[ Upstream commit 96da3f7d489d11b43e7c1af90d876b9a2492cca8 ]

The hash map is now fully converted to bpf_mem_alloc. Its implementation is not allocating synchronously and not calling call_rcu() directly. It's now safe to use non-preallocated hash maps in all types of tracing programs including BPF_PROG_TYPE_PERF_EVENT that runs out of NMI context.

Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Kumar Kartikeya Dwivedi memxor@gmail.com Acked-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20220902211058.60789-13-alexei.starovoitov@gmail... Signed-off-by: Devaansh Kumar devaanshk840@gmail.com --- kernel/bpf/verifier.c | 29 ----------------------------- 1 file changed, 29 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 7049a85a78ab..77a75ccaae5e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -11700,35 +11700,6 @@ static int check_map_prog_compatibility(struct bpf_verifier_env *env,

{ enum bpf_prog_type prog_type = resolve_prog_type(prog); - /* - * Validate that trace type programs use preallocated hash maps. - * - * For programs attached to PERF events this is mandatory as the - * perf NMI can hit any arbitrary code sequence. - * - * All other trace types using preallocated hash maps are unsafe as - * well because tracepoint or kprobes can be inside locked regions - * of the memory allocator or at a place where a recursion into the - * memory allocator would see inconsistent state. - * - * On RT enabled kernels run-time allocation of all trace type - * programs is strictly prohibited due to lock type constraints. On - * !RT kernels it is allowed for backwards compatibility reasons for - * now, but warnings are emitted so developers are made aware of - * the unsafety and can fix their programs before this is enforced. - */ - if (is_tracing_prog_type(prog_type) && !is_preallocated_map(map)) { - if (prog_type == BPF_PROG_TYPE_PERF_EVENT) { - verbose(env, "perf_event programs can only use preallocated hash map\n"); - return -EINVAL; - } - if (IS_ENABLED(CONFIG_PREEMPT_RT)) { - verbose(env, "trace type programs can only use preallocated hash map\n"); - return -EINVAL; - } - WARN_ONCE(1, "trace type BPF program uses run-time allocation\n"); - verbose(env, "trace type programs with run-time allocated hash maps are unsafe. Switch to preallocated hash maps.\n"); - }

if (map_value_has_spin_lock(map)) { if (prog_type == BPF_PROG_TYPE_SOCKET_FILTER) {