From: Matthias Kruk <m@m10k.eu>
Date: Wed, 30 Dec 2020 02:16:03 +0000 (+0900)
Subject: kernel/arch: Add functions for enabling and disabling paging
X-Git-Url: https://git.corax.cc/?a=commitdiff_plain;h=bf84aedad9eb5211fd9f2b3b9d9cbcd369c2b738;p=corax

kernel/arch: Add functions for enabling and disabling paging

The new paging implementation needs to access paging structures in
physical memory, making it necessary to temporarily disable paging.
This commit adds the necessary functions to explicitly disable and
enable paging on a processor.
---

diff --git a/kernel/arch/cpu32.S b/kernel/arch/cpu32.S
index 63eb5a3..99a5fea 100644
--- a/kernel/arch/cpu32.S
+++ b/kernel/arch/cpu32.S
@@ -33,7 +33,6 @@ boot_id:
 */
 
 .global cpu_get_id
-
 cpu_get_id:
 	movl    $APIC_ID_ADDR, %esi
 	movl    (%esi), %eax
@@ -41,7 +40,6 @@ cpu_get_id:
 	ret
 
 .global cpu_get_capabilities
-
 cpu_get_capabilities:
 	pushl   %ebx
 	movl    $1, %eax
@@ -58,7 +56,6 @@ cpu_timestamp:
 	ret
 
 .global cpu_set_pstate
-
 cpu_set_pstate:
 	pushl	%ebx
 	movl	$0x199, %ecx
@@ -69,3 +66,23 @@ cpu_set_pstate:
 	wrmsr
 	popl	%ebx
 	ret
+
+.global cpu_paging_disable
+cpu_paging_disable:
+        movl    %cr0, %eax
+        movl    %eax, %ecx
+        andl    $0x7fffffff, %eax
+        movl    %eax, %cr0
+        movl    %ecx, %eax
+        shr     $31, %eax
+        ret
+
+.global cpu_paging_enable
+cpu_paging_enable:
+        movl    %cr0, %eax
+        movl    %eax, %ecx
+        orl     $0x80000000, %eax
+        movl    %eax, %cr0
+        movl    %ecx, %eax
+        shr     $31, %eax
+        ret
diff --git a/kernel/include/arch.h b/kernel/include/arch.h
index a13ffc1..4407f95 100644
--- a/kernel/include/arch.h
+++ b/kernel/include/arch.h
@@ -222,6 +222,9 @@ u64_t   cpu_timestamp(void);
 
 u32_t   cpu_set_pstate(int pstate);
 
+int     cpu_paging_enable(void);
+int     cpu_paging_disable(void);
+
 int     task_prepare(struct task*, u32_t cr3, u32_t eip, u32_t esp0, u32_t esp, u32_t priv);
 int     task_prepare_fork(struct task*);
 int     task_switch(struct task*);