kernel/linux.git/include/linux/btf.h, branch linux-6.9.y

bpf: simplify btf_get_prog_ctx_type() into btf_is_prog_ctx_type()

2024-02-14T02:46:46+00:00

Return result of btf_get_prog_ctx_type() is never used and callers only check NULL vs non-NULL case to determine if given type matches expected PTR_TO_CTX type. So rename function to `btf_is_prog_ctx_type()` and return a simple true/false. We'll use this simpler interface to handle kprobe program type's special typedef case in the next patch. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240212233221.2575350-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov

bpf: Create argument information for nullable arguments.

2024-02-13T23:16:44+00:00

Collect argument information from the type information of stub functions to mark arguments of BPF struct_ops programs with PTR_MAYBE_NULL if they are nullable. A nullable argument is annotated by suffixing "__nullable" at the argument name of stub function. For nullable arguments, this patch sets a struct bpf_ctx_arg_aux to label their reg_type with PTR_TO_BTF_ID | PTR_TRUSTED | PTR_MAYBE_NULL. This makes the verifier to check programs and ensure that they properly check the pointer. The programs should check if the pointer is null before accessing the pointed memory. The implementer of a struct_ops type should annotate the arguments that can be null. The implementer should define a stub function (empty) as a placeholder for each defined operator. The name of a stub function should be in the pattern "__". For example, for test_maybe_null of struct bpf_testmod_ops, it's stub function name should be "bpf_testmod_ops__test_maybe_null". You mark an argument nullable by suffixing the argument name with "__nullable" at the stub function. Since we already has stub functions for kCFI, we just reuse these stub functions with the naming convention mentioned earlier. These stub functions with the naming convention is only required if there are nullable arguments to annotate. For functions having not nullable arguments, stub functions are not necessary for the purpose of this patch. This patch will prepare a list of struct bpf_ctx_arg_aux, aka arg_info, for each member field of a struct_ops type. "arg_info" will be assigned to "prog->aux->ctx_arg_info" of BPF struct_ops programs in check_struct_ops_btf_id() so that it can be used by btf_ctx_access() later to set reg_type properly for the verifier. Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20240209023750.1153905-4-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau

bpf: Move __kfunc_param_match_suffix() to btf.c.

2024-02-13T23:16:44+00:00

Move __kfunc_param_match_suffix() to btf.c and rename it as btf_param_match_suffix(). It can be reused by bpf_struct_ops later. Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20240209023750.1153905-3-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau

bpf, net: switch to dynamic registration

2024-01-24T01:12:46+00:00

Replace the static list of struct_ops types with per-btf struct_ops_tab to enable dynamic registration. Both bpf_dummy_ops and bpf_tcp_ca now utilize the registration function instead of being listed in bpf_struct_ops_types.h. Cc: netdev@vger.kernel.org Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20240119225005.668602-12-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau

bpf: refactory struct_ops type initialization to a function.

2024-01-24T00:37:43+00:00

Move the majority of the code to bpf_struct_ops_init_one(), which can then be utilized for the initialization of newly registered dynamically allocated struct_ops types in the following patches. Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20240119225005.668602-2-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau

bpf: extract bpf_ctx_convert_map logic and make it more reusable

2024-01-18T04:20:05+00:00

Refactor btf_get_prog_ctx_type() a bit to allow reuse of bpf_ctx_convert_map logic in more than one places. Simplify interface by returning btf_type instead of btf_member (field reference in BTF). To do the above we need to touch and start untangling btf_translate_to_vmlinux() implementation. We do the bare minimum to not regress anything for btf_translate_to_vmlinux(), but its implementation is very questionable for what it claims to be doing. Mapping kfunc argument types to kernel corresponding types conceptually is quite different from recognizing program context types. Fixing this is out of scope for this change though. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240118033143.3384355-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov

bpf: Add __bpf_hook_{start,end} macros

2023-11-02T05:33:53+00:00

Not all uses of __diag_ignore_all(...) in BPF-related code in order to suppress warnings are wrapping kfunc definitions. Some "hook point" definitions - small functions meant to be used as attach points for fentry and similar BPF progs - need to suppress -Wmissing-declarations. We could use __bpf_kfunc_{start,end}_defs added in the previous patch in such cases, but this might be confusing to someone unfamiliar with BPF internals. Instead, this patch adds __bpf_hook_{start,end} macros, currently having the same effect as __bpf_kfunc_{start,end}_defs, then uses them to suppress warnings for two hook points in the kernel itself and some bpf_testmod hook points as well. Signed-off-by: Dave Marchevsky Cc: Yafang Shao Acked-by: Jiri Olsa Acked-by: Yafang Shao Link: https://lore.kernel.org/r/20231031215625.2343848-2-davemarchevsky@fb.com Signed-off-by: Alexei Starovoitov

