81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
#include <linux/ioport.h>
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#include <linux/swap.h>
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#include <asm/cacheflush.h>
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#include <asm/page.h>
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#include <asm/page_types.h>
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#include <asm/sections.h>
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#include <asm/system.h>
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/*
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* devmem_is_allowed() checks to see if /dev/mem access to a certain address
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* is valid. The argument is a physical page number.
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*
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*
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* On x86, access has to be given to the first megabyte of ram because that area
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* contains bios code and data regions used by X and dosemu and similar apps.
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* Access has to be given to non-kernel-ram areas as well, these contain the PCI
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* mmio resources as well as potential bios/acpi data regions.
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*/
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int devmem_is_allowed(unsigned long pagenr)
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{
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if (pagenr <= 256)
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return 1;
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if (iomem_is_exclusive(pagenr << PAGE_SHIFT))
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return 0;
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if (!page_is_ram(pagenr))
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return 1;
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return 0;
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}
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void free_init_pages(char *what, unsigned long begin, unsigned long end)
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{
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unsigned long addr = begin;
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if (addr >= end)
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return;
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/*
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* If debugging page accesses then do not free this memory but
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* mark them not present - any buggy init-section access will
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* create a kernel page fault:
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*/
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#ifdef CONFIG_DEBUG_PAGEALLOC
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printk(KERN_INFO "debug: unmapping init memory %08lx..%08lx\n",
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begin, PAGE_ALIGN(end));
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set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
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#else
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/*
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* We just marked the kernel text read only above, now that
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* we are going to free part of that, we need to make that
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* writeable first.
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*/
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set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);
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printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);
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for (; addr < end; addr += PAGE_SIZE) {
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ClearPageReserved(virt_to_page(addr));
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init_page_count(virt_to_page(addr));
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memset((void *)(addr & ~(PAGE_SIZE-1)),
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POISON_FREE_INITMEM, PAGE_SIZE);
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free_page(addr);
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totalram_pages++;
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}
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#endif
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}
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void free_initmem(void)
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{
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free_init_pages("unused kernel memory",
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(unsigned long)(&__init_begin),
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(unsigned long)(&__init_end));
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}
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#ifdef CONFIG_BLK_DEV_INITRD
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void free_initrd_mem(unsigned long start, unsigned long end)
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{
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free_init_pages("initrd memory", start, end);
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}
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#endif
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