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1100 lines
24 KiB
1100 lines
24 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* linux/drivers/char/mem.c |
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* |
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* Copyright (C) 1991, 1992 Linus Torvalds |
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* |
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* Added devfs support. |
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* Jan-11-1998, C. Scott Ananian <[email protected]> |
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* Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <[email protected]> |
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*/ |
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|
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#include <linux/mm.h> |
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#include <linux/miscdevice.h> |
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#include <linux/slab.h> |
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#include <linux/vmalloc.h> |
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#include <linux/mman.h> |
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#include <linux/random.h> |
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#include <linux/init.h> |
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#include <linux/raw.h> |
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#include <linux/tty.h> |
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#include <linux/capability.h> |
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#include <linux/ptrace.h> |
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#include <linux/device.h> |
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#include <linux/highmem.h> |
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#include <linux/backing-dev.h> |
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#include <linux/shmem_fs.h> |
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#include <linux/splice.h> |
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#include <linux/pfn.h> |
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#include <linux/export.h> |
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#include <linux/io.h> |
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#include <linux/uio.h> |
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#include <linux/uaccess.h> |
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#include <linux/security.h> |
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#include <linux/pseudo_fs.h> |
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#include <uapi/linux/magic.h> |
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#include <linux/mount.h> |
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|
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#ifdef CONFIG_IA64 |
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# include <linux/efi.h> |
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#endif |
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#define DEVMEM_MINOR 1 |
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#define DEVPORT_MINOR 4 |
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static inline unsigned long size_inside_page(unsigned long start, |
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unsigned long size) |
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{ |
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unsigned long sz; |
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sz = PAGE_SIZE - (start & (PAGE_SIZE - 1)); |
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|
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return min(sz, size); |
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} |
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|
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#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE |
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static inline int valid_phys_addr_range(phys_addr_t addr, size_t count) |
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{ |
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return addr + count <= __pa(high_memory); |
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} |
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|
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static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) |
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{ |
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return 1; |
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} |
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#endif |
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|
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#ifdef CONFIG_STRICT_DEVMEM |
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static inline int page_is_allowed(unsigned long pfn) |
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{ |
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return devmem_is_allowed(pfn); |
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} |
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static inline int range_is_allowed(unsigned long pfn, unsigned long size) |
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{ |
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u64 from = ((u64)pfn) << PAGE_SHIFT; |
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u64 to = from + size; |
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u64 cursor = from; |
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|
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while (cursor < to) { |
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if (!devmem_is_allowed(pfn)) |
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return 0; |
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cursor += PAGE_SIZE; |
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pfn++; |
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} |
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return 1; |
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} |
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#else |
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static inline int page_is_allowed(unsigned long pfn) |
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{ |
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return 1; |
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} |
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static inline int range_is_allowed(unsigned long pfn, unsigned long size) |
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{ |
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return 1; |
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} |
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#endif |
