- 04 Sep, 2024 8 commits
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Yonghong Song authored
Daniel Hodges reported a jit error when playing with a sched-ext program. The error message is: unexpected jmp_cond padding: -4 bytes But further investigation shows the error is actual due to failed convergence. The following are some analysis: ... pass4, final_proglen=4391: ... 20e: 48 85 ff test rdi,rdi 211: 74 7d je 0x290 213: 48 8b 77 00 mov rsi,QWORD PTR [rdi+0x0] ... 289: 48 85 ff test rdi,rdi 28c: 74 17 je 0x2a5 28e: e9 7f ff ff ff jmp 0x212 293: bf 03 00 00 00 mov edi,0x3 Note that insn at 0x211 is 2-byte cond jump insn for offset 0x7d (-125) and insn at 0x28e is 5-byte jmp insn with offset -129. pass5, final_proglen=4392: ... 20e: 48 85 ff test rdi,rdi 211: 0f 84 80 00 00 00 je 0x297 217: 48 8b 77 00 mov rsi,QWORD PTR [rdi+0x0] ... 28d: 48 85 ff test rdi,rdi 290: 74 1a je 0x2ac 292: eb 84 jmp 0x218 294: bf 03 00 00 00 mov edi,0x3 Note that insn at 0x211 is 6-byte cond jump insn now since its offset becomes 0x80 based on previous round (0x293 - 0x213 = 0x80). At the same time, insn at 0x292 is a 2-byte insn since its offset is -124. pass6 will repeat the same code as in pass4. pass7 will repeat the same code as in pass5, and so on. This will prevent eventual convergence. Passes 1-14 are with padding = 0. At pass15, padding is 1 and related insn looks like: 211: 0f 84 80 00 00 00 je 0x297 217: 48 8b 77 00 mov rsi,QWORD PTR [rdi+0x0] ... 24d: 48 85 d2 test rdx,rdx The similar code in pass14: 211: 74 7d je 0x290 213: 48 8b 77 00 mov rsi,QWORD PTR [rdi+0x0] ... 249: 48 85 d2 test rdx,rdx 24c: 74 21 je 0x26f 24e: 48 01 f7 add rdi,rsi ... Before generating the following insn, 250: 74 21 je 0x273 "padding = 1" enables some checking to ensure nops is either 0 or 4 where #define INSN_SZ_DIFF (((addrs[i] - addrs[i - 1]) - (prog - temp))) nops = INSN_SZ_DIFF - 2 In this specific case, addrs[i] = 0x24e // from pass14 addrs[i-1] = 0x24d // from pass15 prog - temp = 3 // from 'test rdx,rdx' in pass15 so nops = -4 and this triggers the failure. To fix the issue, we need to break cycles of je <-> jmp. For example, in the above case, we have 211: 74 7d je 0x290 the offset is 0x7d. If 2-byte je insn is generated only if the offset is less than 0x7d (<= 0x7c), the cycle can be break and we can achieve the convergence. I did some study on other cases like je <-> je, jmp <-> je and jmp <-> jmp which may cause cycles. Those cases are not from actual reproducible cases since it is pretty hard to construct a test case for them. the results show that the offset <= 0x7b (0x7b = 123) should be enough to cover all cases. This patch added a new helper to generate 8-bit cond/uncond jmp insns only if the offset range is [-128, 123]. Reported-by:Daniel Hodges <hodgesd@meta.com> Signed-off-by:
Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20240904221251.37109-1-yonghong.song@linux.devSigned-off-by:
Alexei Starovoitov <ast@kernel.org>
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Feng Yang authored
The ARRAY_SIZE macro is more compact and more formal in linux source. Signed-off-by:
Feng Yang <yangfeng@kylinos.cn> Signed-off-by:
Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240903072559.292607-1-yangfeng59949@163.com
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Alexei Starovoitov authored
Martin KaFai Lau says: ==================== bpf: Follow up on gen_epilogue From: Martin KaFai Lau <martin.lau@kernel.org> The set addresses some follow ups on the earlier gen_epilogue patch set. ==================== Acked-by:
Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240904180847.56947-1-martin.lau@linux.devSigned-off-by:
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Martin KaFai Lau authored
There is a report on new indentation issue in epilogue_idx. This patch fixed it. Fixes: 169c3176 ("bpf: Add gen_epilogue to bpf_verifier_ops") Reported-by:
kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202408311622.4GzlzN33-lkp@intel.com/Signed-off-by:
Martin KaFai Lau <martin.lau@kernel.org> Link: https://lore.kernel.org/r/20240904180847.56947-3-martin.lau@linux.devSigned-off-by:
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Martin KaFai Lau authored
This patch removes the insn_buf array stack usage from the inline_bpf_loop(). Instead, the env->insn_buf is used. The usage in inline_bpf_loop() needs more than 16 insn, so the INSN_BUF_SIZE needs to be increased from 16 to 32. The compiler stack size warning on the verifier is gone after this change. Cc: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by:
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Rong Tao authored
In commit ba8de796 ("net: introduce sk_skb_reason_drop function") kfree_skb_reason() becomes an inline function and cannot be traced. samples/bpf is abandonware by now, and we should slowly but surely convert whatever makes sense into BPF selftests under tools/testing/selftests/bpf and just get rid of the rest. Link: https://github.com/torvalds/linux/commit/ba8de796baf4bdc03530774fb284fe3c97875566Signed-off-by:
Rong Tao <rongtao@cestc.cn> Link: https://lore.kernel.org/r/tencent_30ADAC88CB2915CA57E9512D4460035BA107@qq.comSigned-off-by:
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Yuan Chen authored
