From: Matthias Kruk <m@m10k.eu>
Date: Mon, 2 Dec 2019 09:37:16 +0000 (+0900)
Subject: Switch back to the user page directory after having modified the _cpu structure,... 
X-Git-Url: https://git.corax.cc/?a=commitdiff_plain;h=576e6142bb5685a0a361b4fcac846658e3e06d5a;p=corax

Switch back to the user page directory after having modified the _cpu structure, so it can be removed from the process's page directory
---

diff --git a/kernel/arch/entry.S b/kernel/arch/entry.S
index 4ab9ea4..13e63d0 100644
--- a/kernel/arch/entry.S
+++ b/kernel/arch/entry.S
@@ -404,19 +404,16 @@ _already_in_kernel:
 
 _int_restore:
 	/* pop the page directory from the stack */
-	popl	%eax
+	popl	%edi
 
 	/*
 	 * Check if the destination of the iret is in the kernel or user-space.
 	 * In the former case, we can skip rebasing the stack and restoring the
 	 * page directory.
 	 */
-	cmpl	%eax, (_kernel_cr3)
+	cmpl	%edi, (_kernel_cr3)
 	je		_return_to_kernel
 
-	/* switch page directory first since we'll need the register */
-	movl	%eax, %cr3
-
 	cpuidx	%ecx
 	movl	$_cpu, %eax
 0:	subl	$1, %ecx
@@ -432,6 +429,12 @@ _int_restore:
 	subl	OFFSET_TASK_KSTACK(%eax), %ebp
 	addl	$CONFIG_KERNEL_STACK_BASE, %ebp
 
+	/*
+	 * Restore the page directory last since the .bss segement where the _cpu
+	 * structure resides is not mapped into the process address space
+	 */
+	movl	%edi, %cr3
+
 _return_to_kernel:
     popl    %eax
     movw    %ax, %ds