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/backing-dev.h>
25 #include <linux/splice.h>
26 #include <linux/pfn.h>
27 #include <linux/export.h>
29 #include <linux/aio.h>
31 #include <asm/uaccess.h>
34 # include <linux/efi.h>
37 #define DEVPORT_MINOR 4
39 static inline unsigned long size_inside_page(unsigned long start
,
44 sz
= PAGE_SIZE
- (start
& (PAGE_SIZE
- 1));
49 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
50 static inline int valid_phys_addr_range(phys_addr_t addr
, size_t count
)
52 return addr
+ count
<= __pa(high_memory
);
55 static inline int valid_mmap_phys_addr_range(unsigned long pfn
, size_t size
)
61 #ifdef CONFIG_STRICT_DEVMEM
62 static inline int range_is_allowed(unsigned long pfn
, unsigned long size
)
64 u64 from
= ((u64
)pfn
) << PAGE_SHIFT
;
69 if (!devmem_is_allowed(pfn
)) {
71 "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
72 current
->comm
, from
, to
);
81 static inline int range_is_allowed(unsigned long pfn
, unsigned long size
)
87 #ifndef unxlate_dev_mem_ptr
88 #define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
89 void __weak
unxlate_dev_mem_ptr(phys_addr_t phys
, void *addr
)
95 * This funcion reads the *physical* memory. The f_pos points directly to the
98 static ssize_t
read_mem(struct file
*file
, char __user
*buf
,
99 size_t count
, loff_t
*ppos
)
101 phys_addr_t p
= *ppos
;
108 if (!valid_phys_addr_range(p
, count
))
111 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
112 /* we don't have page 0 mapped on sparc and m68k.. */
114 sz
= size_inside_page(p
, count
);
116 if (clear_user(buf
, sz
))
127 unsigned long remaining
;
129 sz
= size_inside_page(p
, count
);
131 if (!range_is_allowed(p
>> PAGE_SHIFT
, count
))
135 * On ia64 if a page has been mapped somewhere as uncached, then
136 * it must also be accessed uncached by the kernel or data
137 * corruption may occur.
139 ptr
= xlate_dev_mem_ptr(p
);
143 remaining
= copy_to_user(buf
, ptr
, sz
);
144 unxlate_dev_mem_ptr(p
, ptr
);
158 static ssize_t
write_mem(struct file
*file
, const char __user
*buf
,
159 size_t count
, loff_t
*ppos
)
161 phys_addr_t p
= *ppos
;
163 unsigned long copied
;
169 if (!valid_phys_addr_range(p
, count
))
174 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
175 /* we don't have page 0 mapped on sparc and m68k.. */
177 sz
= size_inside_page(p
, count
);
178 /* Hmm. Do something? */
187 sz
= size_inside_page(p
, count
);
189 if (!range_is_allowed(p
>> PAGE_SHIFT
, sz
))
193 * On ia64 if a page has been mapped somewhere as uncached, then
194 * it must also be accessed uncached by the kernel or data
195 * corruption may occur.
197 ptr
= xlate_dev_mem_ptr(p
);
204 copied
= copy_from_user(ptr
, buf
, sz
);
205 unxlate_dev_mem_ptr(p
, ptr
);
207 written
+= sz
- copied
;
223 int __weak
phys_mem_access_prot_allowed(struct file
*file
,
224 unsigned long pfn
, unsigned long size
, pgprot_t
*vma_prot
)
229 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
232 * Architectures vary in how they handle caching for addresses
233 * outside of main memory.
236 #ifdef pgprot_noncached
237 static int uncached_access(struct file
*file
, phys_addr_t addr
)
239 #if defined(CONFIG_IA64)
241 * On ia64, we ignore O_DSYNC because we cannot tolerate memory
244 return !(efi_mem_attributes(addr
) & EFI_MEMORY_WB
);
245 #elif defined(CONFIG_MIPS)
247 extern int __uncached_access(struct file
*file
,
250 return __uncached_access(file
, addr
);
254 * Accessing memory above the top the kernel knows about or through a
256 * that was marked O_DSYNC will be done non-cached.
