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Commit 35bc6f3f authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds
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[PATCH] Embed __this_module in module itself. 

	Rather than have the module loader the module structure and
resolve the symbols __this_module to it, make __this_module a real
structure inside the module, using the linkonce trick we used for
module names.

	This saves us an allocation (saving a page per module on
archs which need the module structure close by), and means we don't
have to fill in a few module fields.
parent cd28caa3
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Showing with 66 additions and 76 deletions
include/linux/init.h
View file @ 35bc6f3f
......@@ -147,14 +147,13 @@ struct obs_kernel_param {
#define module_init(initfn) \
static inline initcall_t __inittest(void) \
{ return initfn; } \
int __initfn(void) __attribute__((alias(#initfn)));
int init_module(void) __attribute__((alias(#initfn)));
/* This is only required if you want to be unloadable. */
#define module_exit(exitfn) \
static inline exitcall_t __exittest(void) \
{ return exitfn; } \
void __exitfn(void) __attribute__((alias(#exitfn)));
void cleanup_module(void) __attribute__((alias(#exitfn)));
#define __setup(str,func) /* nothing */
#endif
......
include/linux/module.h
View file @ 35bc6f3f
......@@ -40,12 +40,11 @@ struct kernel_symbol
char name[MODULE_NAME_LEN];
};
#ifdef MODULE
/* These are either module local, or the kernel's dummy ones. */
extern int init_module(void);
extern void cleanup_module(void);
#ifdef KBUILD_MODNAME
static const char __module_name[MODULE_NAME_LEN] __attribute__((section(".gnu.linkonce.modname"))) = \
__stringify(KBUILD_MODNAME);
#endif
#ifdef MODULE
/* For replacement modutils, use an alias not a pointer. */
#define MODULE_GENERIC_TABLE(gtype,name) \
......@@ -56,9 +55,6 @@ static const struct gtype##_id * __module_##gtype##_table \
extern const struct gtype##_id __mod_##gtype##_table \
__attribute__ ((unused, alias(__stringify(name))))
/* This is magically filled in by the linker, but THIS_MODULE must be
a constant so it works in initializers. */
extern struct module __this_module;
#define THIS_MODULE (&__this_module)
#else /* !MODULE */
......@@ -176,7 +172,7 @@ struct module
/* The command line arguments (may be mangled). People like
keeping pointers to this stuff */
char args[0];
char *args;
};
/* FIXME: It'd be nice to isolate modules during init, too, so they
......@@ -289,6 +285,19 @@ static inline const char *module_address_lookup(unsigned long addr,
}
#endif /* CONFIG_MODULES */
#if defined(MODULE) && defined(KBUILD_MODNAME)
/* We make the linker do some of the work. */
struct module __this_module
__attribute__((section(".gnu.linkonce.this_module"))) = {
.name = __stringify(KBUILD_MODNAME),
.symbols = { .owner = &__this_module },
.init = init_module,
#ifdef CONFIG_MODULE_UNLOAD
.exit = cleanup_module,
#endif
};
#endif /* MODULE && KBUILD_MODNAME */
/* For archs to search exception tables */
extern struct list_head extables;
extern spinlock_t modlist_lock;
......@@ -360,13 +369,6 @@ extern int module_dummy_usage;
&& __mod_between((p),(n),(m)->module_init,(m)->init_size)) \
|| __mod_between((p),(n),(m)->module_core,(m)->core_size))
/* Old-style "I'll just call it init_module and it'll be run at
insert". Use module_init(myroutine) instead. */
#ifdef MODULE
#define init_module(voidarg) __initfn(void)
#define cleanup_module(voidarg) __exitfn(void)
#endif
/*
* The exception and symbol tables, and the lock
* to protect them.