When the PROCMAP_QUERY is not defined, a compilation error occurs due to the mismatch of the procmap_query()'s params, procmap_query() only be called in the file where the function is defined, modify the params so they can match. We get a warning when build samples/bpf: trace_helpers.c:252:5: warning: no previous prototype for ‘procmap_query’ [-Wmissing-prototypes] 252 | int procmap_query(int fd, const void *addr, __u32 query_flags, size_t *start, size_t *offset, int *flags) | ^~~~~~~~~~~~~ As this function is only used in the file, mark it as 'static'. Fixes: 4e9e0760 ("selftests/bpf: make use of PROCMAP_QUERY ioctl if available") Signed-off-by:Yuan Chen <chenyuan@kylinos.cn> Link: https://lore.kernel.org/r/20240903012839.3178-1-chenyuan_fl@163.comSigned-off-by:
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Xu Kuohai authored
Currently, BPF_CALL is always jited to indirect call. When target is within the range of direct call, BPF_CALL can be jited to direct call. For example, the following BPF_CALL call __htab_map_lookup_elem is always jited to indirect call: mov x10, #0xffffffffffff18f4 movk x10, #0x821, lsl #16 movk x10, #0x8000, lsl #32 blr x10 When the address of target __htab_map_lookup_elem is within the range of direct call, the BPF_CALL can be jited to: bl 0xfffffffffd33bc98 This patch does such jit optimization by emitting arm64 direct calls for BPF_CALL when possible, indirect calls otherwise. Without this patch, the jit works as follows. 1. First pass A. Determine jited position and size for each bpf instruction. B. Computed the jited image size. 2. Allocate jited image with size computed in step 1. 3. Second pass A. Adjust jump offset for jump instructions B. Write the final image. This works because, for a given bpf prog, regardless of where the jited image is allocated, the jited result for each instruction is fixed. The second pass differs from the first only in adjusting the jump offsets, like changing "jmp imm1" to "jmp imm2", while the position and size of the "jmp" instruction remain unchanged. Now considering whether to jit BPF_CALL to arm64 direct or indirect call instruction. The choice depends solely on the jump offset: direct call if the jump offset is within 128MB, indirect call otherwise. For a given BPF_CALL, the target address is known, so the jump offset is decided by the jited address of the BPF_CALL instruction. In other words, for a given bpf prog, the jited result for each BPF_CALL is determined by its jited address. The jited address for a BPF_CALL is the jited image address plus the total jited size of all preceding instructions. For a given bpf prog, there are clearly no BPF_CALL instructions before the first BPF_CALL instruction. Since the jited result for all other instructions other than BPF_CALL are fixed, the total jited size preceding the first BPF_CALL is also fixed. Therefore, once the jited image is allocated, the jited address for the first BPF_CALL is fixed. Now that the jited result for the first BPF_CALL is fixed, the jited results for all instructions preceding the second BPF_CALL are fixed. So the jited address and result for the second BPF_CALL are also fixed. Similarly, we can conclude that the jited addresses and results for all subsequent BPF_CALL instructions are fixed. This means that, for a given bpf prog, once the jited image is allocated, the jited address and result for all instructions, including all BPF_CALL instructions, are fixed. Based on the observation, with this patch, the jit works as follows. 1. First pass Estimate the maximum jited image size. In this pass, all BPF_CALLs are jited to arm64 indirect calls since the jump offsets are unknown because the jited image is not allocated. 2. Allocate jited image with size estimated in step 1. 3. Second pass A. Determine the jited result for each BPF_CALL. B. Determine jited address and size for each bpf instruction. 4. Third pass A. Adjust jump offset for jump instructions. B. Write the final image. Signed-off-by:Xu Kuohai <xukuohai@huawei.com> Reviewed-by:
Puranjay Mohan <puranjay@kernel.org> Link: https://lore.kernel.org/r/20240903094407.601107-1-xukuohai@huaweicloud.comSigned-off-by:
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- 02 Sep, 2024 2 commits
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Mykyta Yatsenko authored
Wrong function is used to access the first enum64 element. Substituting btf_enum(t) with btf_enum64(t) for BTF_KIND_ENUM64. Fixes: 94133cf2 ("bpftool: Introduce btf c dump sorting") Signed-off-by:
Mykyta Yatsenko <yatsenko@meta.com> Signed-off-by:
Daniel Borkmann <daniel@iogearbox.net> Acked-by:
Quentin Monnet <qmo@kernel.org> Link: https://lore.kernel.org/bpf/20240902171721.105253-1-mykyta.yatsenko5@gmail.com
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Quentin Monnet authored
In bpftool-net documentation, two blank lines are missing in a recently added example, causing docutils to complain: $ cd tools/bpf/bpftool $ make doc DESCEND Documentation GEN bpftool-btf.8 GEN bpftool-cgroup.8 GEN bpftool-feature.8 GEN bpftool-gen.8 GEN bpftool-iter.8 GEN bpftool-link.8 GEN bpftool-map.8 GEN bpftool-net.8 <stdin>:189: (INFO/1) Possible incomplete section title. Treating the overline as ordinary text because it's so short. <stdin>:192: (INFO/1) Blank line missing before literal block (after the "::")? Interpreted as a definition list item. <stdin>:199: (INFO/1) Possible incomplete section title. Treating the overline as ordinary text because it's so short. <stdin>:201: (INFO/1) Blank line missing before literal block (after the "::")? Interpreted as a definition list item. GEN bpftool-perf.8 GEN bpftool-prog.8 GEN bpftool.8 GEN bpftool-struct_ops.8 Add the missing blank lines. Fixes: 0d7c0612 ("bpftool: Add document for net attach/detach on tcx subcommand") Signed-off-by:
