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2024-07-01riscv, bpf: Use bpf_prog_pack for RV64 bpf trampolinePu Lehui
We used bpf_prog_pack to aggregate bpf programs into huge page to relieve the iTLB pressure on the system. We can apply it to bpf trampoline, as Song had been implemented it in core and x86 [0]. This patch is going to use bpf_prog_pack to RV64 bpf trampoline. Since Song and Puranjay have done a lot of work for bpf_prog_pack on RV64, implementing this function will be easy. Signed-off-by: Pu Lehui <pulehui@huawei.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Björn Töpel <bjorn@rivosinc.com> #riscv Link: https://lore.kernel.org/all/20231206224054.492250-1-song@kernel.org [0] Link: https://lore.kernel.org/bpf/20240622030437.3973492-4-pulehui@huaweicloud.com
2024-07-01riscv, bpf: Fix out-of-bounds issue when preparing trampoline imagePu Lehui
We get the size of the trampoline image during the dry run phase and allocate memory based on that size. The allocated image will then be populated with instructions during the real patch phase. But after commit 26ef208c209a ("bpf: Use arch_bpf_trampoline_size"), the `im` argument is inconsistent in the dry run and real patch phase. This may cause emit_imm in RV64 to generate a different number of instructions when generating the 'im' address, potentially causing out-of-bounds issues. Let's emit the maximum number of instructions for the "im" address during dry run to fix this problem. Fixes: 26ef208c209a ("bpf: Use arch_bpf_trampoline_size") Signed-off-by: Pu Lehui <pulehui@huawei.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240622030437.3973492-3-pulehui@huaweicloud.com
2024-07-01bpf: Use precise image size for struct_ops trampolinePu Lehui
For trampoline using bpf_prog_pack, we need to generate a rw_image buffer with size of (image_end - image). For regular trampoline, we use the precise image size generated by arch_bpf_trampoline_size to allocate rw_image. But for struct_ops trampoline, we allocate rw_image directly using close to PAGE_SIZE size. We do not need to allocate for that much, as the patch size is usually much smaller than PAGE_SIZE. Let's use precise image size for it too. Signed-off-by: Pu Lehui <pulehui@huawei.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Björn Töpel <bjorn@rivosinc.com> #riscv Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/bpf/20240622030437.3973492-2-pulehui@huaweicloud.com
2024-07-01libbpf: Fix error handling in btf__distill_base()Alan Maguire
Coverity points out that after calling btf__new_empty_split() the wrong value is checked for error. Fixes: 58e185a0dc35 ("libbpf: Add btf__distill_base() creating split BTF with distilled base BTF") Reported-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240629100058.2866763-1-alan.maguire@oracle.com
2024-07-01selftests/bpf: Add selftest for bpf_xdp_flow_lookup kfuncLorenzo Bianconi
Introduce e2e selftest for bpf_xdp_flow_lookup kfunc through xdp_flowtable utility. Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/b74393fb4539aecbbd5ac7883605f86a95fb0b6b.1719698275.git.lorenzo@kernel.org
2024-07-01netfilter: Add bpf_xdp_flow_lookup kfuncLorenzo Bianconi
Introduce bpf_xdp_flow_lookup kfunc in order to perform the lookup of a given flowtable entry based on a fib tuple of incoming traffic. bpf_xdp_flow_lookup can be used as building block to offload in xdp the processing of sw flowtable when hw flowtable is not available. Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Pablo Neira Ayuso <pablo@netfilter.org> Link: https://lore.kernel.org/bpf/55d38a4e5856f6d1509d823ff4e98aaa6d356097.1719698275.git.lorenzo@kernel.org
2024-07-01netfilter: nf_tables: Add flowtable map for xdp offloadFlorian Westphal
This adds a small internal mapping table so that a new bpf (xdp) kfunc can perform lookups in a flowtable. As-is, xdp program has access to the device pointer, but no way to do a lookup in a flowtable -- there is no way to obtain the needed struct without questionable stunts. This allows to obtain an nf_flowtable pointer given a net_device structure. In order to keep backward compatibility, the infrastructure allows the user to add a given device to multiple flowtables, but it will always return the first added mapping performing the lookup since it assumes the right configuration is 1:1 mapping between flowtables and net_devices. Co-developed-by: Lorenzo Bianconi <lorenzo@kernel.org> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Pablo Neira Ayuso <pablo@netfilter.org> Link: https://lore.kernel.org/bpf/9f20e2c36f494b3bf177328718367f636bb0b2ab.1719698275.git.lorenzo@kernel.org
2024-06-26selftests/bpf: Move ARRAY_SIZE to bpf_misc.hJiri Olsa
ARRAY_SIZE is used on multiple places, move its definition in bpf_misc.h header. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Alan Maguire <alan.maguire@oracle.com> Link: https://lore.kernel.org/bpf/20240626134719.3893748-1-jolsa@kernel.org
2024-06-26libbpf: Fix clang compilation error in btf_relocate.cAlan Maguire
When building with clang for ARCH=i386, the following errors are observed: CC kernel/bpf/btf_relocate.o ./tools/lib/bpf/btf_relocate.c:206:23: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion] 206 | info[id].needs_size = true; | ^ ~ ./tools/lib/bpf/btf_relocate.c:256:25: error: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Werror,-Wsingle-bit-bitfield-constant-conversion] 256 | base_info.needs_size = true; | ^ ~ 2 errors generated. The problem is we use 1-bit, 31-bit bitfields in a signed int. Changing to bool needs_size: 1; unsigned int size:31; ...resolves the error and pahole reports that 4 bytes are used for the underlying representation: $ pahole btf_name_info tools/lib/bpf/btf_relocate.o struct btf_name_info { const char * name; /* 0 8 */ unsigned int needs_size:1; /* 8: 0 4 */ unsigned int size:31; /* 8: 1 4 */ __u32 id; /* 12 4 */ /* size: 16, cachelines: 1, members: 4 */ /* last cacheline: 16 bytes */ }; Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240624192903.854261-1-alan.maguire@oracle.com
