From 391145ba2accc48b596f3d438af1a6255b62a555 Mon Sep 17 00:00:00 2001 From: Dave Marchevsky Date: Tue, 31 Oct 2023 14:56:24 -0700 Subject: bpf: Add __bpf_kfunc_{start,end}_defs macros 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 --- kernel/bpf/cgroup_iter.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'kernel/bpf/cgroup_iter.c') 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(); -- cgit From 0de4f50de25af79c2a46db55d70cdbd8f985c6d1 Mon Sep 17 00:00:00 2001 From: Chuyi Zhou Date: Tue, 7 Nov 2023 21:22:03 +0800 Subject: bpf: Let verifier consider {task,cgroup} is trusted in bpf_iter_reg BTF_TYPE_SAFE_TRUSTED(struct bpf_iter__task) in verifier.c wanted to teach BPF verifier that bpf_iter__task -> task is a trusted ptr. But it doesn't work well. The reason is, bpf_iter__task -> task would go through btf_ctx_access() which enforces the reg_type of 'task' is ctx_arg_info->reg_type, and in task_iter.c, we actually explicitly declare that the ctx_arg_info->reg_type is PTR_TO_BTF_ID_OR_NULL. Actually we have a previous case like this[1] where PTR_TRUSTED is added to the arg flag for map_iter. This patch sets ctx_arg_info->reg_type is PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED in task_reg_info. Similarly, bpf_cgroup_reg_info -> cgroup is also PTR_TRUSTED since we are under the protection of cgroup_mutex and we would check cgroup_is_dead() in __cgroup_iter_seq_show(). This patch is to improve the user experience of the newly introduced bpf_iter_css_task kfunc before hitting the mainline. The Fixes tag is pointing to the commit introduced the bpf_iter_css_task kfunc. Link[1]:https://lore.kernel.org/all/20230706133932.45883-3-aspsk@isovalent.com/ Fixes: 9c66dc94b62a ("bpf: Introduce css_task open-coded iterator kfuncs") Signed-off-by: Chuyi Zhou Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20231107132204.912120-2-zhouchuyi@bytedance.com Signed-off-by: Martin KaFai Lau --- kernel/bpf/cgroup_iter.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/bpf/cgroup_iter.c') diff --git a/kernel/bpf/cgroup_iter.c b/kernel/bpf/cgroup_iter.c index d1b5c5618dd7..f04a468cf6a7 100644 --- a/kernel/bpf/cgroup_iter.c +++ b/kernel/bpf/cgroup_iter.c @@ -282,7 +282,7 @@ static struct bpf_iter_reg bpf_cgroup_reg_info = { .ctx_arg_info_size = 1, .ctx_arg_info = { { offsetof(struct bpf_iter__cgroup, cgroup), - PTR_TO_BTF_ID_OR_NULL }, + PTR_TO_BTF_ID_OR_NULL | PTR_TRUSTED }, }, .seq_info = &cgroup_iter_seq_info, }; -- cgit