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|
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#ifndef unxlate_dev_mem_ptr |
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#define unxlate_dev_mem_ptr unxlate_dev_mem_ptr |
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void __weak unxlate_dev_mem_ptr(phys_addr_t phys, void *addr) |
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{ |
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} |
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#endif |
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static inline bool should_stop_iteration(void) |
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{ |
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if (need_resched()) |
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cond_resched(); |
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return fatal_signal_pending(current); |
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} |
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/* |
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* This funcion reads the *physical* memory. The f_pos points directly to the |
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* memory location. |
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*/ |
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static ssize_t read_mem(struct file *file, char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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phys_addr_t p = *ppos; |
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ssize_t read, sz; |
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void *ptr; |
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char *bounce; |
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int err; |
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if (p != *ppos) |
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return 0; |
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if (!valid_phys_addr_range(p, count)) |
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return -EFAULT; |
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read = 0; |
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#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED |
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/* we don't have page 0 mapped on sparc and m68k.. */ |
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if (p < PAGE_SIZE) { |
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sz = size_inside_page(p, count); |
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if (sz > 0) { |
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if (clear_user(buf, sz)) |
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return -EFAULT; |
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buf += sz; |
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p += sz; |
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count -= sz; |
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read += sz; |
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} |
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} |
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#endif |
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bounce = kmalloc(PAGE_SIZE, GFP_KERNEL); |
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if (!bounce) |
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return -ENOMEM; |
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while (count > 0) { |
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unsigned long remaining; |
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int allowed, probe; |
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sz = size_inside_page(p, count); |
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err = -EPERM; |
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allowed = page_is_allowed(p >> PAGE_SHIFT); |
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if (!allowed) |
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goto failed; |
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err = -EFAULT; |
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if (allowed == 2) { |
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/* Show zeros for restricted memory. */ |
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remaining = clear_user(buf, sz); |
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} else { |
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/* |
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* On ia64 if a page has been mapped somewhere as |
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* uncached, then it must also be accessed uncached |
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* by the kernel or data corruption may occur. |
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*/ |
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ptr = xlate_dev_mem_ptr(p); |
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if (!ptr) |
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goto failed; |
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probe = copy_from_kernel_nofault(bounce, ptr, sz); |
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unxlate_dev_mem_ptr(p, ptr); |
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if (probe) |
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goto failed; |
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remaining = copy_to_user(buf, bounce, sz); |
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} |
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if (remaining) |
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goto failed; |
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buf += sz; |
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p += sz; |
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count -= sz; |
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read += sz; |
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if (should_stop_iteration()) |
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break; |
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} |
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kfree(bounce); |
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*ppos += read; |
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return read; |
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failed: |
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kfree(bounce); |
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return err; |
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} |
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static ssize_t write_mem(struct file *file, const char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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phys_addr_t p = *ppos; |
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ssize_t written, sz; |
