module: Add CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC

Add CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC to allow architectures to request having modules data in vmalloc area instead of module area. This is required on powerpc book3s/32 in order to set data non executable, because it is not possible to set executability on page basis, this is done per 256 Mbytes segments. The module area has exec right, vmalloc area has noexec. This can also be useful on other powerpc/32 in order to maximize the chance of code being close enough to kernel core to avoid branch trampolines. Cc: Jason Wessel <[email protected]> Acked-by: Daniel Thompson <[email protected]> Cc: Douglas Anderson <[email protected]> Signed-off-by: Christophe Leroy <[email protected]> [mcgrof: rebased in light of kernel/module/kdb.c move] Signed-off-by: Luis Chamberlain <[email protected]>
josf · Apr 5, 2022 · 01dc038 · 01dc038
1 parent 6ab9942
commit 01dc038
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Showing 8 changed files with 96 additions and 6 deletions.
diff --git a/arch/Kconfig b/arch/Kconfig
@@ -888,6 +888,12 @@ config MODULES_USE_ELF_REL
 	  Modules only use ELF REL relocations.  Modules with ELF RELA
 	  relocations will give an error.
 
+config ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	bool
+	help
+	  For architectures like powerpc/32 which have constraints on module
+	  allocation and need to allocate module data outside of module area.
+
 config HAVE_IRQ_EXIT_ON_IRQ_STACK
 	bool
 	help

diff --git a/include/linux/module.h b/include/linux/module.h
@@ -422,6 +422,9 @@ struct module {
 	/* Core layout: rbtree is accessed frequently, so keep together. */
 	struct module_layout core_layout __module_layout_align;
 	struct module_layout init_layout;
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	struct module_layout data_layout;
+#endif
 
 	/* Arch-specific module values */
 	struct mod_arch_specific arch;
@@ -569,6 +572,11 @@ bool is_module_text_address(unsigned long addr);
 static inline bool within_module_core(unsigned long addr,
 				      const struct module *mod)
 {
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	if ((unsigned long)mod->data_layout.base <= addr &&
+	    addr < (unsigned long)mod->data_layout.base + mod->data_layout.size)
+		return true;
+#endif
 	return (unsigned long)mod->core_layout.base <= addr &&
 	       addr < (unsigned long)mod->core_layout.base + mod->core_layout.size;
 }

diff --git a/kernel/module/internal.h b/kernel/module/internal.h
@@ -20,7 +20,9 @@
 /* Maximum number of characters written by module_flags() */
 #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)
 
+#ifndef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
 #define	data_layout core_layout
+#endif
 
 /*
  * Modules' sections will be aligned on page boundaries
@@ -154,6 +156,7 @@ struct mod_tree_root {
 };
 
 extern struct mod_tree_root mod_tree;
+extern struct mod_tree_root mod_data_tree;
 
 #ifdef CONFIG_MODULES_TREE_LOOKUP
 void mod_tree_insert(struct module *mod);

diff --git a/kernel/module/kdb.c b/kernel/module/kdb.c
@@ -26,8 +26,11 @@ int kdb_lsmod(int argc, const char **argv)
 		if (mod->state == MODULE_STATE_UNFORMED)
 			continue;
 
-		kdb_printf("%-20s%8u  0x%px ", mod->name,
-			   mod->core_layout.size, (void *)mod);
+		kdb_printf("%-20s%8u", mod->name, mod->core_layout.size);
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+		kdb_printf("/%8u", mod->data_layout.size);
+#endif
+		kdb_printf("  0x%px ", (void *)mod);
 #ifdef CONFIG_MODULE_UNLOAD
 		kdb_printf("%4d ", module_refcount(mod));
 #endif
@@ -38,6 +41,9 @@ int kdb_lsmod(int argc, const char **argv)
 		else
 			kdb_printf(" (Live)");
 		kdb_printf(" 0x%px", mod->core_layout.base);
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+		kdb_printf("/0x%px", mod->data_layout.base);
+#endif
 
 #ifdef CONFIG_MODULE_UNLOAD
 		{

diff --git a/kernel/module/main.c b/kernel/module/main.c
@@ -78,6 +78,12 @@ struct mod_tree_root mod_tree __cacheline_aligned = {
 	.addr_min = -1UL,
 };
 
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+struct mod_tree_root mod_data_tree __cacheline_aligned = {
+	.addr_min = -1UL,
+};
+#endif
+
 #define module_addr_min mod_tree.addr_min
 #define module_addr_max mod_tree.addr_max
 
@@ -107,6 +113,9 @@ static void mod_update_bounds(struct module *mod)
 	__mod_update_bounds(mod->core_layout.base, mod->core_layout.size, &mod_tree);
 	if (mod->init_layout.size)
 		__mod_update_bounds(mod->init_layout.base, mod->init_layout.size, &mod_tree);
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	__mod_update_bounds(mod->data_layout.base, mod->data_layout.size, &mod_data_tree);
+#endif
 }
 
 static void module_assert_mutex_or_preempt(void)
@@ -940,6 +949,17 @@ static ssize_t show_coresize(struct module_attribute *mattr,
 static struct module_attribute modinfo_coresize =
 	__ATTR(coresize, 0444, show_coresize, NULL);
 
