kernel.git/tools/lib/bpf/bpf_helpers.h, branch master

libbpf: Remove extern declaration of bpf_stream_vprintk()

2026-02-18T22:58:47Z

An issue was reported that building BPF program which includes both vmlinux.h and bpf_helpers.h from libbpf fails due to conflicting declarations of bpf_stream_vprintk(). Remove the extern declaration from bpf_helpers.h to address this. In order to use bpf_stream_printk() macro, BPF programs are expected to either include vmlinux.h of the kernel they are targeting, or add their own extern declaration. Reported-by: Luca Boccassi Closes: https://github.com/libbpf/libbpf/issues/947 Signed-off-by: Ihor Solodrai Link: https://lore.kernel.org/r/20260218215651.2057673-3-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov

bpf: Migrate bpf_stream_vprintk() to KF_IMPLICIT_ARGS

2026-01-21T00:22:38Z

Implement bpf_stream_vprintk with an implicit bpf_prog_aux argument, and remote bpf_stream_vprintk_impl from the kernel. Update the selftests to use the new API with implicit argument. bpf_stream_vprintk macro is changed to use the new bpf_stream_vprintk kfunc, and the extern definition of bpf_stream_vprintk_impl is replaced accordingly. Reviewed-by: Eduard Zingerman Signed-off-by: Ihor Solodrai Link: https://lore.kernel.org/r/20260120222638.3976562-11-ihor.solodrai@linux.dev Signed-off-by: Alexei Starovoitov

bpf: add _impl suffix for bpf_stream_vprintk() kfunc

2025-11-05T01:50:25Z

Rename bpf_stream_vprintk() to bpf_stream_vprintk_impl(). This makes bpf_stream_vprintk() follow the already established "_impl" suffix-based naming convention for kfuncs with the bpf_prog_aux argument provided by the verifier implicitly. This convention will be taken advantage of with the upcoming KF_IMPLICIT_ARGS feature to preserve backwards compatibility to BPF programs. Acked-by: Andrii Nakryiko Signed-off-by: Mykyta Yatsenko Link: https://lore.kernel.org/r/20251104-implv2-v3-2-4772b9ae0e06@meta.com Signed-off-by: Alexei Starovoitov Acked-by: Ihor Solodrai

libbpf: __arg_untrusted in bpf_helpers.h

2025-07-07T15:25:07Z

Make btf_decl_tag("arg:untrusted") available for libbpf users via macro. Makes the following usage possible: void foo(struct bar *p __arg_untrusted) { ... } void bar(struct foo *p __arg_trusted) { ... foo(p->buz->bar); // buz derefrence looses __trusted ... } Acked-by: Kumar Kartikeya Dwivedi Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20250704230354.1323244-6-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov

libbpf: Add bpf_stream_printk() macro

2025-07-04T02:30:07Z

Add a convenience macro to print data to the BPF streams. BPF_STDOUT and BPF_STDERR stream IDs in the vmlinux.h can be passed to the macro to print to the respective streams. Acked-by: Andrii Nakryiko Acked-by: Eduard Zingerman Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20250703204818.925464-10-memxor@gmail.com Signed-off-by: Alexei Starovoitov

libbpf: Add likely/unlikely macros and use them in selftests

2025-04-04T15:53:24Z

A few selftests and, more importantly, consequent changes to the bpf_helpers.h file, use likely/unlikely macros, so define them here and remove duplicate definitions from existing selftests. Signed-off-by: Anton Protopopov Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20250331203618.1973691-3-a.s.protopopov@gmail.com

libbpf: define __uptr.

2024-10-24T17:25:59Z

Make __uptr available to BPF programs to enable them to define uptrs. Acked-by: Andrii Nakryiko Signed-off-by: Kui-Feng Lee Signed-off-by: Martin KaFai Lau Link: https://lore.kernel.org/r/20241023234759.860539-8-martin.lau@linux.dev Signed-off-by: Alexei Starovoitov

libbpf: Fix some typos in comments

2024-09-09T23:05:40Z

Fix some spelling errors in the code comments of libbpf: betwen -> between paremeters -> parameters knowning -> knowing definiton -> definition compatiblity -> compatibility overriden -> overridden occured -> occurred proccess -> process managment -> management nessary -> necessary Signed-off-by: Yusheng Zheng Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240909225952.30324-1-yunwei356@gmail.com

libbpf: Fix bpf_ksym_exists() in GCC

2024-05-03T05:47:22Z

The macro bpf_ksym_exists is defined in bpf_helpers.h as: #define bpf_ksym_exists(sym) ({ \ _Static_assert(!__builtin_constant_p(!!sym), #sym " should be marked as __weak"); \ !!sym; \ }) The purpose of the macro is to determine whether a given symbol has been defined, given the address of the object associated with the symbol. It also has a compile-time check to make sure the object whose address is passed to the macro has been declared as weak, which makes the check on `sym' meaningful. As it happens, the check for weak doesn't work in GCC in all cases, because __builtin_constant_p not always folds at parse time when optimizing. This is because optimizations that happen later in the compilation process, like inlining, may make a previously non-constant expression a constant. This results in errors like the following when building the selftests with GCC: bpf_helpers.h:190:24: error: expression in static assertion is not constant 190 | _Static_assert(!__builtin_constant_p(!!sym), #sym " should be marked as __weak"); \ | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ Fortunately recent versions of GCC support a __builtin_has_attribute that can be used to directly check for the __weak__ attribute. This patch changes bpf_helpers.h to use that builtin when building with a recent enough GCC, and to omit the check if GCC is too old to support the builtin. The macro used for GCC becomes: #define bpf_ksym_exists(sym) ({ \ _Static_assert(__builtin_has_attribute (*sym, __weak__), #sym " should be marked as __weak"); \ !!sym; \ }) Note that since bpf_ksym_exists is designed to get the address of the object associated with symbol SYM, we pass *sym to __builtin_has_attribute instead of sym. When an expression is passed to __builtin_has_attribute then it is the type of the passed expression that is checked for the specified attribute. The expression itself is not evaluated. This accommodates well with the existing usages of the macro: - For function objects: struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym __weak; [...] bpf_ksym_exists(bpf_task_acquire) - For variable objects: extern const struct rq runqueues __ksym __weak; /* typed */ [...] bpf_ksym_exists(&runqueues) Note also that BPF support was added in GCC 10 and support for __builtin_has_attribute in GCC 9. Locally tested in bpf-next master branch. No regressions. Signed-of-by: Jose E. Marchesi Signed-off-by: Andrii Nakryiko Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20240428112559.10518-1-jose.marchesi@oracle.com

bpf_helpers.h: Define bpf_tail_call_static when building with GCC

2024-04-26T15:10:04Z

The definition of bpf_tail_call_static in tools/lib/bpf/bpf_helpers.h is guarded by a preprocessor check to assure that clang is recent enough to support it. This patch updates the guard so the function is compiled when using GCC 13 or later as well. Tested in bpf-next master. No regressions. Signed-off-by: Jose E. Marchesi Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20240426145158.14409-1-jose.marchesi@oracle.com