2024-06-26selftests/bpf: Don't close(-1) in serial_test_fexit_stress()Ma Ke
Guard close() with extra link_fd[i] > 0 and fexit_fd[i] > 0 check to prevent close(-1). Signed-off-by: Ma Ke <make24@iscas.ac.cn> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240623131753.2133829-1-make24@iscas.ac.cn
2024-06-26bpf: add new negative selftests to cover missing check_func_arg_reg_off() ↵Matt Bobrowski
and reg->type check Add new negative selftests which are intended to cover the out-of-bounds memory access that could be performed on a CONST_PTR_TO_DYNPTR within functions taking a ARG_PTR_TO_DYNPTR | MEM_RDONLY as an argument, and acceptance of invalid register types i.e. PTR_TO_BTF_ID within functions taking a ARG_PTR_TO_DYNPTR | MEM_RDONLY. Reported-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Matt Bobrowski <mattbobrowski@google.com> Link: https://lore.kernel.org/r/20240625062857.92760-2-mattbobrowski@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-26bpf: add missing check_func_arg_reg_off() to prevent out-of-bounds memory ↵Matt Bobrowski
accesses Currently, it's possible to pass in a modified CONST_PTR_TO_DYNPTR to a global function as an argument. The adverse effects of this is that BPF helpers can continue to make use of this modified CONST_PTR_TO_DYNPTR from within the context of the global function, which can unintentionally result in out-of-bounds memory accesses and therefore compromise overall system stability i.e. [ 244.157771] BUG: KASAN: slab-out-of-bounds in bpf_dynptr_data+0x137/0x140 [ 244.161345] Read of size 8 at addr ffff88810914be68 by task test_progs/302 [ 244.167151] CPU: 0 PID: 302 Comm: test_progs Tainted: G O E 6.10.0-rc3-00131-g66b586715063 #533 [ 244.174318] Call Trace: [ 244.175787] <TASK> [ 244.177356] dump_stack_lvl+0x66/0xa0 [ 244.179531] print_report+0xce/0x670 [ 244.182314] ? __virt_addr_valid+0x200/0x3e0 [ 244.184908] kasan_report+0xd7/0x110 [ 244.187408] ? bpf_dynptr_data+0x137/0x140 [ 244.189714] ? bpf_dynptr_data+0x137/0x140 [ 244.192020] bpf_dynptr_data+0x137/0x140 [ 244.194264] bpf_prog_b02a02fdd2bdc5fa_global_call_bpf_dynptr_data+0x22/0x26 [ 244.198044] bpf_prog_b0fe7b9d7dc3abde_callback_adjust_bpf_dynptr_reg_off+0x1f/0x23 [ 244.202136] bpf_user_ringbuf_drain+0x2c7/0x570 [ 244.204744] ? 0xffffffffc0009e58 [ 244.206593] ? __pfx_bpf_user_ringbuf_drain+0x10/0x10 [ 244.209795] bpf_prog_33ab33f6a804ba2d_user_ringbuf_callback_const_ptr_to_dynptr_reg_off+0x47/0x4b [ 244.215922] bpf_trampoline_6442502480+0x43/0xe3 [ 244.218691] __x64_sys_prlimit64+0x9/0xf0 [ 244.220912] do_syscall_64+0xc1/0x1d0 [ 244.223043] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 244.226458] RIP: 0033:0x7ffa3eb8f059 [ 244.228582] Code: 08 89 e8 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 8f 1d 0d 00 f7 d8 64 89 01 48 [ 244.241307] RSP: 002b:00007ffa3e9c6eb8 EFLAGS: 00000206 ORIG_RAX: 000000000000012e [ 244.246474] RAX: ffffffffffffffda RBX: 00007ffa3e9c7cdc RCX: 00007ffa3eb8f059 [ 244.250478] RDX: 00007ffa3eb162b4 RSI: 0000000000000000 RDI: 00007ffa3e9c7fb0 [ 244.255396] RBP: 00007ffa3e9c6ed0 R08: 00007ffa3e9c76c0 R09: 0000000000000000 [ 244.260195] R10: 0000000000000000 R11: 0000000000000206 R12: ffffffffffffff80 [ 244.264201] R13: 000000000000001c R14: 00007ffc5d6b4260 R15: 00007ffa3e1c7000 [ 244.268303] </TASK> Add a check_func_arg_reg_off() to the path in which the BPF verifier verifies the arguments of global function arguments, specifically those which take an argument of type ARG_PTR_TO_DYNPTR | MEM_RDONLY. Also, process_dynptr_func() doesn't appear to perform any explicit and strict type matching on the supplied register type, so let's also enforce that a register either type PTR_TO_STACK or CONST_PTR_TO_DYNPTR is by the caller. Reported-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Matt Bobrowski <mattbobrowski@google.com> Link: https://lore.kernel.org/r/20240625062857.92760-1-mattbobrowski@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-25bpf: Fix tailcall cases in test_bpfLeon Hwang
Since f663a03c8e35 ("bpf, x64: Remove tail call detection"), tail_call_reachable won't be detected in x86 JIT. And, tail_call_reachable is provided by verifier. Therefore, in test_bpf, the tail_call_reachable must be provided in test cases before running. Fix and test: [ 174.828662] test_bpf: #0 Tail call leaf jited:1 170 PASS [ 174.829574] test_bpf: #1 Tail call 2 jited:1 244 PASS [ 174.830363] test_bpf: #2 Tail call 3 jited:1 296 PASS [ 174.830924] test_bpf: #3 Tail call 4 jited:1 719 PASS [ 174.831863] test_bpf: #4 Tail call load/store leaf jited:1 197 PASS [ 174.832240] test_bpf: #5 Tail call load/store jited:1 326 PASS [ 174.832240] test_bpf: #6 Tail call error path, max count reached jited:1 2214 PASS [ 174.835713] test_bpf: #7 Tail call count preserved across function calls jited:1 609751 PASS [ 175.446098] test_bpf: #8 Tail call error path, NULL target jited:1 472 PASS [ 175.447597] test_bpf: #9 Tail call error path, index out of range jited:1 206 PASS [ 175.448833] test_bpf: test_tail_calls: Summary: 10 PASSED, 0 FAILED, [10/10 JIT'ed] Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202406251415.c51865bc-oliver.sang@intel.com Fixes: f663a03c8e35 ("bpf, x64: Remove tail call detection") Signed-off-by: Leon Hwang <hffilwlqm@gmail.com> Link: https://lore.kernel.org/r/20240625145351.40072-1-hffilwlqm@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-24libbpf: Skip base btf sanity checksAntoine Tenart
