program BTF later when we start searching for kptr fields when building btf_record for program. It can happen when the btf fd is closed. The btf_put() corresponding to the btf_get() in btf_parse_kptr() was supposed to be called by btf_record_free() in btf_free_struct_meta_tab() in btf_free(). However, it will never happen since the invocation of btf_free() depends on the refcount of the btf to become 0 in the first place. Acked-by: Martin KaFai Lau <martin.lau@kernel.org> Acked-by: Hou Tao <houtao1@huawei.com> Signed-off-by: Amery Hung <amery.hung@bytedance.com> Link: https://lore.kernel.org/r/20240813212424.2871455-2-amery.hung@bytedance.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-23selftests/bpf: add multi-uprobe benchmarksAndrii Nakryiko
Add multi-uprobe and multi-uretprobe benchmarks to bench tool. Multi- and classic uprobes/uretprobes have different low-level triggering code paths, so it's sometimes important to be able to benchmark both flavors of uprobes/uretprobes. Sample examples from my dev machine below. Single-threaded peformance almost doesn't differ, but with more parallel CPUs triggering the same uprobe/uretprobe the difference grows. This might be due to [0], but given the code is slightly different, there could be other sources of slowdown. Note, all these numbers will change due to ongoing work to improve uprobe/uretprobe scalability (e.g., [1]), but having benchmark like this is useful for measurements and debugging nevertheless. \#!/bin/bash set -eufo pipefail for p in 1 8 16 32; do for i in uprobe-nop uretprobe-nop uprobe-multi-nop uretprobe-multi-nop; do summary=$(sudo ./bench -w1 -d3 -p$p -a trig-$i | tail -n1) total=$(echo "$summary" | cut -d'(' -f1 | cut -d' ' -f3-) percpu=$(echo "$summary" | cut -d'(' -f2 | cut -d')' -f1 | cut -d'/' -f1) printf "%-21s (%2d cpus): %s (%s/s/cpu)\n" $i $p "$total" "$percpu" done echo done uprobe-nop ( 1 cpus): 1.020 ± 0.005M/s ( 1.020M/s/cpu) uretprobe-nop ( 1 cpus): 0.515 ± 0.009M/s ( 0.515M/s/cpu) uprobe-multi-nop ( 1 cpus): 1.036 ± 0.004M/s ( 1.036M/s/cpu) uretprobe-multi-nop ( 1 cpus): 0.512 ± 0.005M/s ( 0.512M/s/cpu) uprobe-nop ( 8 cpus): 3.481 ± 0.030M/s ( 0.435M/s/cpu) uretprobe-nop ( 8 cpus): 2.222 ± 0.008M/s ( 0.278M/s/cpu) uprobe-multi-nop ( 8 cpus): 3.769 ± 0.094M/s ( 0.471M/s/cpu) uretprobe-multi-nop ( 8 cpus): 2.482 ± 0.007M/s ( 0.310M/s/cpu) uprobe-nop (16 cpus): 2.968 ± 0.011M/s ( 0.185M/s/cpu) uretprobe-nop (16 cpus): 1.870 ± 0.002M/s ( 0.117M/s/cpu) uprobe-multi-nop (16 cpus): 3.541 ± 0.037M/s ( 0.221M/s/cpu) uretprobe-multi-nop (16 cpus): 2.123 ± 0.026M/s ( 0.133M/s/cpu) uprobe-nop (32 cpus): 2.524 ± 0.026M/s ( 0.079M/s/cpu) uretprobe-nop (32 cpus): 1.572 ± 0.003M/s ( 0.049M/s/cpu) uprobe-multi-nop (32 cpus): 2.717 ± 0.003M/s ( 0.085M/s/cpu) uretprobe-multi-nop (32 cpus): 1.687 ± 0.007M/s ( 0.053M/s/cpu) [0] https://lore.kernel.org/linux-trace-kernel/20240805202803.1813090-1-andrii@kernel.org/ [1] https://lore.kernel.org/linux-trace-kernel/20240731214256.3588718-1-andrii@kernel.org/ Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20240806042935.3867862-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-23selftests/bpf: make use of PROCMAP_QUERY ioctl if availableAndrii Nakryiko
Instead of parsing text-based /proc/<pid>/maps file, try to use PROCMAP_QUERY ioctl() to simplify and speed up data fetching. This logic is used to do uprobe file offset calculation, so any bugs in this logic would manifest as failing uprobe BPF selftests. This also serves as a simple demonstration of one of the intended uses. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20240806230319.869734-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-23Merge branch 'follow-up-for-__jited-test-tag'Alexei Starovoitov
Eduard Zingerman says: ==================== follow up for __jited test tag This patch-set is a collection of follow-ups for "__jited test tag to check disassembly after jit" series (see [1]). First patch is most important: as it turns out, I broke all test_loader based tests for s390 CI. E.g. see log [2] for s390 execution of test_progs, note all 'verivier_*' tests being skipped. This happens because of incorrect handling of corner case when get_current_arch() does not know which architecture to return. Second patch makes matching of function return sequence in verifier_tailcall_jit more flexible: -__jited(" retq") +__jited(" {{(retq|jmp 0x)}}") The difference could be seen with and w/o mitigations=off boot parameter for test VM (CI runs with mitigations=off, hence it generates retq). Third patch addresses Alexei's request to add #define and a comment in jit_disasm_helpers.c. [1] https://lore.kernel.org/bpf/20240820102357.3372779-1-eddyz87@gmail.com/ [2] https://github.com/kernel-patches/bpf/actions/runs/10518445973/job/29144511595 ==================== Link: https://lore.kernel.org/r/20240823080644.263943-1-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-23selftests/bpf: #define LOCAL_LABEL_LEN for jit_disasm_helpers.cEduard Zingerman
