[bpf-next,v5,2/9] bpf: Support private stack for struct_ops programs

Commit Message

Yonghong Song Oct. 17, 2024, 10:31 p.m. UTC

Add 'priv_stack_allowed()' callback function in bpf_verifier_ops. If the
callback function returns true, the struct_ops are eligible to
use private stack. Otherwise, normal kernel stack is used.

Signed-off-by: Yonghong Song <[e-mail]>
---
 include/linux/bpf.h   | 1 +
 kernel/bpf/verifier.c | 2 ++
 2 files changed, 3 insertions(+)

Patch

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 6ad8ace7075a..a789cd2f5d6a 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -988,6 +988,7 @@  struct bpf_verifier_ops {
 	int (*btf_struct_access)(struct bpf_verifier_log *log,
 				 const struct bpf_reg_state *reg,
 				 int off, int size);
+	bool (*priv_stack_allowed)(void);
 };
 
 struct bpf_prog_offload_ops {
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a12f5e823284..a14857015ad4 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -5995,6 +5995,8 @@  static bool bpf_enable_private_stack(struct bpf_verifier_env *env)
 	case BPF_PROG_TYPE_PERF_EVENT:
 	case BPF_PROG_TYPE_RAW_TRACEPOINT:
 		return true;
+	case BPF_PROG_TYPE_STRUCT_OPS:
+		return env->ops->priv_stack_allowed && env->ops->priv_stack_allowed();
 	case BPF_PROG_TYPE_TRACING:
 		if (env->prog->expected_attach_type != BPF_TRACE_ITER)
 			return true;