1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6 #include <linux/module.h>
7 #include <linux/memblock.h>
8 #include <linux/mm.h>
9 #include <linux/pfn.h>
10 #include <asm/page.h>
11 #include <asm/sections.h>
12 #include <as-layout.h>
13 #include <init.h>
14 #include <kern.h>
15 #include <kern_util.h>
16 #include <mem_user.h>
17 #include <os.h>
18
19 static int physmem_fd = -1;
20
21 /* Changed during early boot */
22 unsigned long high_physmem;
23 EXPORT_SYMBOL(high_physmem);
24
map_memory(unsigned long virt,unsigned long phys,unsigned long len,int r,int w,int x)25 void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
26 int r, int w, int x)
27 {
28 __u64 offset;
29 int fd, err;
30
31 fd = phys_mapping(phys, &offset);
32 err = os_map_memory((void *) virt, fd, offset, len, r, w, x);
33 if (err) {
34 if (err == -ENOMEM)
35 printk(KERN_ERR "try increasing the host's "
36 "/proc/sys/vm/max_map_count to <physical "
37 "memory size>/4096\n");
38 panic("map_memory(0x%lx, %d, 0x%llx, %ld, %d, %d, %d) failed, "
39 "err = %d\n", virt, fd, offset, len, r, w, x, err);
40 }
41 }
42
43 /**
44 * setup_physmem() - Setup physical memory for UML
45 * @start: Start address of the physical kernel memory,
46 * i.e start address of the executable image.
47 * @reserve_end: end address of the physical kernel memory.
48 * @len: Length of total physical memory that should be mapped/made
49 * available, in bytes.
50 *
51 * Creates an unlinked temporary file of size (len) and memory maps
52 * it on the last executable image address (uml_reserved).
53 *
54 * The offset is needed as the length of the total physical memory
55 * (len) includes the size of the memory used be the executable image,
56 * but the mapped-to address is the last address of the executable image
57 * (uml_reserved == end address of executable image).
58 *
59 * The memory mapped memory of the temporary file is used as backing memory
60 * of all user space processes/kernel tasks.
61 */
setup_physmem(unsigned long start,unsigned long reserve_end,unsigned long len)62 void __init setup_physmem(unsigned long start, unsigned long reserve_end,
63 unsigned long len)
64 {
65 unsigned long reserve = reserve_end - start;
66 unsigned long map_size = len - reserve;
67 int err;
68
69 if (len <= reserve) {
70 os_warn("Too few physical memory! Needed=%lu, given=%lu\n",
71 reserve, len);
72 exit(1);
73 }
74
75 physmem_fd = create_mem_file(len);
76
77 err = os_map_memory((void *) reserve_end, physmem_fd, reserve,
78 map_size, 1, 1, 1);
79 if (err < 0) {
80 os_warn("setup_physmem - mapping %lu bytes of memory at 0x%p "
81 "failed - errno = %d\n", map_size,
82 (void *) reserve_end, err);
83 exit(1);
84 }
85
86 /*
87 * Special kludge - This page will be mapped in to userspace processes
88 * from physmem_fd, so it needs to be written out there.
89 */
90 os_seek_file(physmem_fd, __pa(__syscall_stub_start));
91 os_write_file(physmem_fd, __syscall_stub_start, PAGE_SIZE);
92
93 memblock_add(__pa(start), len);
94 memblock_reserve(__pa(start), reserve);
95
96 min_low_pfn = PFN_UP(__pa(reserve_end));
97 max_low_pfn = min_low_pfn + (map_size >> PAGE_SHIFT);
98 }
99
phys_mapping(unsigned long phys,unsigned long long * offset_out)100 int phys_mapping(unsigned long phys, unsigned long long *offset_out)
101 {
102 int fd = -1;
103
104 if (phys < physmem_size) {
105 fd = physmem_fd;
106 *offset_out = phys;
107 }
108
109 return fd;
110 }
111 EXPORT_SYMBOL(phys_mapping);
112
uml_mem_setup(char * line,int * add)113 static int __init uml_mem_setup(char *line, int *add)
114 {
115 char *retptr;
116
117 *add = 0;
118 physmem_size = memparse(line,&retptr);
119 return 0;
120 }
121 __uml_setup("mem=", uml_mem_setup,
122 "mem=<Amount of desired ram>\n"
123 " This controls how much \"physical\" memory the kernel allocates\n"
124 " for the system. The size is specified as a number followed by\n"
125 " one of 'k', 'K', 'm', 'M', which have the obvious meanings.\n"
126 " This is not related to the amount of memory in the host. It can\n"
127 " be more, and the excess, if it's ever used, will just be swapped out.\n"
128 " Example: mem=64M\n\n"
129 );
130