- 11 Nov, 2020 9 commits
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Andrii Nakryiko authored
Jean-Philippe Brucker says: ==================== A few fixes for cross and out-of-tree build of bpftool and runqslower. These changes allow to build for different target architectures, using the same source tree. Since [v2], I addressed Andrii's comments on patches 3 and 5, and added patch 7 which fixes a build slowdown. [v2] https://lore.kernel.org/bpf/20201109110929.1223538-1-jean-philippe@linaro.org/ ==================== Signed-off-by:
Andrii Nakryiko <andrii@kernel.org>
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Jean-Philippe Brucker authored
Commit ba2fd563 ("tools/bpftool: Support passing BPFTOOL_VERSION to make") changed BPFTOOL_VERSION to a recursively expanded variable, forcing it to be recomputed on every expansion of CFLAGS and dramatically slowing down the bpftool build. Restore BPFTOOL_VERSION as a simply expanded variable, guarded by an ifeq(). Fixes: ba2fd563 ("tools/bpftool: Support passing BPFTOOL_VERSION to make") Signed-off-by:
Jean-Philippe Brucker <jean-philippe@linaro.org> Signed-off-by:
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Jean-Philippe Brucker authored
When cross building runqslower for an other architecture, the intermediate bpftool used to generate a skeleton must be built using the host toolchain. Pass HOSTCC and HOSTLD, defined in Makefile.include, to the bpftool Makefile. Signed-off-by:
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Jean-Philippe Brucker authored
Enable out-of-tree build for runqslower. Only set OUTPUT=.output if it wasn't already set by the user. Signed-off-by:
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Jean-Philippe Brucker authored
Makefile.include defines variables such as OUTPUT and CC for out-of-tree build and cross-build. Include it into the runqslower Makefile and use its $(QUIET*) helpers. Signed-off-by:
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Jean-Philippe Brucker authored
The bpftool build first creates an intermediate binary, executed on the host, to generate skeletons required by the final build. When cross-building bpftool for an architecture different from the host, the intermediate binary should be built using the host compiler (gcc) and the final bpftool using the cross compiler (e.g. aarch64-linux-gnu-gcc). Generate the intermediate objects into the bootstrap/ directory using the host toolchain. Signed-off-by:
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Jean-Philippe Brucker authored
Cleaning a partial build can fail if the output directory for libbpf wasn't created: $ make -C tools/bpf/bpftool O=/tmp/bpf clean /bin/sh: line 0: cd: /tmp/bpf/libbpf/: No such file or directory tools/scripts/Makefile.include:17: *** output directory "/tmp/bpf/libbpf/" does not exist. Stop. make: *** [Makefile:36: /tmp/bpf/libbpf/libbpf.a-clean] Error 2 As a result make never gets around to clearing the leftover objects. Add the libbpf output directory as clean dependency to ensure clean always succeeds (similarly to the "descend" macro). The directory is later removed by the clean recipe. Signed-off-by:
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Jean-Philippe Brucker authored
Several Makefiles in tools/ need to define the host toolchain variables. Move their definition to tools/scripts/Makefile.include Signed-off-by:
Jiri Olsa <jolsa@redhat.com> Acked-by:
Rafael J. Wysocki <rafael.j.wysocki@intel.com> Link: https://lore.kernel.org/bpf/20201110164310.2600671-2-jean-philippe@linaro.org
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Andrii Nakryiko authored
Make sure btf_parse_module() is compiled out if module BTFs are not enabled. Fixes: 36e68442 ("bpf: Load and verify kernel module BTFs") Reported-by:
Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by:
Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20201111040645.903494-1-andrii@kernel.org
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- 10 Nov, 2020 10 commits
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Alexei Starovoitov authored
Hangbin Liu says: ==================== In comment 173ca26e ("samples/bpf: add comprehensive ipip, ipip6, ip6ip6 test") we added some bpf tunnel tests. In commit 933a741e ("selftests/bpf: bpf tunnel test.") when we moved it to the current folder, we missed some points: 1. ip6ip6 test is not added 2. forgot to remove test_ipip.sh in sample folder 3. TCP test code is not removed in test_tunnel_kern.c In this patch set I add back ip6ip6 test and remove unused code. I'm not sure if this should be net or net-next, so just set to net. Here is the test result: ``` Testing IP6IP6 tunnel... PING ::11(::11) 56 data bytes --- ::11 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 63ms rtt min/avg/max/mdev = 0.014/1028.308/2060.906/841.361 ms, pipe 2 PING 1::11(1::11) 56 data bytes --- 1::11 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 48ms rtt min/avg/max/mdev = 0.026/0.029/0.036/0.006 ms PING 1::22(1::22) 56 data bytes --- 1::22 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 47ms rtt min/avg/max/mdev = 0.030/0.048/0.067/0.016 ms PASS: ip6ip6tnl ``` v3: Add back ICMP check as Martin suggested. v2: Keep ip6ip6 section in test_tunnel_kern.c. ==================== Acked-by:
