The BPF core/verifier is hard-coded to permit mixing bpf2bpf and tail
calls for only x86-64. Change the logic to instead rely on a new weak
function 'bool bpf_jit_supports_subprog_tailcalls(void)', which a capable
JIT backend can override.
Update the x86-64 eBPF JIT to reflect this.
Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
[jakub: drop MIPS bits and tweak patch subject]
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220617105735.733938-2-jakub@cloudflare.com
return ERR_PTR(-EINVAL);
return dst;
}
+
+/* Indicate the JIT backend supports mixing bpf2bpf and tailcalls. */
+bool bpf_jit_supports_subprog_tailcalls(void)
+{
+ return true;
+}
struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog);
void bpf_jit_compile(struct bpf_prog *prog);
bool bpf_jit_needs_zext(void);
+bool bpf_jit_supports_subprog_tailcalls(void);
bool bpf_jit_supports_kfunc_call(void);
bool bpf_helper_changes_pkt_data(void *func);
return false;
}
+/* Return TRUE if the JIT backend supports mixing bpf2bpf and tailcalls. */
+bool __weak bpf_jit_supports_subprog_tailcalls(void)
+{
+ return false;
+}
+
bool __weak bpf_jit_supports_kfunc_call(void)
{
return false;
static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env)
{
- return env->prog->jit_requested && IS_ENABLED(CONFIG_X86_64);
+ return env->prog->jit_requested &&
+ bpf_jit_supports_subprog_tailcalls();
}
static int check_map_func_compatibility(struct bpf_verifier_env *env,