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unsigned long copied; |
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void *ptr; |
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if (p != *ppos) |
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return -EFBIG; |
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if (!valid_phys_addr_range(p, count)) |
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return -EFAULT; |
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written = 0; |
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#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED |
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/* we don't have page 0 mapped on sparc and m68k.. */ |
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if (p < PAGE_SIZE) { |
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sz = size_inside_page(p, count); |
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/* Hmm. Do something? */ |
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buf += sz; |
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p += sz; |
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count -= sz; |
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written += sz; |
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} |
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#endif |
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while (count > 0) { |
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int allowed; |
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sz = size_inside_page(p, count); |
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allowed = page_is_allowed(p >> PAGE_SHIFT); |
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if (!allowed) |
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return -EPERM; |
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/* Skip actual writing when a page is marked as restricted. */ |
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if (allowed == 1) { |
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/* |
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* On ia64 if a page has been mapped somewhere as |
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* uncached, then it must also be accessed uncached |
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* by the kernel or data corruption may occur. |
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*/ |
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ptr = xlate_dev_mem_ptr(p); |
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if (!ptr) { |
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if (written) |
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break; |
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return -EFAULT; |
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} |
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copied = copy_from_user(ptr, buf, sz); |
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unxlate_dev_mem_ptr(p, ptr); |
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if (copied) { |
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written += sz - copied; |
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if (written) |
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break; |
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return -EFAULT; |
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} |
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} |
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buf += sz; |
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p += sz; |
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count -= sz; |
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written += sz; |
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if (should_stop_iteration()) |
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break; |
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} |
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*ppos += written; |
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return written; |
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} |
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int __weak phys_mem_access_prot_allowed(struct file *file, |
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unsigned long pfn, unsigned long size, pgprot_t *vma_prot) |
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{ |
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return 1; |
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} |
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#ifndef __HAVE_PHYS_MEM_ACCESS_PROT |
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/* |
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* Architectures vary in how they handle caching for addresses |
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* outside of main memory. |
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* |
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*/ |
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#ifdef pgprot_noncached |
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static int uncached_access(struct file *file, phys_addr_t addr) |
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{ |
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#if defined(CONFIG_IA64) |
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/* |
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* On ia64, we ignore O_DSYNC because we cannot tolerate memory |
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* attribute aliases. |
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*/ |
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return !(efi_mem_attributes(addr) & EFI_MEMORY_WB); |
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#elif defined(CONFIG_MIPS) |
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{ |
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extern int __uncached_access(struct file *file, |
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unsigned long addr); |
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return __uncached_access(file, addr); |
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} |
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#else |
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/* |
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* Accessing memory above the top the kernel knows about or through a |
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* file pointer |
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* that was marked O_DSYNC will be done non-cached. |
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*/ |
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if (file->f_flags & O_DSYNC) |
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return 1; |
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return addr >= __pa(high_memory); |
