[RFC PATCH bpf-next 4/6] bpf: Add module parameter to gen_prologue and gen_epilogue

[Martin KaFai Lau <martin.lau@linux.dev>]

From: Martin KaFai Lau <martin.lau@kernel.org>

This patch adds a "struct module **module" arg to the .gen_prologue
and .gen_epilogue. This will allow the .gen_pro/epilogue to
make kfunc call because the verifer needs to know the kfunc's BTF.
The next patch will figure the kfunc's BTF from the module.
It also exposes the "btf_get_module_btf" function to help
figuring out the btf from a module.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
---
 include/linux/bpf.h                                   | 4 ++--
 include/linux/btf.h                                   | 1 +
 kernel/bpf/btf.c                                      | 2 +-
 kernel/bpf/cgroup.c                                   | 3 ++-
 kernel/bpf/verifier.c                                 | 4 ++--
 net/core/filter.c                                     | 6 +++---
 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c | 4 ++--
 7 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 2de67bc497f4..9787532813e2 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -973,9 +973,9 @@ struct bpf_verifier_ops {
 				const struct bpf_prog *prog,
 				struct bpf_insn_access_aux *info);
 	int (*gen_prologue)(struct bpf_insn *insn, bool direct_write,
-			    const struct bpf_prog *prog);
+			    const struct bpf_prog *prog, struct module **module);
 	int (*gen_epilogue)(struct bpf_insn *insn, const struct bpf_prog *prog,
-			    s16 ctx_stack_off);
+			    s16 ctx_stack_off, struct module **module);
 	int (*gen_ld_abs)(const struct bpf_insn *orig,
 			  struct bpf_insn *insn_buf);
 	u32 (*convert_ctx_access)(enum bpf_access_type type,
diff --git a/include/linux/btf.h b/include/linux/btf.h
index cffb43133c68..177187fa3819 100644
--- a/include/linux/btf.h
+++ b/include/linux/btf.h
@@ -580,6 +580,7 @@ bool btf_is_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
 int get_kern_ctx_btf_id(struct bpf_verifier_log *log, enum bpf_prog_type prog_type);
 bool btf_types_are_same(const struct btf *btf1, u32 id1,
 			const struct btf *btf2, u32 id2);
+struct btf *btf_get_module_btf(const struct module *module);
 #else
 static inline const struct btf_type *btf_type_by_id(const struct btf *btf,
 						    u32 type_id)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 95426d5b634e..b230f7ff9388 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -7970,7 +7970,7 @@ struct module *btf_try_get_module(const struct btf *btf)
 /* Returns struct btf corresponding to the struct module.
  * This function can return NULL or ERR_PTR.
  */
-static struct btf *btf_get_module_btf(const struct module *module)
+struct btf *btf_get_module_btf(const struct module *module)
 {
 #ifdef CONFIG_DEBUG_INFO_BTF_MODULES
 	struct btf_module *btf_mod, *tmp;
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 8ba73042a239..0be053d86b56 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -2503,7 +2503,8 @@ static u32 cg_sockopt_convert_ctx_access(enum bpf_access_type type,
 
 static int cg_sockopt_get_prologue(struct bpf_insn *insn_buf,
 				   bool direct_write,
-				   const struct bpf_prog *prog)
+				   const struct bpf_prog *prog,
+				   struct module **module)
 {
 	/* Nothing to do for sockopt argument. The data is kzalloc'ated.
 	 */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index bbb655f0c7b5..5e995b7884fb 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -19622,7 +19622,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 
 	if (ops->gen_epilogue) {
 		epilogue_cnt = ops->gen_epilogue(epilogue_buf, env->prog,
-						 -(subprogs[0].stack_depth + 8));
+						 -(subprogs[0].stack_depth + 8), NULL);
 		if (epilogue_cnt >= ARRAY_SIZE(epilogue_buf)) {
 			verbose(env, "bpf verifier is misconfigured\n");
 			return -EINVAL;
@@ -19647,7 +19647,7 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
 			return -EINVAL;
 		}
 		cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
-					env->prog);
+					env->prog, NULL);
 		if (cnt >= ARRAY_SIZE(insn_buf)) {
 			verbose(env, "bpf verifier is misconfigured\n");
 			return -EINVAL;
diff --git a/net/core/filter.c b/net/core/filter.c
index 78a6f746ea0b..65d219e71ae8 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -8844,7 +8844,7 @@ static bool sock_filter_is_valid_access(int off, int size,
 }
 
 static int bpf_noop_prologue(struct bpf_insn *insn_buf, bool direct_write,
-			     const struct bpf_prog *prog)
+			     const struct bpf_prog *prog, struct module **module)
 {
 	/* Neither direct read nor direct write requires any preliminary
 	 * action.
@@ -8927,7 +8927,7 @@ static int bpf_gen_ld_abs(const struct bpf_insn *orig,
 }
 
 static int tc_cls_act_prologue(struct bpf_insn *insn_buf, bool direct_write,
-			       const struct bpf_prog *prog)
+			       const struct bpf_prog *prog, struct module **module)
 {
 	return bpf_unclone_prologue(insn_buf, direct_write, prog, TC_ACT_SHOT);
 }
@@ -9263,7 +9263,7 @@ static bool sock_ops_is_valid_access(int off, int size,
 }
 
 static int sk_skb_prologue(struct bpf_insn *insn_buf, bool direct_write,
-			   const struct bpf_prog *prog)
+			   const struct bpf_prog *prog, struct module **module)
 {
 	return bpf_unclone_prologue(insn_buf, direct_write, prog, SK_DROP);
 }
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index 7194330bdefc..4c75346376d9 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -1141,7 +1141,7 @@ static int bpf_test_mod_st_ops__test_pro_epilogue(struct st_ops_args *args)
 }
 
 static int st_ops_gen_prologue(struct bpf_insn *insn_buf, bool direct_write,
-			       const struct bpf_prog *prog)
+			       const struct bpf_prog *prog, struct module **module)
 {
 	struct bpf_insn *insn = insn_buf;
 
@@ -1164,7 +1164,7 @@ static int st_ops_gen_prologue(struct bpf_insn *insn_buf, bool direct_write,
 }
 
 static int st_ops_gen_epilogue(struct bpf_insn *insn_buf, const struct bpf_prog *prog,
-			       s16 ctx_stack_off)
+			       s16 ctx_stack_off, struct module **module)
 {
 	struct bpf_insn *insn = insn_buf;
 
-- 
2.43.5