[PATCH] NOMMU: Set BDI capabilities for /dev/mem and /dev/kmem

[mirror_ubuntu-jammy-kernel.git] / drivers / char / mem.c

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 1fa9fa157c125652fea7cd314534992c4875a73b..4ac70ec697f07f7b6b15c52d231709b7dd64577b 100644 (file)
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -8,7 +8,6 @@
  *  Shared /dev/zero mmaping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
  */
 
-#include <linux/config.h>
 #include <linux/mm.h>
 #include <linux/miscdevice.h>
 #include <linux/slab.h>
@@ -20,7 +19,6 @@
 #include <linux/tty.h>
 #include <linux/capability.h>
 #include <linux/smp_lock.h>
-#include <linux/devfs_fs_kernel.h>
 #include <linux/ptrace.h>
 #include <linux/device.h>
 #include <linux/highmem.h>
@@ -97,7 +95,7 @@ static inline int valid_phys_addr_range(unsigned long addr, size_t count)
        return 1;
 }
 
-static inline int valid_mmap_phys_addr_range(unsigned long addr, size_t size)
+static inline int valid_mmap_phys_addr_range(unsigned long pfn, size_t size)
 {
        return 1;
 }
@@ -240,13 +238,42 @@ 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;
 
-       if (!valid_mmap_phys_addr_range(vma->vm_pgoff << PAGE_SHIFT, size))
+       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);
@@ -778,23 +805,25 @@ static int open_port(struct inode * inode, struct file * filp)
 #define open_kmem      open_mem
 #define open_oldmem    open_mem
 
-static struct file_operations mem_fops = {
+static const struct file_operations mem_fops = {
        .llseek         = memory_lseek,
        .read           = read_mem,
        .write          = write_mem,
        .mmap           = mmap_mem,
        .open           = open_mem,
+       .get_unmapped_area = get_unmapped_area_mem,
 };
 
-static struct file_operations kmem_fops = {
+static const struct file_operations kmem_fops = {
        .llseek         = memory_lseek,
        .read           = read_kmem,
        .write          = write_kmem,
        .mmap           = mmap_kmem,
        .open           = open_kmem,
+       .get_unmapped_area = get_unmapped_area_mem,
 };
 
-static struct file_operations null_fops = {
+static const struct file_operations null_fops = {
        .llseek         = null_lseek,
        .read           = read_null,
        .write          = write_null,
@@ -802,7 +831,7 @@ static struct file_operations null_fops = {
 };
 
 #if defined(CONFIG_ISA) || !defined(__mc68000__)
-static struct file_operations port_fops = {
+static const struct file_operations port_fops = {
        .llseek         = memory_lseek,
        .read           = read_port,
        .write          = write_port,
@@ -810,25 +839,29 @@ static struct file_operations port_fops = {
 };
 #endif
 
-static struct file_operations zero_fops = {
+static const struct file_operations zero_fops = {
        .llseek         = zero_lseek,
        .read           = read_zero,
        .write          = write_zero,
        .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,
 };
 
-static struct file_operations full_fops = {
+static const struct file_operations full_fops = {
        .llseek         = full_lseek,
        .read           = read_full,
        .write          = write_full,
 };
 
 #ifdef CONFIG_CRASH_DUMP
-static struct file_operations oldmem_fops = {
+static const struct file_operations oldmem_fops = {
        .read   = read_oldmem,
        .open   = open_oldmem,
 };
@@ -855,7 +888,7 @@ static ssize_t kmsg_write(struct file * file, const char __user * buf,
        return ret;
 }
 
-static struct file_operations kmsg_fops = {
+static const struct file_operations kmsg_fops = {
        .write =        kmsg_write,
 };
 
@@ -864,9 +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;
@@ -905,7 +942,7 @@ static int memory_open(struct inode * inode, struct file * filp)
        return 0;
 }
 
-static struct file_operations memory_fops = {
+static const struct file_operations memory_fops = {
        .open           = memory_open,  /* just a selector for the real open */
 };
 
@@ -941,13 +978,10 @@ static int __init chr_dev_init(void)
                printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 
        mem_class = class_create(THIS_MODULE, "mem");
-       for (i = 0; i < ARRAY_SIZE(devlist); i++) {
+       for (i = 0; i < ARRAY_SIZE(devlist); i++)
                class_device_create(mem_class, NULL,
                                        MKDEV(MEM_MAJOR, devlist[i].minor),
                                        NULL, devlist[i].name);
-               devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor),
-                               S_IFCHR | devlist[i].mode, devlist[i].name);
-       }
        
        return 0;
 }