41 lines
1.1 KiB
C
41 lines
1.1 KiB
C
#include <rockos/paging.h>
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#include <stdint.h>
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void load_page_dir(uint32_t* page_dir) {
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asm volatile (
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"mov %%eax, %%cr3"
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:
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: "a"(page_dir)
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: "memory"
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);
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}
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void enable_paging() {
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asm volatile (
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"mov %cr0, %eax\n"
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"or $0x80000000, %eax\n"
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"mov %eax, %cr0"
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);
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}
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void paging_init() {
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uint32_t page_dir[PAGE_ENTRIES] __attribute__((aligned(PAGE_SIZE)));
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for(int i = 0; i < PAGE_ENTRIES; i++) {
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// Supervisor: only kernel-mode can access
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// Write Enabled: Can be both read and written to
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// Not Present: Page table not present
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page_dir[i] = 0x00000002;
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}
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uint32_t first_page_table[PAGE_ENTRIES] __attribute__((aligned(PAGE_SIZE)));
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for(unsigned int i = 0; i < PAGE_ENTRIES; i++) {
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// As the address is page aligned, it will leave 12 bits zeroed,
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// which are used by the attributes.
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first_page_table[i] = (i * 0x1000) | 3; // attr: supervisor, r/w, present
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}
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page_dir[0] = ((unsigned int)first_page_table) | 3; //attr: supervisor, r/w, present
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load_page_dir(page_dir);
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enable_paging();
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} |