bpf: get rid of pure_initcall dependency to enable jits
Having a pure_initcall() callback just to permanently enable BPF
JITs under CONFIG_BPF_JIT_ALWAYS_ON is unnecessary and could leave
a small race window in future where JIT is still disabled on boot.
Since we know about the setting at compilation time anyway, just
initialize it properly there. Also consolidate all the individual
bpf_jit_enable variables into a single one and move them under one
location. Moreover, don't allow for setting unspecified garbage
values on them.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 25e723b..bc9c5b1 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -300,6 +300,11 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
}
#ifdef CONFIG_BPF_JIT
+/* All BPF JIT sysctl knobs here. */
+int bpf_jit_enable __read_mostly = IS_BUILTIN(CONFIG_BPF_JIT_ALWAYS_ON);
+int bpf_jit_harden __read_mostly;
+int bpf_jit_kallsyms __read_mostly;
+
static __always_inline void
bpf_get_prog_addr_region(const struct bpf_prog *prog,
unsigned long *symbol_start,
@@ -381,8 +386,6 @@ static DEFINE_SPINLOCK(bpf_lock);
static LIST_HEAD(bpf_kallsyms);
static struct latch_tree_root bpf_tree __cacheline_aligned;
-int bpf_jit_kallsyms __read_mostly;
-
static void bpf_prog_ksym_node_add(struct bpf_prog_aux *aux)
{
WARN_ON_ONCE(!list_empty(&aux->ksym_lnode));
@@ -563,8 +566,6 @@ void __weak bpf_jit_free(struct bpf_prog *fp)
bpf_prog_unlock_free(fp);
}
-int bpf_jit_harden __read_mostly;
-
static int bpf_jit_blind_insn(const struct bpf_insn *from,
const struct bpf_insn *aux,
struct bpf_insn *to_buff)
@@ -1379,9 +1380,13 @@ void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
}
#else
-static unsigned int __bpf_prog_ret0(const void *ctx,
- const struct bpf_insn *insn)
+static unsigned int __bpf_prog_ret0_warn(const void *ctx,
+ const struct bpf_insn *insn)
{
+ /* If this handler ever gets executed, then BPF_JIT_ALWAYS_ON
+ * is not working properly, so warn about it!
+ */
+ WARN_ON_ONCE(1);
return 0;
}
#endif
@@ -1441,7 +1446,7 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
fp->bpf_func = interpreters[(round_up(stack_depth, 32) / 32) - 1];
#else
- fp->bpf_func = __bpf_prog_ret0;
+ fp->bpf_func = __bpf_prog_ret0_warn;
#endif
/* eBPF JITs can rewrite the program in case constant