......
kernel/module.c
View file @ 35bc6f3f
......@@ -60,6 +60,13 @@ struct sizes
unsigned long core_size;
};
/* Stub function for modules which don't have an initfn */
int init_module(void)
{
return 0;
}
EXPORT_SYMBOL(init_module);
/* Find a symbol, return value and the symbol group */
static unsigned long __find_symbol(const char *name,
struct kernel_symbol_group **group)
......@@ -357,6 +364,12 @@ static inline int try_force(unsigned int flags)
}
#endif /* CONFIG_MODULE_FORCE_UNLOAD */
/* Stub function for modules which don't have an exitfn */
void cleanup_module(void)
{
}
EXPORT_SYMBOL(cleanup_module);
asmlinkage long
sys_delete_module(const char *name_user, unsigned int flags)
{
......@@ -406,7 +419,8 @@ sys_delete_module(const char *name_user, unsigned int flags)
}
/* If it has an init func, it must have an exit func to unload */
if ((mod->init && !mod->exit) || mod->unsafe) {
if ((mod->init != init_module && mod->exit == cleanup_module)
|| mod->unsafe) {
forced = try_force(flags);
if (!forced) {
/* This module can't be removed */
......@@ -453,7 +467,6 @@ sys_delete_module(const char *name_user, unsigned int flags)
destroy:
/* Final destruction now noone is using it. */
if (mod->exit)
mod->exit();
free_module(mod);
......@@ -474,7 +487,7 @@ static void print_unload_info(struct seq_file *m, struct module *mod)
if (mod->unsafe)
seq_printf(m, " [unsafe]");
if (mod->init && !mod->exit)
if (mod->init != init_module && mod->exit == cleanup_module)
seq_printf(m, " [permanent]");
seq_printf(m, "\n");
......@@ -708,15 +721,15 @@ static void free_module(struct module *mod)
list_del(&mod->extable.list);
spin_unlock_irq(&modlist_lock);
/* These may be NULL, but that's OK */
module_free(mod, mod->module_init);
module_free(mod, mod->module_core);
/* Module unload stuff */
module_unload_free(mod);
/* Finally, free the module structure */
module_free(mod, mod);
/* This may be NULL, but that's OK */
module_free(mod, mod->module_init);
kfree(mod->args);
/* Finally, free the core (containing the module structure) */
module_free(mod, mod->module_core);
}
void *__symbol_get(const char *symbol)
......@@ -771,27 +784,6 @@ static void *copy_section(const char *name,
return dest;
}
/* Look for the special symbols */
static int grab_private_symbols(Elf_Shdr *sechdrs,
unsigned int symbolsec,
const char *strtab,
struct module *mod)
{
Elf_Sym *sym = (void *)sechdrs[symbolsec].sh_offset;
unsigned int i;
for (i = 1; i < sechdrs[symbolsec].sh_size/sizeof(*sym); i++) {
if (symbol_is("__initfn", strtab + sym[i].st_name))
mod->init = (void *)sym[i].st_value;
#ifdef CONFIG_MODULE_UNLOAD
if (symbol_is("__exitfn", strtab + sym[i].st_name))
mod->exit = (void *)sym[i].st_value;
#endif
}
return 0;
}
/* Deal with the given section */
static int handle_section(const char *name,
Elf_Shdr *sechdrs,
......@@ -810,9 +802,6 @@ static int handle_section(const char *name,
case SHT_RELA:
ret = apply_relocate_add(sechdrs, strtab, symindex, i, mod);
break;
case SHT_SYMTAB:
ret = grab_private_symbols(sechdrs, i, strtab, mod);
break;
default:
DEBUGP("Ignoring section %u: %s\n", i,
sechdrs[i].sh_type==SHT_NULL ? "NULL":
......@@ -920,9 +909,6 @@ static void simplify_symbols(Elf_Shdr *sechdrs,
strtab + sym[i].st_name,
mod,
&ksg);
/* We fake up "__this_module" */
if (symbol_is("__this_module", strtab+sym[i].st_name))
sym[i].st_value = (unsigned long)mod;
}
}
}
......@@ -964,9 +950,9 @@ static struct module *load_module(void *umod,
{
Elf_Ehdr *hdr;
Elf_Shdr *sechdrs;
char *secstrings;
char *secstrings, *args;