Extract local label length as a #define directive and elaborate why 'i % MAX_LOCAL_LABELS' expression is needed for local labels array initialization. Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240823080644.263943-4-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-23selftests/bpf: match both retq/rethunk in verifier_tailcall_jitEduard Zingerman
Depending on kernel parameters, x86 jit generates either retq or jump to rethunk for 'exit' instruction. The difference could be seen when kernel is booted with and without mitigations=off parameter. Relax the verifier_tailcall_jit test case to match both variants. Fixes: e5bdd6a8be78 ("selftests/bpf: validate jit behaviour for tail calls") Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240823080644.263943-3-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-23selftests/bpf: test_loader.c:get_current_arch() should not return 0Eduard Zingerman
At the moment, when test_loader.c:get_current_arch() can't determine the arch, it returns 0. The arch check in run_subtest() looks as follows: if ((get_current_arch() & spec->arch_mask) == 0) { test__skip(); return; } Which means that all test_loader based tests would be skipped if arch could not be determined. get_current_arch() recognizes x86_64, arm64 and riscv64. Which means that CI skips test_loader tests for s390. Fix this by making sure that get_current_arch() always returns non-zero value. In combination with default spec->arch_mask == -1 this should cover all possibilities. Fixes: f406026fefa7 ("selftests/bpf: by default use arch mask allowing all archs") Fixes: 7d743e4c759c ("selftests/bpf: __jited test tag to check disassembly after jit") Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240823080644.263943-2-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22selftests/bpf: Add testcase for updating attached freplace prog to ↵Leon Hwang
prog_array map Add a selftest to confirm the issue, which gets -EINVAL when update attached freplace prog to prog_array map, has been fixed. cd tools/testing/selftests/bpf; ./test_progs -t tailcalls 328/25 tailcalls/tailcall_freplace:OK 328 tailcalls:OK Summary: 1/25 PASSED, 0 SKIPPED, 0 FAILED Acked-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Leon Hwang <leon.hwang@linux.dev> Link: https://lore.kernel.org/r/20240728114612.48486-3-leon.hwang@linux.dev Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpfAlexei Starovoitov
Cross-merge bpf fixes after downstream PR including important fixes (from bpf-next point of view): commit 41c24102af7b ("selftests/bpf: Filter out _GNU_SOURCE when compiling test_cpp") commit fdad456cbcca ("bpf: Fix updating attached freplace prog in prog_array map") No conflicts. Adjacent changes in: include/linux/bpf_verifier.h kernel/bpf/verifier.c tools/testing/selftests/bpf/Makefile Link: https://lore.kernel.org/bpf/20240813234307.82773-1-alexei.starovoitov@gmail.com/ Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22Merge branch 'support-bpf_fastcall-patterns-for-calls-to-kfuncs'Alexei Starovoitov
Eduard Zingerman says: ==================== support bpf_fastcall patterns for calls to kfuncs As an extension of [1], allow bpf_fastcall patterns for kfuncs: - pattern rules are the same as for helpers; - spill/fill removal is allowed only for kfuncs listed in the is_fastcall_kfunc_call (under assumption that such kfuncs would always be members of special_kfunc_list). Allow bpf_fastcall rewrite for bpf_cast_to_kern_ctx() and bpf_rdonly_cast() in order to conjure selftests for this feature. After this patch-set verifier would rewrite the program below: r2 = 1 *(u64 *)(r10 - 32) = r2 call %[bpf_cast_to_kern_ctx] r2 = *(u64 *)(r10 - 32) r0 = r2;" As follows: r2 = 1 /* spill/fill at r10[-32] is removed */ r0 = r1 /* replacement for bpf_cast_to_kern_ctx() */ r0 = r2 exit Also, attribute used by LLVM implementation of the feature had been changed from no_caller_saved_registers to bpf_fastcall (see [2]). This patch-set replaces references to nocsr by references to bpf_fastcall to keep LLVM and Kernel parts in sync. [1] no_caller_saved_registers attribute for helper calls https://lore.kernel.org/bpf/20240722233844.1406874-1-eddyz87@gmail.com/ [2] [BPF] introduce __attribute__((bpf_fastcall)) https://github.com/llvm/llvm-project/pull/105417 Changes v2->v3: - added a patch fixing arch_mask handling in test_loader, otherwise newly added tests for the feature were skipped (a fix for regression introduced by a recent commit); - fixed warning regarding unused 'params' variable; - applied stylistical fixes suggested by Yonghong; - added acks from Yonghong; Changes v1->v2: - added two patches replacing all mentions of nocsr by bpf_fastcall (suggested by Andrii); - removed KF_NOCSR flag (suggested by Yonghong). v1: https://lore.kernel.org/bpf/20240812234356.2089263-1-eddyz87@gmail.com/ v2: https://lore.kernel.org/bpf/20240817015140.1039351-1-eddyz87@gmail.com/ ==================== Link: https://lore.kernel.org/r/20240822084112.3257995-1-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22selftests/bpf: check if bpf_fastcall is recognized for kfuncsEduard Zingerman
