[PATCH bpf-next v13 2/6] bpf: Add bpf_prog_run_array_sleepable()

[Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>]

From: Mykyta Yatsenko <yatsenko@meta.com>

Add bpf_prog_run_array_sleepable() for running BPF program arrays
on faultable tracepoints. Unlike bpf_prog_run_array_uprobe(), it
includes per-program recursion checking for private stack safety
and hardcodes is_uprobe to false.

Skip dummy_bpf_prog at the top of the loop. When
bpf_prog_array_delete_safe() replaces a detached program with
dummy_bpf_prog on allocation failure, the dummy is statically
allocated and has NULL active, stats, and aux fields. Identify
it by prog->len == 0, since every real program has at least one
instruction.

Keep bpf_prog_run_array_uprobe() unchanged for uprobe callers.

Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
---
 include/linux/bpf.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 3cb6b9e70080..d3aea3931b85 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -3079,6 +3079,56 @@ void bpf_dynptr_set_null(struct bpf_dynptr_kern *ptr);
 void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr);
 void bpf_prog_report_arena_violation(bool write, unsigned long addr, unsigned long fault_ip);
 
+static __always_inline u32
+bpf_prog_run_array_sleepable(const struct bpf_prog_array *array,
+			     const void *ctx, bpf_prog_run_fn run_prog)
+{
+	const struct bpf_prog_array_item *item;
+	struct bpf_prog *prog;
+	struct bpf_run_ctx *old_run_ctx;
+	struct bpf_trace_run_ctx run_ctx;
+	u32 ret = 1;
+
+	if (unlikely(!array))
+		return ret;
+
+	migrate_disable();
+
+	run_ctx.is_uprobe = false;
+
+	old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
+	item = &array->items[0];
+	while ((prog = READ_ONCE(item->prog))) {
+		/* Skip dummy_bpf_prog placeholder (len == 0) */
+		if (unlikely(!prog->len)) {
+			item++;
+			continue;
+		}
+
+		if (unlikely(!bpf_prog_get_recursion_context(prog))) {
+			bpf_prog_inc_misses_counter(prog);
+			bpf_prog_put_recursion_context(prog);
+			item++;
+			continue;
+		}
+
+		run_ctx.bpf_cookie = item->bpf_cookie;
+
+		if (!prog->sleepable) {
+			guard(rcu)();
+			ret &= run_prog(prog, ctx);
+		} else {
+			ret &= run_prog(prog, ctx);
+		}
+
+		bpf_prog_put_recursion_context(prog);
+		item++;
+	}
+	bpf_reset_run_ctx(old_run_ctx);
+	migrate_enable();
+	return ret;
+}
+
 #else /* !CONFIG_BPF_SYSCALL */
 static inline struct bpf_prog *bpf_prog_get(u32 ufd)
 {

-- 
2.52.0