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- 30 Aug, 2024 18 commits
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Ihor Solodrai authored
%.bpf.o objects depend on vmlinux.h, which makes them transitively dependent on unnecessary libbpf headers. However vmlinux.h doesn't actually change as often. When generating vmlinux.h, compare it to a previous version and update it only if there are changes. Example of build time improvement (after first clean build): $ touch ../../../lib/bpf/bpf.h $ time make -j8 Before: real 1m37.592s After: real 0m27.310s Notice that %.bpf.o gen step is skipped if vmlinux.h hasn't changed. Signed-off-by:
Ihor Solodrai <ihor.solodrai@pm.me> Signed-off-by:
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Ihor Solodrai authored
Test %.bpf.o objects actually depend only on some libbpf headers. Define a list of required headers and use it as TRUNNER_BPF_OBJS dependency. bpf_*.h list was determined by: $ grep -rh 'include <bpf/bpf_' progs | sort -u Signed-off-by: -
Eduard Zingerman authored
Create a BTF with endianness different from host, make a distilled base/split BTF pair from it, dump as raw bytes, import again and verify that endianness is preserved. Reviewed-by:
Alan Maguire <alan.maguire@oracle.com> Tested-by:
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Tony Ambardar authored
New split BTF needs to preserve base's endianness. Similarly, when creating a distilled BTF, we need to preserve original endianness. Fix by updating libbpf's btf__distill_base() and btf_new_empty() to retain the byte order of any source BTF objects when creating new ones. Fixes: ba451366 ("libbpf: Implement basic split BTF support") Fixes: 58e185a0 ("libbpf: Add btf__distill_base() creating split BTF with distilled base BTF") Reported-by:
Song Liu <song@kernel.org> Reported-by:
Tony Ambardar <tony.ambardar@gmail.com> Signed-off-by:
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Jinjie Ruan authored
Replace fput() with sockfd_put() in bpf_fd_reuseport_array_update_elem(). Signed-off-by:
Jinjie Ruan <ruanjinjie@huawei.com> Acked-by:
Stanislav Fomichev <sdf@fomichev.me> Link: https://lore.kernel.org/r/20240830020756.607877-1-ruanjinjie@huawei.comSigned-off-by:
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Alexey Gladkov authored
According to the documentation, when building a kernel with the C=2 parameter, all source files should be checked. But this does not happen for the kernel/bpf/ directory. $ touch kernel/bpf/core.o $ make C=2 CHECK=true kernel/bpf/core.o Outputs: CHECK scripts/mod/empty.c CALL scripts/checksyscalls.sh DESCEND objtool INSTALL libsubcmd_headers CC kernel/bpf/core.o As can be seen the compilation is done, but CHECK is not executed. This happens because kernel/bpf/Makefile has defined its own rule for compilation and forgotten the macro that does the check. There is no need to duplicate the build code, and this rule can be removed to use generic rules. Acked-by:
Masahiro Yamada <masahiroy@kernel.org> Tested-by:
Oleg Nesterov <oleg@redhat.com> Tested-by:
Alexey Gladkov <legion@kernel.org> Link: https://lore.kernel.org/r/20240830074350.211308-1-legion@kernel.orgSigned-off-by:
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Juntong Deng authored
This patch adds test cases for iter next method returning valid pointer, which can also used as usage examples. Currently iter next method should return valid pointer. iter_next_trusted is the correct usage and test if iter next method return valid pointer. bpf_iter_task_vma_next has KF_RET_NULL flag, so the returned pointer may be NULL. We need to check if the pointer is NULL before using it. iter_next_trusted_or_null is the incorrect usage. There is no checking before using the pointer, so it will be rejected by the verifier. iter_next_rcu and iter_next_rcu_or_null are similar test cases for KF_RCU_PROTECTED iterators. iter_next_rcu_not_trusted is used to test that the pointer returned by iter next method of KF_RCU_PROTECTED iterator cannot be passed in KF_TRUSTED_ARGS kfuncs. iter_next_ptr_mem_not_trusted is used to test that base type PTR_TO_MEM should not be combined with type flag PTR_TRUSTED. Signed-off-by:
Juntong Deng <juntong.deng@outlook.com> Link: https://lore.kernel.org/r/AM6PR03MB5848709758F6922F02AF9F1F99962@AM6PR03MB5848.eurprd03.prod.outlook.comSigned-off-by:
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Juntong Deng authored