When upgrading to libbpf 1.3 we noticed a big performance hit while loading programs using CORE on non base-BTF symbols. This was tracked down to the new BTF sanity check logic. The issue is the base BTF definitions are checked first for the base BTF and then again for every module BTF. Loading 5 dummy programs (using libbpf-rs) that are using CORE on a non-base BTF symbol on my system: - Before this fix: 3s. - With this fix: 0.1s. Fix this by only checking the types starting at the BTF start id. This should ensure the base BTF is still checked as expected but only once (btf->start_id == 1 when creating the base BTF), and then only additional types are checked for each module BTF. Fixes: 3903802bb99a ("libbpf: Add basic BTF sanity validation") Signed-off-by: Antoine Tenart <atenart@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Alan Maguire <alan.maguire@oracle.com> Link: https://lore.kernel.org/bpf/20240624090908.171231-1-atenart@kernel.org
2024-06-23bpf: fix build when CONFIG_DEBUG_INFO_BTF[_MODULES] is undefinedAlan Maguire
Kernel test robot reports that kernel build fails with resilient split BTF changes. Examining the associated config and code we see that btf_relocate_id() is defined under CONFIG_DEBUG_INFO_BTF_MODULES. Moving it outside the #ifdef solves the issue. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202406221742.d2srFLVI-lkp@intel.com/ Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Link: https://lore.kernel.org/r/20240623135224.27981-1-alan.maguire@oracle.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-23bpf, docs: Address comments from IETF Area DirectorsDave Thaler
This patch does the following to address IETF feedback: * Remove mention of "program type" and reference future docs (and mention platform-specific docs exist) for helper functions and BTF. Addresses Roman Danyliw's comments based on GENART review from Ines Robles [0]. * Add reference for endianness as requested by John Scudder [1]. * Added bit numbers to top of 32-bit wide format diagrams as requested by Paul Wouters [2]. * Added more text about why BPF doesn't stand for anything, based on text from ebpf.io [3], as requested by Eric Vyncke and Gunter Van de Velde [4]. * Replaced "htobe16" (and similar) and the direction-specific description with just "be16" (and similar) and a direction-agnostic description, to match the direction-agnostic description in the Byteswap Instructions section. Based on feedback from Eric Vyncke [5]. [0] https://mailarchive.ietf.org/arch/msg/bpf/DvDgDWOiwk05OyNlWlAmELZFPlM/ [1] https://mailarchive.ietf.org/arch/msg/bpf/eKNXpU4jCLjsbZDSw8LjI29M3tM/ [2] https://mailarchive.ietf.org/arch/msg/bpf/hGk8HkYxeZTpdu9qW_MvbGKj7WU/ [3] https://ebpf.io/what-is-ebpf/#what-do-ebpf-and-bpf-stand-for [4] https://mailarchive.ietf.org/arch/msg/bpf/i93lzdN3ewnzzS_JMbinCIYxAIU/ [5] https://mailarchive.ietf.org/arch/msg/bpf/KBWXbMeDcSrq4vsKR_KkBbV6hI4/ Acked-by: David Vernet <void@manifault.com> Signed-off-by: Dave Thaler <dthaler1968@googlemail.com> Link: https://lore.kernel.org/r/20240623150453.10613-1-dthaler1968@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-21Merge branch 'bpf-resilient-split-btf-followups'Andrii Nakryiko
Alan Maguire says: ==================== bpf: resilient split BTF followups Follow-up to resilient split BTF series [1], - cleaning up libbpf relocation code (patch 1); - adding 'struct module' support for base BTF data (patch 2); - splitting out field iteration code into separate file (patch 3); - sharing libbpf relocation code with the kernel (patch 4); - adding a kbuild --btf_features flag to generate distilled base BTF in the module-specific case where KBUILD_EXTMOD is true (patch 5); and - adding test coverage for module-based kfunc dtor (patch 6) Generation of distilled base BTF for modules requires the pahole patch at [2], but without it we just won't get distilled base BTF (and thus BTF relocation on module load) for bpf_testmod.ko. Changes since v1 [3]: - fixed line lengths and made comparison an explicit == 0 (Andrii, patch 1) - moved btf_iter.c changes to separate patch (Andrii, patch 3) - grouped common targets in kernel/bpf/Makefile (Andrii, patch 4) - updated bpf_testmod ctx alloc to use GFP_ATOMIC, and updated dtor selftest to use map-based dtor cleanup (Eduard, patch 6) [1] https://lore.kernel.org/bpf/20240613095014.357981-1-alan.maguire@oracle.com/ [2] https://lore.kernel.org/bpf/20240517102714.4072080-1-alan.maguire@oracle.com/ [3] https://lore.kernel.org/bpf/20240618162449.809994-1-alan.maguire@oracle.com/ ==================== Link: https://lore.kernel.org/r/20240620091733.1967885-1-alan.maguire@oracle.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-06-21selftests/bpf: Add kfunc_call test for simple dtor in bpf_testmodAlan Maguire
add simple kfuncs to create/destroy a context type to bpf_testmod, register them and add a kfunc_call test to use them. This provides test coverage for registration of dtor kfuncs from modules. By transferring the context pointer to a map value as a __kptr we also trigger the map-based dtor cleanup logic, improving test coverage. Suggested-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240620091733.1967885-7-alan.maguire@oracle.com
2024-06-21kbuild,bpf: Add module-specific pahole flags for distilled base BTFAlan Maguire
Support creation of module BTF along with distilled base BTF; the latter is stored in a .BTF.base ELF section and supplements split BTF references to base BTF with information about base types, allowing for later relocation of split BTF with a (possibly changed) base. resolve_btfids detects the presence of a .BTF.base section and will use it instead of the base BTF it is passed in BTF id resolution. Modules will be built with a distilled .BTF.base section for external module build, i.e. make -C. -M=path2/module ...while in-tree module build as part of a normal kernel build will not generate distilled base BTF; this is because in-tree modules change with the kernel and do not require BTF relocation for the running vmlinux. Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20240620091733.1967885-6-alan.maguire@oracle.com
