diff options
| author | Fabian Imhof <fabian.imhof@ost.ch> | 2025-04-06 07:47:27 +0000 |
|---|---|---|
| committer | Fabian Imhof <fabian.imhof@ost.ch> | 2025-04-06 07:47:27 +0000 |
| commit | 350aedae0e50749f9821ac7dc6b8316cf35f24bb (patch) | |
| tree | 21f3c67a1648d5950718dc5b0db32e45b870641f /arch/x86_64/src/boot | |
| parent | a8852f91967a7e55e62e30f5cc07d076092b8b78 (diff) | |
| download | teachos-350aedae0e50749f9821ac7dc6b8316cf35f24bb.tar.xz teachos-350aedae0e50749f9821ac7dc6b8316cf35f24bb.zip | |
wip context switch in asm
Diffstat (limited to 'arch/x86_64/src/boot')
| -rw-r--r-- | arch/x86_64/src/boot/boot.s | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/arch/x86_64/src/boot/boot.s b/arch/x86_64/src/boot/boot.s index 7932045..85ae1a1 100644 --- a/arch/x86_64/src/boot/boot.s +++ b/arch/x86_64/src/boot/boot.s @@ -352,6 +352,35 @@ prepare_page_maps: .section .boot_text, "ax", @progbits .code64 +.global context_switch +context_switch: + // ring 3 data with bottom 2 bits set for ring 3 + mov $((4 * 16) | 3), %rax + mov %rax, %ds + mov %rax, %es + mov %rax, %fs + mov %rax, %gs + // SS is handled by iret https://wiki.osdev.org/Getting_to_Ring_3 + + // set up the stack frame iret expects + mov %rsp, %rax + // user data selector + push $((4 * 16) | 3) + // current exp + push %rax + // push eflags + pushf + // push code selector (ring 3 code with bottom 2 bits set for ring 3) + push $((3 * 16) | 3) + // instruction address to return to + push test_function + + iret + +test_function: + cli + ret + _transition_to_long_mode: xor %rax, %rax mov %rax, %ss |