2 * linux/drivers/char/mem.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
7 * Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
8 * Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
12 #include <linux/miscdevice.h>
13 #include <linux/slab.h>
14 #include <linux/vmalloc.h>
15 #include <linux/mman.h>
16 #include <linux/random.h>
17 #include <linux/init.h>
18 #include <linux/raw.h>
19 #include <linux/tty.h>
20 #include <linux/capability.h>
21 #include <linux/ptrace.h>
22 #include <linux/device.h>
23 #include <linux/highmem.h>
24 #include <linux/crash_dump.h>
25 #include <linux/backing-dev.h>
26 #include <linux/bootmem.h>
27 #include <linux/splice.h>
28 #include <linux/pfn.h>
30 #include <asm/uaccess.h>
34 # include <linux/efi.h>
37 static inline unsigned long size_inside_page(unsigned long start
,
42 sz
= PAGE_SIZE
- (start
& (PAGE_SIZE
- 1));
48 * Architectures vary in how they handle caching for addresses
49 * outside of main memory.
52 static inline int uncached_access(struct file
*file
, unsigned long addr
)
54 #if defined(CONFIG_IA64)
56 * On ia64, we ignore O_DSYNC because we cannot tolerate memory attribute aliases.
58 return !(efi_mem_attributes(addr
) & EFI_MEMORY_WB
);
59 #elif defined(CONFIG_MIPS)
61 extern int __uncached_access(struct file
*file
,
64 return __uncached_access(file
, addr
);
68 * Accessing memory above the top the kernel knows about or through a file pointer
69 * that was marked O_DSYNC will be done non-cached.
71 if (file
->f_flags
& O_DSYNC
)
73 return addr
>= __pa(high_memory
);
77 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
78 static inline int valid_phys_addr_range(unsigned long addr
, size_t count
)
80 if (addr
+ count
> __pa(high_memory
))
86 static inline int valid_mmap_phys_addr_range(unsigned long pfn
, size_t size
)
92 #ifdef CONFIG_STRICT_DEVMEM
93 static inline int range_is_allowed(unsigned long pfn
, unsigned long size
)
95 u64 from
= ((u64
)pfn
) << PAGE_SHIFT
;
100 if (!devmem_is_allowed(pfn
)) {
102 "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
103 current
->comm
, from
, to
);
112 static inline int range_is_allowed(unsigned long pfn
, unsigned long size
)
118 void __attribute__((weak
)) unxlate_dev_mem_ptr(unsigned long phys
, void *addr
)
123 * This funcion reads the *physical* memory. The f_pos points directly to the
126 static ssize_t
read_mem(struct file
* file
, char __user
* buf
,
127 size_t count
, loff_t
*ppos
)
129 unsigned long p
= *ppos
;
133 if (!valid_phys_addr_range(p
, count
))
136 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
137 /* we don't have page 0 mapped on sparc and m68k.. */
139 sz
= size_inside_page(p
, count
);
141 if (clear_user(buf
, sz
))
152 unsigned long remaining
;
154 sz
= size_inside_page(p
, count
);
156 if (!range_is_allowed(p
>> PAGE_SHIFT
, count
))
160 * On ia64 if a page has been mapped somewhere as
161 * uncached, then it must also be accessed uncached
162 * by the kernel or data corruption may occur
164 ptr
= xlate_dev_mem_ptr(p
);
168 remaining
= copy_to_user(buf
, ptr
, sz
);
169 unxlate_dev_mem_ptr(p
, ptr
);
183 static ssize_t
write_mem(struct file
* file
, const char __user
* buf
,
184 size_t count
, loff_t
*ppos
)
186 unsigned long p
= *ppos
;
188 unsigned long copied
;
191 if (!valid_phys_addr_range(p
, count
))
196 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
197 /* we don't have page 0 mapped on sparc and m68k.. */
199 sz
= size_inside_page(p
, count
);
200 /* Hmm. Do something? */
209 sz
= size_inside_page(p
, count
);
211 if (!range_is_allowed(p
>> PAGE_SHIFT
, sz
))
215 * On ia64 if a page has been mapped somewhere as
216 * uncached, then it must also be accessed uncached
217 * by the kernel or data corruption may occur
219 ptr
= xlate_dev_mem_ptr(p
);
226 copied
= copy_from_user(ptr
, buf
, sz
);
227 unxlate_dev_mem_ptr(p
, ptr
);
229 written
+= sz
- copied
;
245 int __attribute__((weak
)) phys_mem_access_prot_allowed(struct file
*file
,
246 unsigned long pfn
, unsigned long size
, pgprot_t
*vma_prot
)
251 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
252 static pgprot_t
phys_mem_access_prot(struct file
*file
, unsigned long pfn
,
253 unsigned long size
, pgprot_t vma_prot
)
255 #ifdef pgprot_noncached
256 unsigned long offset