2024-06-21libbpf,bpf: Share BTF relocate-related code with kernelAlan Maguire
Share relocation implementation with the kernel. As part of this, we also need the type/string iteration functions so also share btf_iter.c file. Relocation code in kernel and userspace is identical save for the impementation of the reparenting of split BTF to the relocated base BTF and retrieval of the BTF header from "struct btf"; these small functions need separate user-space and kernel implementations for the separate "struct btf"s they operate upon. One other wrinkle on the kernel side is we have to map .BTF.ids in modules as they were generated with the type ids used at BTF encoding time. btf_relocate() optionally returns an array mapping from old BTF ids to relocated ids, so we use that to fix up these references where needed for kfuncs. Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20240620091733.1967885-5-alan.maguire@oracle.com
2024-06-21libbpf: Split field iter code into its own file kernelAlan Maguire
This will allow it to be shared with the kernel. No functional change. Suggested-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240620091733.1967885-4-alan.maguire@oracle.com
2024-06-21module, bpf: Store BTF base pointer in struct moduleAlan Maguire
...as this will allow split BTF modules with a base BTF representation (rather than the full vmlinux BTF at time of BTF encoding) to resolve their references to kernel types in a way that is more resilient to small changes in kernel types. This will allow modules that are not built every time the kernel is to provide more resilient BTF, rather than have it invalidated every time BTF ids for core kernel types change. Fields are ordered to avoid holes in struct module. Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240620091733.1967885-3-alan.maguire@oracle.com
2024-06-21libbpf: BTF relocation followup fixing naming, loop logicAlan Maguire
Use less verbose names in BTF relocation code and fix off-by-one error and typo in btf_relocate.c. Simplify loop over matching distilled types, moving from assigning a _next value in loop body to moving match check conditions into the guard. Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com> Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20240620091733.1967885-2-alan.maguire@oracle.com
2024-06-21selftests/bpf: Test struct_ops bpf map auto-attachMykyta Yatsenko
Adding selftest to verify that struct_ops maps are auto attached by bpf skeleton's `*__attach` function. Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240621180324.238379-1-yatsenko@meta.com
2024-06-21bpf, arm64: Inline bpf_get_current_task/_btf() helpersPuranjay Mohan
On ARM64, the pointer to task_struct is always available in the sp_el0 register and therefore the calls to bpf_get_current_task() and bpf_get_current_task_btf() can be inlined into a single MRS instruction. Here is the difference before and after this change: Before: ; struct task_struct *task = bpf_get_current_task_btf(); 54: mov x10, #0xffffffffffff7978 // #-34440 58: movk x10, #0x802b, lsl #16 5c: movk x10, #0x8000, lsl #32 60: blr x10 --------------> 0xffff8000802b7978 <+0>: mrs x0, sp_el0 64: add x7, x0, #0x0 <-------------- 0xffff8000802b797c <+4>: ret After: ; struct task_struct *task = bpf_get_current_task_btf(); 54: mrs x7, sp_el0 This shows around 1% performance improvement in artificial microbenchmark. Signed-off-by: Puranjay Mohan <puranjay@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Xu Kuohai <xukuohai@huawei.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240619131334.4297-1-puranjay@kernel.org
2024-06-21Merge branch 'regular-expression-support-for-test-output-matching'Andrii Nakryiko
Cupertino Miranda says: ==================== Regular expression support for test output matching Hi everyone, This version removes regexp from inline assembly examples that did not require the regular expressions to match. Thanks, Cupertino ==================== Link: https://lore.kernel.org/r/20240617141458.471620-1-cupertino.miranda@oracle.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-06-21selftests/bpf: Match tests against regular expressionCupertino Miranda
This patch changes a few tests to make use of regular expressions. Fixed tests otherwise fail when compiled with GCC. Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20240617141458.471620-3-cupertino.miranda@oracle.com
2024-06-21selftests/bpf: Support checks against a regular expressionCupertino Miranda
Add support for __regex and __regex_unpriv macros to check the test execution output against a regular expression. This is similar to __msg and __msg_unpriv, however those expect do substring matching. Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20240617141458.471620-2-cupertino.miranda@oracle.com
2024-06-21libbpf: Checking the btf_type kind when fixing variable offsetsDonglin Peng
I encountered an issue when building the test_progs from the repository [1]: $ pwd /work/Qemu/x86_64/linux-6.10-rc2/tools/testing/selftests/bpf/ $ make test_progs V=1 [...] ./tools/sbin/bpftool gen object ./ip_check_defrag.bpf.linked2.o ./ip_check_defrag.bpf.linked1.o libbpf: failed to find symbol for variable 'bpf_dynptr_slice' in section '.ksyms' Error: failed to link './ip_check_defrag.bpf.linked1.o': No such file or directory (2) [...] Upon investigation, I discovered that the btf_types referenced in the '.ksyms' section had a kind of BTF_KIND_FUNC instead of BTF_KIND_VAR: $ bpftool btf dump file ./ip_check_defrag.bpf.linked1.o [...] [2] DATASEC '.ksyms' size=0 vlen=2 type_id=16 offset=0 size=0 (FUNC 'bpf_dynptr_from_skb') type_id=17 offset=0 size=0 (FUNC 'bpf_dynptr_slice') [...] [16] FUNC 'bpf_dynptr_from_skb' type_id=82 linkage=extern [17] FUNC 'bpf_dynptr_slice' type_id=85 linkage=extern [...] For a detailed analysis, please refer to [2]. We can add a kind checking to fix the issue. [1] https://github.com/eddyz87/bpf/tree/binsort-btf-dedup [2] https://lore.kernel.org/all/0c0ef20c-c05e-4db9-bad7-2cbc0d6dfae7@oracle.com/ Fixes: 8fd27bf69b86 ("libbpf: Add BPF static linker BTF and BTF.ext support") Signed-off-by: Donglin Peng <dolinux.peng@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Alan Maguire <alan.maguire@oracle.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20240619122355.426405-1-dolinux.peng@gmail.com
