From 7e53464d7bb2187fe0754fbdc04becbdccae11fe Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Sat, 23 May 2020 18:43:22 +0200
Subject: Dynamic paging approach

I think this is it. I really do. I guess.
---
 src/kernel/memory/paging.c | 50 +++++++++++++++++++---------------------------
 1 file changed, 21 insertions(+), 29 deletions(-)

(limited to 'src/kernel/memory/paging.c')

diff --git a/src/kernel/memory/paging.c b/src/kernel/memory/paging.c
index 917a186..db9fc2d 100644
--- a/src/kernel/memory/paging.c
+++ b/src/kernel/memory/paging.c
@@ -4,35 +4,38 @@
 #include <stdint.h>
 #include <system.h>
 
-u32 *current_page_directory;
-u32 (*current_page_tables)[1024];
-u32 kernel_page_directory[1024] __attribute__((aligned(4096)));
+u32 **current_page_directory;
+u32 *kernel_page_directory[1024] __attribute__((aligned(4096)));
 u32 kernel_page_tables[1024][1024] __attribute__((aligned(4096)));
 
-void paging_init(u32 *dir, u32 tables[1024][1024], int user)
+void paging_init(u32 **dir, int user)
 {
 	for (u32 i = 0; i < 1024; i++) {
 		for (u32 j = 0; j < 1024; j++) {
-			tables[i][j] =
-				((j * 0x1000) + (i * 0x400000)) | PT_RW | (user ? PT_USER : 0);
+			dir[i][j] = ((j * 0x1000) + (i * 0x400000)) | PT_RW | (user ? PT_USER : 0);
 		}
 	}
 
 	for (u32 i = 0; i < 1024; i++) {
-		dir[i] = ((u32)tables[i]) | PD_RW | PD_PRESENT | (user ? PD_USER : 0);
+		dir[i] = ((u32)dir[i]) | PD_RW | PD_PRESENT | (user ? PD_USER : 0);
 	}
 }
 
 extern void KERNEL_END();
 void paging_install()
 {
-	paging_init(kernel_page_directory, kernel_page_tables, 0);
-	paging_switch_directory(kernel_page_directory);
+	for (u32 i = 0; i < 1024; i++) {
+		kernel_page_directory[i] = kernel_page_tables[i];
+	}
+
+	paging_init((u32 **)kernel_page_directory, 0);
+	paging_switch_directory((u32 **)kernel_page_directory);
 
 	if (!memory_init())
 		paging_set_present(0, memory_get_all() >> 3);
 	paging_set_used(0, ((u32)KERNEL_END >> 12) + 1);
 
+	log("Installing paging");
 	paging_enable();
 	log("Installed paging");
 
@@ -79,9 +82,8 @@ void paging_enable()
 	paging_enabled = 1;
 }
 
-void paging_switch_directory(u32 *dir)
+void paging_switch_directory(u32 **dir)
 {
-	current_page_tables = dir;
 	current_page_directory = dir;
 	asm("mov %0, %%cr3" ::"r"(current_page_directory));
 }
@@ -95,7 +97,7 @@ void paging_map(u32 phy, u32 virt, u16 flags)
 {
 	u32 pdi = virt >> 22;
 	u32 pti = virt >> 12 & 0x03FF;
-	current_page_tables[pdi][pti] = phy | flags;
+	current_page_directory[pdi][pti] = phy | flags;
 	invlpg(virt);
 }
 
@@ -103,21 +105,21 @@ u32 paging_get_phys(u32 virt)
 {
 	u32 pdi = virt >> 22;
 	u32 pti = (virt >> 12) & 0x03FF;
-	return current_page_tables[pdi][pti] & 0xFFFFF000;
+	return current_page_directory[pdi][pti] & 0xFFFFF000;
 }
 
 u16 paging_get_flags(u32 virt)
 {
 	u32 pdi = virt >> 22;
 	u32 pti = (virt >> 12) & 0x03FF;
-	return current_page_tables[pdi][pti] & 0xFFF;
+	return current_page_directory[pdi][pti] & 0xFFF;
 }
 
 void paging_set_flag_up(u32 virt, u32 count, u32 flag)
 {
 	u32 page_n = virt / 0x1000;
 	for (u32 i = page_n; i < page_n + count; i++) {
-		current_page_tables[i / 1024][i % 1024] |= flag;
+		current_page_directory[i / 1024][i % 1024] |= flag;
 		invlpg(i * 0x1000);
 	}
 }
@@ -126,7 +128,7 @@ void paging_set_flag_down(u32 virt, u32 count, u32 flag)
 {
 	u32 page_n = virt / 0x1000;
 	for (u32 i = page_n; i < page_n + count; i++) {
-		current_page_tables[i / 1024][i % 1024] &= ~flag;
+		current_page_directory[i / 1024][i % 1024] &= ~flag;
 		invlpg(i * 0x1000);
 	}
 }
@@ -151,15 +153,6 @@ void paging_set_free(u32 virt, u32 count)
 	paging_set_flag_down(virt, count, PT_USED);
 }
 
-void paging_set_user(u32 virt, u32 count)
-{
-	u32 page_n = virt / 0x1000;
-	for (u32 i = page_n; i < page_n + count; i += 1024) {
-		current_page_directory[i / 1024] |= PD_USER;
-	}
-	paging_set_flag_up(virt, count, PT_USER);
-}
-
 u32 paging_find_pages(u32 count)
 {
 	u32 continuous = 0;
@@ -167,8 +160,8 @@ u32 paging_find_pages(u32 count)
 	u32 start_page = 0;
 	for (u32 i = 0; i < 1024; i++) {
 		for (u32 j = 0; j < 1024; j++) {
-			if (!(current_page_tables[i][j] & PT_PRESENT) ||
-			    (current_page_tables[i][j] & PT_USED)) {
+			if (!(current_page_directory[i][j] & PT_PRESENT) ||
+			    (current_page_directory[i][j] & PT_USED)) {
 				continuous = 0;
 				start_dir = i;
 				start_page = j + 1;
@@ -187,7 +180,6 @@ u32 paging_alloc_pages(u32 count)
 {
 	u32 ptr = paging_find_pages(count);
 	paging_set_used(ptr, count);
-	paging_set_user(ptr, count);
 	return ptr;
 }
 
@@ -196,7 +188,7 @@ u32 paging_get_used_pages()
 	u32 n = 0;
 	for (u32 i = 0; i < 1024; i++) {
 		for (u32 j = 0; j < 1024; j++) {
-			u8 flags = current_page_tables[i][j] & PT_USED;
+			u8 flags = current_page_directory[i][j] & PT_USED;
 			if (flags == 1)
 				n++;
 		}
-- 
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