Currently we cannot pass the pointer returned by iter next method as argument to KF_TRUSTED_ARGS or KF_RCU kfuncs, because the pointer returned by iter next method is not "valid". This patch sets the pointer returned by iter next method to be valid. This is based on the fact that if the iterator is implemented correctly, then the pointer returned from the iter next method should be valid. This does not make NULL pointer valid. If the iter next method has KF_RET_NULL flag, then the verifier will ask the ebpf program to check NULL pointer. KF_RCU_PROTECTED iterator is a special case, the pointer returned by iter next method should only be valid within RCU critical section, so it should be with MEM_RCU, not PTR_TRUSTED. Another special case is bpf_iter_num_next, which returns a pointer with base type PTR_TO_MEM. PTR_TO_MEM should not be combined with type flag PTR_TRUSTED (PTR_TO_MEM already means the pointer is valid). The pointer returned by iter next method of other types of iterators is with PTR_TRUSTED. In addition, this patch adds get_iter_from_state to help us get the current iterator from the current state. Signed-off-by:
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Alexei Starovoitov authored
Martin KaFai Lau says: ==================== bpf: Add gen_epilogue to bpf_verifier_ops From: Martin KaFai Lau <martin.lau@kernel.org> This set allows the subsystem to patch codes before BPF_EXIT. The verifier ops, .gen_epilogue, is added for this purpose. One of the use case will be in the bpf qdisc, the bpf qdisc subsystem can ensure the skb->dev is in the correct value. The bpf qdisc subsystem can either inline fixing it in the epilogue or call another kernel function to handle it (e.g. drop) in the epilogue. Another use case could be in bpf_tcp_ca.c to enforce snd_cwnd has valid value (e.g. positive value). v5: * Removed the skip_cnt argument from adjust_jmp_off() in patch 2. Instead, reuse the delta argument and skip the [tgt_idx, tgt_idx + delta) instructions. * Added a BPF_JMP32_A macro in patch 3. * Removed pro_epilogue_subprog.c in patch 6. The pro_epilogue_kfunc.c has covered the subprog case. Renamed the file pro_epilogue_kfunc.c to pro_epilogue.c. Some of the SEC names and function names are changed accordingly (mainly shorten them by removing the _kfunc suffix). * Added comments to explain the tail_call result in patch 7. * Fixed the following bpf CI breakages. I ran it in CI manually to confirm: https://github.com/kernel-patches/bpf/actions/runs/10590714532 * s390 zext added "w3 = w3". Adjusted the test to use all ALU64 and BPF_DW to avoid zext. Also changed the "int a" in the "struct st_ops_args" to "u64 a". * llvm17 does not take: *(u64 *)(r1 +0) = 0; so it is changed to: r3 = 0; *(u64 *)(r1 +0) = r3; v4: * Fixed a bug in the memcpy in patch 3 The size in the memcpy should be epilogue_cnt * sizeof(*epilogue_buf) v3: * Moved epilogue_buf[16] to env. Patch 1 is added to move the existing insn_buf[16] to env. * Fixed a case that the bpf prog has a BPF_JMP that goes back to the first instruction of the main prog. The jump back to 1st insn case also applies to the prologue. Patch 2 is added to handle it. * If the bpf main prog has multiple BPF_EXIT, use a BPF_JA to goto the earlier patched epilogue. Note that there are (BPF_JMP32 | BPF_JA) vs (BPF_JMP | BPF_JA) details in the patch 3 commit message. * There are subtle changes in patch 3, so I reset the Reviewed-by. * Added patch 8 and patch 9 to cover the changes in patch 2 and patch 3. * Dropped the kfunc call from pro/epilogue and its selftests. v2: * Remove the RFC tag. Keep the ordering at where .gen_epilogue is called in the verifier relative to the check_max_stack_depth(). This will be consistent with the other extra stack_depth usage like optimize_bpf_loop(). * Use __xlated check provided by the test_loader to check the patched instructions after gen_pro/epilogue (Eduard). * Added Patch 3 by Eduard (Thanks!). ==================== Link: https://lore.kernel.org/r/20240829210833.388152-1-martin.lau@linux.devSigned-off-by:
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Martin KaFai Lau authored
This patch tests the epilogue patching when the main prog has multiple BPF_EXIT. The verifier should have patched the 2nd (and later) BPF_EXIT with a BPF_JA that goes back to the earlier patched epilogue instructions. Acked-by:
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Martin KaFai Lau authored
This patch adds a pro/epilogue test when the main prog has a goto insn that goes back to the very first instruction of the prog. It is to test the correctness of the adjust_jmp_off(prog, 0, delta) after the verifier has applied the prologue and/or epilogue patch. Acked-by:
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Martin KaFai Lau authored
This patch adds a gen_epilogue test to test a main prog using a bpf_tail_call. A non test_loader test is used. The tailcall target program, "test_epilogue_subprog", needs to be used in a struct_ops map before it can be loaded. Another struct_ops map is also needed to host the actual "test_epilogue_tailcall" struct_ops program that does the bpf_tail_call. The earlier test_loader patch will attach all struct_ops maps but the bpf_testmod.c does not support >1 attached struct_ops. The earlier patch used the test_loader which has already covered checking for the patched pro/epilogue instructions. This is done by the __xlated tag. This patch goes for the regular skel load and syscall test to do the tailcall test that can also allow to directly pass the the "struct st_ops_args *args" as ctx_in to the SEC("syscall") program. Acked-by: -
Martin KaFai Lau authored