Martin KaFai Lau <kafai@fb.com> Signed-off-by:
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Hangbin Liu authored
The tcbpf2_kern.o and related kernel sections are moved to bpf selftest folder since b05cd740 ("samples/bpf: remove the bpf tunnel testsuite."). Remove this one as well. Fixes: b05cd740 ("samples/bpf: remove the bpf tunnel testsuite.") Signed-off-by:
Hangbin Liu <liuhangbin@gmail.com> Signed-off-by:
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Hangbin Liu authored
In comment 173ca26e ("samples/bpf: add comprehensive ipip, ipip6, ip6ip6 test") we added ip6ip6 test for bpf tunnel testing. But in commit 933a741e ("selftests/bpf: bpf tunnel test.") when we moved it to the current folder, we didn't add it. This patch add the ip6ip6 test back to bpf tunnel test. Update the ipip6's topology for both IPv4 and IPv6 testing. Since iperf test is removed as currect framework simplified it in purpose, I also removed unused tcp checkings in test_tunnel_kern.c. Fixes: 933a741e ("selftests/bpf: bpf tunnel test.") Signed-off-by:
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Alexei Starovoitov authored
Andrii Nakryiko says: ==================== This patch set adds BTF generation for kernel modules using a compact split BTF approach. Respective patches have all the details. Kernel module BTFs rely on pahole's split BTF support, which is added in [0] and will be available starting from v1.19. Support for it is detected automatically during kernel build time. This patch set implements in-kernel support for split BTF loading and validation. It also extends GET_OBJ_INFO API for BTFs to return BTF's module name and a flag whether BTF itself is in-kernel or user-provided. vmlinux BTF is also exposed to user-space through the same BTF object iteration APIs. Follow up patch set will utilize the fact that vmlinux and module BTFs now have associated ID to provide ability to attach BPF fentry/fexit/etc programs to functions defined in kernel modules. bpftool is also extended to show module/vmlinux BTF's name. [0] https://patchwork.kernel.org/project/netdevbpf/list/?series=378699&state=* v3->v4: - copy_to_user() on ENOSPC in btf_get_info_by_fd() (Martin); v2->v3: - get rid of unnecessary gotos (Song); v2->v1: - drop WARNs, add fewer pr_warn()'s instead (Greg); - properly initialize sysfs binary attribute structure (Greg); - add __maybe_unused to any_section_objs, used conditionally by module BTF; rfc->v1: - CONFIG_DEBUG_INFO_BTF_MODULES is derived automatically (Alexei); - vmlinux BTF now has explicit "vmlinux" name (Alexei); - added sysfs ABI documentation for /sys/kernel/btf/<module> (Greg). Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> ==================== Signed-off-by:
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Andrii Nakryiko authored
Display vmlinux BTF name and kernel module names when listing available BTFs on the system. In human-readable output mode, module BTFs are reported with "name [module-name]", while vmlinux BTF will be reported as "name [vmlinux]". Square brackets are added by bpftool and follow kernel convention when displaying modules in human-readable text outputs. [vmuser@archvm bpf]$ sudo ../../../bpf/bpftool/bpftool btf s 1: name [vmlinux] size 4082281B 6: size 2365B prog_ids 8,6 map_ids 3 7: name [button] size 46895B 8: name [pcspkr] size 42328B 9: name [serio_raw] size 39375B 10: name [floppy] size 57185B 11: name [i2c_core] size 76186B 12: name [crc32c_intel] size 16036B 13: name [i2c_piix4] size 50497B 14: name [irqbypass] size 14124B 15: name [kvm] size 197985B 16: name [kvm_intel] size 123564B 17: name [cryptd] size 42466B 18: name [crypto_simd] size 17187B 19: name [glue_helper] size 39205B 20: name [aesni_intel] size 41034B 25: size 36150B pids bpftool(2519) In JSON mode, two fields (boolean "kernel" and string "name") are reported for each BTF object. vmlinux BTF is reported with name "vmlinux" (kernel itself returns and empty name for vmlinux BTF). [vmuser@archvm bpf]$ sudo ../../../bpf/bpftool/bpftool btf s -jp [{ "id": 1, "size": 4082281, "prog_ids": [], "map_ids": [], "kernel": true, "name": "vmlinux" },{ "id": 6, "size": 2365, "prog_ids": [8,6 ], "map_ids": [3 ], "kernel": false },{ "id": 7, "size": 46895, "prog_ids": [], "map_ids": [], "kernel": true, "name": "button" },{ ... Signed-off-by:Alan Maguire <alan.maguire@oracle.com> Link: https://lore.kernel.org/bpf/20201110011932.3201430-6-andrii@kernel.org
