On Tue, Oct 31, 2023 at 02:56:24PM -0700, Dave Marchevsky wrote: > 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@xxxxxxxxxxxxxx/ > [1]: https://lore.kernel.org/bpf/ZT+2qCc%2FaXep0%2FLf@krava/ > > Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx> > Suggested-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > Cc: Jiri Olsa <olsajiri@xxxxxxxxx> Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx> jirka > --- > > v1 -> v2: https://lore.kernel.org/bpf/20231030210638.2415306-1-davemarchevsky@xxxxxx/ > * Update Documentation/bpf/kfuncs.rst to use new macros (Yafang, Andrii) > * Update recently-added open-coded {task,cgroup} iters to use new > macros (Yafang, Andrii) > * Add Andrii ack > > Documentation/bpf/kfuncs.rst | 6 ++---- > include/linux/btf.h | 9 +++++++++ > kernel/bpf/bpf_iter.c | 6 ++---- > kernel/bpf/cgroup_iter.c | 6 ++---- > kernel/bpf/cpumask.c | 6 ++---- > kernel/bpf/helpers.c | 6 ++---- > kernel/bpf/map_iter.c | 6 ++---- > kernel/bpf/task_iter.c | 18 ++++++------------ > kernel/trace/bpf_trace.c | 6 ++---- > net/bpf/test_run.c | 7 +++---- > net/core/filter.c | 13 ++++--------- > net/core/xdp.c | 6 ++---- > net/ipv4/fou_bpf.c | 6 ++---- > net/netfilter/nf_conntrack_bpf.c | 6 ++---- > net/netfilter/nf_nat_bpf.c | 6 ++---- > net/xfrm/xfrm_interface_bpf.c | 6 ++---- > 16 files changed, 46 insertions(+), 73 deletions(-) > > diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst > index 0d2647fb358d..723408e399ab 100644 > --- a/Documentation/bpf/kfuncs.rst > +++ b/Documentation/bpf/kfuncs.rst > @@ -37,16 +37,14 @@ prototype in a header for the wrapper kfunc. > An example is given below:: > > /* Disables missing prototype warnings */ > - __diag_push(); > - __diag_ignore_all("-Wmissing-prototypes", > - "Global kfuncs as their definitions will be in BTF"); > + __bpf_kfunc_start_defs(); > > __bpf_kfunc struct task_struct *bpf_find_get_task_by_vpid(pid_t nr) > { > return find_get_task_by_vpid(nr); > } > > - __diag_pop(); > + __bpf_kfunc_end_defs(); > > A wrapper kfunc is often needed when we need to annotate parameters of the > kfunc. Otherwise one may directly make the kfunc visible to the BPF program by > diff --git a/include/linux/btf.h b/include/linux/btf.h > index c2231c64d60b..dc5ce962f600 100644 > --- a/include/linux/btf.h > +++ b/include/linux/btf.h > @@ -84,6 +84,15 @@ > */ > #define __bpf_kfunc __used noinline > > +#define __bpf_kfunc_start_defs() \ > + __diag_push(); \ > + __diag_ignore_all("-Wmissing-declarations", \ > + "Global kfuncs as their definitions will be in BTF");\ > + __diag_ignore_all("-Wmissing-prototypes", \ > + "Global kfuncs as their definitions will be in BTF") > + > +#define __bpf_kfunc_end_defs() __diag_pop() > + > /* > * Return the name of the passed struct, if exists, or halt the build if for > * example the structure gets renamed. In this way, developers have to revisit > diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c > index 833faa04461b..0fae79164187 100644 > --- a/kernel/bpf/bpf_iter.c > +++ b/kernel/bpf/bpf_iter.c > @@ -782,9 +782,7 @@ struct bpf_iter_num_kern { > int end; /* final value, exclusive */ > } __aligned(8); > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > > __bpf_kfunc int bpf_iter_num_new(struct bpf_iter_num *it, int start, int end) > { > @@ -843,4 +841,4 @@ __bpf_kfunc void bpf_iter_num_destroy(struct bpf_iter_num *it) > s->cur = s->end = 0; > } > > -__diag_pop(); > +__bpf_kfunc_end_defs(); > diff --git a/kernel/bpf/cgroup_iter.c b/kernel/bpf/cgroup_iter.c > index 