2024-06-21bpf: Add security_file_post_open() LSM hook to sleepable_lsm_hooksMatt Bobrowski
The new generic LSM hook security_file_post_open() was recently added to the LSM framework in commit 8f46ff5767b0b ("security: Introduce file_post_open hook"). Let's proactively add this generic LSM hook to the sleepable_lsm_hooks BTF ID set, because I can't see there being any strong reasons not to, and it's only a matter of time before someone else comes around and asks for it to be there. security_file_post_open() is inherently sleepable as it's purposely situated in the kernel that allows LSMs to directly read out the contents of the backing file if need be. Additionally, it's called directly after security_file_open(), and that LSM hook in itself already exists in the sleepable_lsm_hooks BTF ID set. Signed-off-by: Matt Bobrowski <mattbobrowski@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20240618192923.379852-1-mattbobrowski@google.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
2024-06-21bpf: Change bpf_session_cookie return value to __u64 *Jiri Olsa
This reverts [1] and changes return value for bpf_session_cookie in bpf selftests. Having long * might lead to problems on 32-bit architectures. Fixes: 2b8dd87332cd ("bpf: Make bpf_session_cookie() kfunc return long *") Suggested-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240619081624.1620152-1-jolsa@kernel.org
2024-06-20Merge branch 'use-network-helpers-part-7'Alexei Starovoitov
Geliang Tang says: ==================== use network helpers, part 7 From: Geliang Tang <tanggeliang@kylinos.cn> v6: - update ASSERT strings in patch 4 as Eduard suggested. (thanks) v5: - update patch 1, add getsockopt(SO_PROTOCOL) in connect_to_fd() to fix errors reported by CI. v4: - fix errors reported by CI. v3: - rename start_client to client_socket - Use connect_to_addr in connect_to_fd_opt v2: - update patch 2, extract a new helper start_client. - drop patch 3, keep must_fail in network_helper_opts. Drop type and noconnect from network_helper_opts. And use start_server_str in mptcp and test_tcp_check_syncookie_user. Patches 1-4 address Martin's comments in the previous series. ==================== Link: https://lore.kernel.org/r/cover.1718932493.git.tanggeliang@kylinos.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20selftests/bpf: Use start_server_str in test_tcp_check_syncookie_userGeliang Tang
Since start_server_str() is added now, it can be used in script test_tcp_check_syncookie_user.c instead of start_server_addr() to simplify the code. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Link: https://lore.kernel.org/r/5d2f442261d37cff16c1f1b21a2b188508ab67fa.1718932493.git.tanggeliang@kylinos.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20selftests/bpf: Use start_server_str in mptcpGeliang Tang
Since start_server_str() is added now, it can be used in mptcp.c in start_mptcp_server() instead of using helpers make_sockaddr() and start_server_addr() to simplify the code. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Link: https://lore.kernel.org/r/16fb3e2cd60b64b5470b0e69f1aa233feaf2717c.1718932493.git.tanggeliang@kylinos.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20selftests/bpf: Drop noconnect from network_helper_optsGeliang Tang
In test_bpf_ip_check_defrag_ok(), the new helper client_socket() can be used to replace connect_to_fd_opts() with "noconnect" opts, and the strcut member "noconnect" of network_helper_opts can be dropped now, always connect to server in connect_to_fd_opts(). Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Link: https://lore.kernel.org/r/f45760becce51986e4e08283c7df0f933eb0da14.1718932493.git.tanggeliang@kylinos.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20selftests/bpf: Add client_socket helperGeliang Tang
This patch extracts a new helper client_socket() from connect_to_fd_opts() to create the client socket, but don't connect to the server. Then connect_to_fd_opts() can be implemented using client_socket() and connect_fd_to_addr(). This helper can be used in connect_to_addr() too, and make "noconnect" opts useless. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Link: https://lore.kernel.org/r/4169c554e1cee79223feea49a1adc459d55e1ffe.1718932493.git.tanggeliang@kylinos.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20selftests/bpf: Use connect_to_addr in connect_to_fd_optGeliang Tang
This patch moves "post_socket_cb" and "noconnect" into connect_to_addr(), then connect_to_fd_opts() can be implemented by getsockname() and connect_to_addr(). This change makes connect_to_* interfaces more unified. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Link: https://lore.kernel.org/r/4569c30533e14c22fae6c05070aad809720551c1.1718932493.git.tanggeliang@kylinos.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20selftests/bpf: Drop type from network_helper_optsGeliang Tang
