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| author | Alexei Starovoitov <ast@kernel.org> | 2024-02-05 19:58:47 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-02-05 19:58:47 -0800 |
| commit | 8244ab509f89d63941d5ee207967c5a3e00bb493 (patch) | |
| tree | b0dda80da2bdd867ad47d5d108bbea0e1e5f822c /kernel/bpf/verifier.c | |
| parent | 2d9a925d0fbf0dae99af148adaf4f5cadf1be5e0 (diff) | |
| parent | e8699c4ff85baedcf40f33db816cc487cee39397 (diff) | |
Merge branch 'enable-static-subprog-calls-in-spin-lock-critical-sections'
Kumar Kartikeya Dwivedi says:
====================
Enable static subprog calls in spin lock critical sections
This set allows a BPF program to make a call to a static subprog within
a bpf_spin_lock critical section. This problem has been hit in sched-ext
and ghOSt [0] as well, and is mostly an annoyance which is worked around
by inling the static subprog into the critical section.
In case of sched-ext, there are a lot of other helper/kfunc calls that
need to be allow listed for the support to be complete, but a separate
follow up will deal with that.
Unlike static subprogs, global subprogs cannot be allowed yet as the
verifier will not explore their body when encountering a call
instruction for them. Therefore, we would need an alternative approach
(some sort of function summarization to ensure a lock is never taken
from a global subprog and all its callees).
[0]: https://lore.kernel.org/bpf/bd173bf2-dea6-3e0e-4176-4a9256a9a056@google.com
Changelog:
----------
v1 -> v2
v1: https://lore.kernel.org/bpf/20240204120206.796412-1-memxor@gmail.com
* Indicate global function call in verifier error string (Yonghong, David)
* Add Acks from Yonghong, David
====================
Link: https://lore.kernel.org/r/20240204222349.938118-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/verifier.c')
| -rw-r--r-- | kernel/bpf/verifier.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 64fa188d00ad..7d38b2343ad4 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9493,6 +9493,13 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, if (subprog_is_global(env, subprog)) { const char *sub_name = subprog_name(env, subprog); + /* Only global subprogs cannot be called with a lock held. */ + if (env->cur_state->active_lock.ptr) { + verbose(env, "global function calls are not allowed while holding a lock,\n" + "use static function instead\n"); + return -EINVAL; + } + if (err) { verbose(env, "Caller passes invalid args into func#%d ('%s')\n", subprog, sub_name); @@ -17644,7 +17651,6 @@ static int do_check(struct bpf_verifier_env *env) if (env->cur_state->active_lock.ptr) { if ((insn->src_reg == BPF_REG_0 && insn->imm != BPF_FUNC_spin_unlock) || - (insn->src_reg == BPF_PSEUDO_CALL) || (insn->src_reg == BPF_PSEUDO_KFUNC_CALL && (insn->off != 0 || !is_bpf_graph_api_kfunc(insn->imm)))) { verbose(env, "function calls are not allowed while holding a lock\n"); @@ -17692,8 +17698,7 @@ static int do_check(struct bpf_verifier_env *env) return -EINVAL; } process_bpf_exit_full: - if (env->cur_state->active_lock.ptr && - !in_rbtree_lock_required_cb(env)) { + if (env->cur_state->active_lock.ptr && !env->cur_state->curframe) { verbose(env, "bpf_spin_unlock is missing\n"); return -EINVAL; } |