cregit-Linux how code gets into the kernel

Release 4.14 drivers/char/mem.c

Directory: drivers/char
// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/drivers/char/mem.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Added devfs support.
 *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
 *  Shared /dev/zero mmapping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
 */

#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mman.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/raw.h>
#include <linux/tty.h>
#include <linux/capability.h>
#include <linux/ptrace.h>
#include <linux/device.h>
#include <linux/highmem.h>
#include <linux/backing-dev.h>
#include <linux/shmem_fs.h>
#include <linux/splice.h>
#include <linux/pfn.h>
#include <linux/export.h>
#include <linux/io.h>
#include <linux/uio.h>

#include <linux/uaccess.h>

#ifdef CONFIG_IA64
# include <linux/efi.h>
#endif


#define DEVPORT_MINOR	4


static inline unsigned long size_inside_page(unsigned long start, unsigned long size) { unsigned long sz; sz = PAGE_SIZE - (start & (PAGE_SIZE - 1)); return min(sz, size); }

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Fengguang Wu42100.00%2100.00%
Total42100.00%2100.00%

#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
static inline int valid_phys_addr_range(phys_addr_t addr, size_t count) { return addr + count <= __pa(high_memory); }

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PersonTokensPropCommitsCommitProp
Andrew Morton1773.91%125.00%
Björn Helgaas313.04%125.00%
Changli Gao28.70%125.00%
Cyril Chemparathy14.35%125.00%
Total23100.00%4100.00%


static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) { return 1; }

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PersonTokensPropCommitsCommitProp
Björn Helgaas1694.12%150.00%
Lennert Buytenhek15.88%150.00%
Total17100.00%2100.00%

#endif #ifdef CONFIG_STRICT_DEVMEM
static inline int page_is_allowed(unsigned long pfn) { return devmem_is_allowed(pfn); }

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Kees Cook17100.00%1100.00%
Total17100.00%1100.00%


static inline int range_is_allowed(unsigned long pfn, unsigned long size) { u64 from = ((u64)pfn) << PAGE_SHIFT; u64 to = from + size; u64 cursor = from; while (cursor < to) { if (!devmem_is_allowed(pfn)) return 0; cursor += PAGE_SIZE; pfn++; } return 1; }

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PersonTokensPropCommitsCommitProp
Arjan van de Ven4058.82%150.00%
Venkatesh Pallipadi2841.18%150.00%
Total68100.00%2100.00%

#else
static inline int page_is_allowed(unsigned long pfn) { return 1; }

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Kees Cook14100.00%1100.00%
Total14100.00%1100.00%


static inline int range_is_allowed(unsigned long pfn, unsigned long size) { return 1; }

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PersonTokensPropCommitsCommitProp
Arjan van de Ven1688.89%150.00%
Venkatesh Pallipadi211.11%150.00%
Total18100.00%2100.00%

#endif #ifndef unxlate_dev_mem_ptr #define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
void __weak unxlate_dev_mem_ptr(phys_addr_t phys, void *addr) { }

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PersonTokensPropCommitsCommitProp
Venkatesh Pallipadi650.00%133.33%
Andrew Morton541.67%133.33%
Thierry Reding18.33%133.33%
Total12100.00%3100.00%