258 if (file
->f_flags
& O_DSYNC
)
260 return addr
>= __pa(high_memory
);
265 static pgprot_t
phys_mem_access_prot(struct file
*file
, unsigned long pfn
,
266 unsigned long size
, pgprot_t vma_prot
)
268 #ifdef pgprot_noncached
269 phys_addr_t offset
= pfn
<< PAGE_SHIFT
;
271 if (uncached_access(file
, offset
))
272 return pgprot_noncached(vma_prot
);
279 static unsigned long get_unmapped_area_mem(struct file
*file
,
285 if (!valid_mmap_phys_addr_range(pgoff
, len
))
286 return (unsigned long) -EINVAL
;
287 return pgoff
<< PAGE_SHIFT
;
290 /* can't do an in-place private mapping if there's no MMU */
291 static inline int private_mapping_ok(struct vm_area_struct
*vma
)
293 return vma
->vm_flags
& VM_MAYSHARE
;
296 #define get_unmapped_area_mem NULL
298 static inline int private_mapping_ok(struct vm_area_struct
*vma
)
304 static const struct vm_operations_struct mmap_mem_ops
= {
305 #ifdef CONFIG_HAVE_IOREMAP_PROT
306 .access
= generic_access_phys
310 static int mmap_mem(struct file
*file
, struct vm_area_struct
*vma
)
312 size_t size
= vma
->vm_end
- vma
->vm_start
;
314 if (!valid_mmap_phys_addr_range(vma
->vm_pgoff
, size
))
317 if (!private_mapping_ok(vma
))
320 if (!range_is_allowed(vma
->vm_pgoff
, size
))
323 if (!phys_mem_access_prot_allowed(file
, vma
->vm_pgoff
, size
,
327 vma
->vm_page_prot
= phys_mem_access_prot(file
, vma
->vm_pgoff
,
331 vma
->vm_ops
= &mmap_mem_ops
;
333 /* Remap-pfn-range will mark the range VM_IO */
334 if (remap_pfn_range(vma
,
338 vma
->vm_page_prot
)) {
344 #ifdef CONFIG_DEVKMEM
345 static int mmap_kmem(struct file
*file
, struct vm_area_struct
*vma
)
349 /* Turn a kernel-virtual address into a physical page frame */
350 pfn
= __pa((u64
)vma
->vm_pgoff
<< PAGE_SHIFT
) >> PAGE_SHIFT
;
353 * RED-PEN: on some architectures there is more mapped memory than
354 * available in mem_map which pfn_valid checks for. Perhaps should add a
357 * RED-PEN: vmalloc is not supported right now.
363 return mmap_mem(file
, vma
);
367 #ifdef CONFIG_DEVKMEM
369 * This function reads the *virtual* memory as seen by the kernel.
371 static ssize_t
read_kmem(struct file
*file
, char __user
*buf
,
372 size_t count
, loff_t
*ppos
)
374 unsigned long p
= *ppos
;
375 ssize_t low_count
, read
, sz
;
376 char *kbuf
; /* k-addr because vread() takes vmlist_lock rwlock */
380 if (p
< (unsigned long) high_memory
) {
382 if (count
> (unsigned long)high_memory
- p
)
383 low_count
= (unsigned long)high_memory
- p
;
385 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
386 /* we don't have page 0 mapped on sparc and m68k.. */
387 if (p
< PAGE_SIZE
&& low_count
> 0) {
388 sz
= size_inside_page(p
, low_count
);
389 if (clear_user(buf
, sz
))
398 while (low_count
> 0) {
399 sz
= size_inside_page(p
, low_count
);
402 * On ia64 if a page has been mapped somewhere as
403 * uncached, then it must also be accessed uncached
404 * by the kernel or data corruption may occur
406 kbuf
= xlate_dev_kmem_ptr((void *)p
);
408 if (copy_to_user(buf
, kbuf
, sz
))
419 kbuf
= (char *)__get_free_page(GFP_KERNEL
);
423 sz
= size_inside_page(p
, count
);
424 if (!is_vmalloc_or_module_addr((void *)p
)) {
428 sz
= vread(kbuf
, (char *)p
, sz
);
431 if (copy_to_user(buf
, kbuf
, sz
)) {
440 free_page((unsigned long)kbuf
);
443 return read
? read
: err
;
447 static ssize_t
do_write_kmem(unsigned long p
, const char __user
*buf
,
448 size_t count
, loff_t
*ppos
)
451 unsigned long copied
;
454 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
455 /* we don't have page 0 mapped on sparc and m68k.. */
457 sz
= size_inside_page(p
, count
);
458 /* Hmm. Do something? */
469 sz
= size_inside_page(p
, count
);
472 * On ia64 if a page has been mapped somewhere as uncached, then
473 * it must also be accessed uncached by the kernel or data
474 * corruption may occur.
476 ptr
= xlate_dev_kmem_ptr((void *)p
);
478 copied
= copy_from_user(ptr
, buf
, sz
);
480 written
+= sz
- copied
;
496 * This function writes to the *virtual* memory as seen by the kernel.
