On x86_64 I saw no difference in binary size (compression), but at
runtime this will require a word of memory per export to hold the
namespace. An alternative could be to store namespaced symbols in their
own section and use a separate 'struct namespaced_kernel_symbol' for
that section, at the cost of making the module loader more complex.
Signed-off-by: Martijn Coenen <maco@xxxxxxxxxxx>
---
include/asm-generic/export.h | 2 +-
include/linux/export.h | 83 +++++++++++++++++++++++++++---------
include/linux/module.h | 13 ++++++
kernel/module.c | 79 ++++++++++++++++++++++++++++++++++
4 files changed, 156 insertions(+), 21 deletions(-)
diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h
index 68efb950a918..4c3d1afb702f 100644
--- a/include/asm-generic/export.h
+++ b/include/asm-generic/export.h
@@ -29,7 +29,7 @@
.section ___ksymtab\sec+\name,"a"
.balign KSYM_ALIGN
__ksymtab_\name:
- __put \val, __kstrtab_\name
+ __put \val, __kstrtab_\name, 0
.previous
.section __ksymtab_strings,"a"
__kstrtab_\name:
diff --git a/include/linux/export.h b/include/linux/export.h
index ad6b8e697b27..9f6e70eeb85f 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -22,6 +22,11 @@ struct kernel_symbol
{
unsigned long value;
const char *name;
+ const char *namespace;
+};
+
+struct namespace_import {
+ const char *namespace;
};
#ifdef MODULE
@@ -54,18 +59,28 @@ extern struct module __this_module;
#define __CRC_SYMBOL(sym, sec)
#endif
+#define NS_SEPARATOR "."
+
+#define MODULE_IMPORT_NS(ns) \
+ static const struct namespace_import __knsimport_##ns \
+ asm("__knsimport_" #ns) \
+ __attribute__((section("__knsimport"), used)) \
+ = { #ns }
+
/* For every exported symbol, place a struct in the __ksymtab section */
-#define ___EXPORT_SYMBOL(sym, sec) \
+#define ___EXPORT_SYMBOL(sym, sec, ns, nspost, nspost2) \
extern typeof(sym) sym; \
__CRC_SYMBOL(sym, sec) \
- static const char __kstrtab_##sym[] \
+ static const char __kstrtab_##sym##nspost[] \
__attribute__((section("__ksymtab_strings"), aligned(1))) \
= #sym; \
- static const struct kernel_symbol __ksymtab_##sym \
+ static const struct kernel_symbol __ksymtab_##sym##nspost \
+ asm("__ksymtab_" #sym nspost2) \
__used \
- __attribute__((section("___ksymtab" sec "+" #sym), used)) \
+ __attribute__((section("___ksymtab" sec "+" #sym #nspost))) \
+ __attribute__((used)) \
__attribute__((aligned(sizeof(void *)))) \
- = { (unsigned long)&sym, __kstrtab_##sym }
+ = { (unsigned long)&sym, __kstrtab_##sym##nspost, ns }
#if defined(__KSYM_DEPS__)
@@ -76,52 +91,80 @@ extern struct module __this_module;
* system filters out from the preprocessor output (see ksym_dep_filter
* in scripts/Kbuild.include).