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Andrii Nakryiko authored
Add kernel module listener that will load/validate and unload module BTF. Module BTFs gets ID generated for them, which makes it possible to iterate them with existing BTF iteration API. They are given their respective module's names, which will get reported through GET_OBJ_INFO API. They are also marked as in-kernel BTFs for tooling to distinguish them from user-provided BTFs. Also, similarly to vmlinux BTF, kernel module BTFs are exposed through sysfs as /sys/kernel/btf/<module-name>. This is convenient for user-space tools to inspect module BTF contents and dump their types with existing tools: [vmuser@archvm bpf]$ ls -la /sys/kernel/btf total 0 drwxr-xr-x 2 root root 0 Nov 4 19:46 . drwxr-xr-x 13 root root 0 Nov 4 19:46 .. ... -r--r--r-- 1 root root 888 Nov 4 19:46 irqbypass -r--r--r-- 1 root root 100225 Nov 4 19:46 kvm -r--r--r-- 1 root root 35401 Nov 4 19:46 kvm_intel -r--r--r-- 1 root root 120 Nov 4 19:46 pcspkr -r--r--r-- 1 root root 399 Nov 4 19:46 serio_raw -r--r--r-- 1 root root 4094095 Nov 4 19:46 vmlinux Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/bpf/20201110011932.3201430-5-andrii@kernel.org
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Andrii Nakryiko authored
Detect if pahole supports split BTF generation, and generate BTF for each selected kernel module, if it does. This is exposed to Makefiles and C code as CONFIG_DEBUG_INFO_BTF_MODULES flag. Kernel module BTF has to be re-generated if either vmlinux's BTF changes or module's .ko changes. To achieve that, I needed a helper similar to if_changed, but that would allow to filter out vmlinux from the list of updated dependencies for .ko building. I've put it next to the only place that uses and needs it, but it might be a better idea to just add it along the other if_changed variants into scripts/Kbuild.include. Each kernel module's BTF deduplication is pretty fast, as it does only incremental BTF deduplication on top of already deduplicated vmlinux BTF. To show the added build time, I've first ran make only just built kernel (to establish the baseline) and then forced only BTF re-generation, without regenerating .ko files. The build was performed with -j60 parallelization on 56-core machine. The final time also includes bzImage building, so it's not a pure BTF overhead. $ time make -j60 ... make -j60 27.65s user 10.96s system 782% cpu 4.933 total $ touch ~/linux-build/default/vmlinux && time make -j60 ... make -j60 123.69s user 27.85s system 1566% cpu 9.675 total So 4.6 seconds real time, with noticeable part spent in compressed vmlinux and bzImage building. To show size savings, I've built my kernel configuration with about 700 kernel modules with full BTF per each kernel module (without deduplicating against vmlinux) and with split BTF against deduplicated vmlinux (approach in this patch). Below are top 10 modules with biggest BTF sizes. And total size of BTF data across all kernel modules. It shows that split BTF "compresses" 115MB down to 5MB total. And the biggest kernel modules get a downsize from 500-570KB down to 200-300KB. FULL BTF ======== $ for f in $(find . -name '*.ko'); do size -A -d $f | grep BTF | awk '{print $2}'; done | awk '{ s += $1 } END { print s }' 115710691 $ for f in $(find . -name '*.ko'); do printf "%s %d\n" $f $(size -A -d $f | grep BTF | awk '{print $2}'); done | sort -nr -k2 | head -n10 ./drivers/gpu/drm/i915/i915.ko 570570 ./drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.ko 520240 ./drivers/gpu/drm/radeon/radeon.ko 503849 ./drivers/infiniband/hw/mlx5/mlx5_ib.ko 491777 ./fs/xfs/xfs.ko 411544 ./drivers/net/ethernet/intel/i40e/i40e.ko 403904 ./drivers/net/ethernet/broadcom/bnx2x/bnx2x.ko 398754 ./drivers/infiniband/core/ib_core.ko 397224 ./fs/cifs/cifs.ko 386249 ./fs/nfsd/nfsd.ko 379738 SPLIT BTF ========= $ for f in $(find . -name '*.ko'); do size -A -d $f | grep BTF | awk '{print $2}'; done | awk '{ s += $1 } END { print s }' 5194047 $ for f in $(find . -name '*.ko'); do printf "%s %d\n" $f $(size -A -d $f | grep BTF | awk '{print $2}'); done | sort -nr -k2 | head -n10 ./drivers/gpu/drm/i915/i915.ko 293206 ./drivers/gpu/drm/radeon/radeon.ko 282103 ./fs/xfs/xfs.ko 222150 ./drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.ko 198503 ./drivers/infiniband/hw/mlx5/mlx5_ib.ko 198356 ./drivers/net/ethernet/broadcom/bnx2x/bnx2x.ko 113444 ./fs/cifs/cifs.ko 109379 ./arch/x86/kvm/kvm.ko 100225 ./drivers/gpu/drm/drm.ko 94827 ./drivers/infiniband/core/ib_core.ko 91188 Signed-off-by: -
