TempleOSCDV4.11.ISO

Demo/Lectures/Ring3.HC

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+/*TempleOS runs exclusively in ring 0.
+Ring 0 is part of the $LK,"Charter",A="FI:::/Doc/Charter.DD"$.
+This demo is for you to play around
+with ring 3.  TempleOS is for
+recreational programming, after all.
+
+This redirects the general protection
+fault, switches to ring 3, and generates
+a fault to switch back.
+*/
+
+U8 *old_stk,*new_rip;
+
+asm {
+INT_TO_RING0::	//Set to handle general protection 0xD fault temporarily.
+	INC	U64 [SYS_PROGRESS1]
+	PUSH	U32 CGDT.ds	//STKSEG
+	MOV	RAX,U64 [&old_stk]
+	PUSH	RAX
+	PUSH	U32 0		//FLAGS--interrupts off
+	PUSH	U32 CGDT.cs64
+	MOV	RAX,U64 [&new_rip]
+	PUSH	RAX
+	IRET
+}
+
+U0 Ring3Demo()
+{
+  U8 *old_vect;
+  "Progress1 Before:%X\n",progress1;
+  CLI
+  old_vect=IntEntrySet(0x0D,INT_TO_RING0,IDTET_TRAP,0);
+
+  TSSBusy(Gs->tss->tr_ring3,OFF);
+  SetRAX(Gs->tss->tr_ring3+3);
+  LTR	AX
+
+  asm {
+    MOV	U64 [&old_stk],RSP
+
+    LEA	RAX,[R3_CALLBACK]
+    MOV	U64 [&new_rip],RAX
+
+    MOV	AX,CGDT.ds_ring3+3
+    MOV	DS,AX
+    MOV	ES,AX
+
+    PUSH	U32 CGDT.ds_ring3+3	//STKSEG
+    PUSH	U64 [&old_stk]
+    PUSH	U32 0		//FLAGS--interrupts off
+    PUSH	U32 CGDT.cs64_ring3+3
+    LEA	RAX,[R3_START]
+    PUSH	RAX
+    IRET
+
+    R3_START:
+    INC	U64 [SYS_PROGRESS1]
+    CLI	//This causes general protection fault #13
+
+    R3_CALLBACK:
+    MOV	AX,CGDT.ds
+    MOV	DS,AX
+    MOV	ES,AX
+  }
+
+  TSSBusy(Gs->tss->tr,OFF);
+  SetRAX(Gs->tss->tr);
+  LTR	AX
+
+  IntEntrySet(0x0D,old_vect,IDTET_IRQ,0);
+  STI
+  "Progress1 After :%X\n",progress1;
+}
+
+Ring3Demo;