#endif /* * This funcion reads the *physical* memory. The f_pos points directly to the * memory location. */
static ssize_t read_mem(struct file *file, char __user *buf, size_t count, loff_t *ppos) { phys_addr_t p = *ppos; ssize_t read, sz; void *ptr; if (p != *ppos) return 0; if (!valid_phys_addr_range(p, count)) return -EFAULT; read = 0; #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED /* we don't have page 0 mapped on sparc and m68k.. */ if (p < PAGE_SIZE) { sz = size_inside_page(p, count); if (sz > 0) { if (clear_user(buf, sz)) return -EFAULT; buf += sz; p += sz; count -= sz; read += sz; } } #endif while (count > 0) { unsigned long remaining; int allowed; sz = size_inside_page(p, count); allowed = page_is_allowed(p >> PAGE_SHIFT); if (!allowed) return -EPERM; if (allowed == 2) { /* Show zeros for restricted memory. */ remaining = clear_user(buf, sz); } else { /* * On ia64 if a page has been mapped somewhere as * uncached, then it must also be accessed uncached * by the kernel or data corruption may occur. */ ptr = xlate_dev_mem_ptr(p); if (!ptr) return -EFAULT; remaining = copy_to_user(buf, ptr, sz); unxlate_dev_mem_ptr(p, ptr); } if (remaining) return -EFAULT; buf += sz; p += sz; count -= sz; read += sz; } *ppos += read; return read; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)11042.97%1043.48%
Jes Sorensen4116.02%14.35%
Kees Cook3312.89%14.35%
Venkatesh Pallipadi259.77%28.70%
Fengguang Wu187.03%313.04%
Petr Tesarik103.91%14.35%
Arjan van de Ven83.12%14.35%
Andrew Morton83.12%14.35%
Thierry Reding10.39%14.35%
Al Viro10.39%14.35%
Cyril Chemparathy10.39%14.35%
Total256100.00%23100.00%


static ssize_t write_mem(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { phys_addr_t p = *ppos; ssize_t written, sz; unsigned long copied; void *ptr; if (p != *ppos) return -EFBIG; if (!valid_phys_addr_range(p, count)) return -EFAULT; written = 0; #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED /* we don't have page 0 mapped on sparc and m68k.. */ if (p < PAGE_SIZE) { sz = size_inside_page(p, count); /* Hmm. Do something? */ buf += sz; p += sz; count -= sz; written += sz; } #endif while (count > 0) { int allowed; sz = size_inside_page(p, count); allowed = page_is_allowed(p >> PAGE_SHIFT); if (!allowed) return -EPERM; /* Skip actual writing when a page is marked as restricted. */ if (allowed == 1) { /* * On ia64 if a page has been mapped somewhere as * uncached, then it must also be accessed uncached * by the kernel or data corruption may occur. */ ptr = xlate_dev_mem_ptr(p); if (!ptr) { if (written) break; return -EFAULT; } copied = copy_from_user(ptr, buf, sz); unxlate_dev_mem_ptr(p, ptr); if (copied) { written += sz - copied; if (written) break; return -EFAULT; } } buf += sz; p += sz; count -= sz; written += sz; } *ppos += written; return written; }

Contributors

PersonTokensPropCommitsCommitProp
Jes Sorensen11145.12%14.76%
Linus Torvalds (pre-git)4217.07%838.10%
Venkatesh Pallipadi2510.16%29.52%
Kees Cook218.54%14.76%
Fengguang Wu156.10%314.29%
Petr Tesarik114.47%14.76%
Arjan van de Ven83.25%14.76%
Andrew Morton83.25%14.76%
Jan Beulich31.22%14.76%
Cyril Chemparathy10.41%14.76%
Al Viro10.41%14.76%
Total246100.00%21100.00%


int __weak phys_mem_access_prot_allowed(struct file *file, unsigned long pfn, unsigned long size, pgprot_t *vma_prot) { return 1; }

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PersonTokensPropCommitsCommitProp
Venkatesh Pallipadi1765.38%150.00%
Andrew Morton934.62%150.00%
Total26100.00%2100.00%

#ifndef __HAVE_PHYS_MEM_ACCESS_PROT /* * Architectures vary in how they handle caching for addresses * outside of main memory. * */ #ifdef pgprot_noncached
static int uncached_access(struct file *file, phys_addr_t addr) { #if defined(CONFIG_IA64) /* * On ia64, we ignore O_DSYNC because we cannot tolerate memory * attribute aliases. */ return !(efi_mem_attributes(addr) & EFI_MEMORY_WB); #elif defined(CONFIG_MIPS) { extern int __uncached_access(struct file *file, unsigned long addr); return __uncached_access(file, addr); } #else /* * Accessing memory above the top the kernel knows about or through a * file pointer * that was marked O_DSYNC will be done non-cached. */ if (file->f_flags & O_DSYNC) return 1; return addr >= __pa(high_memory); #endif }