Andrii Nakryiko authored
Allocate ID for vmlinux BTF. This makes it visible when iterating over all BTF objects in the system. To allow distinguishing vmlinux BTF (and later kernel module BTF) from user-provided BTFs, expose extra kernel_btf flag, as well as BTF name ("vmlinux" for vmlinux BTF, will equal to module's name for module BTF). We might want to later allow specifying BTF name for user-provided BTFs as well, if that makes sense. But currently this is reserved only for in-kernel BTFs. Having in-kernel BTFs exposed IDs will allow to extend BPF APIs that require in-kernel BTF type with ability to specify BTF types from kernel modules, not just vmlinux BTF. This will be implemented in a follow up patch set for fentry/fexit/fmod_ret/lsm/etc. Signed-off-by:Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20201110011932.3201430-3-andrii@kernel.org
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Andrii Nakryiko authored
Adjust in-kernel BTF implementation to support a split BTF mode of operation. Changes are mostly mirroring libbpf split BTF changes, with the exception of start_id being 0 for in-kernel implementation due to simpler read-only mode. Otherwise, for split BTF logic, most of the logic of jumping to base BTF, where necessary, is encapsulated in few helper functions. Type numbering and string offset in a split BTF are logically continuing where base BTF ends, so most of the high-level logic is kept without changes. Type verification and size resolution is only doing an added resolution of new split BTF types and relies on already cached size and type resolution results in the base BTF. Signed-off-by:
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Martin KaFai Lau authored
Some globals in the tcp_hdr_options test and btf_skc_cls_ingress test are not using static scope. This patch fixes it. Targeting bpf-next branch as an improvement since it currently does not break the build. Fixes: ad2f8eb0 ("bpf: selftests: Tcp header options") Fixes: 9a856cae ("bpf: selftest: Add test_btf_skc_cls_ingress") Signed-off-by:
John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20201106225402.4135741-1-kafai@fb.com
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- 09 Nov, 2020 2 commits
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Wang Qing authored
Remove duplicate btf_ids.h header which is included twice. Signed-off-by:
Wang Qing <wangqing@vivo.com> Signed-off-by:
Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/1604736650-11197-1-git-send-email-wangqing@vivo.com
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Menglong Dong authored
The 'bpf/bpf.h' include in 'samples/bpf/hbm.c' is duplicated. Signed-off-by:
Menglong Dong <dong.menglong@zte.com.cn> Signed-off-by:
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- 06 Nov, 2020 19 commits
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Alexei Starovoitov authored
pidfd_open was added in 2019. Some versions of libc library don't define it. Define it manually if it's not available. Reported-by:
Sergei Iudin <siudin@fb.com> Signed-off-by:
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KP Singh authored
Use the check_syscall_operations added for task_local_storage to exercise syscall operations for other local storage maps: * Check the absence of an element for the given fd. * Create a new element, retrieve and compare its value. * Delete the element and check again for absence. Signed-off-by:
KP Singh <kpsingh@google.com> Signed-off-by:
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KP Singh authored
The test exercises the syscall based map operations by creating a pidfd for the current process. For verifying kernel / LSM functionality, the test implements a simple MAC policy which denies an executable from unlinking itself. The LSM program bprm_committed_creds sets a task_local_storage with a pointer to the inode. This is then used to detect if the task is trying to unlink itself in the inode_unlink LSM hook. The test copies /bin/rm to /tmp and executes it in a child thread with the intention of deleting itself. A successful test should prevent the the running executable from deleting itself. The bpf programs are also updated to call bpf_spin_{lock, unlock} to trigger the verfier checks for spin locks. The temporary file is cleaned up later in the test. Signed-off-by: -
KP Singh authored
With the fixing of BTF pruning of embedded types being fixed, the test can be simplified to use vmlinux.h Signed-off-by:
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KP Singh authored
