Move kernel_main into the elna code

arch/riscv/common.s

@@ -4,6 +4,11 @@
 
 .include "./arch/riscv/constants.s"
 
+.section .data
+
+.globl pmem_address
+pmem_address: .word
+
 .section .text
 
 # a0 - First pointer.
@@ -245,9 +250,8 @@ memset:
 # Parameters:
 # a0 - Corresponding virtual address.
 # a1 - Physical page address.
-# a2 - Free memory page that can be used to create a leaf page table.
-# a3 - Page table level. If a3 is 0 a superpage is allocated, otherwise a normal page.
-# a4 - Flags.
+# a2 - Page table level. If a2 is 0 a superpage is allocated, otherwise a normal page.
+# a3 - Flags.
 #
 # If the function creates new page tables in a2, it advances a2 by the page size and
 # returns it in a0.
@@ -268,7 +272,7 @@ pmem_map_at:
 	and t2, t2, t5 # VPN[i] * PTESIZE.
 	add t2, t0, t2 # a + VPN[i] * PTESIZE.
 
-	beqz a3, .Lpmem_map_at_leaf
+	beqz a2, .Lpmem_map_at_leaf
 
 	lw t3, (t2)
 	andi t6, t3, 0b1
@@ -281,27 +285,29 @@ pmem_map_at:
 	j .Lpmem_map_at_next
 
 .Lpmem_map_at_create:
+	la a7, pmem_address
 	# Take a chunk of free memory and use it as the next page table.
 	# The beginning addres off the chunk is the base address (a) for the next level.
-	mv t0, a2
+	lw t0, (a7)
 	srli t3, t0, 2
 	ori t3, t3, 0b1
 	sw t3, (t2)
 
 	li t6, PAGE_SIZE
-	add a2, a2, t6
+	add t0, t0, t6
+	sw t0, (a7)
 
 .Lpmem_map_at_next:
 	# Calculate the next page table address for the next level.
 	addi t1, t1, -10
-	addi a3, a3, -1
+	addi a2, a2, -1
 
 	j .Lpmem_map_at_loop
 
 .Lpmem_map_at_leaf:
 	srli t3, a1, 2 # Physical page number mapped to 12 bits of the page table entry.
-	ori a4, a4, 0b1
-	or t3, t3, a4 # Execute, write, read and valid.
+	ori a3, a3, 0b1
+	or t3, t3, a3 # Execute, write, read and valid.
 	sw t3, (t2)
 
 	mv a0, a2