Added EL3 handling code (untested)

0F_executionlevel/OLVASSEL.md

@@ -13,6 +13,8 @@ Exception return from AArch64 EL2 to AArch64 EL1 PC 0x8004c
 Current EL is: 00000001
 ```
 
+FIGYELEM: a teljesség kedvéért hozzáadtam az EL3-at is az Issue #6 miatt, bár semmilyen módon nem tudtam kipróbálni.
+
 Start
 -----
 

0F_executionlevel/README.md

@@ -12,6 +12,8 @@ Exception return from AArch64 EL2 to AArch64 EL1 PC 0x8004c
 Current EL is: 00000001
 ```
 
+NOTE: For completeness, I've added code for EL3 too because of Issue #6, although I had no means to test it.
+
 Start
 -----
 

0F_executionlevel/main.c

@@ -36,7 +36,7 @@ void main()
     asm volatile ("mrs %0, CurrentEL" : "=r" (el));
 
     uart_puts("Current EL is: ");
-    uart_hex(el>>2);
+    uart_hex((el>>2)&3);
     uart_puts("\n");
 
     // echo everything back

0F_executionlevel/start.S

@@ -42,7 +42,22 @@ _start:
 
     // set up EL1
     mrs     x0, CurrentEL
-    cmp     x0, #4
+    and     x0, x0, #12 // clear reserved bits
+
+    // running at EL3?
+    cmp     x0, #12
+    bne     5f
+    // should never be executed, just for completeness
+    mov     x2, #0x5b1
+    msr     scr_el3, x2
+    mov     x2, #0x3c9
+    msr     spsr_el3, x2
+    adr     x2, 5f
+    msr     elr_el3, x2
+    eret
+
+    // running at EL2?
+5:  cmp     x0, #4
     beq     5f
     msr     sp_el1, x1
     // enable CNTP for EL1

10_virtualmemory/start.S

@@ -42,7 +42,22 @@ _start:
 
     // set up EL1
     mrs     x0, CurrentEL
-    cmp     x0, #4
+    and     x0, x0, #12 // clear reserved bits
+
+    // running at EL3?
+    cmp     x0, #12
+    bne     5f
+    // should never be executed, just for completeness
+    mov     x2, #0x5b1
+    msr     scr_el3, x2
+    mov     x2, #0x3c9
+    msr     spsr_el3, x2
+    adr     x2, 5f
+    msr     elr_el3, x2
+    eret
+
+    // running at EL2?
+5:  cmp     x0, #4
     beq     5f
     msr     sp_el1, x1
     // enable CNTP for EL1

11_exceptions/start.S

@@ -42,7 +42,22 @@ _start:
 
     // set up EL1
     mrs     x0, CurrentEL
-    cmp     x0, #4
+    and     x0, x0, #12 // clear reserved bits
+
+    // running at EL3?
+    cmp     x0, #12
+    bne     5f
+    // should never be executed, just for completeness
+    mov     x2, #0x5b1
+    msr     scr_el3, x2
+    mov     x2, #0x3c9
+    msr     spsr_el3, x2
+    adr     x2, 5f
+    msr     elr_el3, x2
+    eret
+
+    // running at EL2?
+5:  cmp     x0, #4
     beq     5f
     msr     sp_el1, x1
     // enable CNTP for EL1