mirror of https://github.com/torvalds/linux.git
130 lines
3.6 KiB
C
130 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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*/
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#include <linux/module.h>
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#include <linux/memblock.h>
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#include <linux/mm.h>
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#include <linux/pfn.h>
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#include <asm/page.h>
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#include <asm/sections.h>
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#include <as-layout.h>
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#include <init.h>
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#include <kern.h>
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#include <kern_util.h>
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#include <mem_user.h>
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#include <os.h>
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static int physmem_fd = -1;
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/* Changed during early boot */
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unsigned long high_physmem;
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EXPORT_SYMBOL(high_physmem);
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void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
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int r, int w, int x)
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{
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__u64 offset;
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int fd, err;
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fd = phys_mapping(phys, &offset);
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err = os_map_memory((void *) virt, fd, offset, len, r, w, x);
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if (err) {
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if (err == -ENOMEM)
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printk(KERN_ERR "try increasing the host's "
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"/proc/sys/vm/max_map_count to <physical "
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"memory size>/4096\n");
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panic("map_memory(0x%lx, %d, 0x%llx, %ld, %d, %d, %d) failed, "
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"err = %d\n", virt, fd, offset, len, r, w, x, err);
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}
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}
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/**
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* setup_physmem() - Setup physical memory for UML
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* @start: Start address of the physical kernel memory,
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* i.e start address of the executable image.
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* @reserve_end: end address of the physical kernel memory.
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* @len: Length of total physical memory that should be mapped/made
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* available, in bytes.
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*
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* Creates an unlinked temporary file of size (len) and memory maps
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* it on the last executable image address (uml_reserved).
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*
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* The offset is needed as the length of the total physical memory
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* (len) includes the size of the memory used be the executable image,
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* but the mapped-to address is the last address of the executable image
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* (uml_reserved == end address of executable image).
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*
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* The memory mapped memory of the temporary file is used as backing memory
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* of all user space processes/kernel tasks.
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*/
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void __init setup_physmem(unsigned long start, unsigned long reserve_end,
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unsigned long len)
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{
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unsigned long reserve = reserve_end - start;
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unsigned long map_size = len - reserve;
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int err;
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if (len <= reserve) {
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os_warn("Too few physical memory! Needed=%lu, given=%lu\n",
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reserve, len);
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exit(1);
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}
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physmem_fd = create_mem_file(len);
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err = os_map_memory((void *) reserve_end, physmem_fd, reserve,
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map_size, 1, 1, 1);
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if (err < 0) {
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os_warn("setup_physmem - mapping %lu bytes of memory at 0x%p "
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"failed - errno = %d\n", map_size,
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(void *) reserve_end, err);
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exit(1);
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}
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/*
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* Special kludge - This page will be mapped in to userspace processes
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* from physmem_fd, so it needs to be written out there.
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*/
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os_seek_file(physmem_fd, __pa(__syscall_stub_start));
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os_write_file(physmem_fd, __syscall_stub_start, PAGE_SIZE);
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memblock_add(__pa(start), len);
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memblock_reserve(__pa(start), reserve);
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min_low_pfn = PFN_UP(__pa(reserve_end));
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max_low_pfn = min_low_pfn + (map_size >> PAGE_SHIFT);
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}
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int phys_mapping(unsigned long phys, unsigned long long *offset_out)
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{
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int fd = -1;
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if (phys < physmem_size) {
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fd = physmem_fd;
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*offset_out = phys;
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}
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return fd;
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}
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EXPORT_SYMBOL(phys_mapping);
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static int __init uml_mem_setup(char *line, int *add)
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{
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char *retptr;
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*add = 0;
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physmem_size = memparse(line,&retptr);
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return 0;
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}
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__uml_setup("mem=", uml_mem_setup,
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"mem=<Amount of desired ram>\n"
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" This controls how much \"physical\" memory the kernel allocates\n"
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" for the system. The size is specified as a number followed by\n"
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" one of 'k', 'K', 'm', 'M', which have the obvious meanings.\n"
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" This is not related to the amount of memory in the host. It can\n"
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" be more, and the excess, if it's ever used, will just be swapped out.\n"
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" Example: mem=64M\n\n"
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);
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