diff options
| -rw-r--r-- | drivers/char/mem.c | 39 | ||||
| -rw-r--r-- | fs/char_dev.c | 20 | ||||
| -rw-r--r-- | include/linux/cdev.h | 2 |
3 files changed, 61 insertions, 0 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 917b20402664..4ac70ec697f0 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -238,6 +238,32 @@ static pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, } #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; +} + +/* 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; +} +#else +#define get_unmapped_area_mem NULL + +static inline int private_mapping_ok(struct vm_area_struct *vma) +{ + return 1; +} +#endif + static int mmap_mem(struct file * file, struct vm_area_struct * vma) { size_t size = vma->vm_end - vma->vm_start; @@ -245,6 +271,9 @@ static int mmap_mem(struct file * file, struct vm_area_struct * vma) if (!valid_mmap_phys_addr_range(vma->vm_pgoff, size)) return -EINVAL; + if (!private_mapping_ok(vma)) + return -ENOSYS; + vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff, size, vma->vm_page_prot); @@ -782,6 +811,7 @@ static const struct file_operations mem_fops = { .write = write_mem, .mmap = mmap_mem, .open = open_mem, + .get_unmapped_area = get_unmapped_area_mem, }; static const struct file_operations kmem_fops = { @@ -790,6 +820,7 @@ static const struct file_operations kmem_fops = { .write = write_kmem, .mmap = mmap_kmem, .open = open_kmem, + .get_unmapped_area = get_unmapped_area_mem, }; static const struct file_operations null_fops = { @@ -815,6 +846,10 @@ static const struct file_operations zero_fops = { .mmap = mmap_zero, }; +/* + * capabilities for /dev/zero + * - permits private mappings, "copies" are taken of the source of zeros + */ static struct backing_dev_info zero_bdi = { .capabilities = BDI_CAP_MAP_COPY, }; @@ -862,9 +897,13 @@ static int memory_open(struct inode * inode, struct file * filp) switch (iminor(inode)) { case 1: filp->f_op = &mem_fops; + filp->f_mapping->backing_dev_info = + &directly_mappable_cdev_bdi; break; case 2: filp->f_op = &kmem_fops; + filp->f_mapping->backing_dev_info = + &directly_mappable_cdev_bdi; break; case 3: filp->f_op = &null_fops; diff --git a/fs/char_dev.c b/fs/char_dev.c index 3483d3cf8087..0009346d827f 100644 --- a/fs/char_dev.c +++ b/fs/char_dev.c @@ -19,11 +19,30 @@ #include <linux/kobj_map.h> #include <linux/cdev.h> #include <linux/mutex.h> +#include <linux/backing-dev.h> #ifdef CONFIG_KMOD #include <linux/kmod.h> #endif +/* + * capabilities for /dev/mem, /dev/kmem and similar directly mappable character + * devices + * - permits shared-mmap for read, write and/or exec + * - does not permit private mmap in NOMMU mode (can't do COW) + * - no readahead or I/O queue unplugging required + */ +struct backing_dev_info directly_mappable_cdev_bdi = { + .capabilities = ( +#ifdef CONFIG_MMU + /* permit private copies of the data to be taken */ + BDI_CAP_MAP_COPY | +#endif + /* permit direct mmap, for read, write or exec */ + BDI_CAP_MAP_DIRECT | + BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP), +}; + static struct kobj_map *cdev_map; static DEFINE_MUTEX(chrdevs_lock); @@ -461,3 +480,4 @@ EXPORT_SYMBOL(cdev_del); EXPORT_SYMBOL(cdev_add); EXPORT_SYMBOL(register_chrdev); EXPORT_SYMBOL(unregister_chrdev); +EXPORT_SYMBOL(directly_mappable_cdev_bdi); diff --git a/include/linux/cdev.h b/include/linux/cdev.h index 2216638962d2..ee5f53f2ca15 100644 --- a/include/linux/cdev.h +++ b/include/linux/cdev.h @@ -23,5 +23,7 @@ void cdev_del(struct cdev *); void cd_forget(struct inode *); +extern struct backing_dev_info directly_mappable_cdev_bdi; + #endif #endif |