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#endif |
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} |
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#endif |
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static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, |
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unsigned long size, pgprot_t vma_prot) |
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{ |
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#ifdef pgprot_noncached |
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phys_addr_t offset = pfn << PAGE_SHIFT; |
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if (uncached_access(file, offset)) |
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return pgprot_noncached(vma_prot); |
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#endif |
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return vma_prot; |
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} |
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#endif |
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#ifndef CONFIG_MMU |
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static unsigned long get_unmapped_area_mem(struct file *file, |
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unsigned long addr, |
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unsigned long len, |
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unsigned long pgoff, |
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unsigned long flags) |
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{ |
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if (!valid_mmap_phys_addr_range(pgoff, len)) |
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return (unsigned long) -EINVAL; |
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return pgoff << PAGE_SHIFT; |
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} |
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/* permit direct mmap, for read, write or exec */ |
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static unsigned memory_mmap_capabilities(struct file *file) |
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{ |
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return NOMMU_MAP_DIRECT | |
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NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC; |
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} |
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static unsigned zero_mmap_capabilities(struct file *file) |
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{ |
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return NOMMU_MAP_COPY; |
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} |
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/* can't do an in-place private mapping if there's no MMU */ |
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static inline int private_mapping_ok(struct vm_area_struct *vma) |
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{ |
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return vma->vm_flags & VM_MAYSHARE; |
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} |
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#else |
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static inline int private_mapping_ok(struct vm_area_struct *vma) |
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{ |
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return 1; |
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} |
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#endif |
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static const struct vm_operations_struct mmap_mem_ops = { |
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#ifdef CONFIG_HAVE_IOREMAP_PROT |
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.access = generic_access_phys |
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#endif |
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}; |
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static int mmap_mem(struct file *file, struct vm_area_struct *vma) |
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{ |
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size_t size = vma->vm_end - vma->vm_start; |
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phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT; |
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/* Does it even fit in phys_addr_t? */ |
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if (offset >> PAGE_SHIFT != vma->vm_pgoff) |
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return -EINVAL; |
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/* It's illegal to wrap around the end of the physical address space. */ |
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if (offset + (phys_addr_t)size - 1 < offset) |
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return -EINVAL; |
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if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) |
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return -EINVAL; |
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if (!private_mapping_ok(vma)) |
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return -ENOSYS; |
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if (!range_is_allowed(vma->vm_pgoff, size)) |
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return -EPERM; |
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if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, |
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&vma->vm_page_prot)) |
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return -EINVAL; |
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vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, |
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size, |
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vma->vm_page_prot); |
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vma->vm_ops = &mmap_mem_ops; |
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/* Remap-pfn-range will mark the range VM_IO */ |
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if (remap_pfn_range(vma, |
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vma->vm_start, |
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vma->vm_pgoff, |
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size, |
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vma->vm_page_prot)) { |
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return -EAGAIN; |
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} |
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return 0; |
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} |
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static int mmap_kmem(struct file *file, struct vm_area_struct *vma) |
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{ |
