#include <linux/errno.h>
#include <linux/kernel.h>
#include <asm/segment.h>
#include <linux/mm.h> /* defines GFP_KERNEL */
#include <linux/string.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/malloc.h>
struct module *module_list = NULL;
int freeing_modules; /* true if some modules are marked for deletion */
struct module *find_module( const char *name);
int get_mod_name( char *user_name, char *buf);
int free_modules( void);
/*
* Allocate space for a module.
*/
//系统调用，创建module，为module分配空间
asmlinkage int
sys_create_module(char *module_name, unsigned long size)
{
int npages;
void* addr;
int len;
char name[MOD_MAX_NAME];
char *savename;
struct module *mp;
int error;
//如果不是超级用户root，则退出
if (!suser())
return -EPERM;
//如果模块的名称为空或者长度为0，则退出
if (module_name == NULL || size == 0)
return -EINVAL;
//根据模块的名称，获取name
if ((error = get_mod_name(module_name, name)) != 0)
return error;
//搜索module
if (find_module(name) != NULL) {
return -EEXIST;
}
len = strlen(name) + 1;
//分配空间
if ((savename = (char*) kmalloc(len, GFP_KERNEL)) == NULL)
return -ENOMEM;
//拷贝名称
memcpy(savename, name, len);
//申请空间
if ((mp = (struct module*) kmalloc(sizeof *mp, GFP_KERNEL)) == NULL) {
kfree(savename);
return -ENOMEM;
}
//计算申请的页数
npages = (size + sizeof (int) + 4095) / 4096;
if ((addr = vmalloc(npages * 4096)) == 0) {
kfree_s(mp, sizeof *mp);
kfree(savename);
return -ENOMEM;
}
mp->name = savename;
mp->size = npages;
mp->addr = addr;
mp->state = MOD_UNINITIALIZED;
* (int *) addr = 0; /* set use count to zero */
mp->cleanup = NULL;
mp->next = module_list;
module_list = mp;
printk("module `%s' (%lu pages @ 0x%08lx) created\n",
mp->name, (unsigned long) mp->size, (unsigned long) mp->addr);
return (int) addr;
}
/*
* Initialize a module.
*/
//初始化module
asmlinkage int
sys_init_module(char *module_name, char *code, unsigned codesize,
struct mod_routines *routines)
{
struct module *mp;
char name[MOD_MAX_NAME];
int error;
struct mod_routines rt;
if (!suser())
return -EPERM;
/*
* First reclaim any memory from dead modules that where not
* freed when deleted. Should I think be done by timers when
* the module was deleted - Jon.
*/
free_modules();
if ((error = get_mod_name(module_name, name)) != 0)
return error;
printk( "initializing module `%s', %d (0x%x) bytes\n",
name, codesize, codesize);
memcpy_fromfs(&rt, routines, sizeof rt);
if ((mp = find_module(name)) == NULL)
return -ENOENT;
if ((codesize + sizeof (int) + 4095) / 4096 > mp->size)
return -EINVAL;
memcpy_fromfs((char *)mp->addr + sizeof (int), code, codesize);
memset((char *)mp->addr + sizeof (int) + codesize, 0,
mp->size * 4096 - (codesize + sizeof (int)));
printk( " init entry @ 0x%08lx, cleanup entry @ 0x%08lx\n",
(unsigned long) rt.init, (unsigned long) rt.cleanup);
mp->cleanup = rt.cleanup;
if ((*rt.init)() != 0)
return -EBUSY;
mp->state = MOD_RUNNING;
return 0;
}
//删除module
asmlinkage int
sys_delete_module(char *module_name)
{
struct module *mp;
char name[MOD_MAX_NAME];
int error;
if (!suser())
return -EPERM;
if (module_name != NULL) {
if ((error = get_mod_name(module_name, name)) != 0)
return error;
if ((mp = find_module(name)) == NULL)
return -ENOENT;
if (mp->state == MOD_RUNNING)
(*mp->cleanup)();
mp->state = MOD_DELETED;
}
free_modules();
return 0;
}
/*
* Copy the kernel symbol table to user space. If the argument is null,
* just return the size of the table.
*/
//获取内核符号表
asmlinkage int
sys_get_kernel_syms(struct kernel_sym *table)
{
struct symbol {
unsigned long addr;
char *name;
};
extern int symbol_table_size;
extern struct symbol symbol_table[];
int i;
struct symbol *from;
struct kernel_sym *to;
struct kernel_sym sym;
if (table != NULL) {
from = symbol_table;
to = table;
i = verify_area(VERIFY_WRITE, to, symbol_table_size * sizeof *table);
if (i)
return i;
for (i = symbol_table_size ; --i >= 0 ; ) {
sym.value = from->addr;
strncpy(sym.name, from->name, sizeof sym.name);
memcpy_tofs(to, &sym, sizeof sym);
from++, to++;
}
}
return symbol_table_size;
}
/*
* Copy the name of a module from user space.
*/
//获取mod的名称
int
get_mod_name(char *user_name, char *buf)
{
int i;
i = 0;
for (i = 0 ; (buf[i] = get_fs_byte(user_name + i)) != '\0' ; ) {
if (++i >= MOD_MAX_NAME)
return -E2BIG;
}
return 0;
}
/*
* Look for a module by name, ignoring modules marked for deletion.
*/
//搜索module
struct module *
find_module( const char *name)
{
struct module *mp;
for (mp = module_list ; mp ; mp = mp->next) {
if (mp->state == MOD_DELETED)
continue;
if (!strcmp(mp->name, name))
break;
}
return mp;
}
/*
* Try to free modules which have been marked for deletion. Returns nonzero
* if a module was actually freed.
*/
//释放module
int
free_modules( void)
{
struct module *mp;
struct module **mpp;
int did_deletion;
did_deletion = 0;
freeing_modules = 0;
mpp = &module_list;
while ((mp = *mpp) != NULL) {
if (mp->state != MOD_DELETED) {
mpp = &mp->next;
} else if (GET_USE_COUNT(mp) != 0) {
freeing_modules = 1;
mpp = &mp->next;
} else { /* delete it */
*mpp = mp->next;
vfree(mp->addr);
kfree(mp->name);
kfree_s(mp, sizeof *mp);
did_deletion = 1;
}
}
return did_deletion;
}
/*
* Called by the /proc file system to return a current list of modules.
*/
//获取所有的module
int get_module_list(char *buf)
{
char *p;
char *q;
int i;
struct module *mp;
char size[32];
p = buf;
for (mp = module_list ; mp ; mp = mp->next) {
if (p - buf > 4096 - 100)
break; /* avoid overflowing buffer */
q = mp->name;
i = 20;
while (*q) {
*p++ = *q++;
i--;
}
sprintf(size, "%d", mp->size);
i -= strlen(size);
if (i <= 0)
i = 1;
while (--i >= 0)
*p++ = ' ';
q = size;
while (*q)
*p++ = *q++;
if (mp->state == MOD_UNINITIALIZED)
q = " (uninitialized)";
else if (mp->state == MOD_RUNNING)
q = "";
else if (mp->state == MOD_DELETED)
q = " (deleted)";
else
q = " (bad state)";
while (*q)
*p++ = *q++;
*p++ = '\n';
}
return p - buf;
}
kernel/module.c
