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Message-ID: <a89af714-b9ee-1efa-d21d-92ffc690a7e7@csgroup.eu>
Date: Thu, 9 Feb 2023 19:43:23 +0000
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Song Liu <song@...nel.org>,
"linux-modules@...r.kernel.org" <linux-modules@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC: "hch@....de" <hch@....de>,
"kernel-team@...a.com" <kernel-team@...a.com>,
Luis Chamberlain <mcgrof@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Zijlstra <peterz@...radead.org>,
Guenter Roeck <linux@...ck-us.net>
Subject: Re: [PATCH] module: clean-up for module_memory
Le 09/02/2023 à 18:56, Song Liu a écrit :
> 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@...nel.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Christophe Leroy <christophe.leroy@...roup.eu>
> Signed-off-by: Song Liu <song@...nel.org>
>
> ---
>
> This is the follow up patch on top of [1]. I would recommend fold this
> into [1].
With this patch folded into [1],
Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>
>
> [1] https://lore.kernel.org/linux-modules/20230207002802.2514802-1-song@kernel.org/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);
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