This test adds a new struct_ops "bpf_testmod_st_ops" in bpf_testmod. The ops of the bpf_testmod_st_ops is triggered by new kfunc calls "bpf_kfunc_st_ops_test_*logue". These new kfunc calls are primarily used by the SEC("syscall") program. The test triggering sequence is like: SEC("syscall") syscall_prologue(struct st_ops_args *args) bpf_kfunc_st_op_test_prologue(args) st_ops->test_prologue(args) .gen_prologue adds 1000 to args->a .gen_epilogue adds 10000 to args->a .gen_epilogue will also set the r0 to 2 * args->a. The .gen_prologue and .gen_epilogue of the bpf_testmod_st_ops will test the prog->aux->attach_func_name to decide if it needs to generate codes. The main programs of the pro_epilogue.c will call a new kfunc bpf_kfunc_st_ops_inc10 which does "args->a += 10". It will also call a subprog() which does "args->a += 1". This patch uses the test_loader infra to check the __xlated instructions patched after gen_prologue and/or gen_epilogue. The __xlated check is based on Eduard's example (Thanks!) in v1. args->a is returned by the struct_ops prog (either the main prog or the epilogue). Thus, the __retval of the SEC("syscall") prog is checked. For example, when triggering the ops in the 'SEC("struct_ops/test_epilogue") int test_epilogue' The expected args->a is +1 (subprog call) + 10 (kfunc call) + 10000 (.gen_epilogue) = 10011. The expected return value is 2 * 10011 (.gen_epilogue). Suggested-by: -
Eduard Zingerman authored
In test_loader based tests to bpf_map__attach_struct_ops() before call to bpf_prog_test_run_opts() in order to trigger bpf_struct_ops->reg() callbacks on kernel side. This allows to use __retval macro for struct_ops tests. Signed-off-by:
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Martin KaFai Lau authored
The bpf_testmod needs to use the bpf_tail_call helper in a later selftest patch. This patch is to EXPORT_GPL_SYMBOL the bpf_base_func_proto. Signed-off-by:
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Martin KaFai Lau authored
This patch adds a .gen_epilogue to the bpf_verifier_ops. It is similar to the existing .gen_prologue. Instead of allowing a subsystem to run code at the beginning of a bpf prog, it allows the subsystem to run code just before the bpf prog exit. One of the use case is to allow the upcoming bpf qdisc to ensure that the skb->dev is the same as the qdisc->dev_queue->dev. The bpf qdisc struct_ops implementation could either fix it up or drop the skb. Another use case could be in bpf_tcp_ca.c to enforce snd_cwnd has sane value (e.g. non zero). The epilogue can do the useful thing (like checking skb->dev) if it can access the bpf prog's ctx. Unlike prologue, r1 may not hold the ctx pointer. This patch saves the r1 in the stack if the .gen_epilogue has returned some instructions in the "epilogue_buf". The existing .gen_prologue is done in convert_ctx_accesses(). The new .gen_epilogue is done in the convert_ctx_accesses() also. When it sees the (BPF_JMP | BPF_EXIT) instruction, it will be patched with the earlier generated "epilogue_buf". The epilogue patching is only done for the main prog. Only one epilogue will be patched to the main program. When the bpf prog has multiple BPF_EXIT instructions, a BPF_JA is used to goto the earlier patched epilogue. Majority of the archs support (BPF_JMP32 | BPF_JA): x86, arm, s390, risv64, loongarch, powerpc and arc. This patch keeps it simple and always use (BPF_JMP32 | BPF_JA). A new macro BPF_JMP32_A is added to generate the (BPF_JMP32 | BPF_JA) insn. Acked-by:
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Martin KaFai Lau authored
The next patch will add a ctx ptr saving instruction "(r1 = *(u64 *)(r10 -8)" at the beginning for the main prog when there is an epilogue patch (by the .gen_epilogue() verifier ops added in the next patch). There is one corner case if the bpf prog has a BPF_JMP that jumps to the 1st instruction. It needs an adjustment such that those BPF_JMP instructions won't jump to the newly added ctx saving instruction. The commit 5337ac4c ("bpf: Fix the corner case with may_goto and jump to the 1st insn.") has the details on this case. Note that the jump back to 1st instruction is not limited to the ctx ptr saving instruction. The same also applies to the prologue. A later test, pro_epilogue_goto_start.c, has a test for the prologue only case. Thus, this patch does one adjustment after gen_prologue and the future ctx ptr saving. It is done by adjust_jmp_off(env->prog, 0, delta) where delta has the total number of instructions in the prologue and the future ctx ptr saving instruction. The adjust_jmp_off(env->prog, 0, delta) assumes that the prologue does not have a goto 1st instruction itself. To accommodate the prologue might have a goto 1st insn itself, this patch changes the adjust_jmp_off() to skip considering the instructions between [tgt_idx, tgt_idx + delta). Signed-off-by:
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Martin KaFai Lau authored
This patch moves the 'struct bpf_insn insn_buf[16]' stack usage to the bpf_verifier_env. A '#define INSN_BUF_SIZE 16' is also added to replace the ARRAY_SIZE(insn_buf) usages. Both convert_ctx_accesses() and do_misc_fixup() are changed to use the env->insn_buf. It is a refactoring work for adding the epilogue_buf[16] in a later patch. With this patch, the stack size usage decreased. Before: ./kernel/bpf/verifier.c:22133:5: warning: stack frame size (2584) After: ./kernel/bpf/verifier.c:22184:5: warning: stack frame size (2264) Reviewed-by:
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- 29 Aug, 2024 6 commits
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Hongbo Li authored
