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/uio.h>
31 #include <linux/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
))
77 static inline int range_is_allowed(unsigned long pfn
, unsigned long size
)
83 #ifndef unxlate_dev_mem_ptr
84 #define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
85 void __weak
unxlate_dev_mem_ptr(phys_addr_t phys
, void *addr
)
91 * This funcion reads the *physical* memory. The f_pos points directly to the
94 static ssize_t
read_mem(struct file
*file
, char __user
*buf
,
95 size_t count
, loff_t
*ppos
)
97 phys_addr_t p
= *ppos
;
104 if (!valid_phys_addr_range(p
, count
))
107 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
108 /* we don't have page 0 mapped on sparc and m68k.. */
110 sz
= size_inside_page(p
, count
);
112 if (clear_user(buf
, sz
))
123 unsigned long remaining
;
125 sz
= size_inside_page(p
, count
);
127 if (!range_is_allowed(p
>> PAGE_SHIFT
, count
))
131 * On ia64 if a page has been mapped somewhere as uncached, then
132 * it must also be accessed uncached by the kernel or data
133 * corruption may occur.
135 ptr
= xlate_dev_mem_ptr(p
);
139 remaining
= copy_to_user(buf
, ptr
, sz
);
140 unxlate_dev_mem_ptr(p
, ptr
);
154 static ssize_t
write_mem(struct file
*file
, const char __user
*buf
,
155 size_t count
, loff_t
*ppos
)
157 phys_addr_t p
= *ppos
;
159 unsigned long copied
;
165 if (!valid_phys_addr_range(p
, count
))
170 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
171 /* we don't have page 0 mapped on sparc and m68k.. */
173 sz
= size_inside_page(p
, count
);
174 /* Hmm. Do something? */
183 sz
= size_inside_page(p
, count
);
185 if (!range_is_allowed(p
>> PAGE_SHIFT
, sz
))
189 * On ia64 if a page has been mapped somewhere as uncached, then
190 * it must also be accessed uncached by the kernel or data
191 * corruption may occur.
193 ptr
= xlate_dev_mem_ptr(p
);
200 copied
= copy_from_user(ptr
, buf
, sz
);
201 unxlate_dev_mem_ptr(p
, ptr
);
203 written
+= sz
- copied
;
219 int __weak
phys_mem_access_prot_allowed(struct file
*file
,
220 unsigned long pfn
, unsigned long size
, pgprot_t
*vma_prot
)
225 #ifndef __HAVE_PHYS_MEM_ACCESS_PROT
228 * Architectures vary in how they handle caching for addresses
229 * outside of main memory.
232 #ifdef pgprot_noncached
233 static int uncached_access(struct file
*file
, phys_addr_t addr
)
235 #if defined(CONFIG_IA64)
237 * On ia64, we ignore O_DSYNC because we cannot tolerate memory
240 return !(efi_mem_attributes(addr
) & EFI_MEMORY_WB
);
241 #elif defined(CONFIG_MIPS)
243 extern int __uncached_access(struct file
*file
,
246 return __uncached_access(file
, addr
);
250 * Accessing memory above the top the kernel knows about or through a
252 * that was marked O_DSYNC will be done non-cached.
