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Use packed struct instead of unreadable ORing

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This commit is contained in:
Braiden Vasco 2017-11-08 07:49:08 +00:00
parent 4ca2c04ce7
commit baf0cbc261
1 changed files with 44 additions and 23 deletions
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67
arch/paging.c
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@ -5,19 +5,6 @@
#include <kernelmq/stdlib.h>
// i386 paging constants
#define I386_VM_PRESENT 0x001 // Page is present
#define I386_VM_WRITE 0x002 // Read/write access allowed
#define I386_VM_READ 0x000 // Read access only
#define I386_VM_USER 0x004 // User access allowed
#define I386_VM_PWT 0x008 // Write through
#define I386_VM_PCD 0x010 // Cache disable
#define I386_VM_ACC 0x020 // Accessed
// Page directory specific flags.
#define I386_VM_BIGPAGE 0x080 // 4MB page
// CR0 bits
#define I386_CR0_PE 0x00000001 // Protected mode
#define I386_CR0_MP 0x00000002 // Monitor Coprocessor
@ -37,6 +24,21 @@
#define I386_CR4_MCE 0x00000040 // Machine check enable
#define I386_CR4_PGE 0x00000080 // Global page flag enable
struct entry {
unsigned int present : 1;
unsigned int writable : 1;
unsigned int user : 1;
unsigned int write_through : 1;
unsigned int cache_disabled : 1;
unsigned int accessed : 1;
unsigned int always_0 : 1;
unsigned int page_size : 1;
unsigned int ignored : 1;
unsigned int unused : 3;
unsigned int addr : 20;
}
__attribute__((packed));
unsigned long read_cr0();
unsigned long read_cr4();
@ -84,16 +86,22 @@ void paging_clear()
void paging_identity()
{
for (int i = 0; i < PAGE_DIR_SIZE; ++i) {
unsigned int flags = I386_VM_PRESENT |
I386_VM_BIGPAGE |
I386_VM_USER |
I386_VM_WRITE;
struct entry entry;
unsigned long phys = i * PAGE_BIG_SIZE;
entry.addr = (i * PAGE_BIG_SIZE) >> 12;
flags |= I386_VM_PWT | I386_VM_PCD;
entry.unused = 0;
entry.ignored = 0;
entry.page_size = 1;
entry.always_0 = 0;
entry.accessed = 0;
entry.cache_disabled = 1;
entry.write_through = 1;
entry.user = 1;
entry.writable = 1;
entry.present = 1;
pagedir[i] = phys | flags;
pagedir[i] = *((unsigned long*)(&entry));
}
}
@ -108,9 +116,22 @@ int paging_mapkernel(const struct KernelMQ_Info *const kinfo)
unsigned long kern_phys = kinfo->kernel_phys_base;
while (mapped < kinfo->kernel_size) {
pagedir[pde] = kern_phys | I386_VM_PRESENT |
I386_VM_BIGPAGE |
I386_VM_WRITE;
struct entry entry;
entry.addr = kern_phys >> 12;
entry.unused = 0;
entry.ignored = 0;
entry.page_size = 1;
entry.always_0 = 0;
entry.accessed = 0;
entry.cache_disabled = 0;
entry.write_through = 0;
entry.user = 0;
entry.writable = 1;
entry.present = 1;
pagedir[pde] = *((unsigned long*)(&entry));
mapped += PAGE_BIG_SIZE;
kern_phys += PAGE_BIG_SIZE;