From 8b757079f0e3355d3c011dfb2db864e8f9fb79bb Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Tue, 6 Sep 2022 15:16:30 -0600
Subject: [PATCH] Allow thunk to set ES
---
asm/x86-unknown-none/thunk.asm | 26 ++++++++++++++++++++------
src/os/bios/thunk.rs | 10 +++++-----
2 files changed, 25 insertions(+), 11 deletions(-)
diff --git a/asm/x86-unknown-none/thunk.asm b/asm/x86-unknown-none/thunk.asm
index 16a3597..4423132 100644
--- a/asm/x86-unknown-none/thunk.asm
+++ b/asm/x86-unknown-none/thunk.asm
@@ -107,10 +107,17 @@ USE16
mov ss, eax
; set stack
- mov esp, 0x7C00 - 16
-
- ; load registers
- popad
+ mov esp, 0x7C00 - 64
+
+ ; load registers and ES
+ pop es
+ pop edi
+ pop esi
+ pop ebp
+ pop ebx
+ pop edx
+ pop ecx
+ pop eax
; enable interrupts
sti
@@ -121,8 +128,15 @@ USE16
; disable interrupts
cli
- ; save registers
- pushad
+ ; save registers and ES
+ push eax
+ push ecx
+ push edx
+ push ebx
+ push ebp
+ push esi
+ push edi
+ push es
; load gdt (BIOS sometimes overwrites this)
lgdt [gdtr]
diff --git a/src/os/bios/thunk.rs b/src/os/bios/thunk.rs
index 8fa4125..118f8f8 100644
--- a/src/os/bios/thunk.rs
+++ b/src/os/bios/thunk.rs
@@ -3,13 +3,13 @@ use core::ptr;
use super::THUNK_STACK_ADDR;
#[allow(dead_code)]
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
#[repr(packed)]
pub struct ThunkData {
+ pub es: u16,
pub edi: u32,
pub esi: u32,
pub ebp: u32,
- esp: u32,
pub ebx: u32,
pub edx: u32,
pub ecx: u32,
@@ -19,10 +19,10 @@ pub struct ThunkData {
impl ThunkData {
pub fn new() -> Self {
Self {
+ es: 0,
edi: 0,
esi: 0,
ebp: 0,
- esp: THUNK_STACK_ADDR as u32,
ebx: 0,
edx: 0,
ecx: 0,
@@ -31,11 +31,11 @@ impl ThunkData {
}
pub unsafe fn save(&self) {
- ptr::write((THUNK_STACK_ADDR - 16) as *mut ThunkData, *self);
+ ptr::write((THUNK_STACK_ADDR - 64) as *mut ThunkData, *self);
}
pub unsafe fn load(&mut self) {
- *self = ptr::read((THUNK_STACK_ADDR - 16) as *const ThunkData);
+ *self = ptr::read((THUNK_STACK_ADDR - 64) as *const ThunkData);
}
pub unsafe fn with(&mut self, f: extern "C" fn()) {
--
GitLab