Merge tag 'modules-for-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux

Pull modules updates from Jessica Yu:
 "The main bulk of this pull request introduces a new exported symbol
  namespaces feature. The number of exported symbols is increasingly
  growing with each release (we're at about 31k exports as of 5.3-rc7)
  and we currently have no way of visualizing how these symbols are
  "clustered" or making sense of this huge export surface.

  Namespacing exported symbols allows kernel developers to more
  explicitly partition and categorize exported symbols, as well as more
  easily limiting the availability of namespaced symbols to other parts
  of the kernel. For starters, we have introduced the USB_STORAGE
  namespace to demonstrate the API's usage. I have briefly summarized
  the feature and its main motivations in the tag below.

  Summary:

   - Introduce exported symbol namespaces.

     This new feature allows subsystem maintainers to partition and
     categorize their exported symbols into explicit namespaces. Module
     authors are now required to import the namespaces they need.

     Some of the main motivations of this feature include: allowing
     kernel developers to better manage the export surface, allow
     subsystem maintainers to explicitly state that usage of some
     exported symbols should only be limited to certain users (think:
     inter-module or inter-driver symbols, debugging symbols, etc), as
     well as more easily limiting the availability of namespaced symbols
     to other parts of the kernel.

     With the module import requirement, it is also easier to spot the
     misuse of exported symbols during patch review.

     Two new macros are introduced: EXPORT_SYMBOL_NS() and
     EXPORT_SYMBOL_NS_GPL(). The API is thoroughly documented in
     Documentation/kbuild/namespaces.rst.

   - Some small code and kbuild cleanups here and there"

* tag 'modules-for-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
  module: Remove leftover '#undef' from export header
  module: remove unneeded casts in cmp_name()
  module: move CONFIG_UNUSED_SYMBOLS to the sub-menu of MODULES
  module: remove redundant 'depends on MODULES'
  module: Fix link failure due to invalid relocation on namespace offset
  usb-storage: export symbols in USB_STORAGE namespace
  usb-storage: remove single-use define for debugging
  docs: Add documentation for Symbol Namespaces
  scripts: Coccinelle script for namespace dependencies.
  modpost: add support for generating namespace dependencies
  export: allow definition default namespaces in Makefiles or sources
  module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
  modpost: add support for symbol namespaces
  module: add support for symbol namespaces.
  export: explicitly align struct kernel_symbol
  module: support reading multiple values per modinfo tag

1 files changed, 66 insertions, 10 deletions

diff --git a/include/linux/export.h b/include/linux/export.h
index 7d8c112a8b61..95f55b7f83a0 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -18,6 +18,8 @@ extern struct module __this_module;
 #define THIS_MODULE ((struct module *)0)
 #endif
 
+#define NS_SEPARATOR "."
+
 #ifdef CONFIG_MODVERSIONS
 /* Mark the CRC weak since genksyms apparently decides not to
  * generate a checksums for some symbols */
@@ -26,13 +28,13 @@ extern struct module __this_module;
 	asm("	.section \"___kcrctab" sec "+" #sym "\", \"a\"	\n"	\
 	    "	.weak	__crc_" #sym "				\n"	\
 	    "	.long	__crc_" #sym " - .			\n"	\
-	    "	.previous					\n");
+	    "	.previous					\n")
 #else
 #define __CRC_SYMBOL(sym, sec)						\
 	asm("	.section \"___kcrctab" sec "+" #sym "\", \"a\"	\n"	\
 	    "	.weak	__crc_" #sym "				\n"	\
 	    "	.long	__crc_" #sym "				\n"	\
-	    "	.previous					\n");
+	    "	.previous					\n")
 #endif
 #else
 #define __CRC_SYMBOL(sym, sec)
@@ -46,44 +48,77 @@ extern struct module __this_module;
  * absolute relocations that require runtime processing on relocatable
  * kernels.
  */
+#define __KSYMTAB_ENTRY_NS(sym, sec, ns)				\
+	__ADDRESSABLE(sym)						\
+	asm("	.section \"___ksymtab" sec "+" #sym "\", \"a\"	\n"	\
+	    "	.balign	4					\n"	\
+	    "__ksymtab_" #sym NS_SEPARATOR #ns ":		\n"	\
+	    "	.long	" #sym "- .				\n"	\
+	    "	.long	__kstrtab_" #sym "- .			\n"	\
+	    "	.long	__kstrtab_ns_" #sym "- .		\n"	\
+	    "	.previous					\n")
+
 #define __KSYMTAB_ENTRY(sym, sec)					\
 	__ADDRESSABLE(sym)						\
 	asm("	.section \"___ksymtab" sec "+" #sym "\", \"a\"	\n"	\
-	    "	.balign	8					\n"	\
+	    "	.balign 4					\n"	\
 	    "__ksymtab_" #sym ":				\n"	\
 	    "	.long	" #sym "- .				\n"	\
 	    "	.long	__kstrtab_" #sym "- .			\n"	\
+	    "	.long	0					\n"	\
 	    "	.previous					\n")
 
