[PATCH v6][makedumpfile 05/10] Implement kernel module's btf resolving

Same as the previous patch, with kernel's kallsyms and btf ready,
we can locate and iterate all kernel modules' btf data. So kernel
modules' types specified within .init_ksyms section will be resolved.

Reviewed-by: Stephen Brennan <[email protected]>
Signed-off-by: Tao Liu <[email protected]>
---
 btf_info.c | 133 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 btf_info.h |   2 +
 2 files changed, 135 insertions(+)

diff --git a/btf_info.c b/btf_info.c
index 8d907f6..fbb487b 100644
--- a/btf_info.c
+++ b/btf_info.c
@@ -234,5 +234,138 @@ out:
 		free(buf);
 	return ret;
 }
+
+INIT_MOD_SYM(vmlinux, btf_modules);
+
+INIT_MOD_STRUCT_MEMBER(vmlinux, btf_module, list);
+INIT_MOD_STRUCT_MEMBER(vmlinux, btf_module, btf);
+INIT_MOD_STRUCT_MEMBER(vmlinux, btf_module, module);
+DECLARE_MOD_STRUCT_MEMBER(vmlinux, module, name);
+INIT_MOD_STRUCT_MEMBER(vmlinux, btf, data);
+INIT_MOD_STRUCT_MEMBER(vmlinux, btf, data_size);
+
+#define KERN_STRUCT_MEMBER_EXIST(S, M) MOD_STRUCT_MEMBER_EXIST(vmlinux, S, M)
+#define MEMBER_OFF(S, M) GET_MOD_STRUCT_MEMBER_MOFF(vmlinux, S, M) / 8
+#define GET_KERN_STRUCT_MEMBER_MSIZE(S, M) GET_MOD_STRUCT_MEMBER_MSIZE(vmlinux, S, M)
+#define GET_KERN_SYM(SYM) GET_MOD_SYM(vmlinux, SYM)
+
+bool init_module_btf(void)
+{
+	struct btf *btf_mod;
+	uint64_t btf_modules, list;
+	uint64_t btf = 0, data = 0, module = 0;
+	int data_size = 0;
+	bool ret = false;
+	char *btf_buf = NULL;
+	char *modname = NULL;
+	struct ktype_info **p;
+
+	btf_modules = GET_KERN_SYM(btf_modules);
+	if (!KERN_SYM_EXIST(btf_modules))
+		/* Maybe module is not enabled, this is not an error */
+		return true;
+
+	if (!KERN_STRUCT_MEMBER_EXIST(btf_module, list) ||
+	    !KERN_STRUCT_MEMBER_EXIST(btf_module, btf) ||
+	    !KERN_STRUCT_MEMBER_EXIST(btf_module, module) ||
+	    !KERN_STRUCT_MEMBER_EXIST(btf, data) ||
+	    !KERN_STRUCT_MEMBER_EXIST(btf, data_size)) {
+		/* Fail when module enabled but any required types not found */
+		ERRMSG("Missing required btf syms/types!\n");
+		goto out;
+	}
+
+	modname = (char *)malloc(GET_KERN_STRUCT_MEMBER_MSIZE(module, name));
+	if (!modname)
+		goto no_mem;
+
+	for (list = next_list(btf_modules); list != btf_modules; list = next_list(list)) {
+		if (!readmem(VADDR, list - MEMBER_OFF(btf_module, list) +
+				MEMBER_OFF(btf_module, btf),
+			&btf, GET_KERN_STRUCT_MEMBER_MSIZE(btf_module, btf))) {
+			ERRMSG("Can't get btf_module member btf!\n");
+			goto out;
+		}
+		if (!readmem(VADDR, list - MEMBER_OFF(btf_module, list) +
+				MEMBER_OFF(btf_module, module),
+			&module, GET_KERN_STRUCT_MEMBER_MSIZE(btf_module, module))) {
+			ERRMSG("Can't get btf_module member module!\n");
+			goto out;
+		}
+		if (!readmem(VADDR, module + MEMBER_OFF(module, name),
+			modname, GET_KERN_STRUCT_MEMBER_MSIZE(module, name))) {
+			ERRMSG("Can't get module modname!\n");
+			goto out;
+		}
+		if (!check_ktypes_require_modname(modname, NULL)) {
+			continue;
+		}
+		if (!readmem(VADDR, btf + MEMBER_OFF(btf, data),
+			&data, GET_KERN_STRUCT_MEMBER_MSIZE(btf, data))) {
+			ERRMSG("Can't get module btf address!\n");
+			goto out;
+		}
+		if (!readmem(VADDR, btf + MEMBER_OFF(btf, data_size),
+			&data_size, GET_KERN_STRUCT_MEMBER_MSIZE(btf, data_size))) {
+			ERRMSG("Can't get module btf data size!\n");
+			goto out;
+		}
+		btf_buf = (char *)malloc(data_size);
+		if (!btf_buf)
+			goto no_mem;
+		if (!readmem(VADDR, data, btf_buf, data_size)) {
+			ERRMSG("Can't get module btf data!\n");
+			goto out;
+		}
+		btf_mod = btf__new_split(btf_buf, data_size, btf_arr[0]->btf);
+		free(btf_buf);
+		if (libbpf_get_error(btf_mod) != 0 ||
+		    add_to_btf_arr(btf_mod, strdup(modname)) == false) {
+			ERRMSG("init %s btf fail\n", modname);
+			goto out;
+		}
+	}
+
+	/* OK, we have loaded all needed modules's btf, now resolve the types */
+	for (int i = 0; i < sr_len; i++) {
+		for (p = (struct ktype_info **)(sr[i]->start);
+		     p < (struct ktype_info **)(sr[i]->stop);
+		     p++)
+			get_ktype_info(*p, NULL);
+	}
+
+	ret = true;
+	goto out;
+
+no_mem:
+	ERRMSG("Not enough memory!\n");
+out:
+	if (modname)
+		free(modname);
+	return ret;
+}
+
+static void cleanup_btf_arr(void)
+{
+	for (int i = 0; i < btf_arr_len; i++) {
+		free(btf_arr[i]->module);
+		btf__free(btf_arr[i]->btf);
+		free(btf_arr[i]);
+	}
+	if (btf_arr) {
+		free(btf_arr);
+		btf_arr = NULL;
+	}
+	btf_arr_len = 0;
+	btf_arr_cap = 0;
+}
+
+void cleanup_btf(void)
+{
+	cleanup_btf_arr();
+	cleanup_ktypes_section_range();
+	cleanup_ktypes_modname();
+}
+
 #endif /* EXTENSION */
 
diff --git a/btf_info.h b/btf_info.h
index 8eace67..a6c3bba 100644
--- a/btf_info.h
+++ b/btf_info.h
@@ -22,6 +22,8 @@ struct ktype_info {
 bool check_ktypes_require_modname(char *modname, int *total);
 bool register_ktype_section(char *start, char *stop);
 bool init_kernel_btf(void);
+bool init_module_btf(void);
+void cleanup_btf(void);
 
 #define _GEN_NAME_PTR_IMPL(PTR, NAME)		PTR##NAME
 #define _GEN_NAME_PTR(PTR, NAME)		_GEN_NAME_PTR_IMPL(PTR, NAME)
-- 
2.54.0