498 static ssize_t
write_kmem(struct file
*file
, const char __user
*buf
,
499 size_t count
, loff_t
*ppos
)
501 unsigned long p
= *ppos
;
504 char *kbuf
; /* k-addr because vwrite() takes vmlist_lock rwlock */
507 if (p
< (unsigned long) high_memory
) {
508 unsigned long to_write
= min_t(unsigned long, count
,
509 (unsigned long)high_memory
- p
);
510 wrote
= do_write_kmem(p
, buf
, to_write
, ppos
);
511 if (wrote
!= to_write
)
519 kbuf
= (char *)__get_free_page(GFP_KERNEL
);
521 return wrote
? wrote
: -ENOMEM
;
523 unsigned long sz
= size_inside_page(p
, count
);
526 if (!is_vmalloc_or_module_addr((void *)p
)) {
530 n
= copy_from_user(kbuf
, buf
, sz
);
535 vwrite(kbuf
, (char *)p
, sz
);
541 free_page((unsigned long)kbuf
);
545 return virtr
+ wrote
? : err
;
549 #ifdef CONFIG_DEVPORT
550 static ssize_t
read_port(struct file
*file
, char __user
*buf
,
551 size_t count
, loff_t
*ppos
)
553 unsigned long i
= *ppos
;
554 char __user
*tmp
= buf
;
556 if (!access_ok(VERIFY_WRITE
, buf
, count
))
558 while (count
-- > 0 && i
< 65536) {
559 if (__put_user(inb(i
), tmp
) < 0)
568 static ssize_t
write_port(struct file
*file
, const char __user
*buf
,
569 size_t count
, loff_t
*ppos
)
571 unsigned long i
= *ppos
;
572 const char __user
*tmp
= buf
;
574 if (!access_ok(VERIFY_READ
, buf
, count
))
576 while (count
-- > 0 && i
< 65536) {
578 if (__get_user(c
, tmp
)) {
592 static ssize_t
read_null(struct file
*file
, char __user
*buf
,
593 size_t count
, loff_t
*ppos
)
598 static ssize_t
write_null(struct file
*file
, const char __user
*buf
,
599 size_t count
, loff_t
*ppos
)
604 static ssize_t
aio_read_null(struct kiocb
*iocb
, const struct iovec
*iov
,
605 unsigned long nr_segs
, loff_t pos
)
610 static ssize_t
aio_write_null(struct kiocb
*iocb
, const struct iovec
*iov
,
611 unsigned long nr_segs
, loff_t pos
)
613 return iov_length(iov
, nr_segs
);
616 static int pipe_to_null(struct pipe_inode_info
*info
, struct pipe_buffer
*buf
,
617 struct splice_desc
*sd
)
622 static ssize_t
splice_write_null(struct pipe_inode_info
*pipe
, struct file
*out
,
623 loff_t
*ppos
, size_t len
, unsigned int flags
)
625 return splice_from_pipe(pipe
, out
, ppos
, len
, flags
, pipe_to_null
);
628 static ssize_t
read_iter_zero(struct kiocb
*iocb
, struct iov_iter
*iter
)
632 while (iov_iter_count(iter
)) {
633 size_t chunk
= iov_iter_count(iter
), n
;
634 if (chunk
> PAGE_SIZE
)
635 chunk
= PAGE_SIZE
; /* Just for latency reasons */
636 n
= iov_iter_zero(chunk
, iter
);
637 if (!n
&& iov_iter_count(iter
))
638 return written
? written
: -EFAULT
;
640 if (signal_pending(current
))
641 return written
? written
: -ERESTARTSYS
;
647 static int mmap_zero(struct file
*file
, struct vm_area_struct
*vma
)
652 if (vma
->vm_flags
& VM_SHARED
)
653 return shmem_zero_setup(vma
);
657 static ssize_t
write_full(struct file
*file
, const char __user
*buf
,
658 size_t count
, loff_t
*ppos
)
664 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
665 * can fopen() both devices with "a" now. This was previously impossible.
668 static loff_t
null_lseek(struct file
*file
, loff_t offset
, int orig
)
670 return file
->f_pos
= 0;
674 * The memory devices use the full 32/64 bits of the offset, and so we cannot
675 * check against negative addresses: they are ok. The return value is weird,
676 * though, in that case (0).
678 * also note that seeking relative to the "end of file" isn't supported:
679 * it has no meaning, so it returns -EINVAL.