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unsigned long pfn; |
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|
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/* Turn a kernel-virtual address into a physical page frame */ |
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pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT; |
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/* |
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* RED-PEN: on some architectures there is more mapped memory than |
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* available in mem_map which pfn_valid checks for. Perhaps should add a |
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* new macro here. |
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* |
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* RED-PEN: vmalloc is not supported right now. |
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*/ |
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if (!pfn_valid(pfn)) |
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return -EIO; |
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vma->vm_pgoff = pfn; |
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return mmap_mem(file, vma); |
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} |
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/* |
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* This function reads the *virtual* memory as seen by the kernel. |
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*/ |
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static ssize_t read_kmem(struct file *file, char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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unsigned long p = *ppos; |
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ssize_t low_count, read, sz; |
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char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ |
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int err = 0; |
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read = 0; |
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if (p < (unsigned long) high_memory) { |
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low_count = count; |
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if (count > (unsigned long)high_memory - p) |
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low_count = (unsigned long)high_memory - p; |
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#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED |
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/* we don't have page 0 mapped on sparc and m68k.. */ |
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if (p < PAGE_SIZE && low_count > 0) { |
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sz = size_inside_page(p, low_count); |
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if (clear_user(buf, sz)) |
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return -EFAULT; |
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buf += sz; |
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p += sz; |
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read += sz; |
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low_count -= sz; |
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count -= sz; |
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} |
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#endif |
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while (low_count > 0) { |
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sz = size_inside_page(p, low_count); |
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|
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/* |
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* On ia64 if a page has been mapped somewhere as |
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* uncached, then it must also be accessed uncached |
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* by the kernel or data corruption may occur |
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*/ |
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kbuf = xlate_dev_kmem_ptr((void *)p); |
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if (!virt_addr_valid(kbuf)) |
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return -ENXIO; |
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if (copy_to_user(buf, kbuf, sz)) |
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return -EFAULT; |
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buf += sz; |
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p += sz; |
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read += sz; |
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low_count -= sz; |
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count -= sz; |
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if (should_stop_iteration()) { |
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count = 0; |
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break; |
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} |
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} |
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} |
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if (count > 0) { |
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kbuf = (char *)__get_free_page(GFP_KERNEL); |
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if (!kbuf) |
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return -ENOMEM; |
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while (count > 0) { |
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sz = size_inside_page(p, count); |
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if (!is_vmalloc_or_module_addr((void *)p)) { |
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err = -ENXIO; |
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break; |
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} |
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sz = vread(kbuf, (char *)p, sz); |
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if (!sz) |
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break; |
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if (copy_to_user(buf, kbuf, sz)) { |
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err = -EFAULT; |
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break; |
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} |
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count -= sz; |
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buf += sz; |
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read += sz; |
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p += sz; |
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if (should_stop_iteration()) |
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break; |
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} |