Use kvmemdup instead of kvmalloc() + memcpy() to simplify the code. No functional change intended. Acked-by:
Hongbo Li <lihongbo22@huawei.com> Link: https://lore.kernel.org/r/20240828062128.1223417-1-lihongbo22@huawei.comSigned-off-by:
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Yiming Xiang authored
In verifier.rst, there is a typo in section 'Register parentage chains'. Caller saved registers are r0-r5, callee saved registers are r6-r9. Here by context it means callee saved registers rather than caller saved registers. This may confuse users. Signed-off-by:
Yiming Xiang <kxiang@umich.edu> Link: https://lore.kernel.org/r/20240829031712.198489-1-kxiang@umich.eduSigned-off-by:
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Amery Hung authored
When dropping a local kptr, any kptr stashed into it is supposed to be freed through bpf_obj_free_fields->__bpf_obj_drop_impl recursively. Add a test to make sure it happens. The test first stashes a referenced kptr to "struct task" into a local kptr and gets the reference count of the task. Then, it drops the local kptr and reads the reference count of the task again. Since bpf_obj_free_fields and __bpf_obj_drop_impl will go through the local kptr recursively during bpf_obj_drop, the dtor of the stashed task kptr should eventually be called. The second reference count should be one less than the first one. Signed-off-by:
Amery Hung <amery.hung@bytedance.com> Acked-by:
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Andrii Nakryiko authored
We do an ugly copying of options in bpf_object__open_skeleton() just to be able to set object name from skeleton's recorded name (while still allowing user to override it through opts->object_name). This is not just ugly, but it also is broken due to memcpy() that doesn't take into account potential skel_opts' and user-provided opts' sizes differences due to backward and forward compatibility. This leads to copying over extra bytes and then failing to validate options properly. It could, technically, lead also to SIGSEGV, if we are unlucky. So just get rid of that memory copy completely and instead pass default object name into bpf_object_open() directly, simplifying all this significantly. The rule now is that obj_name should be non-NULL for bpf_object_open() when called with in-memory buffer, so validate that explicitly as well. We adopt bpf_object__open_mem() to this as well and generate default name (based on buffer memory address and size) outside of bpf_object_open(). Fixes: d66562fb ("libbpf: Add BPF object skeleton support") Reported-by:
Daniel Müller <deso@posteo.net> Signed-off-by:
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Juntong Deng authored
This patch adds test cases for zero offset (implicit cast) or non-zero offset pointer as KF_ACQUIRE kfuncs argument. Currently KF_ACQUIRE kfuncs should support passing in pointers like &sk->sk_write_queue (non-zero offset) or &sk->__sk_common (zero offset) and not be rejected by the verifier. Signed-off-by:
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Juntong Deng authored
Currently we cannot pass zero offset (implicit cast) or non-zero offset pointers to KF_ACQUIRE kfuncs. This is because KF_ACQUIRE kfuncs requires strict type matching, but zero offset or non-zero offset does not change the type of pointer, which causes the ebpf program to be rejected by the verifier. This can cause some problems, one example is that bpf_skb_peek_tail kfunc [0] cannot be implemented by just passing in non-zero offset pointers. We cannot pass pointers like &sk->sk_write_queue (non-zero offset) or &sk->__sk_common (zero offset) to KF_ACQUIRE kfuncs. This patch makes KF_ACQUIRE kfuncs not require strict type matching. [0]: https://lore.kernel.org/bpf/AM6PR03MB5848CA39CB4B7A4397D380B099B12@AM6PR03MB5848.eurprd03.prod.outlook.com/Signed-off-by:
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- 28 Aug, 2024 4 commits
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Hao Ge authored
Smatch reported the following warning: ./tools/testing/selftests/bpf/testing_helpers.c:455 get_xlated_program() warn: variable dereferenced before check 'buf' (see line 454) It seems correct,so let's modify it based on it's suggestion. Actually,commit b23ed4d7 ("selftests/bpf: Fix invalid pointer check in get_xlated_program()") fixed an issue in the test_verifier.c once,but it was reverted this time. Let's solve this issue with the minimal changes possible. Reported-by:Dan Carpenter <dan.carpenter@linaro.org> Closes: https://lore.kernel.org/all/1eb3732f-605a-479d-ba64-cd14250cbf91@stanley.mountain/ Fixes: b4b7a409 ("selftests/bpf: Factor out get_xlated_program() helper") Signed-off-by:
Hao Ge <gehao@kylinos.cn> Link: https://lore.kernel.org/r/20240820023622.29190-1-hao.ge@linux.devSigned-off-by:
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Alexei Starovoitov authored
