Modules updates for v4.10

Summary of modules changes for the 4.10 merge window:
 
 * The rodata= cmdline parameter has been extended to additionally
   apply to module mappings
 
 * Fix a hard to hit race between module loader error/clean up
   handling and ftrace registration
 
 * Some code cleanups, notably panic.c and modules code use a
   unified taint_flags table now. This is much cleaner than
   duplicating the taint flag code in modules.c
 
 Signed-off-by: Jessica Yu <jeyu@redhat.com>
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Merge tag 'modules-for-v4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux

Pull modules updates from Jessica Yu:
 "Summary of modules changes for the 4.10 merge window:

   - The rodata= cmdline parameter has been extended to additionally
     apply to module mappings

   - Fix a hard to hit race between module loader error/clean up
     handling and ftrace registration

   - Some code cleanups, notably panic.c and modules code use a unified
     taint_flags table now. This is much cleaner than duplicating the
     taint flag code in modules.c"

* tag 'modules-for-v4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
  module: fix DEBUG_SET_MODULE_RONX typo
  module: extend 'rodata=off' boot cmdline parameter to module mappings
  module: Fix a comment above strong_try_module_get()
  module: When modifying a module's text ignore modules which are going away too
  module: Ensure a module's state is set accordingly during module coming cleanup code
  module: remove trailing whitespace
  taint/module: Clean up global and module taint flags handling
  modpost: free allocated memory

include/linux/init.h

@@ -126,6 +126,9 @@ void prepare_namespace(void);
 void __init load_default_modules(void);
 int __init init_rootfs(void);
 
+#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX)
+extern bool rodata_enabled;
+#endif
 #ifdef CONFIG_DEBUG_RODATA
 void mark_rodata_ro(void);
 #endif

include/linux/kernel.h

@@ -511,6 +511,15 @@ extern enum system_states {
 #define TAINT_UNSIGNED_MODULE		13
 #define TAINT_SOFTLOCKUP		14
 #define TAINT_LIVEPATCH			15
+#define TAINT_FLAGS_COUNT		16
+
+struct taint_flag {
+	char true;	/* character printed when tainted */
+	char false;	/* character printed when not tainted */
+	bool module;	/* also show as a per-module taint flag */
+};
+
+extern const struct taint_flag taint_flags[TAINT_FLAGS_COUNT];
 
 extern const char hex_asc[];
 #define hex_asc_lo(x)	hex_asc[((x) & 0x0f)]

include/linux/module.h

@@ -399,7 +399,7 @@ struct module {
 	/* Arch-specific module values */
 	struct mod_arch_specific arch;
 
-	unsigned int taints;	/* same bits as kernel:tainted */
+	unsigned long taints;	/* same bits as kernel:taint_flags */
 
 #ifdef CONFIG_GENERIC_BUG
 	/* Support for BUG */
@@ -412,7 +412,7 @@ struct module {
 	/* Protected by RCU and/or module_mutex: use rcu_dereference() */
 	struct mod_kallsyms *kallsyms;
 	struct mod_kallsyms core_kallsyms;
-	
+
 	/* Section attributes */
 	struct module_sect_attrs *sect_attrs;
 

init/main.c

@@ -81,6 +81,7 @@
 #include <linux/integrity.h>
 #include <linux/proc_ns.h>
 #include <linux/io.h>
+#include <linux/cache.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -925,14 +926,16 @@ static int try_to_run_init_process(const char *init_filename)
 
 static noinline void __init kernel_init_freeable(void);
 
-#ifdef CONFIG_DEBUG_RODATA
+#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX)
-static bool rodata_enabled = true;
+bool rodata_enabled __ro_after_init = true;
 static int __init set_debug_rodata(char *str)
 {
 	return strtobool(str, &rodata_enabled);
 }
 __setup("rodata=", set_debug_rodata);
+#endif
 
+#ifdef CONFIG_DEBUG_RODATA
 static void mark_readonly(void)
 {
 	if (rodata_enabled)

kernel/module.c

@@ -313,8 +313,11 @@ struct load_info {
 	} index;
 };
 
-/* We require a truly strong try_module_get(): 0 means failure due to
+/*
-   ongoing or failed initialization etc. */
+ * We require a truly strong try_module_get(): 0 means success.
+ * Otherwise an error is returned due to ongoing or failed
+ * initialization etc.
+ */
 static inline int strong_try_module_get(struct module *mod)
 {
 	BUG_ON(mod && mod->state == MODULE_STATE_UNFORMED);
@@ -330,7 +333,7 @@ static inline void add_taint_module(struct module *mod, unsigned flag,
 				    enum lockdep_ok lockdep_ok)
 {
 	add_taint(flag, lockdep_ok);
-	mod->taints |= (1U << flag);
+	set_bit(flag, &mod->taints);
 }
 