*/
-#define __EXPORT_SYMBOL(sym, sec) === __KSYM_##sym ===
+#define __EXPORT_SYMBOL(sym, sec, ns, nspost, nspost2) === __KSYM_##sym ===
#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
#include <generated/autoksyms.h>
-#define __EXPORT_SYMBOL(sym, sec) \
- __cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
-#define __cond_export_sym(sym, sec, conf) \
- ___cond_export_sym(sym, sec, conf)
-#define ___cond_export_sym(sym, sec, enabled) \
- __cond_export_sym_##enabled(sym, sec)
-#define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
-#define __cond_export_sym_0(sym, sec) /* nothing */
+#define __EXPORT_SYMBOL(sym, sec, ns, nspost, nspost2) \
+ __cond_export_sym(sym, sec, ns, nspost, nspost2, \
+ __is_defined(__KSYM_##sym))
+#define __cond_export_sym(sym, sec, ns, nspost, nspost2, conf) \
+ ___cond_export_sym(sym, sec, ns, nspost, nspost2, conf)
+#define ___cond_export_sym(sym, sec, ns, nspost, nspost2, enabled) \
+ __cond_export_sym_##enabled(sym, sec, ns, nspost, nspost2)
+#define __cond_export_sym_1(sym, sec, ns, nspost, nspost2) \
+ ___EXPORT_SYMBOL(sym, sec, ns, nspost, nspost2)
+#define __cond_export_sym_0(sym, sec, ns, nspost, nspost2) /* nothing */
#else
#define __EXPORT_SYMBOL ___EXPORT_SYMBOL
#endif
#define EXPORT_SYMBOL(sym) \
- __EXPORT_SYMBOL(sym, "")
+ __EXPORT_SYMBOL(sym, "", NULL, ,)
#define EXPORT_SYMBOL_GPL(sym) \
- __EXPORT_SYMBOL(sym, "_gpl")
+ __EXPORT_SYMBOL(sym, "_gpl", NULL, ,)
#define EXPORT_SYMBOL_GPL_FUTURE(sym) \
- __EXPORT_SYMBOL(sym, "_gpl_future")
+ __EXPORT_SYMBOL(sym, "_gpl_future", NULL, ,)
+
+#define EXPORT_SYMBOL_NS(sym, ns) \
+ __EXPORT_SYMBOL(sym, "", #ns, __##ns, NS_SEPARATOR #ns)
+
+#define EXPORT_SYMBOL_NS_GPL(sym, ns) \
+ __EXPORT_SYMBOL(sym, "_gpl", #ns, __##ns, NS_SEPARATOR #ns)
#ifdef CONFIG_UNUSED_SYMBOLS
-#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
-#define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
+#define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused", , ,)
+#define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl", , ,)
#else
#define EXPORT_UNUSED_SYMBOL(sym)
#define EXPORT_UNUSED_SYMBOL_GPL(sym)
#endif
-#endif /* __GENKSYMS__ */
+#endif /* __KERNEL__ && !__GENKSYMS__ */
+
+#if defined(__GENKSYMS__)
+/*
+ * When we're running genksyms, ignore the namespace and make the _NS
+ * variants look like the normal ones. There are two reasons for this:
+ * 1) In the normal definition of EXPORT_SYMBOL_NS, the 'ns' macro
+ * argument is itself not expanded because it's always tokenized or
+ * concatenated; but when running genksyms, a blank definition of the
+ * macro does allow the argument to be expanded; if a namespace
+ * happens to collide with a #define, this can cause issues.
+ * 2) There's no need to modify genksyms to deal with the _NS variants
+ */
+#define EXPORT_SYMBOL_NS(sym, ns) \
+ EXPORT_SYMBOL(sym)
+#define EXPORT_SYMBOL_NS_GPL(sym, ns) \
+ EXPORT_SYMBOL_GPL(sym)
+#endif
#else /* !CONFIG_MODULES... */
#define EXPORT_SYMBOL(sym)
+#define EXPORT_SYMBOL_NS(sym, ns)
+#define EXPORT_SYMBOL_NS_GPL(sym, ns)
#define EXPORT_SYMBOL_GPL(sym)
#define EXPORT_SYMBOL_GPL_FUTURE(sym)
#define EXPORT_UNUSED_SYMBOL(sym)
#define EXPORT_UNUSED_SYMBOL_GPL(sym)
+#define MODULE_IMPORT_NS(ns)
#endif /* CONFIG_MODULES */
#endif /* !__ASSEMBLY__ */
diff --git a/include/linux/module.h b/include/linux/module.h
index d44df9b2c131..afab4e8fa188 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -268,6 +268,12 @@ void *__symbol_get(const char *symbol);
void *__symbol_get_gpl(const char *symbol);
#define symbol_get(x) ((typeof(&x))(__symbol_get(VMLINUX_SYMBOL_STR(x))))
+/* namespace dependencies of the module */
+struct module_ns_dep {
+ struct list_head ns_dep;
+ const char *namespace;
+};
+