bpf: Add __bpf_kfunc_{start,end}_defs macros

2023-11-02T05:33:53+00:00

BPF kfuncs are meant to be called from BPF programs. Accordingly, most kfuncs are not called from anywhere in the kernel, which the -Wmissing-prototypes warning is unhappy about. We've peppered __diag_ignore_all("-Wmissing-prototypes", ... everywhere kfuncs are defined in the codebase to suppress this warning. This patch adds two macros meant to bound one or many kfunc definitions. All existing kfunc definitions which use these __diag calls to suppress -Wmissing-prototypes are migrated to use the newly-introduced macros. A new __diag_ignore_all - for "-Wmissing-declarations" - is added to the __bpf_kfunc_start_defs macro based on feedback from Andrii on an earlier version of this patch [0] and another recent mailing list thread [1]. In the future we might need to ignore different warnings or do other kfunc-specific things. This change will make it easier to make such modifications for all kfunc defs. [0]: https://lore.kernel.org/bpf/CAEf4BzaE5dRWtK6RPLnjTW-MW9sx9K3Fn6uwqCTChK2Dcb1Xig@mail.gmail.com/ [1]: https://lore.kernel.org/bpf/ZT+2qCc%2FaXep0%2FLf@krava/ Signed-off-by: Dave Marchevsky Suggested-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Cc: Jiri Olsa Acked-by: Jiri Olsa Acked-by: David Vernet Acked-by: Yafang Shao Link: https://lore.kernel.org/r/20231031215625.2343848-1-davemarchevsky@fb.com Signed-off-by: Alexei Starovoitov

bpf: teach the verifier to enforce css_iter and task_iter in RCU CS

2023-10-20T00:02:46+00:00

css_iter and task_iter should be used in rcu section. Specifically, in sleepable progs explicit bpf_rcu_read_lock() is needed before use these iters. In normal bpf progs that have implicit rcu_read_lock(), it's OK to use them directly. This patch adds a new a KF flag KF_RCU_PROTECTED for bpf_iter_task_new and bpf_iter_css_new. It means the kfunc should be used in RCU CS. We check whether we are in rcu cs before we want to invoke this kfunc. If the rcu protection is guaranteed, we would let st->type = PTR_TO_STACK | MEM_RCU. Once user do rcu_unlock during the iteration, state MEM_RCU of regs would be cleared. is_iter_reg_valid_init() will reject if reg->type is UNTRUSTED. It is worth noting that currently, bpf_rcu_read_unlock does not clear the state of the STACK_ITER reg, since bpf_for_each_spilled_reg only considers STACK_SPILL. This patch also let bpf_for_each_spilled_reg search STACK_ITER. Signed-off-by: Chuyi Zhou Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20231018061746.111364-6-zhouchuyi@bytedance.com Signed-off-by: Alexei Starovoitov

Merge tag 'probes-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2023-09-02T18:10:50+00:00

Pull probes updates from Masami Hiramatsu: - kprobes: use struct_size() for variable size kretprobe_instance data structure. - eprobe: Simplify trace_eprobe list iteration. - probe events: Data structure field access support on BTF argument. - Update BTF argument support on the functions in the kernel loadable modules (only loaded modules are supported). - Move generic BTF access function (search function prototype and get function parameters) to a separated file. - Add a function to search a member of data structure in BTF. - Support accessing BTF data structure member from probe args by C-like arrow('->') and dot('.') operators. e.g. 't sched_switch next=next->pid vruntime=next->se.vruntime' - Support accessing BTF data structure member from $retval. e.g. 'f getname_flags%return +0($retval->name):string' - Add string type checking if BTF type info is available. This will reject if user specify ":string" type for non "char pointer" type. - Automatically assume the fprobe event as a function return event if $retval is used. - selftests/ftrace: Add BTF data field access test cases. - Documentation: Update fprobe event example with BTF data field. * tag 'probes-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: Documentation: tracing: Update fprobe event example with BTF field selftests/ftrace: Add BTF fields access testcases tracing/fprobe-event: Assume fprobe is a return event by $retval tracing/probes: Add string type check with BTF tracing/probes: Support BTF field access from $retval tracing/probes: Support BTF based data structure field access tracing/probes: Add a function to search a member of a struct/union tracing/probes: Move finding func-proto API and getting func-param API to trace_btf tracing/probes: Support BTF argument on module functions tracing/eprobe: Iterate trace_eprobe directly kernel: kprobes: Use struct_size()