= pfn
<< PAGE_SHIFT
;
258 if (uncached_access(file
, offset
))
259 return pgprot_noncached(vma_prot
);
266 static unsigned long get_unmapped_area_mem(struct file
*file
,
272 if (!valid_mmap_phys_addr_range(pgoff
, len
))
273 return (unsigned long) -EINVAL
;
274 return pgoff
<< PAGE_SHIFT
;
277 /* can't do an in-place private mapping if there's no MMU */
278 static inline int private_mapping_ok(struct vm_area_struct
*vma
)
280 return vma
->vm_flags
& VM_MAYSHARE
;
283 #define get_unmapped_area_mem NULL
285 static inline int private_mapping_ok(struct vm_area_struct
*vma
)
291 static const struct vm_operations_struct mmap_mem_ops
= {
292 #ifdef CONFIG_HAVE_IOREMAP_PROT
293 .access
= generic_access_phys
297 static int mmap_mem(struct file
* file
, struct vm_area_struct
* vma
)
299 size_t size
= vma
->vm_end
- vma
->vm_start
;
301 if (!valid_mmap_phys_addr_range(vma
->vm_pgoff
, size
))
304 if (!private_mapping_ok(vma
))
307 if (!range_is_allowed(vma
->vm_pgoff
, size
))
310 if (!phys_mem_access_prot_allowed(file
, vma
->vm_pgoff
, size
,
314 vma
->vm_page_prot
= phys_mem_access_prot(file
, vma
->vm_pgoff
,
318 vma
->vm_ops
= &mmap_mem_ops
;
320 /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
321 if (remap_pfn_range(vma
,
325 vma
->vm_page_prot
)) {
331 #ifdef CONFIG_DEVKMEM
332 static int mmap_kmem(struct file
* file
, struct vm_area_struct
* vma
)
336 /* Turn a kernel-virtual address into a physical page frame */
337 pfn
= __pa((u64
)vma
->vm_pgoff
<< PAGE_SHIFT
) >> PAGE_SHIFT
;
340 * RED-PEN: on some architectures there is more mapped memory
341 * than available in mem_map which pfn_valid checks
342 * for. Perhaps should add a new macro here.
344 * RED-PEN: vmalloc is not supported right now.
350 return mmap_mem(file
, vma
);
354 #ifdef CONFIG_CRASH_DUMP
356 * Read memory corresponding to the old kernel.
358 static ssize_t
read_oldmem(struct file
*file
, char __user
*buf
,
359 size_t count
, loff_t
*ppos
)
361 unsigned long pfn
, offset
;
362 size_t read
= 0, csize
;
366 pfn
= *ppos
/ PAGE_SIZE
;
367 if (pfn
> saved_max_pfn
)
370 offset
= (unsigned long)(*ppos
% PAGE_SIZE
);
371 if (count
> PAGE_SIZE
- offset
)
372 csize
= PAGE_SIZE
- offset
;
376 rc
= copy_oldmem_page(pfn
, buf
, csize
, offset
, 1);
388 #ifdef CONFIG_DEVKMEM
390 * This function reads the *virtual* memory as seen by the kernel.
392 static ssize_t
read_kmem(struct file
*file
, char __user
*buf
,
393 size_t count
, loff_t
*ppos
)
395 unsigned long p
= *ppos
;
396 ssize_t low_count
, read
, sz
;
397 char * kbuf
; /* k-addr because vread() takes vmlist_lock rwlock */
400 if (p
< (unsigned long) high_memory
) {
402 if (count
> (unsigned long) high_memory
- p
)
403 low_count
= (unsigned long) high_memory
- p
;
405 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
406 /* we don't have page 0 mapped on sparc and m68k.. */
407 if (p
< PAGE_SIZE
&& low_count
> 0) {
408 sz
= size_inside_page(p
, low_count
);
409 if (clear_user(buf
, sz
))
418 while (low_count
> 0) {
419 sz
= size_inside_page(p
, low_count
);
422 * On ia64 if a page has been mapped somewhere as
423 * uncached, then it must also be accessed uncached
424 * by the kernel or data corruption may occur
426 kbuf
= xlate_dev_kmem_ptr((char *)p
);
428 if (copy_to_user(buf
, kbuf
, sz
))
439 kbuf
= (char *)__get_free_page(GFP_KERNEL
);
443 sz
= size_inside_page(p
, count
);
444 sz
= vread(kbuf
, (char *)p
, sz
);
447 if (copy_to_user(buf
, kbuf
, sz
)) {
448 free_page((unsigned long)kbuf
);
456 free_page((unsigned long)kbuf
);
463 static inline ssize_t
464 do_write_kmem(unsigned long p
, const char __user
*buf
,
465 size_t count
, loff_t
*ppos
)
468 unsigned long copied
;
471 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
472 /* we don't have page 0 mapped on sparc and m68k.. */
474 sz
= size_inside_page(p
, count
);
475 /* Hmm. Do something? */
486 sz
= size_inside_page(p
, count
);
489 * On ia64 if a page has been mapped somewhere as
490 * uncached, then it must also be accessed uncached
491 * by the kernel or data corruption may occur
493 ptr
= xlate_dev_kmem_ptr((char *)p
);
495 copied
= copy_from_user(ptr
, buf
, sz
);
497 written
+= sz
- copied
;
514 * This function writes to the *virtual* memory as seen by the kernel.