 /*
@@ -1138,24 +1141,13 @@ static inline int module_unload_init(struct module *mod)
 static size_t module_flags_taint(struct module *mod, char *buf)
 {
 	size_t l = 0;
+	int i;
+
+	for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
+		if (taint_flags[i].module && test_bit(i, &mod->taints))
+			buf[l++] = taint_flags[i].true;
+	}
 
-	if (mod->taints & (1 << TAINT_PROPRIETARY_MODULE))
-		buf[l++] = 'P';
-	if (mod->taints & (1 << TAINT_OOT_MODULE))
-		buf[l++] = 'O';
-	if (mod->taints & (1 << TAINT_FORCED_MODULE))
-		buf[l++] = 'F';
-	if (mod->taints & (1 << TAINT_CRAP))
-		buf[l++] = 'C';
-	if (mod->taints & (1 << TAINT_UNSIGNED_MODULE))
-		buf[l++] = 'E';
-	if (mod->taints & (1 << TAINT_LIVEPATCH))
-		buf[l++] = 'K';
-	/*
-	 * TAINT_FORCED_RMMOD: could be added.
-	 * TAINT_CPU_OUT_OF_SPEC, TAINT_MACHINE_CHECK, TAINT_BAD_PAGE don't
-	 * apply to modules.
-	 */
 	return l;
 }
 
@@ -1911,6 +1903,9 @@ static void frob_writable_data(const struct module_layout *layout,
 /* livepatching wants to disable read-only so it can frob module. */
 void module_disable_ro(const struct module *mod)
 {
+	if (!rodata_enabled)
+		return;
+
 	frob_text(&mod->core_layout, set_memory_rw);
 	frob_rodata(&mod->core_layout, set_memory_rw);
 	frob_ro_after_init(&mod->core_layout, set_memory_rw);
@@ -1920,6 +1915,9 @@ void module_disable_ro(const struct module *mod)
 
 void module_enable_ro(const struct module *mod, bool after_init)
 {
+	if (!rodata_enabled)
+		return;
+
 	frob_text(&mod->core_layout, set_memory_ro);
 	frob_rodata(&mod->core_layout, set_memory_ro);
 	frob_text(&mod->init_layout, set_memory_ro);
@@ -1952,6 +1950,9 @@ void set_all_modules_text_rw(void)
 {
 	struct module *mod;
 
+	if (!rodata_enabled)
+		return;
+
 	mutex_lock(&module_mutex);
 	list_for_each_entry_rcu(mod, &modules, list) {
 		if (mod->state == MODULE_STATE_UNFORMED)
@@ -1968,9 +1969,18 @@ void set_all_modules_text_ro(void)
 {
 	struct module *mod;
 
+	if (!rodata_enabled)
+		return;
+
 	mutex_lock(&module_mutex);
 	list_for_each_entry_rcu(mod, &modules, list) {
-		if (mod->state == MODULE_STATE_UNFORMED)
+		/*
+		 * Ignore going modules since it's possible that ro
+		 * protection has already been disabled, otherwise we'll
+		 * run into protection faults at module deallocation.
+		 */
+		if (mod->state == MODULE_STATE_UNFORMED ||
+			mod->state == MODULE_STATE_GOING)
 			continue;
 
 		frob_text(&mod->core_layout, set_memory_ro);
@@ -1981,10 +1991,12 @@ void set_all_modules_text_ro(void)
 
 static void disable_ro_nx(const struct module_layout *layout)
 {
-	frob_text(layout, set_memory_rw);
+	if (rodata_enabled) {
-	frob_rodata(layout, set_memory_rw);
+		frob_text(layout, set_memory_rw);
+		frob_rodata(layout, set_memory_rw);
+		frob_ro_after_init(layout, set_memory_rw);
+	}
 	frob_rodata(layout, set_memory_x);
-	frob_ro_after_init(layout, set_memory_rw);
 	frob_ro_after_init(layout, set_memory_x);
 	frob_writable_data(layout, set_memory_x);
 }
@@ -3709,6 +3721,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
  sysfs_cleanup:
 	mod_sysfs_teardown(mod);
  coming_cleanup:
+	mod->state = MODULE_STATE_GOING;
 	blocking_notifier_call_chain(&module_notify_list,
 				     MODULE_STATE_GOING, mod);
 	klp_module_going(mod);
@@ -4042,6 +4055,10 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
 }
 #endif /* CONFIG_KALLSYMS */
 
+/* Maximum number of characters written by module_flags() */
+#define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)
+
+/* Keep in sync with MODULE_FLAGS_BUF_SIZE !!! */
 static char *module_flags(struct module *mod, char *buf)
 {
 	int bx = 0;
@@ -4086,7 +4103,7 @@ static void m_stop(struct seq_file *m, void *p)
 static int m_show(struct seq_file *m, void *p)
 {
 	struct module *mod = list_entry(p, struct module, list);
-	char buf[8];
+	char buf[MODULE_FLAGS_BUF_SIZE];
 
 	/* We always ignore unformed modules. */
 	if (mod->state == MODULE_STATE_UNFORMED)
@@ -4257,7 +4274,7 @@ EXPORT_SYMBOL_GPL(__module_text_address);
 void print_modules(void)
 {
 	struct module *mod;
-	char buf[8];
+	char buf[MODULE_FLAGS_BUF_SIZE];
 
 	printk(KERN_DEFAULT "Modules linked in:");
 	/* Most callers should already have preempt disabled, but make sure */

kernel/panic.c

@@ -298,30 +298,27 @@ void panic(const char *fmt, ...)
 