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PersonTokensPropCommitsCommitProp
Andrew Morton8598.84%150.00%
Cyril Chemparathy11.16%150.00%
Total86100.00%2100.00%

#endif
static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size, pgprot_t vma_prot) { #ifdef pgprot_noncached phys_addr_t offset = pfn << PAGE_SHIFT; if (uncached_access(file, offset)) return pgprot_noncached(vma_prot); #endif return vma_prot; }

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PersonTokensPropCommitsCommitProp
Björn Helgaas5198.08%150.00%
Cyril Chemparathy11.92%150.00%
Total52100.00%2100.00%

#endif #ifndef CONFIG_MMU
static unsigned long get_unmapped_area_mem(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags) { if (!valid_mmap_phys_addr_range(pgoff, len)) return (unsigned long) -EINVAL; return pgoff << PAGE_SHIFT; }

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PersonTokensPropCommitsCommitProp
David Howells4996.08%150.00%
Benjamin Herrenschmidt23.92%150.00%
Total51100.00%2100.00%

/* permit direct mmap, for read, write or exec */
static unsigned memory_mmap_capabilities(struct file *file) { return NOMMU_MAP_DIRECT | NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC; }

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PersonTokensPropCommitsCommitProp
Christoph Hellwig20100.00%1100.00%
Total20100.00%1100.00%


static unsigned zero_mmap_capabilities(struct file *file) { return NOMMU_MAP_COPY; }

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PersonTokensPropCommitsCommitProp
Christoph Hellwig14100.00%1100.00%
Total14100.00%1100.00%

/* can't do an in-place private mapping if there's no MMU */
static inline int private_mapping_ok(struct vm_area_struct *vma) { return vma->vm_flags & VM_MAYSHARE; }

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PersonTokensPropCommitsCommitProp
David Howells19100.00%1100.00%
Total19100.00%1100.00%

#else
static inline int private_mapping_ok(struct vm_area_struct *vma) { return 1; }

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PersonTokensPropCommitsCommitProp
David Howells15100.00%1100.00%
Total15100.00%1100.00%

#endif static const struct vm_operations_struct mmap_mem_ops = { #ifdef CONFIG_HAVE_IOREMAP_PROT .access = generic_access_phys #endif };
static int mmap_mem(struct file *file, struct vm_area_struct *vma) { size_t size = vma->vm_end - vma->vm_start; phys_addr_t offset = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT; /* It's illegal to wrap around the end of the physical address space. */ if (offset + (phys_addr_t)size - 1 < offset) return -EINVAL; if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) return -EINVAL; if (!private_mapping_ok(vma)) return -ENOSYS; if (!range_is_allowed(vma->vm_pgoff, size)) return -EPERM; if (!phys_mem_access_prot_allowed(file, vma->vm_pgoff, size, &vma->vm_page_prot)) return -EINVAL; vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, size, vma->vm_page_prot); vma->vm_ops = &mmap_mem_ops; /* Remap-pfn-range will mark the range VM_IO */ if (remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff, size, vma->vm_page_prot)) { return -EAGAIN; } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Venkatesh Pallipadi4826.52%318.75%
Linus Torvalds (pre-git)3720.44%425.00%
Julius Werner3016.57%212.50%
Björn Helgaas2916.02%16.25%
Benjamin Herrenschmidt158.29%16.25%
David Howells126.63%16.25%
Linus Torvalds63.31%212.50%
Roland Dreier31.66%16.25%
Konstantin Khlebnikov10.55%16.25%
Total181100.00%16100.00%


static int mmap_kmem(struct file *file, struct vm_area_struct *vma) { unsigned long pfn; /* Turn a kernel-virtual address into a physical page frame */ pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT; /* * RED-PEN: on some architectures there is more mapped memory than * available in mem_map which pfn_valid checks for. Perhaps should add a * new macro here. * * RED-PEN: vmalloc is not supported right now. */ if (!pfn_valid(pfn)) return -EIO; vma->vm_pgoff = pfn; return mmap_mem(file, vma); }