The {inode,sk}_storage_result checking if the correct value was retrieved was being clobbered unconditionally by the return value of the bpf_{inode,sk}_storage_delete call. Also, consistently use the newly added BPF_LOCAL_STORAGE_GET_F_CREATE flag. Fixes: cd324d7a ("bpf: Add selftests for local_storage") Signed-off-by: -
KP Singh authored
The currently available bpf_get_current_task returns an unsigned integer which can be used along with BPF_CORE_READ to read data from the task_struct but still cannot be used as an input argument to a helper that accepts an ARG_PTR_TO_BTF_ID of type task_struct. In order to implement this helper a new return type, RET_PTR_TO_BTF_ID, is added. This is similar to RET_PTR_TO_BTF_ID_OR_NULL but does not require checking the nullness of returned pointer. Signed-off-by:
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KP Singh authored
Updates the binary to handle the BPF_MAP_TYPE_TASK_STORAGE as "task_storage" for printing and parsing. Also updates the documentation and bash completion Signed-off-by:
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KP Singh authored
Updates the bpf_probe_map_type API to also support BPF_MAP_TYPE_TASK_STORAGE similar to other local storage maps. Signed-off-by:
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KP Singh authored
Similar to bpf_local_storage for sockets and inodes add local storage for task_struct. The life-cycle of storage is managed with the life-cycle of the task_struct. i.e. the storage is destroyed along with the owning task with a callback to the bpf_task_storage_free from the task_free LSM hook. The BPF LSM allocates an __rcu pointer to the bpf_local_storage in the security blob which are now stackable and can co-exist with other LSMs. The userspace map operations can be done by using a pid fd as a key passed to the lookup, update and delete operations. Signed-off-by:
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KP Singh authored
Usage of spin locks was not allowed for tracing programs due to insufficient preemption checks. The verifier does not currently prevent LSM programs from using spin locks, but the helpers are not exposed via bpf_lsm_func_proto. Based on the discussion in [1], non-sleepable LSM programs should be able to use bpf_spin_{lock, unlock}. Sleepable LSM programs can be preempted which means that allowng spin locks will need more work (disabling preemption and the verifier ensuring that no sleepable helpers are called when a spin lock is held). [1]: https://lore.kernel.org/bpf/20201103153132.2717326-1-kpsingh@chromium.org/T/#md601a053229287659071600d3483523f752cd2fbSigned-off-by: -
Florian Lehner authored
Currently key_size of hashtab is limited to MAX_BPF_STACK. As the key of hashtab can also be a value from a per cpu map it can be larger than MAX_BPF_STACK. The use-case for this patch originates to implement allow/disallow lists for files and file paths. The maximum length of file paths is defined by PATH_MAX with 4096 chars including nul. This limit exceeds MAX_BPF_STACK. Changelog: v5: - Fix cast overflow v4: - Utilize BPF skeleton in tests - Rebase v3: - Rebase v2: - Add a test for bpf side Signed-off-by:
Florian Lehner <dev@der-flo.net> Signed-off-by:
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Alexei Starovoitov authored
Andrii Nakryiko says: ==================== This patch set adds support for generating and deduplicating split BTF. This is an enhancement to the BTF, which allows to designate one BTF as the "base BTF" (e.g., vmlinux BTF), and one or more other BTFs as "split BTF" (e.g., kernel module BTF), which are building upon and extending base BTF with extra types and strings. Once loaded, split BTF appears as a single unified BTF superset of base BTF, with continuous and transparent numbering scheme. This allows all the existing users of BTF to work correctly and stay agnostic to the base/split BTFs composition. The only difference is in how to instantiate split BTF: it requires base BTF to be alread instantiated and passed to btf__new_xxx_split() or btf__parse_xxx_split() "constructors" explicitly. This split approach is necessary if we are to have a reasonably-sized kernel module BTFs. By deduping each kernel module's BTF individually, resulting module BTFs contain copies of a lot of kernel types that are already present in vmlinux BTF. Even those single copies result in a big BTF size bloat. On my kernel configuration with 700 modules built, non-split BTF approach results in 115MBs of BTFs across all modules. With split BTF deduplication approach, total size is down to 5.2MBs total, which is on part with vmlinux BTF (at around 4MBs). This seems reasonable and practical. As to why we'd need kernel module BTFs, that should be pretty obvious to anyone using BPF at this point, as it allows all the