ftrace: host klp and bpf trampoline together #537
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This enables users of ftrace_direct_multi to specify the flags based on the actual use case. For example, some users may not set flag IPMODIFY. Signed-off-by: Song Liu <song@kernel.org>
This is similar to modify_ftrace_direct_multi, but does not acquire direct_mutex. This is useful when direct_mutex is already locked by the user. Signed-off-by: Song Liu <song@kernel.org>
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live patch and BPF trampoline (kfunc/kretfunc in bpftrace) are important features for modern systems. Currently, it is not possible to use live patch and BPF trampoline on the same kernel function at the same time. This is because of the resitriction that only one ftrace_ops with flag FTRACE_OPS_FL_IPMODIFY on the same kernel function. BPF trampoline uses direct ftrace_ops, which assumes IPMODIFY. However, not all direct ftrace_ops would overwrite the actual function. This means it is possible to have a non-IPMODIFY direct ftrace_ops to share the same kernel function with an IPMODIFY ftrace_ops. Introduce FTRACE_OPS_FL_SHARE_IPMODIFY, which allows the direct ftrace_ops to share with IPMODIFY ftrace_ops. With FTRACE_OPS_FL_SHARE_IPMODIFY flag set, the direct ftrace_ops would call the target function picked by the IPMODIFY ftrace_ops. Comment "IPMODIFY, DIRECT, and SHARE_IPMODIFY" in include/linux/ftrace.h contains more information about how SHARE_IPMODIFY interacts with IPMODIFY and DIRECT flags. Signed-off-by: Song Liu <song@kernel.org>
Currently we call the original function by using the absolute address given at the JIT generation. That's not usable when having trampoline attached to multiple functions, or the target address changes dynamically (in case of live patch). In such cases we need to take the return address from the stack. Adding support to retrieve the original function address from the stack by adding new BPF_TRAMP_F_ORIG_STACK flag for arch_prepare_bpf_trampoline function. Basically we take the return address of the 'fentry' call: function + 0: call fentry # stores 'function + 5' address on stack function + 5: ... The 'function + 5' address will be used as the address for the original function to call. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Song Liu <song@kernel.org>
This allows bpf trampoline to trace kernel functions with live patch. Also, move bpf trampoline to *_ftrace_direct_multi APIs, which allows setting different flags of ftrace_ops. Signed-off-by: Song Liu <song@kernel.org>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=646972 expired. Closing PR. |
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Nov 22, 2025
Puranjay Mohan says: ==================== bpf: arm64: Indirect jumps Changes in v1->v2: v1: https://lore.kernel.org/all/20251117004656.33292-1-puranjay@kernel.org/ - Dropped patch 3 that was ignoring relocations for .jumptables. LLVM has been fixed to not emit relocations for .jumptables, so this patch is not needed. - Added Reviewed-by: Anton Protopopov <a.s.protopopov@gmail.com> This set adds the support of indirect jumps to the arm64 JIT. It involves calling bpf_prog_update_insn_ptrs() to support instructions array map. The second piece is supporting BPF_JMP|BPF_X|BPF_JA, SRC=0, DST=Rx, off=0, imm=0 instruction that is trivial to implement on arm64. The final patch enables selftests on arm64: [root@localhost bpf]# ./test_progs-cpuv4 -a "*gotox*" #20/1 bpf_gotox/one-switch:OK #20/2 bpf_gotox/one-switch-non-zero-sec-offset:OK #20/3 bpf_gotox/two-switches:OK #20/4 bpf_gotox/big-jump-table:OK #20/5 bpf_gotox/static-global:OK #20/6 bpf_gotox/nonstatic-global:OK #20/7 bpf_gotox/other-sec:OK #20/8 bpf_gotox/static-global-other-sec:OK #20/9 bpf_gotox/nonstatic-global-other-sec:OK #20/10 bpf_gotox/one-jump-two-maps:OK #20/11 bpf_gotox/one-map-two-jumps:OK #20 bpf_gotox:OK #537/1 verifier_gotox/jump_table_ok:OK #537/2 verifier_gotox/jump_table_reserved_field_src_reg:OK #537/3 verifier_gotox/jump_table_reserved_field_non_zero_off:OK #537/4 verifier_gotox/jump_table_reserved_field_non_zero_imm:OK #537/5 verifier_gotox/jump_table_no_jump_table:OK #537/6 verifier_gotox/jump_table_incorrect_dst_reg_type:OK #537/7 verifier_gotox/jump_table_invalid_read_size_u32:OK #537/8 verifier_gotox/jump_table_invalid_read_size_u16:OK #537/9 verifier_gotox/jump_table_invalid_read_size_u8:OK #537/10 verifier_gotox/jump_table_misaligned_access:OK #537/11 verifier_gotox/jump_table_invalid_mem_acceess_pos:OK #537/12 verifier_gotox/jump_table_invalid_mem_acceess_neg:OK #537/13 verifier_gotox/jump_table_add_sub_ok:OK #537/14 verifier_gotox/jump_table_no_writes:OK #537/15 verifier_gotox/jump_table_use_reg_r0:OK #537/16 verifier_gotox/jump_table_use_reg_r1:OK #537/17 verifier_gotox/jump_table_use_reg_r2:OK #537/18 verifier_gotox/jump_table_use_reg_r3:OK #537/19 verifier_gotox/jump_table_use_reg_r4:OK #537/20 verifier_gotox/jump_table_use_reg_r5:OK #537/21 verifier_gotox/jump_table_use_reg_r6:OK #537/22 verifier_gotox/jump_table_use_reg_r7:OK #537/23 verifier_gotox/jump_table_use_reg_r8:OK #537/24 verifier_gotox/jump_table_use_reg_r9:OK #537/25 verifier_gotox/jump_table_outside_subprog:OK #537/26 verifier_gotox/jump_table_contains_non_unique_values:OK #537 verifier_gotox:OK Summary: 2/37 PASSED, 0 SKIPPED, 0 FAILED ==================== Link: https://patch.msgid.link/20251117130732.11107-1-puranjay@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Pull request for series with
subject: ftrace: host klp and bpf trampoline together
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=646640