[PATCH] module: clean-up for module_memory

[Song Liu]

Three changes here:

1. Shorter variable names in arch/arc/kernel/unwind.c:unwind_add_table, to
   make it easier to read.
2. Rewrite free_mod_mem() so it is more obvious that MOD_DATA need to be
   freed last.
3. Clean up the use of CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC.

Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Signed-off-by: Song Liu <song@xxxxxxxxxx>

---

This is the follow up patch on top of [1]. I would recommend fold this
into [1].

[1] https://lore.kernel.org/linux-modules/20230207002802.2514802-1-song@xxxxxxxxxx/T/#u
---
 arch/arc/kernel/unwind.c | 15 ++++------
 kernel/module/main.c     | 61 +++++++++++-----------------------------
 2 files changed, 22 insertions(+), 54 deletions(-)

diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c
index 933451f4494f..9270d0a713c3 100644
--- a/arch/arc/kernel/unwind.c
+++ b/arch/arc/kernel/unwind.c
@@ -369,8 +369,8 @@ void *unwind_add_table(struct module *module, const void *table_start,
 		       unsigned long table_size)
 {
 	struct unwind_table *table;
-	struct module_memory *mod_mem_core_text;
-	struct module_memory *mod_mem_init_text;
+	struct module_memory *core_text;
+	struct module_memory *init_text;
 
 	if (table_size <= 0)
 		return NULL;
@@ -379,14 +379,11 @@ void *unwind_add_table(struct module *module, const void *table_start,
 	if (!table)
 		return NULL;
 
-	mod_mem_core_text = &module->mem[MOD_TEXT];
-	mod_mem_init_text = &module->mem[MOD_INIT_TEXT];
+	core_text = &module->mem[MOD_TEXT];
+	init_text = &module->mem[MOD_INIT_TEXT];
 
-	init_unwind_table(table, module->name,
-			  mod_mem_core_text->base, mod_mem_core_text->size,
-			  mod_mem_init_text->base, mod_mem_init_text->size,
-			  table_start, table_size,
-			  NULL, 0);
+	init_unwind_table(table, module->name, core_text->base, core_text->size,
+			  init_text->base, init_text->size, table_start, table_size, NULL, 0);
 
 	init_unwind_hdr(table, unw_hdr_alloc);
 
diff --git a/kernel/module/main.c b/kernel/module/main.c
index c598f11e7016..2724bc1b9a90 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -927,26 +927,17 @@ static ssize_t store_uevent(struct module_attribute *mattr,
 struct module_attribute module_uevent =
 	__ATTR(uevent, 0200, NULL, store_uevent);
 
-#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
-
-static ssize_t show_coresize(struct module_attribute *mattr,
-			     struct module_kobject *mk, char *buffer)
-{
-	return sprintf(buffer, "%u\n", mk->mod->mem[MOD_TEXT].size);
-}
-
-#else
-
 static ssize_t show_coresize(struct module_attribute *mattr,
 			     struct module_kobject *mk, char *buffer)
 {
-	unsigned int size = 0;
+	unsigned int size = mk->mod->mem[MOD_TEXT].size;
 
-	for_class_mod_mem_type(type, core)
-		size += mk->mod->mem[type].size;
+	if (!IS_ENABLED(CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC)) {
+		for_class_mod_mem_type(type, core_data)
+			size += mk->mod->mem[type].size;
+	}
 	return sprintf(buffer, "%u\n", size);
 }
-#endif
 
 static struct module_attribute modinfo_coresize =
 	__ATTR(coresize, 0444, show_coresize, NULL);
@@ -1170,17 +1161,11 @@ void __weak module_arch_freeing_init(struct module *mod)
 {
 }
 
-#ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
 static bool mod_mem_use_vmalloc(enum mod_mem_type type)
 {
-	return mod_mem_type_is_core_data(type);
-}
-#else
-static bool mod_mem_use_vmalloc(enum mod_mem_type type)
-{
-	return false;
+	return IS_ENABLED(CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC) &&
+		mod_mem_type_is_core_data(type);
 }
-#endif
 
 static void *module_memory_alloc(unsigned int size, enum mod_mem_type type)
 {
@@ -1199,34 +1184,21 @@ static void module_memory_free(void *ptr, enum mod_mem_type type)
 
 static void free_mod_mem(struct module *mod)
 {
-	/* free the memory in the right order to avoid use-after-free */
-	static enum mod_mem_type mod_mem_free_order[MOD_MEM_NUM_TYPES] = {
-		/* first free init sections */
-		MOD_INIT_TEXT,
-		MOD_INIT_DATA,
-		MOD_INIT_RODATA,
-
-		/* then core sections, except rw data */
-		MOD_TEXT,
-		MOD_RODATA,
-		MOD_RO_AFTER_INIT,
-
-		/* rw data need to be freed last, as it hosts mod */
-		MOD_DATA,
-	};
-	int i;
-
-	BUILD_BUG_ON(ARRAY_SIZE(mod_mem_free_order) != MOD_MEM_NUM_TYPES);
-
-	for (i = 0; i < MOD_MEM_NUM_TYPES; i++) {
-		enum mod_mem_type type = mod_mem_free_order[i];
+	for_each_mod_mem_type(type) {
 		struct module_memory *mod_mem = &mod->mem[type];
 
+		if (type == MOD_DATA)
+			continue;
+
 		/* Free lock-classes; relies on the preceding sync_rcu(). */
 		lockdep_free_key_range(mod_mem->base, mod_mem->size);
 		if (mod_mem->size)
 			module_memory_free(mod_mem->base, type);
 	}
+
+	/* MOD_DATA hosts mod, so free it at last */
+	lockdep_free_key_range(mod->mem[MOD_DATA].base, mod->mem[MOD_DATA].size);
+	module_memory_free(mod->mem[MOD_DATA].base, MOD_DATA);
 }
 
 /* Free a module, remove from lists, etc. */
@@ -2211,8 +2183,7 @@ static int move_module(struct module *mod, struct load_info *info)
 		if (!(shdr->sh_flags & SHF_ALLOC))
 			continue;
 
-		dest = mod->mem[type].base +
-			(shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK);
+		dest = mod->mem[type].base + (shdr->sh_entsize & SH_ENTSIZE_OFFSET_MASK);
 
 		if (shdr->sh_type != SHT_NOBITS)
 			memcpy(dest, (void *)shdr->sh_addr, shdr->sh_size);
-- 
2.30.2