3 files changed, 24 insertions, 0 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 7750df973494..580f89c450b5 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1897,6 +1897,7 @@ struct bpf_prog_aux {
 	bool changes_pkt_data;
 	bool has_prologue;
 	bool might_sleep;
+	bool can_unwind;
 	bool kprobe_write_ctx;
 	/* has insns that work with the arena base, see bpf_prog_has_arena_insns() */
 	bool uses_arena_insns;
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index 54481da4ed2d..6606b341351e 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -532,6 +532,8 @@ struct bpf_verifier_state {
 
 	bool speculative;
 	bool in_sleepable;
+	/* The callee left with unwind_exit. Next insn is unwind_goto. */
+	bool unwound;
 
 	/*
 	 * First and last insn idx of this verifier state.
@@ -957,6 +959,7 @@ struct bpf_subprog_info {
 	s16 fastcall_stack_off;
 	bool has_tail_call: 1;
 	bool might_throw: 1;
+	bool can_unwind: 1; /* has unwind_exit */
 	bool tail_call_reachable: 1;
 	bool has_ld_abs: 1;
 	bool is_cb: 1;
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 6f4c9bd024a0..fccd8db33647 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -254,6 +254,25 @@ static inline bool insn_is_mov_percpu_addr(const struct bpf_insn *insn)
 		.off   = 0,					\
 		.imm   = 1 })
 
+static inline bool bpf_is_unwind_goto(const struct bpf_insn *insn)
+{
+	return insn->code == (BPF_JMP | BPF_JCOND) && insn->src_reg == BPF_UNWIND_GOTO;
+}
+
+static inline bool bpf_is_unwind_exit(const struct bpf_insn *insn)
+{
+	return insn->code == (BPF_JMP | BPF_EXIT) && insn->src_reg == BPF_UNWIND_EXIT;
+}
+
+/*
+ * The caller of the main prog doesn't tell unwind_exit from exit. An extension
+ * is different: its caller is the caller of the subprog that it replaced.
+ */
+static inline bool bpf_prog_can_unwind(const struct bpf_prog *prog)
+{
+	return bpf_is_subprog(prog) || prog->type == BPF_PROG_TYPE_EXT;
+}
+
 static inline bool insn_is_zext(const struct bpf_insn *insn)
 {
 	return insn->code == (BPF_ALU | BPF_MOV | BPF_X) && insn->imm == 1;
@@ -1257,6 +1276,7 @@ bool bpf_jit_supports_percpu_insn(void);
 bool bpf_jit_supports_kfunc_call(void);
 bool bpf_jit_supports_callx(void);
 bool bpf_jit_supports_kfunc_ret_reg_pair(void);
+bool bpf_jit_supports_unwind(void);
 bool bpf_jit_supports_stack_args(void);
 bool bpf_jit_supports_arena_args(void);
 bool bpf_jit_supports_far_kfunc_call(void);