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free_page((unsigned long)kbuf); |
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} |
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*ppos = p; |
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return read ? read : err; |
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} |
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static ssize_t do_write_kmem(unsigned long p, const char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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ssize_t written, sz; |
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unsigned long copied; |
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written = 0; |
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#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED |
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/* we don't have page 0 mapped on sparc and m68k.. */ |
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if (p < PAGE_SIZE) { |
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sz = size_inside_page(p, count); |
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/* Hmm. Do something? */ |
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buf += sz; |
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p += sz; |
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count -= sz; |
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written += sz; |
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} |
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#endif |
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|
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while (count > 0) { |
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void *ptr; |
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|
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sz = size_inside_page(p, count); |
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|
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/* |
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* On ia64 if a page has been mapped somewhere as uncached, then |
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* it must also be accessed uncached by the kernel or data |
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* corruption may occur. |
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*/ |
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ptr = xlate_dev_kmem_ptr((void *)p); |
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if (!virt_addr_valid(ptr)) |
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return -ENXIO; |
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|
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copied = copy_from_user(ptr, buf, sz); |
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if (copied) { |
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written += sz - copied; |
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if (written) |
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break; |
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return -EFAULT; |
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} |
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buf += sz; |
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p += sz; |
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count -= sz; |
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written += sz; |
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if (should_stop_iteration()) |
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break; |
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} |
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|
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*ppos += written; |
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return written; |
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} |
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|
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/* |
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* This function writes to the *virtual* memory as seen by the kernel. |
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*/ |
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static ssize_t write_kmem(struct file *file, const char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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unsigned long p = *ppos; |
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ssize_t wrote = 0; |
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ssize_t virtr = 0; |
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char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ |
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int err = 0; |
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|
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if (p < (unsigned long) high_memory) { |
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unsigned long to_write = min_t(unsigned long, count, |
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(unsigned long)high_memory - p); |
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wrote = do_write_kmem(p, buf, to_write, ppos); |
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if (wrote != to_write) |
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return wrote; |
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p += wrote; |
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buf += wrote; |
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count -= wrote; |
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} |
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|
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if (count > 0) { |
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kbuf = (char *)__get_free_page(GFP_KERNEL); |
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if (!kbuf) |
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return wrote ? wrote : -ENOMEM; |
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while (count > 0) { |
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unsigned long sz = size_inside_page(p, count); |
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unsigned long n; |
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|
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if (!is_vmalloc_or_module_addr((void *)p)) { |
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err = -ENXIO; |
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break; |
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} |
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n = copy_from_user(kbuf, buf, sz); |
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if (n) { |
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err = -EFAULT; |
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break; |
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} |