516 static ssize_t
write_kmem(struct file
* file
, const char __user
* buf
,
517 size_t count
, loff_t
*ppos
)
519 unsigned long p
= *ppos
;
522 char * kbuf
; /* k-addr because vwrite() takes vmlist_lock rwlock */
524 if (p
< (unsigned long) high_memory
) {
525 unsigned long to_write
= min_t(unsigned long, count
,
526 (unsigned long)high_memory
- p
);
527 wrote
= do_write_kmem(p
, buf
, to_write
, ppos
);
528 if (wrote
!= to_write
)
536 kbuf
= (char *)__get_free_page(GFP_KERNEL
);
538 return wrote
? wrote
: -ENOMEM
;
540 unsigned long sz
= size_inside_page(p
, count
);
543 n
= copy_from_user(kbuf
, buf
, sz
);
547 free_page((unsigned long)kbuf
);
550 sz
= vwrite(kbuf
, (char *)p
, sz
);
556 free_page((unsigned long)kbuf
);
560 return virtr
+ wrote
;
564 #ifdef CONFIG_DEVPORT
565 static ssize_t
read_port(struct file
* file
, char __user
* buf
,
566 size_t count
, loff_t
*ppos
)
568 unsigned long i
= *ppos
;
569 char __user
*tmp
= buf
;
571 if (!access_ok(VERIFY_WRITE
, buf
, count
))
573 while (count
-- > 0 && i
< 65536) {
574 if (__put_user(inb(i
),tmp
) < 0)
583 static ssize_t
write_port(struct file
* file
, const char __user
* buf
,
584 size_t count
, loff_t
*ppos
)
586 unsigned long i
= *ppos
;
587 const char __user
* tmp
= buf
;
589 if (!access_ok(VERIFY_READ
,buf
,count
))
591 while (count
-- > 0 && i
< 65536) {
593 if (__get_user(c
, tmp
)) {
607 static ssize_t
read_null(struct file
* file
, char __user
* buf
,
608 size_t count
, loff_t
*ppos
)
613 static ssize_t
write_null(struct file
* file
, const char __user
* buf
,
614 size_t count
, loff_t
*ppos
)
619 static int pipe_to_null(struct pipe_inode_info
*info
, struct pipe_buffer
*buf
,
620 struct splice_desc
*sd
)
625 static ssize_t
splice_write_null(struct pipe_inode_info
*pipe
,struct file
*out
,
626 loff_t
*ppos
, size_t len
, unsigned int flags
)
628 return splice_from_pipe(pipe
, out
, ppos
, len
, flags
, pipe_to_null
);
631 static ssize_t
read_zero(struct file
* file
, char __user
* buf
,
632 size_t count
, loff_t
*ppos
)
639 if (!access_ok(VERIFY_WRITE
, buf
, count
))
644 unsigned long unwritten
;
645 size_t chunk
= count
;
647 if (chunk
> PAGE_SIZE
)
648 chunk
= PAGE_SIZE
; /* Just for latency reasons */
649 unwritten
= __clear_user(buf
, chunk
);
650 written
+= chunk
- unwritten
;
653 if (signal_pending(current
))
654 return written
? written
: -ERESTARTSYS
;
659 return written
? written
: -EFAULT
;
662 static int mmap_zero(struct file
* file
, struct vm_area_struct
* vma
)
667 if (vma
->vm_flags
& VM_SHARED
)
668 return shmem_zero_setup(vma
);
672 static ssize_t
write_full(struct file
* file
, const char __user
* buf
,
673 size_t count
, loff_t
*ppos
)
679 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
680 * can fopen() both devices with "a" now. This was previously impossible.
684 static loff_t
null_lseek(struct file
* file
, loff_t offset
, int orig
)
686 return file
->f_pos
= 0;
690 * The memory devices use the full 32/64 bits of the offset, and so we cannot
691 * check against negative addresses: they are ok. The return value is weird,
692 * though, in that case (0).
694 * also note that seeking relative to the "end of file" isn't supported:
695 * it has no meaning, so it returns -EINVAL.