Xu Kuohai says: ==================== bpf, arm64: Simplify jited prologue/epilogue From: Xu Kuohai <xukuohai@huawei.com> The arm64 jit blindly saves/restores all callee-saved registers, making the jited result looks a bit too compliated. For example, for an empty prog, the jited result is: 0: bti jc 4: mov x9, lr 8: nop c: paciasp 10: stp fp, lr, [sp, #-16]! 14: mov fp, sp 18: stp x19, x20, [sp, #-16]! 1c: stp x21, x22, [sp, #-16]! 20: stp x26, x25, [sp, #-16]! 24: mov x26, #0 28: stp x26, x25, [sp, #-16]! 2c: mov x26, sp 30: stp x27, x28, [sp, #-16]! 34: mov x25, sp 38: bti j // tailcall target 3c: sub sp, sp, #0 40: mov x7, #0 44: add sp, sp, #0 48: ldp x27, x28, [sp], #16 4c: ldp x26, x25, [sp], #16 50: ldp x26, x25, [sp], #16 54: ldp x21, x22, [sp], #16 58: ldp x19, x20, [sp], #16 5c: ldp fp, lr, [sp], #16 60: mov x0, x7 64: autiasp 68: ret Clearly, there is no need to save/restore unused callee-saved registers. This patch does this change, making the jited image to only save/restore the callee-saved registers it uses. Now the jited result of empty prog is: 0: bti jc 4: mov x9, lr 8: nop c: paciasp 10: stp fp, lr, [sp, #-16]! 14: mov fp, sp 18: stp xzr, x26, [sp, #-16]! 1c: mov x26, sp 20: bti j // tailcall target 24: mov x7, #0 28: ldp xzr, x26, [sp], #16 2c: ldp fp, lr, [sp], #16 30: mov x0, x7 34: autiasp 38: ret ==================== Acked-by:
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Xu Kuohai authored
The arm64 jit blindly saves/restores all callee-saved registers, making the jited result looks a bit too compliated. For example, for an empty prog, the jited result is: 0: bti jc 4: mov x9, lr 8: nop c: paciasp 10: stp fp, lr, [sp, #-16]! 14: mov fp, sp 18: stp x19, x20, [sp, #-16]! 1c: stp x21, x22, [sp, #-16]! 20: stp x26, x25, [sp, #-16]! 24: mov x26, #0 28: stp x26, x25, [sp, #-16]! 2c: mov x26, sp 30: stp x27, x28, [sp, #-16]! 34: mov x25, sp 38: bti j // tailcall target 3c: sub sp, sp, #0 40: mov x7, #0 44: add sp, sp, #0 48: ldp x27, x28, [sp], #16 4c: ldp x26, x25, [sp], #16 50: ldp x26, x25, [sp], #16 54: ldp x21, x22, [sp], #16 58: ldp x19, x20, [sp], #16 5c: ldp fp, lr, [sp], #16 60: mov x0, x7 64: autiasp 68: ret Clearly, there is no need to save/restore unused callee-saved registers. This patch does this change, making the jited image to only save/restore the callee-saved registers it uses. Now the jited result of empty prog is: 0: bti jc 4: mov x9, lr 8: nop c: paciasp 10: stp fp, lr, [sp, #-16]! 14: mov fp, sp 18: stp xzr, x26, [sp, #-16]! 1c: mov x26, sp 20: bti j // tailcall target 24: mov x7, #0 28: ldp xzr, x26, [sp], #16 2c: ldp fp, lr, [sp], #16 30: mov x0, x7 34: autiasp 38: ret Since bpf prog saves/restores its own callee-saved registers as needed, to make tailcall work correctly, the caller needs to restore its saved registers before tailcall, and the callee needs to save its callee-saved registers after tailcall. This extra restoring/saving instructions increases preformance overhead. [1] provides 2 benchmarks for tailcall scenarios. Below is the perf number measured in an arm64 KVM guest. The result indicates that the performance difference before and after the patch in typical tailcall scenarios is negligible. - Before: Performance counter stats for './test_progs -t tailcalls' (5 runs): 4313.43 msec task-clock # 0.874 CPUs utilized ( +- 0.16% ) 574 context-switches # 133.073 /sec ( +- 1.14% ) 0 cpu-migrations # 0.000 /sec 538 page-faults # 124.727 /sec ( +- 0.57% ) 10697772784 cycles # 2.480 GHz ( +- 0.22% ) (61.19%) 25511241955 instructions # 2.38 insn per cycle ( +- 0.08% ) (66.70%) 5108910557 branches # 1.184 G/sec ( +- 0.08% ) (72.38%) 2800459 branch-misses # 0.05% of all branches ( +- 0.51% ) (72.36%) TopDownL1 # 0.60 retiring ( +- 0.09% ) (66.84%) # 0.21 frontend_bound ( +- 0.15% ) (61.31%) # 0.12 bad_speculation ( +- 0.08% ) (50.11%) # 0.07 backend_bound ( +- 0.16% ) (33.30%) 8274201819 L1-dcache-loads # 1.918 G/sec ( +- 0.18% ) (33.15%) 468268 L1-dcache-load-misses # 0.01% of all L1-dcache accesses ( +- 4.69% ) (33.16%) 385383 LLC-loads # 89.345 K/sec ( +- 5.22% ) (33.16%) 38296 LLC-load-misses # 9.94% of all LL-cache accesses ( +- 42.52% ) (38.69%) 6886576501 L1-icache-loads # 1.597 G/sec ( +- 0.35% ) (38.69%) 1848585 L1-icache-load-misses # 0.03% of all L1-icache accesses ( +- 4.52% ) (44.23%) 9043645883 dTLB-loads # 2.097 G/sec ( +- 0.10% ) (44.33%) 416672 dTLB-load-misses # 0.00% of all dTLB cache accesses ( +- 5.15% ) (49.89%) 6925626111 iTLB-loads # 1.606 G/sec ( +- 0.35% ) (55.46%) 66220 iTLB-load-misses # 0.00% of all iTLB cache accesses ( +- 1.88% ) (55.50%) <not supported> L1-dcache-prefetches <not supported> L1-dcache-prefetch-misses 4.9372 +- 0.0526 seconds time elapsed ( +- 1.07% ) Performance counter stats for './test_progs -t flow_dissector' (5 runs): 10924.50 msec task-clock # 0.945 CPUs utilized ( +- 0.08% ) 603 context-switches # 55.197 /sec ( +- 1.13% ) 0 cpu-migrations # 0.000 /sec 566 page-faults # 51.810 /sec ( +- 0.42% ) 27381270695 cycles # 2.506 GHz ( +- 0.18% ) (60.46%) 56996583922 instructions # 2.08 insn per cycle ( +- 0.21% ) (66.11%) 10321647567 branches # 944.816 M/sec ( +- 0.17% ) (71.79%) 3347735 branch-misses # 0.03% of all branches ( +- 3.72% ) (72.15%) TopDownL1 # 0.52 retiring ( +- 0.13% ) (66.74%) # 0.27 frontend_bound ( +- 0.14% ) (61.27%) # 0.14 bad_speculation ( +- 0.19% ) (50.36%) # 0.07 backend_bound ( +- 0.42% ) (33.89%) 18740797617 L1-dcache-loads # 1.715 G/sec ( +- 0.43% ) (33.71%) 13715669 L1-dcache-load-misses # 0.07% of all L1-dcache accesses ( +- 32.85% ) (33.34%) 4087551 LLC-loads # 374.164 K/sec ( +- 29.53% ) (33.26%) 267906 LLC-load-misses # 6.55% of all LL-cache accesses ( +- 23.90% ) (38.76%) 15811864229 L1-icache-loads # 1.447 G/sec ( +- 0.12% ) (38.73%) 2976833 L1-icache-load-misses # 0.02% of all