254 if (file
->f_flags
& O_DSYNC
)
256 return addr
>= __pa(high_memory
);
261 static pgprot_t
phys_mem_access_prot(struct file
*file
, unsigned long pfn
,
262 unsigned long size
, pgprot_t vma_prot
)
264 #ifdef pgprot_noncached
265 phys_addr_t offset
= pfn
<< PAGE_SHIFT
;
267 if (uncached_access(file
, offset
))
268 return pgprot_noncached(vma_prot
);
275 static unsigned long get_unmapped_area_mem(struct file
*file
,
281 if (!valid_mmap_phys_addr_range(pgoff
, len
))
282 return (unsigned long) -EINVAL
;
283 return pgoff
<< PAGE_SHIFT
;
286 /* permit direct mmap, for read, write or exec */
287 static unsigned memory_mmap_capabilities(struct file
*file
)
289 return NOMMU_MAP_DIRECT
|
290 NOMMU_MAP_READ
| NOMMU_MAP_WRITE
| NOMMU_MAP_EXEC
;
293 static unsigned zero_mmap_capabilities(struct file
*file
)
295 return NOMMU_MAP_COPY
;
298 /* can't do an in-place private mapping if there's no MMU */
299 static inline int private_mapping_ok(struct vm_area_struct
*vma
)
301 return vma
->vm_flags
& VM_MAYSHARE
;
305 static inline int private_mapping_ok(struct vm_area_struct
*vma
)
311 static const struct vm_operations_struct mmap_mem_ops
= {
312 #ifdef CONFIG_HAVE_IOREMAP_PROT
313 .access
= generic_access_phys
317 static int mmap_mem(struct file
*file
, struct vm_area_struct
*vma
)
319 size_t size
= vma
->vm_end
- vma
->vm_start
;
321 if (!valid_mmap_phys_addr_range(vma
->vm_pgoff
, size
))
324 if (!private_mapping_ok(vma
))
327 if (!range_is_allowed(vma
->vm_pgoff
, size
))
330 if (!phys_mem_access_prot_allowed(file
, vma
->vm_pgoff
, size
,
334 vma
->vm_page_prot
= phys_mem_access_prot(file
, vma
->vm_pgoff
,
338 vma
->vm_ops
= &mmap_mem_ops
;
340 /* Remap-pfn-range will mark the range VM_IO */
341 if (remap_pfn_range(vma
,
345 vma
->vm_page_prot
)) {
351 static int mmap_kmem(struct file
*file
, struct vm_area_struct
*vma
)
355 /* Turn a kernel-virtual address into a physical page frame */
356 pfn
= __pa((u64
)vma
->vm_pgoff
<< PAGE_SHIFT
) >> PAGE_SHIFT
;
359 * RED-PEN: on some architectures there is more mapped memory than
360 * available in mem_map which pfn_valid checks for. Perhaps should add a
363 * RED-PEN: vmalloc is not supported right now.
369 return mmap_mem(file
, vma
);
373 * This function reads the *virtual* memory as seen by the kernel.
375 static ssize_t
read_kmem(struct file
*file
, char __user
*buf
,
376 size_t count
, loff_t
*ppos
)
378 unsigned long p
= *ppos
;
379 ssize_t low_count
, read
, sz
;
380 char *kbuf
; /* k-addr because vread() takes vmlist_lock rwlock */
384 if (p
< (unsigned long) high_memory
) {
386 if (count
> (unsigned long)high_memory
- p
)
387 low_count
= (unsigned long)high_memory
- p
;
389 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
390 /* we don't have page 0 mapped on sparc and m68k.. */
391 if (p
< PAGE_SIZE
&& low_count
> 0) {
392 sz
= size_inside_page(p
, low_count
);
393 if (clear_user(buf
, sz
))
402 while (low_count
> 0) {
403 sz
= size_inside_page(p
, low_count
);
406 * On ia64 if a page has been mapped somewhere as
407 * uncached, then it must also be accessed uncached
408 * by the kernel or data corruption may occur
410 kbuf
= xlate_dev_kmem_ptr((void *)p
);
412 if (copy_to_user(buf
, kbuf
, sz
))
423 kbuf
= (char *)__get_free_page(GFP_KERNEL
);
427 sz
= size_inside_page(p
, count
);
428 if (!is_vmalloc_or_module_addr((void *)p
)) {
432 sz
= vread(kbuf
, (char *)p
, sz
);
435 if (copy_to_user(buf
, kbuf
, sz
)) {
444 free_page((unsigned long)kbuf
);
447 return read
? read
: err
;
451 static ssize_t
do_write_kmem(unsigned long p
, const char __user
*buf
,
452 size_t count
, loff_t
*ppos
)
455 unsigned long copied
;
458 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
459 /* we don't have page 0 mapped on sparc and m68k.. */
461 sz
= size_inside_page(p
, count
);
462 /* Hmm. Do something? */
473 sz
= size_inside_page(p
, count
);
476 * On ia64 if a page has been mapped somewhere as uncached, then
477 * it must also be accessed uncached by the kernel or data
478 * corruption may occur.
480 ptr
= xlate_dev_kmem_ptr((void *)p
);
482 copied
= copy_from_user(ptr
, buf
, sz
);
484 written
+= sz
- copied
;
500 * This function writes to the *virtual* memory as seen by the kernel.