209e5135f9fb..d1b5c5618dd7 100644 > --- a/kernel/bpf/cgroup_iter.c > +++ b/kernel/bpf/cgroup_iter.c > @@ -305,9 +305,7 @@ struct bpf_iter_css_kern { > unsigned int flags; > } __attribute__((aligned(8))); > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > > __bpf_kfunc int bpf_iter_css_new(struct bpf_iter_css *it, > struct cgroup_subsys_state *start, unsigned int flags) > @@ -358,4 +356,4 @@ __bpf_kfunc void bpf_iter_css_destroy(struct bpf_iter_css *it) > { > } > > -__diag_pop(); > \ No newline at end of file > +__bpf_kfunc_end_defs(); > diff --git a/kernel/bpf/cpumask.c b/kernel/bpf/cpumask.c > index 6983af8e093c..e01c741e54e7 100644 > --- a/kernel/bpf/cpumask.c > +++ b/kernel/bpf/cpumask.c > @@ -34,9 +34,7 @@ static bool cpu_valid(u32 cpu) > return cpu < nr_cpu_ids; > } > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global kfuncs as their definitions will be in BTF"); > +__bpf_kfunc_start_defs(); > > /** > * bpf_cpumask_create() - Create a mutable BPF cpumask. > @@ -407,7 +405,7 @@ __bpf_kfunc u32 bpf_cpumask_any_and_distribute(const struct cpumask *src1, > return cpumask_any_and_distribute(src1, src2); > } > > -__diag_pop(); > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(cpumask_kfunc_btf_ids) > BTF_ID_FLAGS(func, bpf_cpumask_create, KF_ACQUIRE | KF_RET_NULL) > diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c > index e46ac288a108..0e4657606eaa 100644 > --- a/kernel/bpf/helpers.c > +++ b/kernel/bpf/helpers.c > @@ -1886,9 +1886,7 @@ void bpf_rb_root_free(const struct btf_field *field, void *rb_root, > } > } > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > > __bpf_kfunc void *bpf_obj_new_impl(u64 local_type_id__k, void *meta__ign) > { > @@ -2505,7 +2503,7 @@ __bpf_kfunc void bpf_throw(u64 cookie) > WARN(1, "A call to BPF exception callback should never return\n"); > } > > -__diag_pop(); > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(generic_btf_ids) > #ifdef CONFIG_KEXEC_CORE > diff --git a/kernel/bpf/map_iter.c b/kernel/bpf/map_iter.c > index 6fc9dae9edc8..6abd7c5df4b3 100644 > --- a/kernel/bpf/map_iter.c > +++ b/kernel/bpf/map_iter.c > @@ -193,9 +193,7 @@ static int __init bpf_map_iter_init(void) > > late_initcall(bpf_map_iter_init); > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > > __bpf_kfunc s64 bpf_map_sum_elem_count(const struct bpf_map *map) > { > @@ -213,7 +211,7 @@ __bpf_kfunc s64 bpf_map_sum_elem_count(const struct bpf_map *map) > return ret; > } > > -__diag_pop(); > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(bpf_map_iter_kfunc_ids) > BTF_ID_FLAGS(func, bpf_map_sum_elem_count, KF_TRUSTED_ARGS) > diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c > index 59e747938bdb..6cd8295c9683 100644 > --- a/kernel/bpf/task_iter.c > +++ b/kernel/bpf/task_iter.c > @@ -824,9 +824,7 @@ struct bpf_iter_task_vma_kern { > struct bpf_iter_task_vma_kern_data *data; > } __attribute__((aligned(8))); > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > > __bpf_kfunc int bpf_iter_task_vma_new(struct bpf_iter_task_vma *it, > struct task_struct *task, u64 addr) > @@ -892,7 +890,7 @@ __bpf_kfunc void bpf_iter_task_vma_destroy(struct bpf_iter_task_vma *it) > } > } > > -__diag_pop(); > +__bpf_kfunc_end_defs(); > > struct bpf_iter_css_task { > __u64 __opaque[1]; > @@ -902,9 +900,7 @@ struct bpf_iter_css_task_kern { > struct css_task_iter *css_it; > } __attribute__((aligned(8))); > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > > __bpf_kfunc int bpf_iter_css_task_new(struct bpf_iter_css_task *it, > struct