BTF-powered features to be used with kernel modules: tp_btf, fentry/fexit/fmod_ret, lsm, bpf_iter, etc. This patch set is a pre-requisite to adding split BTF support to pahole, which is a prerequisite to integrating split BTF into the Linux kernel build setup to generate BTF for kernel modules. The latter will come as a follow-up patch series once this series makes it to the libbpf and pahole makes use of it. Patch #4 introduces necessary basic support for split BTF into libbpf APIs. Patch #8 implements minimal changes to BTF dedup algorithm to allow deduplicating split BTFs. Patch #11 adds extra -B flag to bpftool to allow to specify the path to base BTF for cases when one wants to dump or inspect split BTF. All the rest are refactorings, clean ups, bug fixes and selftests. v1->v2: - addressed Song's feedback. ==================== Signed-off-by: -
Andrii Nakryiko authored
Add ability to work with split BTF by providing extra -B flag, which allows to specify the path to the base BTF file. Signed-off-by:
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Andrii Nakryiko authored
Add selftests validating BTF deduplication for split BTF case. Add a helper macro that allows to validate entire BTF with raw BTF dump, not just type-by-type. This saves tons of code and complexity. Signed-off-by:
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Andrii Nakryiko authored
In some cases compiler seems to generate distinct DWARF types for identical arrays within the same CU. That seems like a bug, but it's already out there and breaks type graph equivalence checks, so accommodate it anyway by checking for identical arrays, regardless of their type ID. Signed-off-by:
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Andrii Nakryiko authored
Add support for deduplication split BTFs. When deduplicating split BTF, base BTF is considered to be immutable and can't be modified or adjusted. 99% of BTF deduplication logic is left intact (module some type numbering adjustments). There are only two differences. First, each type in base BTF gets hashed (expect VAR and DATASEC, of course, those are always considered to be self-canonical instances) and added into a table of canonical table candidates. Hashing is a shallow, fast operation, so mostly eliminates the overhead of having entire base BTF to be a part of BTF dedup. Second difference is very critical and subtle. While deduplicating split BTF types, it is possible to discover that one of immutable base BTF BTF_KIND_FWD types can and should be resolved to a full STRUCT/UNION type from the split BTF part. This is, obviously, can't happen because we can't modify the base BTF types anymore. So because of that, any type in split BTF that directly or indirectly references that newly-to-be-resolved FWD type can't be considered to be equivalent to the corresponding canonical types in base BTF, because that would result in a loss of type resolution information. So in such case, split BTF types will be deduplicated separately and will cause some duplication of type information, which is unavoidable. With those two changes, the rest of the algorithm manages to deduplicate split BTF correctly, pointing all the duplicates to their canonical counter-parts in base BTF, but also is deduplicating whatever unique types are present in split BTF on their own. Also, theoretically, split BTF after deduplication could end up with either empty type section or empty string section. This is handled by libbpf correctly in one of previous patches in the series. Signed-off-by:
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Andrii Nakryiko authored
Make data section layout checks stricter, disallowing overlap of types and strings data. Additionally, allow BTFs with no type data. There is nothing inherently wrong with having BTF with no types (put potentially with some strings). This could be a situation with kernel module BTFs, if module doesn't introduce any new type information. Also fix invalid offset alignment check for btf->hdr->type_off. Fixes: 8a138aed ("bpf: btf: Add BTF support to libbpf") Signed-off-by:
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Andrii Nakryiko authored
Add re-usable btf_helpers.{c,h} to provide BTF-related testing routines. Start with adding a raw BTF dumping helpers. Raw BTF dump is the most succinct and at the same time a very human-friendly way to validate exact contents of BTF types. Cross-validate raw BTF dump and writable BTF in a single selftest. Raw type dump checks also serve as a good self-documentation. Signed-off-by: -
Andrii Nakryiko authored
Add selftest validating ability to programmatically generate and then dump split BTF. Signed-off-by:
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