697 static loff_t
memory_lseek(struct file
* file
, loff_t offset
, int orig
)
701 mutex_lock(&file
->f_path
.dentry
->d_inode
->i_mutex
);
704 file
->f_pos
= offset
;
706 force_successful_syscall_return();
709 file
->f_pos
+= offset
;
711 force_successful_syscall_return();
716 mutex_unlock(&file
->f_path
.dentry
->d_inode
->i_mutex
);
720 static int open_port(struct inode
* inode
, struct file
* filp
)
722 return capable(CAP_SYS_RAWIO
) ? 0 : -EPERM
;
725 #define zero_lseek null_lseek
726 #define full_lseek null_lseek
727 #define write_zero write_null
728 #define read_full read_zero
729 #define open_mem open_port
730 #define open_kmem open_mem
731 #define open_oldmem open_mem
733 static const struct file_operations mem_fops
= {
734 .llseek
= memory_lseek
,
739 .get_unmapped_area
= get_unmapped_area_mem
,
742 #ifdef CONFIG_DEVKMEM
743 static const struct file_operations kmem_fops
= {
744 .llseek
= memory_lseek
,
749 .get_unmapped_area
= get_unmapped_area_mem
,
753 static const struct file_operations null_fops
= {
754 .llseek
= null_lseek
,
757 .splice_write
= splice_write_null
,
760 #ifdef CONFIG_DEVPORT
761 static const struct file_operations port_fops
= {
762 .llseek
= memory_lseek
,
769 static const struct file_operations zero_fops
= {
770 .llseek
= zero_lseek
,
777 * capabilities for /dev/zero
778 * - permits private mappings, "copies" are taken of the source of zeros
780 static struct backing_dev_info zero_bdi
= {
782 .capabilities
= BDI_CAP_MAP_COPY
,
785 static const struct file_operations full_fops
= {
786 .llseek
= full_lseek
,
791 #ifdef CONFIG_CRASH_DUMP
792 static const struct file_operations oldmem_fops
= {
798 static ssize_t
kmsg_write(struct file
* file
, const char __user
* buf
,
799 size_t count
, loff_t
*ppos
)
804 tmp
= kmalloc(count
+ 1, GFP_KERNEL
);
808 if (!copy_from_user(tmp
, buf
, count
)) {
810 ret
= printk("%s", tmp
);
812 /* printk can add a prefix */
819 static const struct file_operations kmsg_fops
= {
823 static const struct memdev
{
826 const struct file_operations
*fops
;
827 struct backing_dev_info
*dev_info
;
829 [1] = { "mem", 0, &mem_fops
, &directly_mappable_cdev_bdi
},
830 #ifdef CONFIG_DEVKMEM
831 [2] = { "kmem", 0, &kmem_fops
, &directly_mappable_cdev_bdi
},
833 [3] = { "null", 0666, &null_fops
, NULL
},
834 #ifdef CONFIG_DEVPORT
835 [4] = { "port", 0, &port_fops
, NULL
},
837 [5] = { "zero", 0666, &zero_fops
, &zero_bdi
},
838 [7] = { "full", 0666, &full_fops
, NULL
},
839 [8] = { "random", 0666, &random_fops
, NULL
},
840 [9] = { "urandom", 0666, &urandom_fops
, NULL
},
841 [11] = { "kmsg", 0, &kmsg_fops
, NULL
},
842 #ifdef CONFIG_CRASH_DUMP
843 [12] = { "oldmem", 0, &oldmem_fops
, NULL
},
847 static int memory_open(struct inode
*inode
, struct file
*filp
)
850 const struct memdev
*dev
;
852 minor
= iminor(inode
);
853 if (minor
>= ARRAY_SIZE(devlist
))
856 dev
= &devlist
[minor
];
860 filp
->f_op
= dev
->fops
;
862 filp
->f_mapping
->backing_dev_info
= dev
->dev_info
;
865 return dev
->fops
->open(inode
, filp
);
870 static const struct file_operations memory_fops
= {
874 static char *mem_devnode(struct device
*dev
, mode_t
*mode
)
876 if (mode
&& devlist
[MINOR(dev
->devt
)].mode
)
877 *mode
= devlist
[MINOR(dev
->devt
)].mode
;
881 static struct class *mem_class
;
883 static int __init
chr_dev_init(void)
888 err
= bdi_init(&zero_bdi
);
892 if (register_chrdev(MEM_MAJOR
,"mem",&memory_fops
))
893 printk("unable to get major %d for memory devs\n", MEM_MAJOR
);
895 mem_class
= class_create(THIS_MODULE
, "mem");
896 mem_class
->devnode
= mem_devnode
;
897 for (minor
= 1; minor
< ARRAY_SIZE(devlist
); minor
++) {
898 if (!devlist
[minor
].name
)
900 device_create(mem_class
, NULL
, MKDEV(MEM_MAJOR
, minor
),
901 NULL
, devlist
[minor
].name
);
907 fs_initcall(chr_dev_init
);