[PATCH bpf-next v6 02/12] bpf: Disallow interpreter fallback for user BPF_ADDR_SPACE_CAST insn

[Leon Hwang]

Since interpreter is unable to handle the 'insn_is_cast_user()' insn,
require JIT in __bpf_prog_select_runtime() when the prog has the insn.

Fixes: 142fd4d2dcf5 ("bpf: Add x86-64 JIT support for bpf_addr_space_cast 
instruction.")
Signed-off-by: Leon Hwang <leon.hw...@linux.dev>
---
 include/linux/bpf.h | 1 +
 kernel/bpf/core.c   | 1 +
 kernel/bpf/fixups.c | 2 ++
 3 files changed, 4 insertions(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 56f5da2b437f..5f48a6ab8a1a 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1780,6 +1780,7 @@ struct bpf_prog_aux {
        bool changes_pkt_data;
        bool might_sleep;
        bool kprobe_write_ctx;
+       bool has_addr_space_cast_insn;
        struct {
                s32 keyring_serial;
                u8 keyring_type;
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 649cce41e13f..49398b5bd172 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2620,6 +2620,7 @@ struct bpf_prog *__bpf_prog_select_runtime(struct 
bpf_verifier_env *env, struct
                goto finalize;
 
        if (IS_ENABLED(CONFIG_BPF_JIT_ALWAYS_ON) ||
+           fp->aux->has_addr_space_cast_insn ||
            bpf_prog_has_kfunc_call(fp))
                jit_needed = true;
 
diff --git a/kernel/bpf/fixups.c b/kernel/bpf/fixups.c
index 3cf2cc6e3ab6..2d5958774b61 100644
--- a/kernel/bpf/fixups.c
+++ b/kernel/bpf/fixups.c
@@ -1523,6 +1523,8 @@ int bpf_do_misc_fixups(struct bpf_verifier_env *env)
                                insn->off = 0;
                                insn->imm = 0;
                        } /* cast from as(0) to as(1) should be handled by JIT 
*/
+                       if (insn_is_cast_user(insn))
+                               prog->aux->has_addr_space_cast_insn = true;
                        goto next_insn;
                }
 
-- 
2.54.0