Use kfunc_bpf_cast_to_kern_ctx() and kfunc_bpf_rdonly_cast() to verify that bpf_fastcall pattern is recognized for kfunc calls. Acked-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240822084112.3257995-7-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22selftests/bpf: by default use arch mask allowing all archsEduard Zingerman
If test case does not specify architecture via __arch_* macro consider that it should be run for all architectures. Fixes: 7d743e4c759c ("selftests/bpf: __jited test tag to check disassembly after jit") Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240822084112.3257995-6-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22bpf: allow bpf_fastcall for bpf_cast_to_kern_ctx and bpf_rdonly_castEduard Zingerman
do_misc_fixups() relaces bpf_cast_to_kern_ctx() and bpf_rdonly_cast() by a single instruction "r0 = r1". This follows bpf_fastcall contract. This commit allows bpf_fastcall pattern rewrite for these two functions in order to use them in bpf_fastcall selftests. Acked-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240822084112.3257995-5-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22bpf: support bpf_fastcall patterns for kfuncsEduard Zingerman
Recognize bpf_fastcall patterns around kfunc calls. For example, suppose bpf_cast_to_kern_ctx() follows bpf_fastcall contract (which it does), in such a case allow verifier to rewrite BPF program below: r2 = 1; *(u64 *)(r10 - 32) = r2; call %[bpf_cast_to_kern_ctx]; r2 = *(u64 *)(r10 - 32); r0 = r2; By removing the spill/fill pair: r2 = 1; call %[bpf_cast_to_kern_ctx]; r0 = r2; Acked-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240822084112.3257995-4-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22selftests/bpf: rename nocsr -> bpf_fastcall in selftestsEduard Zingerman
Attribute used by LLVM implementation of the feature had been changed from no_caller_saved_registers to bpf_fastcall (see [1]). This commit replaces references to nocsr by references to bpf_fastcall to keep LLVM and selftests parts in sync. [1] https://github.com/llvm/llvm-project/pull/105417 Acked-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240822084112.3257995-3-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22bpf: rename nocsr -> bpf_fastcall in verifierEduard Zingerman
Attribute used by LLVM implementation of the feature had been changed from no_caller_saved_registers to bpf_fastcall (see [1]). This commit replaces references to nocsr by references to bpf_fastcall to keep LLVM and Kernel parts in sync. [1] https://github.com/llvm/llvm-project/pull/105417 Acked-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240822084112.3257995-2-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22bpf: Fix percpu address space issuesUros Bizjak
In arraymap.c: In bpf_array_map_seq_start() and bpf_array_map_seq_next() cast return values from the __percpu address space to the generic address space via uintptr_t [1]. Correct the declaration of pptr pointer in __bpf_array_map_seq_show() to void __percpu * and cast the value from the generic address space to the __percpu address space via uintptr_t [1]. In hashtab.c: Assign the return value from bpf_mem_cache_alloc() to void pointer and cast the value to void __percpu ** (void pointer to percpu void pointer) before dereferencing. In memalloc.c: Explicitly declare __percpu variables. Cast obj to void __percpu **. In helpers.c: Cast ptr in BPF_CALL_1 and BPF_CALL_2 from generic address space to __percpu address space via const uintptr_t [1]. Found by GCC's named address space checks. There were no changes in the resulting object files. [1] https://sparse.docs.kernel.org/en/latest/annotations.html#address-space-name Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Martin KaFai Lau <martin.lau@linux.dev> Cc: Eduard Zingerman <eddyz87@gmail.com> Cc: Song Liu <song@kernel.org> Cc: Yonghong Song <yonghong.song@linux.dev> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Stanislav Fomichev <sdf@fomichev.me> Cc: Hao Luo <haoluo@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240811161414.56744-1-ubizjak@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22Merge branch ↵Alexei Starovoitov
