From 2bd8511dbd19ec09aa92cec2888a5ec3c8b1fded Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Tue, 20 Jul 2021 21:26:46 +0200
Subject: only enable paging when jumping into ring 0
The kernel can't use the limited paging tables of user processes.
Alternatively, sysenter could accept a parameter with a new cr3. That
would allow/require using paging in the kernel - so I'll switch to it
later, but I want to get other stuff done first.
---
src/kernel/arch/i386/pagedir.c | 7 +------
src/kernel/arch/i386/sysenter.s | 5 +++++
2 files changed, 6 insertions(+), 6 deletions(-)
(limited to 'src')
diff --git a/src/kernel/arch/i386/pagedir.c b/src/kernel/arch/i386/pagedir.c
index 264508b..b52075d 100644
--- a/src/kernel/arch/i386/pagedir.c
+++ b/src/kernel/arch/i386/pagedir.c
@@ -89,10 +89,5 @@ void pagedir_map(struct pagedir *dir, void *virt, void *phys,
}
void pagedir_use(struct pagedir *dir) {
- asm volatile("mov %0, %%cr3;"
-
- "mov %%cr0, %%eax;"
- "or $0x80000001, %%eax;"
- "mov %%eax, %%cr0;"
- : : "r" (dir) : "eax");
+ asm volatile("mov %0, %%cr3;" : : "r" (dir) : "memory");
}
diff --git a/src/kernel/arch/i386/sysenter.s b/src/kernel/arch/i386/sysenter.s
index 666c0f0..5630c3b 100644
--- a/src/kernel/arch/i386/sysenter.s
+++ b/src/kernel/arch/i386/sysenter.s
@@ -18,6 +18,11 @@ sysexit:
mov %ax, %fs
mov %ax, %gs
+ // enable paging
+ mov %cr0, %eax
+ or $0x80000000, %eax
+ mov %eax, %cr0
+
sysexit
--
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