From c00e76f35e78329c0aa01e90a7766b457dcc4e66 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Mon, 3 May 2021 14:25:39 +0200
Subject: Fixed TSS

---
 kernel/drivers/gdt.c        | 9 +++------
 kernel/drivers/interrupts.c | 3 +--
 kernel/features/proc.c      | 4 ++--
 kernel/inc/gdt.h            | 2 +-
 4 files changed, 7 insertions(+), 11 deletions(-)

(limited to 'kernel')

diff --git a/kernel/drivers/gdt.c b/kernel/drivers/gdt.c
index 3e7da94..0e8086f 100644
--- a/kernel/drivers/gdt.c
+++ b/kernel/drivers/gdt.c
@@ -41,11 +41,10 @@ CLEAR static void gdt_set_gate(u32 num, u32 base, u32 limit, u8 access, u8 gran)
 	gdt[num].access = access;
 }
 
-// TODO: Fix GPF for in/out operations in userspace (not necessarily a TSS problem)
 CLEAR static void tss_write(u32 num, u16 ss0, u32 esp0)
 {
 	u32 base = (u32)&tss;
-	u32 limit = base + sizeof(tss);
+	u32 limit = sizeof(tss) - 1;
 
 	gdt_set_gate(num, base, limit, GDT_PRESENT | GDT_RING3 | GDT_EXECUTABLE | GDT_ACCESSED,
 		     GDT_SIZE);
@@ -56,7 +55,7 @@ CLEAR static void tss_write(u32 num, u16 ss0, u32 esp0)
 	tss.esp0 = esp0;
 	tss.cs = GDT_SUPER_CODE_OFFSET | 3;
 	tss.ss = tss.ds = tss.es = tss.fs = tss.gs = GDT_SUPER_DATA_OFFSET | 3;
-	tss.iomap_base = U16_MAX;
+	tss.iomap_base = sizeof(tss);
 }
 
 CLEAR static void tss_flush(void)
@@ -69,11 +68,9 @@ CLEAR static void gdt_flush(void)
 	__asm__ volatile("lgdt %0" ::"m"(gp) : "memory");
 }
 
-void tss_set_stack(u32 ss, u32 esp)
+void tss_set_stack(u32 esp)
 {
-	assert(ss && esp);
 	tss.esp0 = esp;
-	tss.ss0 = ss;
 }
 
 CLEAR void gdt_install(u32 esp)
diff --git a/kernel/drivers/interrupts.c b/kernel/drivers/interrupts.c
index 7a57a91..92971e4 100644
--- a/kernel/drivers/interrupts.c
+++ b/kernel/drivers/interrupts.c
@@ -15,8 +15,7 @@
  * IDT
  */
 
-// TODO: Why does PROTECTED on idt only work when debug mode is disabled? File size?
-static struct idt_entry idt[256] = { 0 };
+PROTECTED static struct idt_entry idt[256] = { 0 };
 PROTECTED static struct idt_ptr idt_ptr = { 0 };
 
 CLEAR void idt_set_gate(u8 num, u32 base, u16 sel, u8 flags)
diff --git a/kernel/features/proc.c b/kernel/features/proc.c
index 3039231..3dd8114 100644
--- a/kernel/features/proc.c
+++ b/kernel/features/proc.c
@@ -54,7 +54,7 @@ HOT FLATTEN void scheduler(struct regs *regs)
 		current = idle_proc;
 	}
 
-	tss_set_stack(GDT_SUPER_DATA_OFFSET, PROC(current)->stack.kernel);
+	tss_set_stack(PROC(current)->stack.kernel);
 	memory_switch_dir(PROC(current)->page_dir);
 	memcpy(regs, &PROC(current)->regs, sizeof(*regs));
 
@@ -369,7 +369,7 @@ NORETURN void proc_init(void)
 	// We'll shortly jump to usermode. Clear and protect every secret!
 	memory_user_hook();
 
-	tss_set_stack(GDT_SUPER_DATA_OFFSET, init->stack.kernel);
+	tss_set_stack(init->stack.kernel);
 	memory_switch_dir(init->page_dir);
 	printf("Jumping to userspace!\n");
 
diff --git a/kernel/inc/gdt.h b/kernel/inc/gdt.h
index 9de0ad3..7b9c65a 100644
--- a/kernel/inc/gdt.h
+++ b/kernel/inc/gdt.h
@@ -63,6 +63,6 @@ struct tss_entry {
 
 CONST u8 gdt_offset(u8 gate);
 void gdt_install(u32 esp);
-void tss_set_stack(u32 ss, u32 esp);
+void tss_set_stack(u32 esp);
 
 #endif
-- 
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