- /*
- * 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");
- }