mirror of https://github.com/tailix/kernel.git
128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
#include "paging.h"
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#include "pagedir.h"
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#include "panic.h"
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#include <kernelmq/stdlib.h>
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// CR0 bits
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#define I386_CR0_PE 0x00000001 // Protected mode
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#define I386_CR0_MP 0x00000002 // Monitor Coprocessor
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#define I386_CR0_EM 0x00000004 // Emulate
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#define I386_CR0_TS 0x00000008 // Task Switched
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#define I386_CR0_ET 0x00000010 // Extension Type
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#define I386_CR0_WP 0x00010000 // Enable paging
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#define I386_CR0_PG 0x80000000 // Enable paging
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// some CR4 bits
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#define I386_CR4_VME 0x00000001 // Virtual 8086
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#define I386_CR4_PVI 0x00000002 // Virtual ints
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#define I386_CR4_TSD 0x00000004 // RDTSC privileged
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#define I386_CR4_DE 0x00000008 // Debugging extensions
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#define I386_CR4_PSE 0x00000010 // Page size extensions
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#define I386_CR4_PAE 0x00000020 // Physical addr extens
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#define I386_CR4_MCE 0x00000040 // Machine check enable
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#define I386_CR4_PGE 0x00000080 // Global page flag enable
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unsigned long read_cr0();
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unsigned long read_cr4();
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void write_cr0(volatile unsigned long);
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void write_cr3(volatile unsigned long);
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void write_cr4(volatile unsigned long);
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static PageDir pagedir;
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void paging_enable()
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{
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unsigned long cr0 = read_cr0();
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unsigned long cr4 = read_cr4();
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assert(cr0 & I386_CR0_PE, "The boot loader should have put us in protected mode.");
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// First clear PG and PGE flag, as PGE must be enabled after PG.
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write_cr0(cr0 & ~I386_CR0_PG);
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write_cr4(cr4 & ~(I386_CR4_PGE | I386_CR4_PSE));
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cr0 = read_cr0();
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cr4 = read_cr4();
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// Our page table contains 4MB entries.
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cr4 |= I386_CR4_PSE;
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write_cr4(cr4);
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// First enable paging, then enable global page flag.
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cr0 |= I386_CR0_PG;
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write_cr0(cr0);
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cr0 |= I386_CR0_WP;
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write_cr0(cr0);
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write_cr4(cr4);
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}
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void paging_clear()
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{
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kmemset(pagedir, 0, sizeof(pagedir));
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}
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void paging_identity()
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{
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for (int i = 0; i < PAGE_DIR_LENGTH; ++i) {
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pagedir[i].addr = PAGE_DIR_ADDR(i * PAGE_BIG_SIZE);
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pagedir[i].unused = 0;
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pagedir[i].ignored = 0;
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pagedir[i].page_size = 1;
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pagedir[i].always_0 = 0;
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pagedir[i].accessed = 0;
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pagedir[i].cache_disabled = 1;
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pagedir[i].write_through = 1;
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pagedir[i].user = 1;
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pagedir[i].writable = 1;
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pagedir[i].present = 1;
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}
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}
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int paging_mapkernel(const struct KernelMQ_Info *const kinfo)
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{
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assert(!(kinfo->kernel_phys_base % PAGE_BIG_SIZE), "Kernel physical address is not aligned.");
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assert(!(kinfo->kernel_virt_base % PAGE_BIG_SIZE), "Kernel virtual address is not aligned.");
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int pde = kinfo->kernel_virt_base / PAGE_BIG_SIZE;
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unsigned long mapped = 0;
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unsigned long kern_phys = kinfo->kernel_phys_base;
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while (mapped < kinfo->kernel_size) {
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pagedir[pde].addr = PAGE_DIR_ADDR(kern_phys);
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pagedir[pde].unused = 0;
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pagedir[pde].ignored = 0;
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pagedir[pde].page_size = 1;
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pagedir[pde].always_0 = 0;
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pagedir[pde].accessed = 0;
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pagedir[pde].cache_disabled = 0;
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pagedir[pde].write_through = 0;
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pagedir[pde].user = 0;
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pagedir[pde].writable = 1;
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pagedir[pde].present = 1;
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mapped += PAGE_BIG_SIZE;
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kern_phys += PAGE_BIG_SIZE;
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++pde;
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}
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return pde;
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}
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unsigned long paging_load()
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{
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unsigned long pagedir_phys = (unsigned long)pagedir;
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write_cr3(pagedir_phys);
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return pagedir_phys;
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}
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