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vwrite(kbuf, (char *)p, sz); |
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count -= sz; |
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buf += sz; |
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virtr += sz; |
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p += sz; |
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if (should_stop_iteration()) |
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break; |
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} |
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free_page((unsigned long)kbuf); |
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} |
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|
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*ppos = p; |
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return virtr + wrote ? : err; |
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} |
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|
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static ssize_t read_port(struct file *file, char __user *buf, |
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size_t count, loff_t *ppos) |
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{ |
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unsigned long i = *ppos; |
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char __user *tmp = buf; |
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|
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if (!access_ok(buf, count)) |
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return -EFAULT; |
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while (count-- > 0 && i < 65536) { |
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if (__put_user(inb(i), tmp) < 0) |
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return -EFAULT; |
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i++; |
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tmp++; |
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} |
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*ppos = i; |
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return tmp-buf; |
|
} |
|
|
|
static ssize_t write_port(struct file *file, const char __user *buf, |
|
size_t count, loff_t *ppos) |
|
{ |
|
unsigned long i = *ppos; |
|
const char __user *tmp = buf; |
|
|
|
if (!access_ok(buf, count)) |
|
return -EFAULT; |
|
while (count-- > 0 && i < 65536) { |
|
char c; |
|
|
|
if (__get_user(c, tmp)) { |
|
if (tmp > buf) |
|
break; |
|
return -EFAULT; |
|
} |
|
outb(c, i); |
|
i++; |
|
tmp++; |
|
} |
|
*ppos = i; |
|
return tmp-buf; |
|
} |
|
|
|
static ssize_t read_null(struct file *file, char __user *buf, |
|
size_t count, loff_t *ppos) |
|
{ |
|
return 0; |
|
} |
|
|
|
static ssize_t write_null(struct file *file, const char __user *buf, |
|
size_t count, loff_t *ppos) |
|
{ |
|
return count; |
|
} |
|
|
|
static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to) |
|
{ |
|
return 0; |
|
} |
|
|
|
static ssize_t write_iter_null(struct kiocb *iocb, struct iov_iter *from) |
|
{ |
|
size_t count = iov_iter_count(from); |
|
iov_iter_advance(from, count); |
|
return count; |
|
} |
|
|
|
static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, |
|
struct splice_desc *sd) |
|
{ |
|
return sd->len; |
|
} |
|
|
|
static ssize_t splice_write_null(struct pipe_inode_info *pipe, struct file *out, |
|
loff_t *ppos, size_t len, unsigned int flags) |
|
{ |
|
return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_null); |
|
} |
|
|
|
static ssize_t read_iter_zero(struct kiocb *iocb, struct iov_iter *iter) |
|
{ |
|
size_t written = 0; |
|
|
|
while (iov_iter_count(iter)) { |
|
size_t chunk = iov_iter_count(iter), n; |
|
|
|
if (chunk > PAGE_SIZE) |
|
chunk = PAGE_SIZE; /* Just for latency reasons */ |
|
n = iov_iter_zero(chunk, iter); |
|
if (!n && iov_iter_count(iter)) |
|
return written ? written : -EFAULT; |
|
written += n; |
|
if (signal_pending(current)) |
|
return written ? written : -ERESTARTSYS; |
|
cond_resched(); |
|
} |
|
return written; |
|
} |
|
|
|
static ssize_t read_zero(struct file *file, char __user *buf, |
|
size_t count, loff_t *ppos) |
|
{ |
|
size_t cleared = 0; |
|
|
|
while (count) { |
|
size_t chunk = min_t(size_t, count, PAGE_SIZE); |
|
size_t left; |
|
|
|
left = clear_user(buf + cleared, chunk); |
|
if (unlikely(left)) { |
|
cleared += (chunk - left); |
|
if (!cleared) |
|
return -EFAULT; |
|
break; |
|
} |
|
cleared += chunk; |
|
count -= chunk; |
|
|
|
if (signal_pending(current)) |
|
break; |
|
cond_resched(); |
|
} |
|
|
|
return cleared; |
|
} |
|
|
|
static int mmap_zero(struct file *file, struct vm_area_struct *vma) |
|
{ |
|
#ifndef CONFIG_MMU |
|
return -ENOSYS; |
|
#endif |
|
if (vma->vm_flags & VM_SHARED) |
|
return shmem_zero_setup(vma); |
|
vma_set_anonymous(vma); |
|
return 0; |
|
} |
|
|
|
static unsigned long get_unmapped_area_zero(struct file *file, |
|
unsigned long addr, unsigned long len, |
|
unsigned long pgoff, unsigned long flags) |
|
{ |
|
#ifdef CONFIG_MMU |
|
if (flags & MAP_SHARED) { |
|
/* |
|
* mmap_zero() will call shmem_zero_setup() to create a file, |
|
* so use shmem's get_unmapped_area in case it can be huge; |
|
* and pass NULL for file as in mmap.c's get_unmapped_area(), |
|
* so as not to confuse shmem with our handle on "/dev/zero". |
|
*/ |
|
return shmem_get_unmapped_area(NULL, addr, len, pgoff, flags); |
|
} |
|
|
|
/* Otherwise flags & MAP_PRIVATE: with no shmem object beneath it */ |
|
return current->mm->get_unmapped_area(file, addr, len, pgoff, flags); |
|
#else |
|
return -ENOSYS; |
|
#endif |
|
} |
|
|
|
static ssize_t write_full(struct file *file, const char __user *buf, |
|
size_t count, loff_t *ppos) |
|
{ |
|
return -ENOSPC; |
|
} |
|
|
|
/* |
|
* Special lseek() function for /dev/null and /dev/zero. Most notably, you |
|
* can fopen() both devices with "a" now. This was previously impossible. |
|
* -- SRB. |
|
*/ |
|
static loff_t null_lseek(struct file *file, loff_t offset, int orig) |
|
{ |
|
return file->f_pos = 0; |
|
} |
|
|
|
/* |
|
* The memory devices use the full 32/64 bits of the offset, and so we cannot |
|
* check against negative addresses: they are ok. The return value is weird, |
|
* though, in that case (0). |
|
* |
|
* also note that seeking relative to the "end of file" isn't supported: |
|
* it has no meaning, so it returns -EINVAL. |
|
*/ |
|
static loff_t memory_lseek(struct file *file, loff_t offset, int orig) |
|
{ |
|
loff_t ret; |
|
|
|
inode_lock(file_inode(file)); |
|
switch (orig) { |
|
case SEEK_CUR: |
|
offset += file->f_pos; |
|
fallthrough; |
|
case SEEK_SET: |
|
/* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */ |
|
if ((unsigned long long)offset >= -MAX_ERRNO) { |
|
ret = -EOVERFLOW; |
|
break; |
|
} |
|
file->f_pos = offset; |
|
ret = file->f_pos; |
|
force_successful_syscall_return(); |
|
break; |
|
default: |
|
ret = -EINVAL; |
|
} |
|