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+static ssize_t show_datasize(struct module_attribute *mattr,
+			     struct module_kobject *mk, char *buffer)
+{
+	return sprintf(buffer, "%u\n", mk->mod->data_layout.size);
+}
+
+static struct module_attribute modinfo_datasize =
+	__ATTR(datasize, 0444, show_datasize, NULL);
+#endif
+
 static ssize_t show_initsize(struct module_attribute *mattr,
 			     struct module_kobject *mk, char *buffer)
 {
@@ -968,6 +988,9 @@ struct module_attribute *modinfo_attrs[] = {
 	&modinfo_srcversion,
 	&modinfo_initstate,
 	&modinfo_coresize,
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	&modinfo_datasize,
+#endif
 	&modinfo_initsize,
 	&modinfo_taint,
 #ifdef CONFIG_MODULE_UNLOAD
@@ -1194,6 +1217,9 @@ static void free_module(struct module *mod)
 
 	/* Finally, free the core (containing the module structure) */
 	module_memfree(mod->core_layout.base);
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	vfree(mod->data_layout.base);
+#endif
 }
 
 void *__symbol_get(const char *symbol)
@@ -2124,6 +2150,24 @@ static int move_module(struct module *mod, struct load_info *info)
 	} else
 		mod->init_layout.base = NULL;
 
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	/* Do the allocs. */
+	ptr = vmalloc(mod->data_layout.size);
+	/*
+	 * The pointer to this block is stored in the module structure
+	 * which is inside the block. Just mark it as not being a
+	 * leak.
+	 */
+	kmemleak_not_leak(ptr);
+	if (!ptr) {
+		module_memfree(mod->core_layout.base);
+		module_memfree(mod->init_layout.base);
+		return -ENOMEM;
+	}
+
+	memset(ptr, 0, mod->data_layout.size);
+	mod->data_layout.base = ptr;
+#endif
 	/* Transfer each section which specifies SHF_ALLOC */
 	pr_debug("final section addresses:\n");
 	for (i = 0; i < info->hdr->e_shnum; i++) {
@@ -2299,6 +2343,9 @@ static void module_deallocate(struct module *mod, struct load_info *info)
 	module_arch_freeing_init(mod);
 	module_memfree(mod->init_layout.base);
 	module_memfree(mod->core_layout.base);
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	vfree(mod->data_layout.base);
+#endif
 }
 
 int __weak module_finalize(const Elf_Ehdr *hdr,
@@ -3015,13 +3062,20 @@ bool is_module_address(unsigned long addr)
 struct module *__module_address(unsigned long addr)
 {
 	struct module *mod;
+	struct mod_tree_root *tree;
 
-	if (addr < module_addr_min || addr > module_addr_max)
+	if (addr >= mod_tree.addr_min && addr <= mod_tree.addr_max)
+		tree = &mod_tree;
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	else if (addr >= mod_data_tree.addr_min && addr <= mod_data_tree.addr_max)
+		tree = &mod_data_tree;
+#endif
+	else
 		return NULL;
 
 	module_assert_mutex_or_preempt();
 
-	mod = mod_find(addr, &mod_tree);
+	mod = mod_find(addr, tree);
 	if (mod) {
 		BUG_ON(!within_module(addr, mod));
 		if (mod->state == MODULE_STATE_UNFORMED)

diff --git a/kernel/module/procfs.c b/kernel/module/procfs.c
@@ -67,13 +67,17 @@ static int m_show(struct seq_file *m, void *p)
 	struct module *mod = list_entry(p, struct module, list);
 	char buf[MODULE_FLAGS_BUF_SIZE];
 	void *value;
+	unsigned int size;
 
 	/* We always ignore unformed modules. */
 	if (mod->state == MODULE_STATE_UNFORMED)
 		return 0;
 
-	seq_printf(m, "%s %u",
-		   mod->name, mod->init_layout.size + mod->core_layout.size);
+	size = mod->init_layout.size + mod->core_layout.size;
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	size += mod->data_layout.size;
+#endif
+	seq_printf(m, "%s %u", mod->name, size);
 	print_unload_info(m, mod);
 
 	/* Informative for users. */

diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c
@@ -75,6 +75,7 @@ bool module_check_misalignment(const struct module *mod)
 		return false;
 
 	return layout_check_misalignment(&mod->core_layout) ||
+	       layout_check_misalignment(&mod->data_layout) ||
 	       layout_check_misalignment(&mod->init_layout);
 }
 

diff --git a/kernel/module/tree_lookup.c b/kernel/module/tree_lookup.c
@@ -83,6 +83,11 @@ void mod_tree_insert(struct module *mod)
 	__mod_tree_insert(&mod->core_layout.mtn, &mod_tree);
 	if (mod->init_layout.size)
 		__mod_tree_insert(&mod->init_layout.mtn, &mod_tree);
+
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	mod->data_layout.mtn.mod = mod;
+	__mod_tree_insert(&mod->data_layout.mtn, &mod_data_tree);
+#endif
 }
 
 void mod_tree_remove_init(struct module *mod)
@@ -95,6 +100,9 @@ void mod_tree_remove(struct module *mod)
 {
 	__mod_tree_remove(&mod->core_layout.mtn, &mod_tree);
 	mod_tree_remove_init(mod);
+#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
+	__mod_tree_remove(&mod->data_layout.mtn, &mod_data_tree);
+#endif
 }
 
 struct module *mod_find(unsigned long addr, struct mod_tree_root *tree)