'bpf-fix-null-pointer-access-for-malformed-bpf_core_type_id_local-relos' Eduard Zingerman says: ==================== bpf: fix null pointer access for malformed BPF_CORE_TYPE_ID_LOCAL relos Liu RuiTong reported an in-kernel null pointer derefence when processing BPF_CORE_TYPE_ID_LOCAL relocations referencing non-existing BTF types. Fix this by adding proper id checks. Changes v2->v3: - selftest update suggested by Andrii: avoid memset(0) for log buffer and do memset(0) for bpf_attr. Changes v1->v2: - moved check from bpf_core_calc_relo_insn() to bpf_core_apply() now both in kernel and in libbpf relocation type id is guaranteed to exist when bpf_core_calc_relo_insn() is called; - added a test case. v1: https://lore.kernel.org/bpf/20240821164620.1056362-1-eddyz87@gmail.com/ v2: https://lore.kernel.org/bpf/20240822001837.2715909-1-eddyz87@gmail.com/ ==================== Link: https://lore.kernel.org/r/20240822080124.2995724-1-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22selftests/bpf: test for malformed BPF_CORE_TYPE_ID_LOCAL relocationEduard Zingerman
Check that verifier rejects BPF program containing relocation pointing to non-existent BTF type. To force relocation resolution on kernel side test case uses bpf_attr->core_relos field. This field is not exposed by libbpf, so directly do BPF system call in the test. Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240822080124.2995724-3-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22bpf: correctly handle malformed BPF_CORE_TYPE_ID_LOCAL relosEduard Zingerman
In case of malformed relocation record of kind BPF_CORE_TYPE_ID_LOCAL referencing a non-existing BTF type, function bpf_core_calc_relo_insn would cause a null pointer deference. Fix this by adding a proper check upper in call stack, as malformed relocation records could be passed from user space. Simplest reproducer is a program: r0 = 0 exit With a single relocation record: .insn_off = 0, /* patch first instruction */ .type_id = 100500, /* this type id does not exist */ .access_str_off = 6, /* offset of string "0" */ .kind = BPF_CORE_TYPE_ID_LOCAL, See the link for original reproducer or next commit for a test case. Fixes: 74753e1462e7 ("libbpf: Replace btf__type_by_id() with btf_type_by_id().") Reported-by: Liu RuiTong <cnitlrt@gmail.com> Closes: https://lore.kernel.org/bpf/CAK55_s6do7C+DVwbwY_7nKfUz0YLDoiA1v6X3Y9+p0sWzipFSA@mail.gmail.com/ Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240822080124.2995724-2-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-22bpf: Use kmemdup_array instead of kmemdup for multiple allocationYu Jiaoliang
Let the kmemdup_array() take care about multiplication and possible overflows. Signed-off-by: Yu Jiaoliang <yujiaoliang@vivo.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240821073709.4067177-1-yujiaoliang@vivo.com
2024-08-22Merge tag 'platform-drivers-x86-v6.11-4' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86 Pull x86 platform driver fixes from Ilpo Järvinen: - ISST: Fix an error-handling corner case - platform/surface: aggregator: Minor corner case fix and new HW support * tag 'platform-drivers-x86-v6.11-4' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86: platform/x86: ISST: Fix return value on last invalid resource platform/surface: aggregator: Fix warning when controller is destroyed in probe platform/surface: aggregator_registry: Add support for Surface Laptop 6 platform/surface: aggregator_registry: Add fan and thermal sensor support for Surface Laptop 5 platform/surface: aggregator_registry: Add support for Surface Laptop Studio 2 platform/surface: aggregator_registry: Add support for Surface Laptop Go 3 platform/surface: aggregator_registry: Add Support for Surface Pro 10 platform/x86: asus-wmi: Add quirk for ROG Ally X
2024-08-22Merge tag 'erofs-for-6.11-rc5-fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs Pull erofs fixes from Gao Xiang: "As I mentioned in the merge window pull request, there is a regression which could cause system hang due to page migration. The corresponding fix landed upstream through MM tree last week (commit 2e6506e1c4ee: "mm/migrate: fix deadlock in migrate_pages_batch() on large folios"), therefore large folios can be safely allowed for compressed inodes and stress tests have been running on my fleet for over 20 days without any regression. Users have explicitly requested this for months, so let's allow large folios for EROFS full cases now for wider testing. Additionally, there is a fix which addresses invalid memory accesses on a failure path triggered by fault injection and two minor cleanups to simplify the codebase. Summary: - Allow large folios on compressed inodes - Fix invalid memory accesses if z_erofs_gbuf_growsize() partially fails - Two minor cleanups" * tag 'erofs-for-6.11-rc5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs: erofs: fix out-of-bound access when z_erofs_gbuf_growsize() partially fails erofs: allow large folios for compressed files erofs: get rid of check_layout_compatibility() erofs: simplify readdir operation