681 static loff_t
memory_lseek(struct file
*file
, loff_t offset
, int orig
)
685 mutex_lock(&file_inode(file
)->i_mutex
);
688 offset
+= file
->f_pos
;
690 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
691 if (IS_ERR_VALUE((unsigned long long)offset
)) {
695 file
->f_pos
= offset
;
697 force_successful_syscall_return();
702 mutex_unlock(&file_inode(file
)->i_mutex
);
706 static int open_port(struct inode
*inode
, struct file
*filp
)
708 return capable(CAP_SYS_RAWIO
) ? 0 : -EPERM
;
711 #define zero_lseek null_lseek
712 #define full_lseek null_lseek
713 #define write_zero write_null
714 #define aio_write_zero aio_write_null
715 #define open_mem open_port
716 #define open_kmem open_mem
718 static const struct file_operations mem_fops
= {
719 .llseek
= memory_lseek
,
724 .get_unmapped_area
= get_unmapped_area_mem
,
727 #ifdef CONFIG_DEVKMEM
728 static const struct file_operations kmem_fops
= {
729 .llseek
= memory_lseek
,
734 .get_unmapped_area
= get_unmapped_area_mem
,
738 static const struct file_operations null_fops
= {
739 .llseek
= null_lseek
,
742 .aio_read
= aio_read_null
,
743 .aio_write
= aio_write_null
,
744 .splice_write
= splice_write_null
,
747 #ifdef CONFIG_DEVPORT
748 static const struct file_operations port_fops
= {
749 .llseek
= memory_lseek
,
756 static const struct file_operations zero_fops
= {
757 .llseek
= zero_lseek
,
758 .read
= new_sync_read
,
760 .read_iter
= read_iter_zero
,
761 .aio_write
= aio_write_zero
,
766 * capabilities for /dev/zero
767 * - permits private mappings, "copies" are taken of the source of zeros
768 * - no writeback happens
770 static struct backing_dev_info zero_bdi
= {
772 .capabilities
= BDI_CAP_MAP_COPY
| BDI_CAP_NO_ACCT_AND_WRITEBACK
,
775 static const struct file_operations full_fops
= {
776 .llseek
= full_lseek
,
777 .read
= new_sync_read
,
778 .read_iter
= read_iter_zero
,
782 static const struct memdev
{
785 const struct file_operations
*fops
;
786 struct backing_dev_info
*dev_info
;
788 [1] = { "mem", 0, &mem_fops
, &directly_mappable_cdev_bdi
},
789 #ifdef CONFIG_DEVKMEM
790 [2] = { "kmem", 0, &kmem_fops
, &directly_mappable_cdev_bdi
},
792 [3] = { "null", 0666, &null_fops
, NULL
},
793 #ifdef CONFIG_DEVPORT
794 [4] = { "port", 0, &port_fops
, NULL
},
796 [5] = { "zero", 0666, &zero_fops
, &zero_bdi
},
797 [7] = { "full", 0666, &full_fops
, NULL
},
798 [8] = { "random", 0666, &random_fops
, NULL
},
799 [9] = { "urandom", 0666, &urandom_fops
, NULL
},
801 [11] = { "kmsg", 0644, &kmsg_fops
, NULL
},
805 static int memory_open(struct inode
*inode
, struct file
*filp
)
808 const struct memdev
*dev
;
810 minor
= iminor(inode
);
811 if (minor
>= ARRAY_SIZE(devlist
))
814 dev
= &devlist
[minor
];
818 filp
->f_op
= dev
->fops
;
820 filp
->f_mapping
->backing_dev_info
= dev
->dev_info
;
822 /* Is /dev/mem or /dev/kmem ? */
823 if (dev
->dev_info
== &directly_mappable_cdev_bdi
)
824 filp
->f_mode
|= FMODE_UNSIGNED_OFFSET
;
827 return dev
->fops
->open(inode
, filp
);
832 static const struct file_operations memory_fops
= {
834 .llseek
= noop_llseek
,
837 static char *mem_devnode(struct device
*dev
, umode_t
*mode
)
839 if (mode
&& devlist
[MINOR(dev
->devt
)].mode
)
840 *mode
= devlist
[MINOR(dev
->devt
)].mode
;
844 static struct class *mem_class
;
846 static int __init
chr_dev_init(void)
851 err
= bdi_init(&zero_bdi
);
855 if (register_chrdev(MEM_MAJOR
, "mem", &memory_fops
))
856 printk("unable to get major %d for memory devs\n", MEM_MAJOR
);
858 mem_class
= class_create(THIS_MODULE
, "mem");
859 if (IS_ERR(mem_class
))
860 return PTR_ERR(mem_class
);
862 mem_class
->devnode
= mem_devnode
;
863 for (minor
= 1; minor
< ARRAY_SIZE(devlist
); minor
++) {
864 if (!devlist
[minor
].name
)
870 if ((minor
== DEVPORT_MINOR
) && !arch_has_dev_port())
873 device_create(mem_class
, NULL
, MKDEV(MEM_MAJOR
, minor
),
874 NULL
, devlist
[minor
].name
);
880 fs_initcall(chr_dev_init
);