/* modules using other modules: kdb wants to see this. */
struct module_use {
struct list_head source_list;
@@ -359,6 +365,13 @@ struct module {
const struct kernel_symbol *gpl_syms;
const s32 *gpl_crcs;
+ /* Namespace imports */
+ unsigned int num_ns_imports;
+ const struct namespace_import *ns_imports;
+
+ /* Namespace dependencies */
+ struct list_head ns_dependencies;
+
#ifdef CONFIG_UNUSED_SYMBOLS
/* unused exported symbols. */
const struct kernel_symbol *unused_syms;
diff --git a/kernel/module.c b/kernel/module.c
index f475f30eed8c..63de0fe849f9 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1166,6 +1166,51 @@ static inline int module_unload_init(struct module *mod)
}
#endif /* CONFIG_MODULE_UNLOAD */
+static bool module_has_ns_dependency(struct module *mod, const char *ns)
+{
+ struct module_ns_dep *ns_dep;
+
+ list_for_each_entry(ns_dep, &mod->ns_dependencies, ns_dep) {
+ if (strcmp(ns_dep->namespace, ns) == 0)
+ return true;
+ }
+
+ return false;
+}
+
+static int add_module_ns_dependency(struct module *mod, const char *ns)
+{
+ struct module_ns_dep *ns_dep;
+
+ if (module_has_ns_dependency(mod, ns))
+ return 0;
+
+ ns_dep = kmalloc(sizeof(*ns_dep), GFP_ATOMIC);
+ if (!ns_dep)
+ return -ENOMEM;
+
+ ns_dep->namespace = ns;
+
+ list_add(&ns_dep->ns_dep, &mod->ns_dependencies);
+
+ return 0;
+}
+
+static bool module_imports_ns(struct module *mod, const char *ns)
+{
+ size_t i;
+
+ if (!ns)
+ return true;
+
+ for (i = 0; i < mod->num_ns_imports; ++i) {
+ if (!strcmp(mod->ns_imports[i].namespace, ns))
+ return true;
+ }
+
+ return false;
+}
+
static size_t module_flags_taint(struct module *mod, char *buf)
{
size_t l = 0;
@@ -1415,6 +1460,18 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
goto getname;
}
+ /*
+ * We can't yet verify that the module actually imports this
+ * namespace, because the imports themselves are only available
+ * after processing the symbol table and doing relocation; so
+ * instead just record the dependency and check later.
+ */
+ if (sym->namespace) {
+ err = add_module_ns_dependency(mod, sym->namespace);
+ if (err)
+ sym = ERR_PTR(err);
+ }
+
getname:
/* We must make copy under the lock if we failed to get ref. */
strncpy(ownername, module_name(owner), MODULE_NAME_LEN);
@@ -3061,6 +3118,11 @@ static int find_module_sections(struct module *mod, struct load_info *info)
sizeof(*mod->gpl_syms),
&mod->num_gpl_syms);
mod->gpl_crcs = section_addr(info, "__kcrctab_gpl");
+
+ mod->ns_imports = section_objs(info, "__knsimport",
+ sizeof(*mod->ns_imports),
+ &mod->num_ns_imports);
+
mod->gpl_future_syms = section_objs(info,
"__ksymtab_gpl_future",
sizeof(*mod->gpl_future_syms),
@@ -3381,6 +3443,19 @@ static int post_relocation(struct module *mod, const struct load_info *info)
return module_finalize(info->hdr, info->sechdrs, mod);
}
+static void verify_namespace_dependencies(struct module *mod)
+{
+ struct module_ns_dep *ns_dep;
+
+ list_for_each_entry(ns_dep, &mod->ns_dependencies, ns_dep) {
+ if (!module_imports_ns(mod, ns_dep->namespace)) {
+ pr_warn("%s: module uses symbols from namespace %s,"
+ " but does not import it.\n",
+ mod->name, ns_dep->namespace);
+ }
+ }
+}
+
/* Is this module of this name done loading? No locks held. */
static bool finished_loading(const char *name)
{
@@ -3682,6 +3757,8 @@ static int load_module(struct load_info *info, const char __user *uargs,
if (err)
goto free_module;
+ INIT_LIST_HEAD(&mod->ns_dependencies);
+
#ifdef CONFIG_MODULE_SIG
mod->sig_ok = info->sig_ok;
if (!mod->sig_ok) {
@@ -3730,6 +3807,8 @@ static int load_module(struct load_info *info, const char __user *uargs,
if (err < 0)
goto free_modinfo;
+ verify_namespace_dependencies(mod);
+
flush_module_icache(mod);
/* Now copy in args */
--
2.18.0.203.gfac676dfb9-goog