2024-08-21Merge branch '__jited-test-tag-to-check-disassembly-after-jit'Alexei Starovoitov
Eduard Zingerman says: ==================== __jited test tag to check disassembly after jit Some of the logic in the BPF jits might be non-trivial. It might be useful to allow testing this logic by comparing generated native code with expected code template. This patch set adds a macro __jited() that could be used for test_loader based tests in a following manner: SEC("tp") __arch_x86_64 __jited(" endbr64") __jited(" nopl (%rax,%rax)") __jited(" xorq %rax, %rax") ... __naked void some_test(void) { ... } Also add a test for jit code generated for tail calls handling to demonstrate the feature. The feature uses LLVM libraries to do the disassembly. At selftests compilation time Makefile detects if these libraries are available. When libraries are not available tests using __jit_x86() are skipped. Current CI environment does not include llvm development libraries, but changes to add these are trivial. This was previously discussed here: https://lore.kernel.org/bpf/20240718205158.3651529-1-yonghong.song@linux.dev/ Patch-set includes a few auxiliary steps: - patches #2 and #3 fix a few bugs in test_loader behaviour; - patch #4 replaces __regex macro with ability to specify regular expressions in __msg and __xlated using "{{" "}}" escapes; - patch #8 updates __xlated to match disassembly lines consequently, same way as __jited does. Changes v2->v3: - changed macro name from __jit_x86 to __jited with __arch_* to specify disassembly arch (Yonghong); - __jited matches disassembly lines consequently with "..." allowing to skip some number of lines (Andrii); - __xlated matches disassembly lines consequently, same as __jited; - "{{...}}" regex brackets instead of __regex macro; - bug fixes for old commits. Changes v1->v2: - stylistic changes suggested by Yonghong; - fix for -Wformat-truncation related warning when compiled with llvm15 (Yonghong). v1: https://lore.kernel.org/bpf/20240809010518.1137758-1-eddyz87@gmail.com/ v2: https://lore.kernel.org/bpf/20240815205449.242556-1-eddyz87@gmail.com/ ==================== Link: https://lore.kernel.org/r/20240820102357.3372779-1-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21selftests/bpf: validate __xlated same way as __jitedEduard Zingerman
Both __xlated and __jited work with disassembly. It is logical to have both work in a similar manner. This commit updates __xlated macro handling in test_loader.c by making it expect matches on sequential lines, same way as __jited operates. For example: __xlated("1: *(u64 *)(r10 -16) = r1") ;; matched on line N __xlated("3: r0 = &(void __percpu *)(r0)") ;; matched on line N+1 Also: __xlated("1: *(u64 *)(r10 -16) = r1") ;; matched on line N __xlated("...") ;; not matched __xlated("3: r0 = &(void __percpu *)(r0)") ;; mantched on any ;; line >= N Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240820102357.3372779-10-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21selftests/bpf: validate jit behaviour for tail callsEduard Zingerman
A program calling sub-program which does a tail call. The idea is to verify instructions generated by jit for tail calls: - in program and sub-program prologues; - for subprogram call instruction; - for tail call itself. Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240820102357.3372779-9-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21selftests/bpf: __jited test tag to check disassembly after jitEduard Zingerman
Allow to verify jit behaviour by writing tests as below: SEC("tp") __arch_x86_64 __jited(" endbr64") __jited(" nopl (%rax,%rax)") __jited(" xorq %rax, %rax") ... __naked void some_test(void) { asm volatile (... ::: __clobber_all); } Allow regular expressions in patterns, same way as in __msg. By default assume that each __jited pattern has to be matched on the next consecutive line of the disassembly, e.g.: __jited(" endbr64") # matched on line N __jited(" nopl (%rax,%rax)") # matched on line N+1 If match occurs on a wrong line an error is reported. To override this behaviour use __jited("..."), e.g.: __jited(" endbr64") # matched on line N __jited("...") # not matched __jited(" nopl (%rax,%rax)") # matched on any line >= N Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240820102357.3372779-7-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21selftests/bpf: utility function to get program disassembly after jitEduard Zingerman