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PersonTokensPropCommitsCommitProp
Andi Kleen4367.19%125.00%
Linus Torvalds2031.25%250.00%
Andrew Morton11.56%125.00%
Total64100.00%4100.00%

/* * This function reads the *virtual* memory as seen by the kernel. */
static ssize_t read_kmem(struct file *file, char __user *buf, size_t count, loff_t *ppos) { unsigned long p = *ppos; ssize_t low_count, read, sz; char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ int err = 0; read = 0; if (p < (unsigned long) high_memory) { low_count = count; if (count > (unsigned long)high_memory - p) low_count = (unsigned long)high_memory - p; #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED /* we don't have page 0 mapped on sparc and m68k.. */ if (p < PAGE_SIZE && low_count > 0) { sz = size_inside_page(p, low_count); if (clear_user(buf, sz)) return -EFAULT; buf += sz; p += sz; read += sz; low_count -= sz; count -= sz; } #endif while (low_count > 0) { sz = size_inside_page(p, low_count); /* * On ia64 if a page has been mapped somewhere as * uncached, then it must also be accessed uncached * by the kernel or data corruption may occur */ kbuf = xlate_dev_kmem_ptr((void *)p); if (!virt_addr_valid(kbuf)) return -ENXIO; if (copy_to_user(buf, kbuf, sz)) return -EFAULT; buf += sz; p += sz; read += sz; low_count -= sz; count -= sz; } } if (count > 0) { kbuf = (char *)__get_free_page(GFP_KERNEL); if (!kbuf) return -ENOMEM; while (count > 0) { sz = size_inside_page(p, count); if (!is_vmalloc_or_module_addr((void *)p)) { err = -ENXIO; break; } sz = vread(kbuf, (char *)p, sz); if (!sz) break; if (copy_to_user(buf, kbuf, sz)) { err = -EFAULT; break; } count -= sz; buf += sz; read += sz; p += sz; } free_page((unsigned long)kbuf); } *ppos = p; return read ? read : err; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)22561.31%741.18%
Jes Sorensen4411.99%15.88%
Kamezawa Hiroyuki338.99%15.88%
Fengguang Wu318.45%317.65%
Hirofumi Ogawa154.09%15.88%
Robin Murphy123.27%15.88%
Linus Torvalds51.36%15.88%
Al Viro10.27%15.88%
Thierry Reding10.27%15.88%
Total367100.00%17100.00%


static ssize_t do_write_kmem(unsigned long p, const char __user *buf, size_t count, loff_t *ppos) { ssize_t written, sz; unsigned long copied; written = 0; #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED /* we don't have page 0 mapped on sparc and m68k.. */ if (p < PAGE_SIZE) { sz = size_inside_page(p, count); /* Hmm. Do something? */ buf += sz; p += sz; count -= sz; written += sz; } #endif while (count > 0) { void *ptr; sz = size_inside_page(p, count); /* * On ia64 if a page has been mapped somewhere as uncached, then * it must also be accessed uncached by the kernel or data * corruption may occur. */ ptr = xlate_dev_kmem_ptr((void *)p); if (!virt_addr_valid(ptr)) return -ENXIO; copied = copy_from_user(ptr, buf, sz); if (copied) { written += sz - copied; if (written) break; return -EFAULT; } buf += sz; p += sz; count -= sz; written += sz; } *ppos += written; return written; }

Contributors

PersonTokensPropCommitsCommitProp
Jes Sorensen14682.49%112.50%
Fengguang Wu137.34%337.50%
Robin Murphy126.78%112.50%
Jan Beulich31.69%112.50%
Thierry Reding21.13%112.50%
Andrew Morton10.56%112.50%
Total177100.00%8100.00%