The opts.{type, noconnect} is at least a bit non intuitive or unnecessary. The only use case now is in test_bpf_ip_check_defrag_ok which ends up bypassing most (or at least some) of the connect_to_fd_opts() logic. It's much better that test should have its own connect_to_fd_opts() instead. This patch adds a new "type" parameter for connect_to_fd_opts(), then opts->type and getsockopt(SO_TYPE) can be replaced by "type" parameter in it. In connect_to_fd(), use getsockopt(SO_TYPE) to get "type" value and pass it to connect_to_fd_opts(). In bpf_tcp_ca.c and cgroup_v1v2.c, "SOCK_STREAM" types are passed to connect_to_fd_opts(), and in ip_check_defrag.c, different types "SOCK_RAW" and "SOCK_DGRAM" are passed to it. With these changes, the strcut member "type" of network_helper_opts can be dropped now. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn> Link: https://lore.kernel.org/r/cfd20b5ad4085c1d1af5e79df3b09013a407199f.1718932493.git.tanggeliang@kylinos.cn Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20Merge branch 'fix-compiler-warnings-looking-for-suggestions'Alexei Starovoitov
Rafael Passos says: ==================== Fix compiler warnings, looking for suggestions Hi, This patchset has a few fixes to compiler warnings. I am studying the BPF subsystem and wish to bring more tangible contributions. I would appreciate receiving suggestions on things to investigate. I also documented a bit in my blog. I could help with docs here, too. https://rcpassos.me/post/linux-ebpf-understanding-kernel-level-mechanics Thanks! Changelog V1 -> V2: - rebased all commits to updated for-next base - removes new cases of the extra parameter for bpf_jit_binary_pack_finalize - built and tested for ARM64 - sent the series for the test workflow: https://github.com/kernel-patches/bpf/pull/7198 ==================== Acked-by: Puranjay Mohan <puranjay@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20240615022641.210320-1-rafael@rcpassos.me Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20bpf: remove redeclaration of new_n in bpf_verifier_vlogRafael Passos
This new_n is defined in the start of this function. Its value is overwritten by `new_n = min(n, log->len_total);` a couple lines before my change, rendering the shadow declaration unnecessary. Signed-off-by: Rafael Passos <rafael@rcpassos.me> Link: https://lore.kernel.org/r/20240615022641.210320-4-rafael@rcpassos.me Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20bpf: remove unused parameter in __bpf_free_used_btfsRafael Passos
Fixes a compiler warning. The __bpf_free_used_btfs function was taking an extra unused struct bpf_prog_aux *aux param Signed-off-by: Rafael Passos <rafael@rcpassos.me> Link: https://lore.kernel.org/r/20240615022641.210320-3-rafael@rcpassos.me Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20bpf: remove unused parameter in bpf_jit_binary_pack_finalizeRafael Passos
Fixes a compiler warning. the bpf_jit_binary_pack_finalize function was taking an extra bpf_prog parameter that went unused. This removves it and updates the callers accordingly. Signed-off-by: Rafael Passos <rafael@rcpassos.me> Link: https://lore.kernel.org/r/20240615022641.210320-2-rafael@rcpassos.me Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20Merge branch 'bpf-verifier-correct-tail_call_reachable-for-bpf-prog'Alexei Starovoitov
Leon Hwang says: ==================== bpf, verifier: Correct tail_call_reachable for bpf prog It's confusing to inspect 'prog->aux->tail_call_reachable' with drgn[0], when bpf prog has tail call but 'tail_call_reachable' is false. This patch corrects 'tail_call_reachable' when bpf prog has tail call. Therefore, it's unnecessary to detect tail call in x86 jit. Let's remove it. Changes: v1 -> v2: * Address comment from Yonghong: * Remove unnecessary tail call detection in x86 jit. Acked-by: Eduard Zingerman <eddyz87@gmail.com> --- Links: [0] https://github.com/osandov/drgn ==================== Link: https://lore.kernel.org/r/20240610124224.34673-1-hffilwlqm@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20bpf, x64: Remove tail call detectionLeon Hwang
As 'prog->aux->tail_call_reachable' is correct for tail call present, it's unnecessary to detect tail call in x86 jit. Therefore, let's remove it. Signed-off-by: Leon Hwang <hffilwlqm@gmail.com> Link: https://lore.kernel.org/r/20240610124224.34673-3-hffilwlqm@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-20bpf, verifier: Correct tail_call_reachable for bpf progLeon Hwang
It's confusing to inspect 'prog->aux->tail_call_reachable' with drgn[0], when bpf prog has tail call but 'tail_call_reachable' is false. This patch corrects 'tail_call_reachable' when bpf prog has tail call. Signed-off-by: Leon Hwang <hffilwlqm@gmail.com> Link: https://lore.kernel.org/r/20240610124224.34673-2-hffilwlqm@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2024-06-17Merge branch 'bpf-support-resilient-split-btf'Andrii Nakryiko
Alan Maguire says: ==================== bpf: support resilient split BTF Split BPF Type Format (BTF) provides huge advantages in that kernel modules only have to provide type information for types that they do not share with the core kernel; for core kernel types, split BTF refers to core kernel BTF type ids. So for a STRUCT sk_buff, a module that uses that structure (or a pointer to it) simply needs to refer to the core kernel type id, saving the need to define the structure and its many dependents. This cuts down on duplication and makes BTF as compact as possible. However, there is a downside. This scheme requires the references from split BTF to base BTF to be valid not just at encoding time, but at use time (when the module is loaded). Even a small change in kernel types can perturb the type ids in core kernel BTF, and - if the new reproducible BTF option is not used - pahole's parallel processing of compilation units can lead to different type ids for the same kernel if the BTF is regenerated. So we have a robustness problem for split BTF for cases where a module is not always compiled at the same time as the kernel. This problem is particularly acute for distros which generally want module builders to be able to compile a module for the lifetime of a Linux