This commit adds a utility function to get disassembled text for jited representation of a BPF program designated by file descriptor. Function prototype looks as follows: int get_jited_program_text(int fd, char *text, size_t text_sz) Where 'fd' is a file descriptor for the program, 'text' and 'text_sz' refer to a destination buffer for disassembled text. Output format looks as follows: 18: 77 06 ja L0 1a: 50 pushq %rax 1b: 48 89 e0 movq %rsp, %rax 1e: eb 01 jmp L1 20: 50 L0: pushq %rax 21: 50 L1: pushq %rax ^ ^^^^^^^^ ^ ^^^^^^^^^^^^^^^^^^ | binary insn | textual insn | representation | representation | | instruction offset inferred local label name The code and makefile changes are inspired by jit_disasm.c from bpftool. Use llvm libraries to disassemble BPF program instead of libbfd to avoid issues with disassembly output stability pointed out in [1]. Selftests makefile uses Makefile.feature to detect if LLVM libraries are available. If that is not the case selftests build proceeds but the function returns -EOPNOTSUPP at runtime. [1] commit eb9d1acf634b ("bpftool: Add LLVM as default library for disassembling JIT-ed programs") Acked-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240820102357.3372779-6-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21selftests/bpf: replace __regex macro with "{{...}}" patternsEduard Zingerman
Upcoming changes require a notation to specify regular expression matches for regular verifier log messages, disassembly of BPF instructions, disassembly of jited instructions. Neither basic nor extended POSIX regular expressions w/o additional escaping are good for this role because of wide use of special characters in disassembly, for example: movq -0x10(%rbp), %rax ;; () are special characters cmpq $0x21, %rax ;; $ is a special character *(u64 *)(r10 -16) = r1 ;; * and () are special characters This commit borrows syntax from LLVM's FileCheck utility. It replaces __regex macro with ability to embed regular expressions in __msg patters using "{{" "}}" pairs for escaping. Syntax for __msg patterns: pattern := (<verbatim text> | regex)* regex := "{{" <posix extended regular expression> "}}" For example, pattern "foo{{[0-9]+}}" matches strings like "foo0", "foo007", etc. Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240820102357.3372779-5-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21selftests/bpf: fix to avoid __msg tag de-duplication by clangEduard Zingerman
__msg, __regex and __xlated tags are based on __attribute__((btf_decl_tag("..."))) annotations. Clang de-duplicates such annotations, e.g. the following two sequences of tags are identical in final BTF: /* seq A */ /* seq B */ __tag("foo") __tag("foo") __tag("bar") __tag("bar") __tag("foo") Fix this by adding a unique suffix for each tag using __COUNTER__ pre-processor macro. E.g. here is a new definition for __msg: #define __msg(msg) \ __attribute__((btf_decl_tag("comment:test_expect_msg=" XSTR(__COUNTER__) "=" msg))) Using this definition the "seq A" from example above is translated to BTF as follows: [..] DECL_TAG 'comment:test_expect_msg=0=foo' type_id=X component_idx=-1 [..] DECL_TAG 'comment:test_expect_msg=1=bar' type_id=X component_idx=-1 [..] DECL_TAG 'comment:test_expect_msg=2=foo' type_id=X component_idx=-1 Surprisingly, this bug affects a single existing test: verifier_spill_fill/old_stack_misc_vs_cur_ctx_ptr, where sequence of identical messages was expected in the log. Fixes: 537c3f66eac1 ("selftests/bpf: add generic BPF program tester-loader") Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240820102357.3372779-4-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21selftests/bpf: correctly move 'log' upon successful matchEduard Zingerman
Suppose log="foo bar buz" and msg->substr="bar". In such case current match processing logic would update 'log' as follows: log += strlen(msg->substr); -> log += 3 -> log=" bar". However, the intent behind the 'log' update is to make it point after the successful match, e.g. to make log=" buz" in the example above. Fixes: 4ef5d6af4935 ("selftests/bpf: no need to track next_match_pos in struct test_loader") Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240820102357.3372779-3-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21selftests/bpf: less spam in the log for message matchingEduard Zingerman
When running test_loader based tests in the verbose mode each matched message leaves a trace in the stderr, e.g.: ./test_progs -vvv -t ... validate_msgs:PASS:expect_msg 0 nsec validate_msgs:PASS:expect_msg 0 nsec validate_msgs:PASS:expect_msg 0 nsec validate_msgs:PASS:expect_msg 0 nsec validate_msgs:PASS:expect_msg 0 nsec This is not very helpful when debugging such tests and clobbers the log a lot. Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240820102357.3372779-2-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21Merge branch 'support-passing-bpf-iterator-to-kfuncs'Alexei Starovoitov
