From 39f77533b6c16e7fbd72e2560e13c9435d2602f5 Mon Sep 17 00:00:00 2001 From: Emil Tsalapatis Date: Tue, 6 Jan 2026 18:36:44 -0500 Subject: [PATCH] bpf: Allow calls to arena functions while holding spinlocks The bpf_arena_*_pages() kfuncs can be called from sleepable contexts, but the verifier still prevents BPF programs from calling them while holding a spinlock. Amend the verifier to allow for BPF programs calling arena page management functions while holding a lock. Signed-off-by: Emil Tsalapatis Link: https://lore.kernel.org/r/20260106-arena-under-lock-v2-2-378e9eab3066@etsalapatis.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7f82e27dd7e7c..53635ea2e41bb 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12373,6 +12373,7 @@ enum special_kfunc_type { KF_bpf_task_work_schedule_resume_impl, KF_bpf_arena_alloc_pages, KF_bpf_arena_free_pages, + KF_bpf_arena_reserve_pages, }; BTF_ID_LIST(special_kfunc_list) @@ -12449,6 +12450,7 @@ BTF_ID(func, bpf_task_work_schedule_signal_impl) BTF_ID(func, bpf_task_work_schedule_resume_impl) BTF_ID(func, bpf_arena_alloc_pages) BTF_ID(func, bpf_arena_free_pages) +BTF_ID(func, bpf_arena_reserve_pages) static bool is_task_work_add_kfunc(u32 func_id) { @@ -12884,10 +12886,17 @@ static bool is_bpf_res_spin_lock_kfunc(u32 btf_id) btf_id == special_kfunc_list[KF_bpf_res_spin_unlock_irqrestore]; } +static bool is_bpf_arena_kfunc(u32 btf_id) +{ + return btf_id == special_kfunc_list[KF_bpf_arena_alloc_pages] || + btf_id == special_kfunc_list[KF_bpf_arena_free_pages] || + btf_id == special_kfunc_list[KF_bpf_arena_reserve_pages]; +} + static bool kfunc_spin_allowed(u32 btf_id) { return is_bpf_graph_api_kfunc(btf_id) || is_bpf_iter_num_api_kfunc(btf_id) || - is_bpf_res_spin_lock_kfunc(btf_id); + is_bpf_res_spin_lock_kfunc(btf_id) || is_bpf_arena_kfunc(btf_id); } static bool is_sync_callback_calling_kfunc(u32 btf_id) -- 2.47.3