unsigned int i, symindex, exportindex, strindex, setupindex, exindex,
modnameindex, obsparmindex;
modindex, obsparmindex;
long arglen;
unsigned long common_length;
struct sizes sizes, used;
......@@ -1007,7 +993,7 @@ static struct module *load_module(void *umod,
exportindex = setupindex = obsparmindex = 0;
/* And these should exist, but gcc whinges if we don't init them */
symindex = strindex = exindex = modnameindex = 0;
symindex = strindex = exindex = modindex = 0;
/* Find where important sections are */
for (i = 1; i < hdr->e_shnum; i++) {
......@@ -1016,10 +1002,10 @@ static struct module *load_module(void *umod,
DEBUGP("Symbol table in section %u\n", i);
symindex = i;
} else if (strcmp(secstrings+sechdrs[i].sh_name,
".gnu.linkonce.modname") == 0) {
/* This module's name */
DEBUGP("Module name in section %u\n", i);
modnameindex = i;
".gnu.linkonce.this_module") == 0) {
/* The module struct */
DEBUGP("Module in section %u\n", i);
modindex = i;
} else if (strcmp(secstrings+sechdrs[i].sh_name, "__ksymtab")
== 0) {
/* Exported symbols. */
......@@ -1058,39 +1044,35 @@ static struct module *load_module(void *umod,
#endif
}
if (!modnameindex) {
DEBUGP("Module has no name!\n");
if (!modindex) {
printk(KERN_WARNING "No module found in object\n");
err = -ENOEXEC;
goto free_hdr;
}
mod = (void *)hdr + sechdrs[modindex].sh_offset;
/* Now allocate space for the module proper, and copy name and args. */
/* Now copy in args */
err = strlen_user(uargs);
if (err < 0)
goto free_hdr;
arglen = err;
mod = module_alloc(sizeof(*mod) + arglen+1);
if (!mod) {
args = kmalloc(arglen+1, GFP_KERNEL);
if (!args) {
err = -ENOMEM;
goto free_hdr;
}
memset(mod, 0, sizeof(*mod) + arglen+1);
if (copy_from_user(mod->args, uargs, arglen) != 0) {
if (copy_from_user(args, uargs, arglen+1) != 0) {
err = -EFAULT;
goto free_mod;
}
strncpy(mod->name, (char *)hdr + sechdrs[modnameindex].sh_offset,
sizeof(mod->name)-1);
if (find_module(mod->name)) {
err = -EEXIST;
goto free_mod;
}
mod->symbols.owner = mod;
mod->state = MODULE_STATE_COMING;
module_unload_init(mod);
/* How much space will we need? (Common area in first) */
common_length = read_commons(hdr, &sechdrs[symindex]);
......@@ -1139,6 +1121,9 @@ static struct module *load_module(void *umod,
if (IS_ERR(ptr))
goto cleanup;
sechdrs[i].sh_offset = (unsigned long)ptr;
/* Have we just copied __this_module across? */
if (i == modindex)
mod = ptr;
} else {
sechdrs[i].sh_offset += (unsigned long)hdr;
}
......@@ -1147,6 +1132,9 @@ static struct module *load_module(void *umod,
if (used.init_size > mod->init_size || used.core_size > mod->core_size)
BUG();
/* Now we've moved module, initialize linked lists, etc. */
module_unload_init(mod);
/* Fix up syms, so that st_value is a pointer to location. */
simplify_symbols(sechdrs, symindex, strindex, mod->module_core, mod);
......@@ -1183,6 +1171,7 @@ static struct module *load_module(void *umod,
if (err < 0)
goto cleanup;
mod->args = args;
if (obsparmindex) {
err = obsolete_params(mod->name, mod->args,
(struct obsolete_modparm *)
......@@ -1215,7 +1204,7 @@ static struct module *load_module(void *umod,
free_core:
module_free(mod, mod->module_core);
free_mod:
module_free(mod, mod);
kfree(args);
free_hdr:
vfree(hdr);
if (err < 0) return ERR_PTR(err);
......@@ -1266,7 +1255,7 @@ sys_init_module(void *umod,
up(&module_mutex);
/* Start the module */
ret = mod->init ? mod->init() : 0;
ret = mod->init();
if (ret < 0) {
/* Init routine failed: abort. Try to protect us from
buggy refcounters. */
......
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