[PATCH bpf-next v2 07/11] bpf: Enable stack argument support for x86_64

[Yonghong Song <yonghong.song@linux.dev>]

Add stack argument support for x86_64.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
 arch/x86/net/bpf_jit_comp.c | 5 +++++
 include/linux/filter.h      | 1 +
 kernel/bpf/btf.c            | 9 ++++++++-
 kernel/bpf/core.c           | 5 +++++
 4 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index e9b78040d703..32864dbc2c4e 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -3937,6 +3937,11 @@ bool bpf_jit_supports_kfunc_call(void)
 	return true;
 }
 
+bool bpf_jit_supports_stack_args(void)
+{
+	return true;
+}
+
 void *bpf_arch_text_copy(void *dst, void *src, size_t len)
 {
 	if (text_poke_copy(dst, src, len) == NULL)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 68f018dd4b9c..a5035fb80a6b 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1160,6 +1160,7 @@ bool bpf_jit_inlines_helper_call(s32 imm);
 bool bpf_jit_supports_subprog_tailcalls(void);
 bool bpf_jit_supports_percpu_insn(void);
 bool bpf_jit_supports_kfunc_call(void);
+bool bpf_jit_supports_stack_args(void);
 bool bpf_jit_supports_far_kfunc_call(void);
 bool bpf_jit_supports_exceptions(void);
 bool bpf_jit_supports_ptr_xchg(void);
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index c5f3aa05d5a3..1cbe0f2b0e41 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -20,6 +20,7 @@
 #include <linux/btf.h>
 #include <linux/btf_ids.h>
 #include <linux/bpf.h>
+#include <linux/filter.h>
 #include <linux/bpf_lsm.h>
 #include <linux/skmsg.h>
 #include <linux/perf_event.h>
@@ -7897,8 +7898,14 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog)
 			tname, nargs, MAX_BPF_FUNC_REG_ARGS);
 		return -EINVAL;
 	}
-	if (nargs > MAX_BPF_FUNC_REG_ARGS)
+	if (nargs > MAX_BPF_FUNC_REG_ARGS) {
+		if (!bpf_jit_supports_stack_args()) {
+			bpf_log(log, "JIT does not support function %s() with %d args\n",
+				tname, nargs);
+			return -ENOTSUPP;
+		}
 		sub->incoming_stack_arg_depth = (nargs - MAX_BPF_FUNC_REG_ARGS) * BPF_REG_SIZE;
+	}
 
 	/* check that function is void or returns int, exception cb also requires this */
 	t = btf_type_by_id(btf, t->type);
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index a04b31eb4c49..01de4f7f3a82 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -3156,6 +3156,11 @@ bool __weak bpf_jit_supports_kfunc_call(void)
 	return false;
 }
 
+bool __weak bpf_jit_supports_stack_args(void)
+{
+	return false;
+}
+
 bool __weak bpf_jit_supports_far_kfunc_call(void)
 {
 	return false;
-- 
2.52.0