 EXPORT_SYMBOL(panic);
 
-
+/*
-struct tnt {
+ * TAINT_FORCED_RMMOD could be a per-module flag but the module
-	u8	bit;
+ * is being removed anyway.
-	char	true;
+ */
-	char	false;
+const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
-};
+	{ 'P', 'G', true },	/* TAINT_PROPRIETARY_MODULE */
-
+	{ 'F', ' ', true },	/* TAINT_FORCED_MODULE */
-static const struct tnt tnts[] = {
+	{ 'S', ' ', false },	/* TAINT_CPU_OUT_OF_SPEC */
-	{ TAINT_PROPRIETARY_MODULE,	'P', 'G' },
+	{ 'R', ' ', false },	/* TAINT_FORCED_RMMOD */
-	{ TAINT_FORCED_MODULE,		'F', ' ' },
+	{ 'M', ' ', false },	/* TAINT_MACHINE_CHECK */
-	{ TAINT_CPU_OUT_OF_SPEC,	'S', ' ' },
+	{ 'B', ' ', false },	/* TAINT_BAD_PAGE */
-	{ TAINT_FORCED_RMMOD,		'R', ' ' },
+	{ 'U', ' ', false },	/* TAINT_USER */
-	{ TAINT_MACHINE_CHECK,		'M', ' ' },
+	{ 'D', ' ', false },	/* TAINT_DIE */
-	{ TAINT_BAD_PAGE,		'B', ' ' },
+	{ 'A', ' ', false },	/* TAINT_OVERRIDDEN_ACPI_TABLE */
-	{ TAINT_USER,			'U', ' ' },
+	{ 'W', ' ', false },	/* TAINT_WARN */
-	{ TAINT_DIE,			'D', ' ' },
+	{ 'C', ' ', true },	/* TAINT_CRAP */
-	{ TAINT_OVERRIDDEN_ACPI_TABLE,	'A', ' ' },
+	{ 'I', ' ', false },	/* TAINT_FIRMWARE_WORKAROUND */
-	{ TAINT_WARN,			'W', ' ' },
+	{ 'O', ' ', true },	/* TAINT_OOT_MODULE */
-	{ TAINT_CRAP,			'C', ' ' },
+	{ 'E', ' ', true },	/* TAINT_UNSIGNED_MODULE */
-	{ TAINT_FIRMWARE_WORKAROUND,	'I', ' ' },
+	{ 'L', ' ', false },	/* TAINT_SOFTLOCKUP */
-	{ TAINT_OOT_MODULE,		'O', ' ' },
+	{ 'K', ' ', true },	/* TAINT_LIVEPATCH */
-	{ TAINT_UNSIGNED_MODULE,	'E', ' ' },
-	{ TAINT_SOFTLOCKUP,		'L', ' ' },
-	{ TAINT_LIVEPATCH,		'K', ' ' },
 };
 
 /**
@@ -348,16 +345,16 @@ static const struct tnt tnts[] = {
  */
 const char *print_tainted(void)
 {
-	static char buf[ARRAY_SIZE(tnts) + sizeof("Tainted: ")];
+	static char buf[TAINT_FLAGS_COUNT + sizeof("Tainted: ")];
 
 	if (tainted_mask) {
 		char *s;
 		int i;
 
 		s = buf + sprintf(buf, "Tainted: ");
-		for (i = 0; i < ARRAY_SIZE(tnts); i++) {
+		for (i = 0; i < TAINT_FLAGS_COUNT; i++) {
-			const struct tnt *t = &tnts[i];
+			const struct taint_flag *t = &taint_flags[i];
-			*s++ = test_bit(t->bit, &tainted_mask) ?
+			*s++ = test_bit(i, &tainted_mask) ?
 					t->true : t->false;
 		}
 		*s = 0;

scripts/mod/modpost.c

@@ -2371,6 +2371,7 @@ static void write_dump(const char *fname)
 		}
 	}
 	write_if_changed(&buf, fname);
+	free(buf.p);
 }
 
 struct ext_sym_list {
@@ -2496,6 +2497,7 @@ int main(int argc, char **argv)
 			      "Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.\n");
 		}
 	}
+	free(buf.p);
 
 	return err;
 }