inode_unlock(file_inode(file)); |
|
return ret; |
|
} |
|
|
|
static struct inode *devmem_inode; |
|
|
|
#ifdef CONFIG_IO_STRICT_DEVMEM |
|
void revoke_devmem(struct resource *res) |
|
{ |
|
/* pairs with smp_store_release() in devmem_init_inode() */ |
|
struct inode *inode = smp_load_acquire(&devmem_inode); |
|
|
|
/* |
|
* Check that the initialization has completed. Losing the race |
|
* is ok because it means drivers are claiming resources before |
|
* the fs_initcall level of init and prevent /dev/mem from |
|
* establishing mappings. |
|
*/ |
|
if (!inode) |
|
return; |
|
|
|
/* |
|
* The expectation is that the driver has successfully marked |
|
* the resource busy by this point, so devmem_is_allowed() |
|
* should start returning false, however for performance this |
|
* does not iterate the entire resource range. |
|
*/ |
|
if (devmem_is_allowed(PHYS_PFN(res->start)) && |
|
devmem_is_allowed(PHYS_PFN(res->end))) { |
|
/* |
|
* *cringe* iomem=relaxed says "go ahead, what's the |
|
* worst that can happen?" |
|
*/ |
|
return; |
|
} |
|
|
|
unmap_mapping_range(inode->i_mapping, res->start, resource_size(res), 1); |
|
} |
|
#endif |
|
|
|
static int open_port(struct inode *inode, struct file *filp) |
|
{ |
|
int rc; |
|
|
|
if (!capable(CAP_SYS_RAWIO)) |
|
return -EPERM; |
|
|
|
rc = security_locked_down(LOCKDOWN_DEV_MEM); |
|
if (rc) |
|
return rc; |
|
|
|
if (iminor(inode) != DEVMEM_MINOR) |
|
return 0; |
|
|
|
/* |
|
* Use a unified address space to have a single point to manage |
|
* revocations when drivers want to take over a /dev/mem mapped |
|
* range. |
|
*/ |
|
inode->i_mapping = devmem_inode->i_mapping; |
|
filp->f_mapping = inode->i_mapping; |
|
|
|
return 0; |
|
} |
|
|
|
#define zero_lseek null_lseek |
|
#define full_lseek null_lseek |
|
#define write_zero write_null |
|
#define write_iter_zero write_iter_null |
|
#define open_mem open_port |
|
#define open_kmem open_mem |
|
|
|
static const struct file_operations __maybe_unused mem_fops = { |
|
.llseek = memory_lseek, |
|
.read = read_mem, |
|
.write = write_mem, |
|
.mmap = mmap_mem, |
|
.open = open_mem, |
|
#ifndef CONFIG_MMU |
|
.get_unmapped_area = get_unmapped_area_mem, |
|
.mmap_capabilities = memory_mmap_capabilities, |
|
#endif |
|
}; |
|
|
|
static const struct file_operations __maybe_unused kmem_fops = { |
|
.llseek = memory_lseek, |
|
.read = read_kmem, |
|
.write = write_kmem, |
|
.mmap = mmap_kmem, |
|
.open = open_kmem, |
|
#ifndef CONFIG_MMU |
|
.get_unmapped_area = get_unmapped_area_mem, |
|
.mmap_capabilities = memory_mmap_capabilities, |
|
#endif |
|
}; |
|
|
|
static const struct file_operations null_fops = { |
|
.llseek = null_lseek, |
|
.read = read_null, |
|
.write = write_null, |
|
.read_iter = read_iter_null, |
|
.write_iter = write_iter_null, |
|
.splice_write = splice_write_null, |
|
}; |
|
|
|
static const struct file_operations __maybe_unused port_fops = { |
|
.llseek = memory_lseek, |
|
.read = read_port, |
|
.write = write_port, |
|
.open = open_port, |
|
}; |
|
|
|
static const struct file_operations zero_fops = { |
|
.llseek = zero_lseek, |
|
.write = write_zero, |
|
.read_iter = read_iter_zero, |
|
.read = read_zero, |
|
.write_iter = write_iter_zero, |
|
.mmap = mmap_zero, |
|
.get_unmapped_area = get_unmapped_area_zero, |
|
#ifndef CONFIG_MMU |
|
.mmap_capabilities = zero_mmap_capabilities, |
|
#endif |
|
}; |
|
|
|
static const struct file_operations full_fops = { |
|
.llseek = full_lseek, |
|
.read_iter = read_iter_zero, |
|
.write = write_full, |
|
}; |
|
|
|
static const struct memdev { |
|
const char *name; |
|
umode_t mode; |
|
const struct file_operations *fops; |
|
fmode_t fmode; |
|
} devlist[] = { |
|
#ifdef CONFIG_DEVMEM |
|
[DEVMEM_MINOR] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET }, |
|
#endif |
|
#ifdef CONFIG_DEVKMEM |
|
[2] = { "kmem", 0, &kmem_fops, FMODE_UNSIGNED_OFFSET }, |
|
#endif |
|
[3] = { "null", 0666, &null_fops, 0 }, |
|
#ifdef CONFIG_DEVPORT |
|
[4] = { "port", 0, &port_fops, 0 }, |
|
#endif |
|
[5] = { "zero", 0666, &zero_fops, 0 }, |
|
[7] = { "full", 0666, &full_fops, 0 }, |
|
[8] = { "random", 0666, &random_fops, 0 }, |
|
[9] = { "urandom", 0666, &urandom_fops, 0 }, |
|
#ifdef CONFIG_PRINTK |
|
[11] = { "kmsg", 0644, &kmsg_fops, 0 }, |
|
#endif |
|
}; |
|
|
|
static int memory_open(struct inode *inode, struct file *filp) |
|
{ |
|
int minor; |
|
const struct memdev *dev; |
|
|
|
minor = iminor(inode); |
|
if (minor >= ARRAY_SIZE(devlist)) |
|
return -ENXIO; |
|
|
|
dev = &devlist[minor]; |
|
if (!dev->fops) |
|
return -ENXIO; |
|
|
|
filp->f_op = dev->fops; |
|
filp->f_mode |= dev->fmode; |
|
|
|
if (dev->fops->open) |
|
return dev->fops->open(inode, filp); |
|
|
|
return 0; |
|
} |
|
|
|
static const struct file_operations memory_fops = { |
|
.open = memory_open, |
|
.llseek = noop_llseek, |
|
}; |
|
|
|
static char *mem_devnode(struct device *dev, umode_t *mode) |
|
{ |
|
if (mode && devlist[MINOR(dev->devt)].mode) |
|
*mode = devlist[MINOR(dev->devt)].mode; |
|
return NULL; |
|
} |
|
|
|
static struct class *mem_class; |
|
|
|
static int devmem_fs_init_fs_context(struct fs_context *fc) |
|
{ |
|
return init_pseudo(fc, DEVMEM_MAGIC) ? 0 : -ENOMEM; |
|
} |
|
|
|
static struct file_system_type devmem_fs_type = { |
|
.name = "devmem", |
|
.owner = THIS_MODULE, |
|
.init_fs_context = devmem_fs_init_fs_context, |
|
.kill_sb = kill_anon_super, |
|
}; |
|
|
|
static int devmem_init_inode(void) |
|
{ |
|
static struct vfsmount *devmem_vfs_mount; |
|
static int devmem_fs_cnt; |
|
struct inode *inode; |
|
int rc; |
|
|
|
rc = simple_pin_fs(&devmem_fs_type, &devmem_vfs_mount, &devmem_fs_cnt); |
|
if (rc < 0) { |
|
pr_err("Cannot mount /dev/mem pseudo filesystem: %d\n", rc); |
|
return rc; |
|
} |
|
|
|
inode = alloc_anon_inode(devmem_vfs_mount->mnt_sb); |
|
if (IS_ERR(inode)) { |
|
rc = PTR_ERR(inode); |
|
pr_err("Cannot allocate inode for /dev/mem: %d\n", rc); |
|
simple_release_fs(&devmem_vfs_mount, &devmem_fs_cnt); |
|
return rc; |
|
} |
|
|
|
/* |
|
* Publish /dev/mem initialized. |
|
* Pairs with smp_load_acquire() in revoke_devmem(). |
|
*/ |
|
smp_store_release(&devmem_inode, inode); |
|
|
|
return 0; |
|
} |
|
|
|
static int __init chr_dev_init(void) |
|
{ |
|
int minor; |
|
|
|
if (register_chrdev(MEM_MAJOR, "mem", &memory_fops)) |
|
printk("unable to get major %d for memory devs\n", MEM_MAJOR); |
|
|
|
mem_class = class_create(THIS_MODULE, "mem"); |
|
if (IS_ERR(mem_class)) |
|
return PTR_ERR(mem_class); |
|
|
|
mem_class->devnode = mem_devnode; |
|
for (minor = 1; minor < ARRAY_SIZE(devlist); minor++) { |
|
if (!devlist[minor].name) |
|
continue; |
|
|
|
/* |
|
* Create /dev/port? |
|
*/ |
|
if ((minor == DEVPORT_MINOR) && !arch_has_dev_port()) |
|
continue; |
|
if ((minor == DEVMEM_MINOR) && devmem_init_inode() != 0) |
|
continue; |
|
|
|
device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), |
|
NULL, devlist[minor].name); |
|
} |
|
|
|
return tty_init(); |
|
} |
|
|
|
fs_initcall(chr_dev_init);
|
|
|