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bpf: Allow calls to arena functions while holding spinlocks

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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 <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260106-arena-under-lock-v2-2-378e9eab3066@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Emil Tsalapatis 2026-01-06 18:36:44 -05:00 committed by Alexei Starovoitov
parent b25b48c7d3
commit 39f77533b6
1 changed files with 10 additions and 1 deletions
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11
kernel/bpf/verifier.c
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@ -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)