502 static ssize_t
write_kmem(struct file
*file
, const char __user
*buf
,
503 size_t count
, loff_t
*ppos
)
505 unsigned long p
= *ppos
;
508 char *kbuf
; /* k-addr because vwrite() takes vmlist_lock rwlock */
511 if (p
< (unsigned long) high_memory
) {
512 unsigned long to_write
= min_t(unsigned long, count
,
513 (unsigned long)high_memory
- p
);
514 wrote
= do_write_kmem(p
, buf
, to_write
, ppos
);
515 if (wrote
!= to_write
)
523 kbuf
= (char *)__get_free_page(GFP_KERNEL
);
525 return wrote
? wrote
: -ENOMEM
;
527 unsigned long sz
= size_inside_page(p
, count
);
530 if (!is_vmalloc_or_module_addr((void *)p
)) {
534 n
= copy_from_user(kbuf
, buf
, sz
);
539 vwrite(kbuf
, (char *)p
, sz
);
545 free_page((unsigned long)kbuf
);
549 return virtr
+ wrote
? : err
;
552 static ssize_t
read_port(struct file
*file
, char __user
*buf
,
553 size_t count
, loff_t
*ppos
)
555 unsigned long i
= *ppos
;
556 char __user
*tmp
= buf
;
558 if (!access_ok(VERIFY_WRITE
, buf
, count
))
560 while (count
-- > 0 && i
< 65536) {
561 if (__put_user(inb(i
), tmp
) < 0)
570 static ssize_t
write_port(struct file
*file
, const char __user
*buf
,
571 size_t count
, loff_t
*ppos
)
573 unsigned long i
= *ppos
;
574 const char __user
*tmp
= buf
;
576 if (!access_ok(VERIFY_READ
, buf
, count
))
578 while (count
-- > 0 && i
< 65536) {
581 if (__get_user(c
, tmp
)) {
594 static ssize_t
read_null(struct file
*file
, char __user
*buf
,
595 size_t count
, loff_t
*ppos
)
600 static ssize_t
write_null(struct file
*file
, const char __user
*buf
,
601 size_t count
, loff_t
*ppos
)
606 static ssize_t
read_iter_null(struct kiocb
*iocb
, struct iov_iter
*to
)
611 static ssize_t
write_iter_null(struct kiocb
*iocb
, struct iov_iter
*from
)
613 size_t count
= iov_iter_count(from
);
614 iov_iter_advance(from
, count
);
618 static int pipe_to_null(struct pipe_inode_info
*info
, struct pipe_buffer
*buf
,
619 struct splice_desc
*sd
)
624 static ssize_t
splice_write_null(struct pipe_inode_info
*pipe
, struct file
*out
,
625 loff_t
*ppos
, size_t len
, unsigned int flags
)
627 return splice_from_pipe(pipe
, out
, ppos
, len
, flags
, pipe_to_null
);
630 static ssize_t
read_iter_zero(struct kiocb
*iocb
, struct iov_iter
*iter
)
634 while (iov_iter_count(iter
)) {
635 size_t chunk
= iov_iter_count(iter
), n
;
637 if (chunk
> PAGE_SIZE
)
638 chunk
= PAGE_SIZE
; /* Just for latency reasons */
639 n
= iov_iter_zero(chunk
, iter
);
640 if (!n
&& iov_iter_count(iter
))
641 return written
? written
: -EFAULT
;
643 if (signal_pending(current
))
644 return written
? written
: -ERESTARTSYS
;
650 static int mmap_zero(struct file
*file
, struct vm_area_struct
*vma
)
655 if (vma
->vm_flags
& VM_SHARED
)
656 return shmem_zero_setup(vma
);
660 static ssize_t
write_full(struct file
*file
, const char __user
*buf
,
661 size_t count
, loff_t
*ppos
)
667 * Special lseek() function for /dev/null and /dev/zero. Most notably, you
668 * can fopen() both devices with "a" now. This was previously impossible.
671 static loff_t
null_lseek(struct file
*file
, loff_t offset
, int orig
)
673 return file
->f_pos
= 0;
677 * The memory devices use the full 32/64 bits of the offset, and so we cannot
678 * check against negative addresses: they are ok. The return value is weird,
679 * though, in that case (0).
681 * also note that seeking relative to the "end of file" isn't supported:
682 * it has no meaning, so it returns -EINVAL.