stable-based release, and have it continue to be valid over the lifetime of that release, even as changes in data structures (and hence BTF types) accrue. Today it's not possible to generate BTF for modules that works beyond the initial kernel it is compiled against - kernel bugfixes etc invalidate the split BTF references to vmlinux BTF, and BTF is no longer usable for the module. The goal of this series is to provide options to provide additional context for cases like this. That context comes in the form of distilled base BTF; it stands in for the base BTF, and contains information about the types referenced from split BTF, but not their full descriptions. The modified split BTF will refer to type ids in this .BTF.base section, and when the kernel loads such modules it will use that .BTF.base to map references from split BTF to the equivalent current vmlinux base BTF types. Once this relocation process has succeeded, the module BTF available in /sys/kernel/btf will look exactly as if it was built with the current vmlinux; references to base types will be fixed up etc. A module builder - using this series along with the pahole changes - can then build a module with distilled base BTF via an out-of-tree module build, i.e. make -C . M=path/2/module The module will have a .BTF section (the split BTF) and a .BTF.base section. The latter is small in size - distilled base BTF does not need full struct/union/enum information for named types for example. For 2667 modules built with distilled base BTF, the average size observed was 1556 bytes (stddev 1563). The overall size added to this 2667 modules was 5.3Mb. Note that for the in-tree modules, this approach is not needed as split and base BTF in the case of in-tree modules are always built and re-built together. The series first focuses on generating split BTF with distilled base BTF; then relocation support is added to allow split BTF with an associated distlled base to be relocated with a new base BTF. Next Eduard's patch allows BTF ELF parsing to work with both .BTF and .BTF.base sections; this ensures that bpftool will be able to dump BTF for a module with a .BTF.base section for example, or indeed dump relocated BTF where a module and a "-B vmlinux" is supplied. Then we add support to resolve_btfids to ignore base BTF - i.e. to avoid relocation - if a .BTF.base section is found. This ensures the .BTF.ids section is populated with ids relative to the distilled base (these will be relocated as part of module load). Finally the series supports storage of .BTF.base data/size in modules and supports sharing of relocation code with the kernel to allow relocation of module BTF. For the kernel, this relocation process happens at module load time, and we relocate split BTF references to point at types in the current vmlinux BTF. As part of this, .BTF.ids references need to be mapped also. So concretely, what happens is - we generate split BTF in the .BTF section of a module that refers to types in the .BTF.base section as base types; the latter are not full type descriptions but provide information about the base type. So a STRUCT sk_buff would be represented as a FWD struct sk_buff in distilled base BTF for example. - when the module is loaded, the split BTF is relocated with vmlinux BTF; in the case of the FWD struct sk_buff, we find the STRUCT sk_buff in vmlinux BTF and map all split BTF references to the distilled base FWD sk_buff, replacing them with references to the vmlinux BTF STRUCT sk_buff. A previous approach to this problem [1] utilized standalone BTF for such cases - where the BTF is not defined relative to base BTF so there is no relocation required. The problem with that approach is that from the verifier perspective, some types are special, and having a custom representation of a core kernel type that did not necessarily match the current representation is not tenable. So the approach taken here was to preserve the split BTF model while minimizing the representation of the context needed to relocate split and current vmlinux BTF. To generate distilled .BTF.base sections the associated dwarves patch (to be applied on the "next" branch there) is needed [3] Without it, things will still work but modules will not be built with a .BTF.base section. Changes since v5[4]: - Update search of distilled types to return the first occurrence of a string (or a string+size pair); this allows us to iterate over all matches in distilled base BTF (Andrii, patch 3) - Update to use BTF field iterators (Andrii, patches 1, 3 and 8) - Update tests to cover multiple match and associated error cases (Eduard, patch 4) - Rename elf_sections_info to btf_elf_secs, remove use of libbpf_get_error(), reset btf->owns_base when relocation succeeds (Andrii, patch 5) Changes since v4[5]: - Moved embeddedness, duplicate name checks to relocation time and record struct/union size for all distilled struct/unions instead of using forwards. This allows us to carry out type compatibility checks based on the base BTF we want to relocate with (Eduard, patches 1, 3) - Moved to using qsort() instead of qsort_r() as support for qsort_r() appears to be missing in Android libc (Andrii, patch 3) - Sorting/searching now incorporates size matching depending on BTF kind and embeddedness of struct/union (Eduard, Andrii, patch 3) - Improved naming of various types during relocation to avoid confusion (Andrii, patch 3) - Incorporated Eduard's patch (patch 5) which handles .BTF.base sections internally in btf_parse_elf(). This makes ELF parsing work with split BTF, split BTF with a distilled base, split BTF with a distilled base _and_ base BTF (by relocating) etc. Having this avoids the need for bpftool changes; it will work as-is with .BTF.base sections (Eduard, patch 4) - Updated resolve_btfids to _not_ relocate BTF for modules where a .BTF.base section is present; in that one case we do not want to relocate BTF as the .BTF.ids section should reflect ids in .BTF.base which will later be relocated on module load (Eduard, Andrii, patch 5) Changes since v3[6]: - distill now checks for duplicate-named struct/unions and records them as a sized struct/union to help identify which of the multiple base BTF structs/unions it refers to (Eduard, patch 1) - added test support for multiple name handling (Eduard, patch 2) - simplified the string mapping when updating split BTF to use base BTF instead of distilled base. Since the only string references split BTF can make to base BTF are the names of the base types, create a string map from distilled string offset -> base BTF string offset and update string offsets by visiting all strings in split BTF; this saves having to do costly searches of base BTF (Eduard, patch 7,10) - fixed bpftool manpage and indentation issues (Quentin, patch 11) Also explored Eduard's suggestion of doing an implicit fallback to checking for .BTF.base section in btf__parse() when it is called to get base BTF. However while it is doable, it turned out to be difficult operationally. Since fallback is implicit we do not know the source of the BTF - was it from .BTF or .BTF.base? In bpftool, we want to try first standalone BTF, then split, then split with distilled base. Having a way to explicitly request .BTF.base via btf__parse_opts() fits that model better. Changes since v2[7]: - submitted patch to use --btf_features in Makefile.btf for pahole v1.26 and later separately (Andrii). That has landed in bpf-next now. - distilled base now encodes ENUM64 as fwd ENUM (size 8), eliminating the need for support for ENUM64 in btf__add_fwd (patch 1, Andrii) - moved to distilling only named types, augmenting split BTF with associated reference types; this simplifies greatly the distilled base BTF and the mapping operation between distilled and base BTF when relocating (most of the series changes, Andrii) - relocation now iterates over base BTF, looking for matches based on name in distilled BTF. Distilled BTF is pre-sorted by name (Andrii, patch 8) - removed most redundant compabitiliby checks aside from struct size for base types/embedded structs and kind compatibility (since we only match on name) (Andrii, patch 8) - btf__parse_opts() now replaces btf_parse() internally in libbpf (Eduard, patch 3) Changes since RFC [8]: - updated terminology; we replace clunky "base reference" BTF with distilling base BTF into a .BTF.base section. Similarly BTF reconcilation becomes BTF relocation (Andrii, most patches) - add distilled base BTF by default for out-of-tree modules (Alexei, patch 8) - distill algorithm updated to record size of embedded struct/union by recording it as a 0-vlen STRUCT/UNION with size preserved (Andrii, patch 2) - verify size match on relocation for such STRUCT/UNIONs (Andrii, patch 9) - with embedded STRUCT/UNION recording size, we can have bpftool dump a header representation using .BTF.base + .BTF sections rather than special-casing and refusing to use "format c" for that case (patch 5) - match enum with enum64 and vice versa (Andrii, patch 9) - ensure that resolve_btfids works with BTF without .BTF.base section (patch 7) - update tests to cover embedded types, arrays and function prototypes (patches 3, 12) [1] https://lore.kernel.org/bpf/20231112124834.388735-14-alan.maguire@oracle.com/ [2] https://lore.kernel.org/bpf/20240501175035.2476830-1-alan.maguire@oracle.com/ [3] https://lore.kernel.org/bpf/20240517102714.4072080-1-alan.maguire@oracle.com/ [4] https://lore.kernel.org/bpf/20240528122408.3154936-1-alan.maguire@oracle.com/ [5] https://lore.kernel.org/bpf/20240517102246.4070184-1-alan.maguire@oracle.com/ [6] https://lore.kernel.org/bpf/20240510103052.850012-1-alan.maguire@oracle.com/ [7] https://lore.kernel.org/bpf/20240424154806.3417662-1-alan.maguire@oracle.com/ [8] https://lore.kernel.org/bpf/20240322102455.98558-1-alan.maguire@oracle.com/ ==================== Link: https://lore.kernel.org/r/20240613095014.357981-1-alan.maguire@oracle.com Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
2024-06-17resolve_btfids: Handle presence of .BTF.base sectionAlan Maguire
Now that btf_parse_elf() handles .BTF.base section presence, we need to ensure that resolve_btfids uses .BTF.base when present rather than the vmlinux base BTF passed in via the -B option. Detect .BTF.base section presence and unset the base BTF path to ensure that BTF ELF parsing will do the right thing. Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20240613095014.357981-7-alan.maguire@oracle.com
2024-06-17libbpf: Make btf_parse_elf process .BTF.base transparentlyEduard Zingerman
Update btf_parse_elf() to check if .BTF.base section is present. The logic is as follows: if .BTF.base section exists: distilled_base := btf_new(.BTF.base) if distilled_base: btf := btf_new(.BTF, .base_btf=distilled_base) if base_btf: btf_relocate(btf, base_btf) else: btf := btf_new(.BTF) return btf In other words: - if .BTF.base section exists, load BTF from it and use it as a base for .BTF load; - if base_btf is specified and .BTF.base section exist, relocate newly loaded .BTF against base_btf. Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240613095014.357981-6-alan.maguire@oracle.com
2024-06-17selftests/bpf: Extend distilled BTF tests to cover BTF relocationAlan Maguire
Ensure relocated BTF looks as expected; in this case identical to original split BTF, with a few duplicate anonymous types added to split BTF by the relocation process. Also add relocation tests for edge cases like missing type in base BTF and multiple types of the same name. Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/bpf/20240613095014.357981-5-alan.maguire@oracle.com
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