cgroup_subsys_state *css, unsigned int flags) > @@ -950,7 +946,7 @@ __bpf_kfunc void bpf_iter_css_task_destroy(struct bpf_iter_css_task *it) > bpf_mem_free(&bpf_global_ma, kit->css_it); > } > > -__diag_pop(); > +__bpf_kfunc_end_defs(); > > struct bpf_iter_task { > __u64 __opaque[3]; > @@ -971,9 +967,7 @@ enum { > BPF_TASK_ITER_PROC_THREADS > }; > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > > __bpf_kfunc int bpf_iter_task_new(struct bpf_iter_task *it, > struct task_struct *task__nullable, unsigned int flags) > @@ -1043,7 +1037,7 @@ __bpf_kfunc void bpf_iter_task_destroy(struct bpf_iter_task *it) > { > } > > -__diag_pop(); > +__bpf_kfunc_end_defs(); > > DEFINE_PER_CPU(struct mmap_unlock_irq_work, mmap_unlock_work); > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index df697c74d519..84e8a0f6e4e0 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -1252,9 +1252,7 @@ static const struct bpf_func_proto bpf_get_func_arg_cnt_proto = { > }; > > #ifdef CONFIG_KEYS > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "kfuncs which will be used in BPF programs"); > +__bpf_kfunc_start_defs(); > > /** > * bpf_lookup_user_key - lookup a key by its serial > @@ -1404,7 +1402,7 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr, > } > #endif /* CONFIG_SYSTEM_DATA_VERIFICATION */ > > -__diag_pop(); > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(key_sig_kfunc_set) > BTF_ID_FLAGS(func, bpf_lookup_user_key, KF_ACQUIRE | KF_RET_NULL | KF_SLEEPABLE) > diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c > index 0841f8d82419..c9fdcc5cdce1 100644 > --- a/net/bpf/test_run.c > +++ b/net/bpf/test_run.c > @@ -503,9 +503,8 @@ static int bpf_test_finish(const union bpf_attr *kattr, > * architecture dependent calling conventions. 7+ can be supported in the > * future. > */ > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > + > __bpf_kfunc int bpf_fentry_test1(int a) > { > return a + 1; > @@ -605,7 +604,7 @@ __bpf_kfunc void bpf_kfunc_call_memb_release(struct prog_test_member *p) > { > } > > -__diag_pop(); > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(bpf_test_modify_return_ids) > BTF_ID_FLAGS(func, bpf_modify_return_test) > diff --git a/net/core/filter.c b/net/core/filter.c > index 21d75108c2e9..383f96b0a1c7 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -11767,9 +11767,7 @@ bpf_sk_base_func_proto(enum bpf_func_id func_id) > return func; > } > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > __bpf_kfunc int bpf_dynptr_from_skb(struct sk_buff *skb, u64 flags, > struct bpf_dynptr_kern *ptr__uninit) > { > @@ -11816,7 +11814,7 @@ __bpf_kfunc int bpf_sock_addr_set_sun_path(struct bpf_sock_addr_kern *sa_kern, > > return 0; > } > -__diag_pop(); > +__bpf_kfunc_end_defs(); > > int bpf_dynptr_from_skb_rdonly(struct sk_buff *skb, u64 flags, > struct bpf_dynptr_kern *ptr__uninit) > @@ -11879,10 +11877,7 @@ static int __init bpf_kfunc_init(void) > } > late_initcall(bpf_kfunc_init); > > -/* Disables missing prototype warnings */ > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > > /* bpf_sock_destroy: Destroy the given socket with ECONNABORTED error code. > * > @@ -11916,7 +11911,7 @@ __bpf_kfunc int bpf_sock_destroy(struct sock_common *sock) > return sk->sk_prot->diag_destroy(sk, ECONNABORTED); > } > > -__diag_pop() > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(bpf_sk_iter_kfunc_ids) > BTF_ID_FLAGS(func, bpf_sock_destroy, KF_TRUSTED_ARGS) > diff --git a/net/core/xdp.c b/net/core/xdp.c > index df4789ab512d..b6f1d6dab3f2 100644 > --- a/net/core/xdp.c > +++ b/net/core/xdp.c > @@ -696,9 +696,7 @@ struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf) > return nxdpf; > } > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in vmlinux BTF"); > +__bpf_kfunc_start_defs(); > > /** > * bpf_xdp_metadata_rx_timestamp - Read XDP frame RX timestamp. > @@ -738,7 +736,7 @@ __bpf_kfunc int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, u32 *hash, > return -EOPNOTSUPP; > } > > -__diag_pop(); > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(xdp_metadata_kfunc_ids) > #define XDP_METADATA_KFUNC(_, __, name, ___) BTF_ID_FLAGS(func, name, KF_TRUSTED_ARGS) > diff --git a/net/ipv4/fou_bpf.c b/net/ipv4/fou_bpf.c > index 3760a14b6b57..4da03bf45c9b 100644 > --- a/net/ipv4/fou_bpf.c > +++ b/net/ipv4/fou_bpf.c > @@ -22,9 +22,7 @@ enum bpf_fou_encap_type { > FOU_BPF_ENCAP_GUE, > }; > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in BTF"); > +__bpf_kfunc_start_defs(); > > /* bpf_skb_set_fou_encap - Set FOU encap parameters > * > @@ -100,7 +98,7 @@ __bpf_kfunc int bpf_skb_get_fou_encap(struct __sk_buff *skb_ctx, > return 0; > } > > -__diag_pop() > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(fou_kfunc_set) > BTF_ID_FLAGS(func, bpf_skb_set_fou_encap) > diff --git a/net/netfilter/nf_conntrack_bpf.c b/net/netfilter/nf_conntrack_bpf.c > index b21799d468d2..475358ec8212 100644 > --- a/net/netfilter/nf_conntrack_bpf.c > +++ b/net/netfilter/nf_conntrack_bpf.c > @@ -230,9 +230,7 @@ static int _nf_conntrack_btf_struct_access(struct bpf_verifier_log *log, > return 0; > } > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in nf_conntrack BTF"); > +__bpf_kfunc_start_defs(); > > /* bpf_xdp_ct_alloc - Allocate a new CT entry > * > @@ -467,7 +465,7 @@ __bpf_kfunc int bpf_ct_change_status(struct nf_conn *nfct, u32 status) > return nf_ct_change_status_common(nfct, status); > } > > -__diag_pop() > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(nf_ct_kfunc_set) > BTF_ID_FLAGS(func, bpf_xdp_ct_alloc, KF_ACQUIRE | KF_RET_NULL) > diff --git a/net/netfilter/nf_nat_bpf.c b/net/netfilter/nf_nat_bpf.c > index 141ee7783223..6e3b2f58855f 100644 > --- a/net/netfilter/nf_nat_bpf.c > +++ b/net/netfilter/nf_nat_bpf.c > @@ -12,9 +12,7 @@ > #include <net/netfilter/nf_conntrack_core.h> > #include <net/netfilter/nf_nat.h> > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in nf_nat BTF"); > +__bpf_kfunc_start_defs(); > > /* bpf_ct_set_nat_info - Set source or destination nat address > * > @@ -54,7 +52,7 @@ __bpf_kfunc int bpf_ct_set_nat_info(struct nf_conn___init *nfct, > return nf_nat_setup_info(ct, &range, manip) == NF_DROP ? -ENOMEM : 0; > } > > -__diag_pop() > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(nf_nat_kfunc_set) > BTF_ID_FLAGS(func, bpf_ct_set_nat_info, KF_TRUSTED_ARGS) > diff --git a/net/xfrm/xfrm_interface_bpf.c b/net/xfrm/xfrm_interface_bpf.c > index d74f3fd20f2b..7d5e920141e9 100644 > --- a/net/xfrm/xfrm_interface_bpf.c > +++ b/net/xfrm/xfrm_interface_bpf.c > @@ -27,9 +27,7 @@ struct bpf_xfrm_info { > int link; > }; > > -__diag_push(); > -__diag_ignore_all("-Wmissing-prototypes", > - "Global functions as their definitions will be in xfrm_interface BTF"); > +__bpf_kfunc_start_defs(); > > /* bpf_skb_get_xfrm_info - Get XFRM metadata > * > @@ -93,7 +91,7 @@ __bpf_kfunc int bpf_skb_set_xfrm_info(struct __sk_buff *skb_ctx, const struct bp > return 0; > } > > -__diag_pop() > +__bpf_kfunc_end_defs(); > > BTF_SET8_START(xfrm_ifc_kfunc_set) > BTF_ID_FLAGS(func, bpf_skb_get_xfrm_info) > -- > 2.34.1 >