/* * This function writes to the *virtual* memory as seen by the kernel. */
static ssize_t write_kmem(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { unsigned long p = *ppos; ssize_t wrote = 0; ssize_t virtr = 0; char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p); wrote = do_write_kmem(p, buf, to_write, ppos); if (wrote != to_write) return wrote; p += wrote; buf += wrote; count -= wrote; } if (count > 0) { kbuf = (char *)__get_free_page(GFP_KERNEL); if (!kbuf) return wrote ? wrote : -ENOMEM; while (count > 0) { unsigned long sz = size_inside_page(p, count); unsigned long n; if (!is_vmalloc_or_module_addr((void *)p)) { err = -ENXIO; break; } n = copy_from_user(kbuf, buf, sz); if (n) { err = -EFAULT; break; } vwrite(kbuf, (char *)p, sz); count -= sz; buf += sz; virtr += sz; p += sz; } free_page((unsigned long)kbuf); } *ppos = p; return virtr + wrote ? : err; }

Contributors

PersonTokensPropCommitsCommitProp
Dave Jones12548.26%19.09%
Linus Torvalds (pre-git)5119.69%436.36%
Fengguang Wu3513.51%218.18%
Kamezawa Hiroyuki3212.36%19.09%
Andrew Morton145.41%19.09%
Al Viro10.39%19.09%
Jes Sorensen10.39%19.09%
Total259100.00%11100.00%


static ssize_t read_port(struct file *file, char __user *buf, size_t count, loff_t *ppos) { unsigned long i = *ppos; char __user *tmp = buf; if (!access_ok(VERIFY_WRITE, buf, count)) return -EFAULT; while (count-- > 0 && i < 65536) { if (__put_user(inb(i), tmp) < 0) return -EFAULT; i++; tmp++; } *ppos = i; return tmp-buf; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)9696.00%466.67%
Al Viro22.00%116.67%
Jesper Juhl22.00%116.67%
Total100100.00%6100.00%


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(VERIFY_READ, 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; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)10388.79%666.67%
Jan Beulich97.76%111.11%
Al Viro21.72%111.11%
Jesper Juhl21.72%111.11%
Total116100.00%9100.00%


static ssize_t read_null(struct file *file, char __user *buf, size_t count, loff_t *ppos) { return 0; }

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PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)2596.15%266.67%
Al Viro13.85%133.33%
Total26100.00%3100.00%


static ssize_t write_null(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { return count; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)2696.30%375.00%
Al Viro13.70%125.00%
Total27100.00%4100.00%


static ssize_t read_iter_null(struct kiocb *iocb, struct iov_iter *to) { return 0; }

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PersonTokensPropCommitsCommitProp
Zach Brown1684.21%150.00%
Al Viro315.79%150.00%
Total19100.00%2100.00%


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; }

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PersonTokensPropCommitsCommitProp
Zach Brown1750.00%150.00%
Al Viro1750.00%150.00%
Total34100.00%2100.00%


static int pipe_to_null(struct pipe_inode_info *info, struct pipe_buffer *buf, struct splice_desc *sd) { return sd->len; }

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PersonTokensPropCommitsCommitProp
Jens Axboe26100.00%1100.00%
Total26100.00%1100.00%


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); }

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PersonTokensPropCommitsCommitProp
Jens Axboe43100.00%1100.00%
Total43100.00%1100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro3937.86%112.50%
Linus Torvalds (pre-git)3332.04%450.00%
Nicholas Piggin1312.62%112.50%
Salman Qazi1211.65%112.50%
Zach Brown65.83%112.50%
Total103100.00%8100.00%


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); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)3071.43%675.00%
Nicholas Piggin1023.81%112.50%
Christoph Hellwig24.76%112.50%
Total42100.00%8100.00%


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 }

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PersonTokensPropCommitsCommitProp
Hugh Dickins81100.00%1100.00%
Total81100.00%1100.00%


static ssize_t write_full(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { return -ENOSPC; }

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PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)2796.43%375.00%
Al Viro13.57%125.00%
Total28100.00%4100.00%

/* * 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; }

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Linus Torvalds (pre-git)24100.00%2100.00%
Total24100.00%2100.00%

/* * 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; 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; }