Andrii Nakryiko says: ==================== Support passing BPF iterator to kfuncs Add support for passing BPF iterator state to any kfunc. Such kfunc has to declare such argument with valid `struct bpf_iter_<type> *` type and should use "__iter" suffix in argument name, following the established suffix-based convention. We add a simple test/demo iterator getter in bpf_testmod. ==================== Link: https://lore.kernel.org/r/20240808232230.2848712-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21selftests/bpf: test passing iterator to a kfuncAndrii Nakryiko
Define BPF iterator "getter" kfunc, which accepts iterator pointer as one of the arguments. Make sure that argument passed doesn't have to be the very first argument (unlike new-next-destroy combo). Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20240808232230.2848712-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21bpf: allow passing struct bpf_iter_<type> as kfunc argumentsAndrii Nakryiko
There are potentially useful cases where a specific iterator type might need to be passed into some kfunc. So, in addition to existing bpf_iter_<type>_{new,next,destroy}() kfuncs, allow to pass iterator pointer to any kfunc. We employ "__iter" naming suffix for arguments that are meant to accept iterators. We also enforce that they accept PTR -> STRUCT btf_iter_<type> type chain and point to a valid initialized on-the-stack iterator state. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20240808232230.2848712-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-21bpf: extract iterator argument type and name validation logicAndrii Nakryiko
Verifier enforces that all iterator structs are named `bpf_iter_<name>` and that whenever iterator is passed to a kfunc it's passed as a valid PTR -> STRUCT chain (with potentially const modifiers in between). We'll need this check for upcoming changes, so instead of duplicating the logic, extract it into a helper function. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240808232230.2848712-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-08-20Merge tag '6.11-rc4-server-fixes' of git://git.samba.org/ksmbdLinus Torvalds
Pull smb server fixes from Steve French: - important reconnect fix - fix for memcpy issues on mount - two minor cleanup patches * tag '6.11-rc4-server-fixes' of git://git.samba.org/ksmbd: ksmbd: Replace one-element arrays with flexible-array members ksmbd: fix spelling mistakes in documentation ksmbd: fix race condition between destroy_previous_session() and smb2 operations() ksmbd: Use unsafe_memcpy() for ntlm_negotiate
2024-08-21erofs: fix out-of-bound access when z_erofs_gbuf_growsize() partially failsGao Xiang
If z_erofs_gbuf_growsize() partially fails on a global buffer due to memory allocation failure or fault injection (as reported by syzbot [1]), new pages need to be freed by comparing to the existing pages to avoid memory leaks. However, the old gbuf->pages[] array may not be large enough, which can lead to null-ptr-deref or out-of-bound access. Fix this by checking against gbuf->nrpages in advance. [1] https://lore.kernel.org/r/000000000000f7b96e062018c6e3@google.com Reported-by: syzbot+242ee56aaa9585553766@syzkaller.appspotmail.com Fixes: d6db47e571dc ("erofs: do not use pagepool in z_erofs_gbuf_growsize()") Cc: <stable@vger.kernel.org> # 6.10+ Reviewed-by: Chunhai Guo <guochunhai@vivo.com> Reviewed-by: Sandeep Dhavale <dhavale@google.com> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com> Link: https://lore.kernel.org/r/20240820085619.1375963-1-hsiangkao@linux.alibaba.com
2024-08-20Merge tag 'for-linus-iommufd' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd Pull iommufd fixes from Jason Gunthorpe: - Incorrect error unwind in iommufd_device_do_replace() - Correct a sparse warning missing static * tag 'for-linus-iommufd' of git://git.kernel.org/pub/scm/linux/kernel/git/jgg/iommufd: iommufd/selftest: Make dirty_ops static iommufd/device: Fix hwpt at err_unresv in iommufd_device_do_replace()
2024-08-20Merge tag 'cxl-fixes-6.11-rc5' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl Pull cxl fixes from Dave Jiang: "Check for RCH dport before accessing pci_host_bridge and a fix to address a KASAN warning for the cxl regression test suite cxl-test" * tag 'cxl-fixes-6.11-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: cxl/test: Skip cxl_setup_parent_dport() for emulated dports cxl/pci: Get AER capability address from RCRB only for RCH dport
2024-08-20platform/x86: ISST: Fix return value on last invalid resourceSrinivas Pandruvada