 struct kernel_symbol {
 	int value_offset;
 	int name_offset;
+	int namespace_offset;
 };
 #else
+#define __KSYMTAB_ENTRY_NS(sym, sec, ns)				\
+	static const struct kernel_symbol __ksymtab_##sym##__##ns	\
+	asm("__ksymtab_" #sym NS_SEPARATOR #ns)				\
+	__attribute__((section("___ksymtab" sec "+" #sym), used))	\
+	__aligned(sizeof(void *))					\
+	= { (unsigned long)&sym, __kstrtab_##sym, __kstrtab_ns_##sym }
+
 #define __KSYMTAB_ENTRY(sym, sec)					\
 	static const struct kernel_symbol __ksymtab_##sym		\
+	asm("__ksymtab_" #sym)						\
 	__attribute__((section("___ksymtab" sec "+" #sym), used))	\
-	= { (unsigned long)&sym, __kstrtab_##sym }
+	__aligned(sizeof(void *))					\
+	= { (unsigned long)&sym, __kstrtab_##sym, NULL }
 
 struct kernel_symbol {
 	unsigned long value;
 	const char *name;
+	const char *namespace;
 };
 #endif
 
 #ifdef __GENKSYMS__
 
-#define ___EXPORT_SYMBOL(sym, sec)	__GENKSYMS_EXPORT_SYMBOL(sym)
+#define ___EXPORT_SYMBOL(sym,sec)	__GENKSYMS_EXPORT_SYMBOL(sym)
+#define ___EXPORT_SYMBOL_NS(sym,sec,ns)	__GENKSYMS_EXPORT_SYMBOL(sym)
 
 #else
 
-/* For every exported symbol, place a struct in the __ksymtab section */
-#define ___EXPORT_SYMBOL(sym, sec)					\
+#define ___export_symbol_common(sym, sec)				\
 	extern typeof(sym) sym;						\
-	__CRC_SYMBOL(sym, sec)						\
+	__CRC_SYMBOL(sym, sec);						\
 	static const char __kstrtab_##sym[]				\
 	__attribute__((section("__ksymtab_strings"), used, aligned(1)))	\
-	= #sym;								\
+	= #sym								\
+
+/* For every exported symbol, place a struct in the __ksymtab section */
+#define ___EXPORT_SYMBOL_NS(sym, sec, ns)				\
+	___export_symbol_common(sym, sec);				\
+	static const char __kstrtab_ns_##sym[]				\
+	__attribute__((section("__ksymtab_strings"), used, aligned(1)))	\
+	= #ns;								\
+	__KSYMTAB_ENTRY_NS(sym, sec, ns)
+
+#define ___EXPORT_SYMBOL(sym, sec)					\
+	___export_symbol_common(sym, sec);				\
 	__KSYMTAB_ENTRY(sym, sec)
 
 #endif
@@ -95,6 +130,7 @@ struct kernel_symbol {
  * be reused in other execution contexts such as the UEFI stub or the
  * decompressor.
  */
+#define __EXPORT_SYMBOL_NS(sym, sec, ns)
 #define __EXPORT_SYMBOL(sym, sec)
 
 #elif defined(CONFIG_TRIM_UNUSED_KSYMS)
@@ -121,15 +157,35 @@ struct kernel_symbol {
 #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
 #define __cond_export_sym_0(sym, sec) /* nothing */
 
+#define __EXPORT_SYMBOL_NS(sym, sec, ns)				\
+	__ksym_marker(sym);						\
+	__cond_export_ns_sym(sym, sec, ns, __is_defined(__KSYM_##sym))
+#define __cond_export_ns_sym(sym, sec, ns, conf)			\
+	___cond_export_ns_sym(sym, sec, ns, conf)
+#define ___cond_export_ns_sym(sym, sec, ns, enabled)			\
+	__cond_export_ns_sym_##enabled(sym, sec, ns)
+#define __cond_export_ns_sym_1(sym, sec, ns) ___EXPORT_SYMBOL_NS(sym, sec, ns)
+#define __cond_export_ns_sym_0(sym, sec, ns) /* nothing */
+
 #else
 
-#define __EXPORT_SYMBOL(sym, sec)	___EXPORT_SYMBOL(sym, sec)
+#define __EXPORT_SYMBOL_NS(sym,sec,ns)	___EXPORT_SYMBOL_NS(sym,sec,ns)
+#define __EXPORT_SYMBOL(sym,sec)	___EXPORT_SYMBOL(sym,sec)
 
 #endif /* CONFIG_MODULES */
 
+#ifdef DEFAULT_SYMBOL_NAMESPACE
+#undef __EXPORT_SYMBOL
+#define __EXPORT_SYMBOL(sym, sec)				\
+	__EXPORT_SYMBOL_NS(sym, sec, DEFAULT_SYMBOL_NAMESPACE)
+#endif
+
 #define EXPORT_SYMBOL(sym)		__EXPORT_SYMBOL(sym, "")
 #define EXPORT_SYMBOL_GPL(sym)		__EXPORT_SYMBOL(sym, "_gpl")
 #define EXPORT_SYMBOL_GPL_FUTURE(sym)	__EXPORT_SYMBOL(sym, "_gpl_future")
+#define EXPORT_SYMBOL_NS(sym, ns)	__EXPORT_SYMBOL_NS(sym, "", ns)
+#define EXPORT_SYMBOL_NS_GPL(sym, ns)	__EXPORT_SYMBOL_NS(sym, "_gpl", 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")