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PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)4242.00%436.36%
Fengguang Wu2323.00%19.09%
Robert Love1414.00%19.09%
Andrew Morton1010.00%218.18%
Al Viro88.00%218.18%
Andrzej Hajda33.00%19.09%
Total100100.00%11100.00%


static int open_port(struct inode *inode, struct file *filp) { return capable(CAP_SYS_RAWIO) ? 0 : -EPERM; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)27100.00%1100.00%
Total27100.00%1100.00%

#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, .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 [1] = { "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; }

Contributors

PersonTokensPropCommitsCommitProp
Adriano dos Santos Fernandes4947.57%120.00%
Kay Sievers3533.98%120.00%
Frédéric Weisbecker1110.68%120.00%
Kamezawa Hiroyuki54.85%120.00%
Christoph Hellwig32.91%120.00%
Total103100.00%5100.00%

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; }

Contributors

PersonTokensPropCommitsCommitProp
Kay Sievers4998.00%150.00%
Al Viro12.00%150.00%
Total50100.00%2100.00%

static struct class *mem_class;
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; device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), NULL, devlist[minor].name); } return tty_init(); }

Contributors

PersonTokensPropCommitsCommitProp
Greg Kroah-Hartman3124.03%533.33%
Andrew Morton2922.48%16.67%
Kay Sievers2519.38%213.33%
Linus Torvalds (pre-git)1511.63%320.00%
Anton Blanchard1310.08%16.67%
Haren Myneni1310.08%16.67%
David Howells21.55%16.67%
Hans Grob10.78%16.67%
Total129100.00%15100.00%

fs_initcall(chr_dev_init);

Overall Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)114830.70%4429.14%
Jes Sorensen3439.17%10.66%
Andrew Morton2115.64%85.30%
Fengguang Wu1774.73%63.97%
Kay Sievers1714.57%42.65%
Venkatesh Pallipadi1594.25%42.65%
Dave Jones1253.34%10.66%
David Howells1253.34%42.65%
Björn Helgaas1042.78%31.99%
Al Viro932.49%63.97%
Hugh Dickins892.38%10.66%
Arjan van de Ven882.35%42.65%
Kees Cook852.27%10.66%
Christoph Hellwig852.27%31.99%
Jens Axboe792.11%31.99%
Adriano dos Santos Fernandes711.90%10.66%
Kamezawa Hiroyuki701.87%21.32%
Zach Brown531.42%10.66%
Art Haas451.20%10.66%
Andi Kleen431.15%10.66%
Linus Torvalds431.15%95.96%
Greg Kroah-Hartman411.10%63.97%
Julius Werner300.80%21.32%
Robin Murphy240.64%10.66%
Nicholas Piggin230.62%10.66%
Petr Tesarik210.56%10.66%
Haren Myneni180.48%10.66%
Benjamin Herrenschmidt170.45%21.32%
Hirofumi Ogawa150.40%10.66%
Jan Beulich150.40%10.66%
Thierry Reding140.37%10.66%
Robert Love140.37%10.66%
Anton Blanchard130.35%10.66%
Salman Qazi120.32%10.66%
Frédéric Weisbecker110.29%10.66%
Rob Ward90.24%42.65%
Rik Van Riel90.24%10.66%
Cyril Chemparathy50.13%10.66%
Arnd Bergmann50.13%10.66%
Vivek Goyal50.13%10.66%
Jesper Juhl40.11%10.66%
Russell King30.08%10.66%
Paul Gortmaker30.08%10.66%
Andrzej Hajda30.08%10.66%
Roland Dreier30.08%10.66%
Ingo Molnar30.08%10.66%
Changli Gao20.05%10.66%
Kent Overstreet20.05%10.66%
Geert Uytterhoeven20.05%10.66%
Jin Dongming20.05%10.66%
Hans Grob10.03%10.66%
Alexey Dobriyan10.03%10.66%
Konstantin Khlebnikov10.03%10.66%
Lennert Buytenhek10.03%10.66%
Total3739100.00%151100.00%
Directory: drivers/char
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