L1-icache accesses ( +- 9.73% ) (44.22%) 20138907471 dTLB-loads # 1.843 G/sec ( +- 0.18% ) (44.15%) 732850 dTLB-load-misses # 0.00% of all dTLB cache accesses ( +- 11.18% ) (49.64%) 15895726702 iTLB-loads # 1.455 G/sec ( +- 0.15% ) (55.13%) 152075 iTLB-load-misses # 0.00% of all iTLB cache accesses ( +- 4.71% ) (54.98%) <not supported> L1-dcache-prefetches <not supported> L1-dcache-prefetch-misses 11.5613 +- 0.0317 seconds time elapsed ( +- 0.27% ) - After: Performance counter stats for './test_progs -t tailcalls' (5 runs): 4278.78 msec task-clock # 0.871 CPUs utilized ( +- 0.15% ) 569 context-switches # 132.982 /sec ( +- 0.58% ) 0 cpu-migrations # 0.000 /sec 539 page-faults # 125.970 /sec ( +- 0.43% ) 10588986432 cycles # 2.475 GHz ( +- 0.20% ) (60.91%) 25303825043 instructions # 2.39 insn per cycle ( +- 0.08% ) (66.48%) 5110756256 branches # 1.194 G/sec ( +- 0.07% ) (72.03%) 2719569 branch-misses # 0.05% of all branches ( +- 2.42% ) (72.03%) TopDownL1 # 0.60 retiring ( +- 0.22% ) (66.31%) # 0.22 frontend_bound ( +- 0.21% ) (60.83%) # 0.12 bad_speculation ( +- 0.26% ) (50.25%) # 0.06 backend_bound ( +- 0.17% ) (33.52%) 8163648527 L1-dcache-loads # 1.908 G/sec ( +- 0.33% ) (33.52%) 694979 L1-dcache-load-misses # 0.01% of all L1-dcache accesses ( +- 30.53% ) (33.52%) 1902347 LLC-loads # 444.600 K/sec ( +- 48.84% ) (33.69%) 96677 LLC-load-misses # 5.08% of all LL-cache accesses ( +- 43.48% ) (39.30%) 6863517589 L1-icache-loads # 1.604 G/sec ( +- 0.37% ) (39.17%) 1871519 L1-icache-load-misses # 0.03% of all L1-icache accesses ( +- 6.78% ) (44.56%) 8927782813 dTLB-loads # 2.087 G/sec ( +- 0.14% ) (44.37%) 438237 dTLB-load-misses # 0.00% of all dTLB cache accesses ( +- 6.00% ) (49.75%) 6886906831 iTLB-loads # 1.610 G/sec ( +- 0.36% ) (55.08%) 67568 iTLB-load-misses # 0.00% of all iTLB cache accesses ( +- 3.27% ) (54.86%) <not supported> L1-dcache-prefetches <not supported> L1-dcache-prefetch-misses 4.9114 +- 0.0309 seconds time elapsed ( +- 0.63% ) Performance counter stats for './test_progs -t flow_dissector' (5 runs): 10948.40 msec task-clock # 0.942 CPUs utilized ( +- 0.05% ) 615 context-switches # 56.173 /sec ( +- 1.65% ) 1 cpu-migrations # 0.091 /sec ( +- 31.62% ) 567 page-faults # 51.788 /sec ( +- 0.44% ) 27334194328 cycles # 2.497 GHz ( +- 0.08% ) (61.05%) 56656528828 instructions # 2.07 insn per cycle ( +- 0.08% ) (66.67%) 10270389422 branches # 938.072 M/sec ( +- 0.10% ) (72.21%) 3453837 branch-misses # 0.03% of all branches ( +- 3.75% ) (72.27%) TopDownL1 # 0.52 retiring ( +- 0.16% ) (66.55%) # 0.27 frontend_bound ( +- 0.09% ) (60.91%) # 0.14 bad_speculation ( +- 0.08% ) (49.85%) # 0.07 backend_bound ( +- 0.16% ) (33.33%) 18982866028 L1-dcache-loads # 1.734 G/sec ( +- 0.24% ) (33.34%) 8802454 L1-dcache-load-misses # 0.05% of all L1-dcache accesses ( +- 52.30% ) (33.31%) 2612962 LLC-loads # 238.661 K/sec ( +- 29.78% ) (33.45%) 264107 LLC-load-misses # 10.11% of all LL-cache accesses ( +- 18.34% ) (39.07%) 15793205997 L1-icache-loads # 1.443 G/sec ( +- 0.15% ) (39.09%) 3930802 L1-icache-load-misses # 0.02% of all L1-icache accesses ( +- 3.72% ) (44.66%) 20097828496 dTLB-loads # 1.836 G/sec ( +- 0.09% ) (44.68%) 961757 dTLB-load-misses # 0.00% of all dTLB cache accesses ( +- 3.32% ) (50.15%) 15838728506 iTLB-loads # 1.447 G/sec ( +- 0.09% ) (55.62%) 167652 iTLB-load-misses # 0.00% of all iTLB cache accesses ( +- 1.28% ) (55.52%) <not supported> L1-dcache-prefetches <not supported> L1-dcache-prefetch-misses 11.6173 +- 0.0268 seconds time elapsed ( +- 0.23% ) [1] https://lore.kernel.org/bpf/20200724123644.5096-1-maciej.fijalkowski@intel.com/Signed-off-by: -
Xu Kuohai authored
bpf prog accesses stack using BPF_FP as the base address and a negative immediate number as offset. But arm64 ldr/str instructions only support non-negative immediate number as offset. To simplify the jited result, commit 5b3d19b9 ("bpf, arm64: Adjust the offset of str/ldr(immediate) to positive number") introduced FPB to represent the lowest stack address that the bpf prog being jited may access, and with this address as the baseline, it converts BPF_FP plus negative immediate offset number to FPB plus non-negative immediate offset. Considering that for a given bpf prog, the jited stack space is fixed with A64_SP as the lowest address and BPF_FP as the highest address. Thus we can get rid of FPB and converts BPF_FP plus negative immediate offset to A64_SP plus non-negative immediate offset. Signed-off-by:
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- 27 Aug, 2024 1 commit
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Rong Tao authored
commit 7bd230a2 ("mm/slab: enable slab allocation tagging for kmalloc and friends") [1] swap kmem_cache_alloc_node() to kmem_cache_alloc_node_noprof(). linux/samples/bpf$ sudo ./tracex4 libbpf: prog 'bpf_prog2': failed to create kretprobe 'kmem_cache_alloc_node+0x0' perf event: No such file or directory ERROR: bpf_program__attach failed Signed-off-by:
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- 23 Aug, 2024 1 commit
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Jordan Rome authored
This adds tests for both the happy path and the error path. Signed-off-by:
Jordan Rome <linux@jordanrome.com> Link: https://lore.kernel.org/r/20240823195101.3621028-2-linux@jordanrome.comSigned-off-by:
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