When only the last resource is invalid, tpmi_sst_dev_add() is returing error even if there are other valid resources before. This function should return error when there are no valid resources. Here tpmi_sst_dev_add() is returning "ret" variable. But this "ret" variable contains the failure status of last call to sst_main(), which failed for the invalid resource. But there may be other valid resources before the last entry. To address this, do not update "ret" variable for sst_main() return status. If there are no valid resources, it is already checked for by !inst below the loop and -ENODEV is returned. Fixes: 9d1d36268f3d ("platform/x86: ISST: Support partitioned systems") Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Cc: stable@vger.kernel.org # 6.10+ Link: https://lore.kernel.org/r/20240816163626.415762-1-srinivas.pandruvada@linux.intel.com Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
2024-08-19Merge branch 'correct-recent-gcc-incompatible-changes'Andrii Nakryiko
Cupertino Miranda says: ==================== Correct recent GCC incompatible changes. Hi everyone, Apologies for the previous patches which did not include a cover letter. My wish was to send 3 indepepdent patches but after the initial mistake lets keep this as a series although they are all independent from themselves. The changes in this patch series is related to recovering GCC support to build the selftests. A few tests and a makefile change have broken the support for GCC in the last few months. Looking forward to your comments. Best regards, Cupertino ==================== Link: https://lore.kernel.org/r/20240819151129.1366484-1-cupertino.miranda@oracle.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-08-19selftest/bpf: Adapt inline asm operand constraint for GCC supportCupertino Miranda
GCC errors when compiling tailcall_bpf2bpf_hierarchy2.c and tailcall_bpf2bpf_hierarchy3.c with the following error: progs/tailcall_bpf2bpf_hierarchy2.c: In function 'tailcall_bpf2bpf_hierarchy_2': progs/tailcall_bpf2bpf_hierarchy2.c:66:9: error: input operand constraint contains '+' 66 | asm volatile (""::"r+"(ret)); | ^~~ Changed implementation to make use of __sink macro that abstracts the desired behaviour. The proposed change seems valid for both GCC and CLANG. Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240819151129.1366484-4-cupertino.miranda@oracle.com
2024-08-19selftests/bpf: Disable strict aliasing for verifier_nocsr.cCupertino Miranda
verfifier_nocsr.c fails to compile in GCC. The reason behind it was initially explained in commit 27a90b14b93d3b2e1efd10764e456af7e2a42991. "A few BPF selftests perform type punning and they may break strict aliasing rules, which are exploited by both GCC and clang by default while optimizing. This can lead to broken compiled programs." Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240819151129.1366484-2-cupertino.miranda@oracle.com
2024-08-19Merge branch 'bpf-enable-some-functions-in-cgroup-programs'Andrii Nakryiko
Matteo Croce says: ==================== bpf: enable some functions in cgroup programs From: Matteo Croce <teknoraver@meta.com> Enable some BPF kfuncs and the helper bpf_current_task_under_cgroup() for program types BPF_CGROUP_*. These will be used by systemd-networkd: https://github.com/systemd/systemd/pull/32212 v5->v6: Called register_btf_kfunc_id_set() only once Fixed build error with !CONFIG_CGROUPS v4->v5: Same code, but v4 had an old cover letter v3->v4: Reset all the acked-by tags because the code changed a bit. Signed-off-by: Matteo Croce <teknoraver@meta.com> ==================== Link: https://lore.kernel.org/r/20240819162805.78235-1-technoboy85@gmail.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-08-19bpf: Allow bpf_current_task_under_cgroup() with BPF_CGROUP_*Matteo Croce
The helper bpf_current_task_under_cgroup() currently is only allowed for tracing programs, allow its usage also in the BPF_CGROUP_* program types. Move the code from kernel/trace/bpf_trace.c to kernel/bpf/helpers.c, so it compiles also without CONFIG_BPF_EVENTS. This will be used in systemd-networkd to monitor the sysctl writes, and filter it's own writes from others: https://github.com/systemd/systemd/pull/32212 Signed-off-by: Matteo Croce <teknoraver@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240819162805.78235-3-technoboy85@gmail.com
2024-08-19bpf: Enable generic kfuncs for BPF_CGROUP_* programsMatteo Croce
These kfuncs are enabled even in BPF_PROG_TYPE_TRACING, so they should be safe also in BPF_CGROUP_* programs. Since all BPF_CGROUP_* programs share the same hook, call register_btf_kfunc_id_set() only once. In enum btf_kfunc_hook, rename BTF_KFUNC_HOOK_CGROUP_SKB to a more generic BTF_KFUNC_HOOK_CGROUP, since it's used for all the cgroup related program types. Signed-off-by: Matteo Croce <teknoraver@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240819162805.78235-2-technoboy85@gmail.com