684 static loff_t
memory_lseek(struct file
*file
, loff_t offset
, int orig
)
688 inode_lock(file_inode(file
));
691 offset
+= file
->f_pos
;
693 /* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
694 if ((unsigned long long)offset
>= -MAX_ERRNO
) {
698 file
->f_pos
= offset
;
700 force_successful_syscall_return();
705 inode_unlock(file_inode(file
));
709 static int open_port(struct inode
*inode
, struct file
*filp
)
711 return capable(CAP_SYS_RAWIO
) ? 0 : -EPERM
;
714 #define zero_lseek null_lseek
715 #define full_lseek null_lseek
716 #define write_zero write_null
717 #define write_iter_zero write_iter_null
718 #define open_mem open_port
719 #define open_kmem open_mem
721 static const struct file_operations __maybe_unused mem_fops
= {
722 .llseek
= memory_lseek
,
728 .get_unmapped_area
= get_unmapped_area_mem
,
729 .mmap_capabilities
= memory_mmap_capabilities
,
733 static const struct file_operations __maybe_unused kmem_fops
= {
734 .llseek
= memory_lseek
,
740 .get_unmapped_area
= get_unmapped_area_mem
,
741 .mmap_capabilities
= memory_mmap_capabilities
,
745 static const struct file_operations null_fops
= {
746 .llseek
= null_lseek
,
749 .read_iter
= read_iter_null
,
750 .write_iter
= write_iter_null
,
751 .splice_write
= splice_write_null
,
754 static const struct file_operations __maybe_unused port_fops
= {
755 .llseek
= memory_lseek
,
761 static const struct file_operations zero_fops
= {
762 .llseek
= zero_lseek
,
764 .read_iter
= read_iter_zero
,
765 .write_iter
= write_iter_zero
,
768 .mmap_capabilities
= zero_mmap_capabilities
,
772 static const struct file_operations full_fops
= {
773 .llseek
= full_lseek
,
774 .read_iter
= read_iter_zero
,
778 static const struct memdev
{
781 const struct file_operations
*fops
;
785 [1] = { "mem", 0, &mem_fops
, FMODE_UNSIGNED_OFFSET
},
787 #ifdef CONFIG_DEVKMEM
788 [2] = { "kmem", 0, &kmem_fops
, FMODE_UNSIGNED_OFFSET
},
790 [3] = { "null", 0666, &null_fops
, 0 },
791 #ifdef CONFIG_DEVPORT
792 [4] = { "port", 0, &port_fops
, 0 },
794 [5] = { "zero", 0666, &zero_fops
, 0 },
795 [7] = { "full", 0666, &full_fops
, 0 },
796 [8] = { "random", 0666, &random_fops
, 0 },
797 [9] = { "urandom", 0666, &urandom_fops
, 0 },
799 [11] = { "kmsg", 0644, &kmsg_fops
, 0 },
803 static int memory_open(struct inode
*inode
, struct file
*filp
)
806 const struct memdev
*dev
;
808 minor
= iminor(inode
);
809 if (minor
>= ARRAY_SIZE(devlist
))
812 dev
= &devlist
[minor
];
816 filp
->f_op
= dev
->fops
;
817 filp
->f_mode
|= dev
->fmode
;
820 return dev
->fops
->open(inode
, filp
);
825 static const struct file_operations memory_fops
= {
827 .llseek
= noop_llseek
,
830 static char *mem_devnode(struct device
*dev
, umode_t
*mode
)
832 if (mode
&& devlist
[MINOR(dev
->devt
)].mode
)
833 *mode
= devlist
[MINOR(dev
->devt
)].mode
;
837 static struct class *mem_class
;
839 static int __init
chr_dev_init(void)
843 if (register_chrdev(MEM_MAJOR
, "mem", &memory_fops
))
844 printk("unable to get major %d for memory devs\n", MEM_MAJOR
);
846 mem_class
= class_create(THIS_MODULE
, "mem");
847 if (IS_ERR(mem_class
))
848 return PTR_ERR(mem_class
);
850 mem_class
->devnode
= mem_devnode
;
851 for (minor
= 1; minor
< ARRAY_SIZE(devlist
); minor
++) {
852 if (!devlist
[minor
].name
)
858 if ((minor
== DEVPORT_MINOR
) && !arch_has_dev_port())
861 device_create(mem_class
, NULL
, MKDEV(MEM_MAJOR
, minor
),
862 NULL
, devlist
[minor
].name
);
868 fs_initcall(chr_dev_init
);