316 lines
4.8 KiB
ArmAsm
316 lines
4.8 KiB
ArmAsm
.global _entry, __bss, __bss_end, __stack_top
|
|
|
|
.section .rodata
|
|
|
|
panic_message: .asciz "\nPanic"
|
|
.equ PANIC_MESSAGE_SIZE, . - panic_message
|
|
|
|
.section .text
|
|
|
|
bzero:
|
|
la t0, __bss
|
|
la t1, __bss_end
|
|
|
|
.Lbzero_loop:
|
|
bgt t0, t1, .Lbzero_end
|
|
sw zero, (t0)
|
|
addi t0, t0, 4
|
|
|
|
.Lbzero_end:
|
|
ret
|
|
|
|
# Maps a page of physical memory to the identical virtual memory.
|
|
#
|
|
# Parameters:
|
|
# a0 - Physical page address.
|
|
# a1 - Free memory page that can be used to create a leaf page table.
|
|
# a2 - Page table level. If a2 is 0 a superpage is allocated, otherwise a normal page.
|
|
#
|
|
# Returns virtual page address in a0.
|
|
.type imem_map_at, @function
|
|
imem_map_at:
|
|
csrr t0, satp
|
|
slli t0, t0, 12 # Root table address.
|
|
|
|
li t1, 0xffc # 10 bit * PTESIZE mask.
|
|
srli t4, a0, 2 # Physical page number.
|
|
|
|
# Multiply VPN[1] by 4 and add to the start address of the page table.
|
|
# This gives the physical address of the page table entry.
|
|
srli t2, a0, 20
|
|
and t2, t2, t1 # VPN[1] * PTESIZE.
|
|
add t2, t0, t2 # a + VPN[1] * PTESIZE.
|
|
|
|
beqz a2, .Limem_map_at_super
|
|
|
|
srli t3, a1, 2
|
|
ori t3, t3, 0b1
|
|
sw t3, (t2)
|
|
|
|
srli t2, a0, 10
|
|
and t2, t2, t1 # VPN[0] * PTESIZE.
|
|
add t2, a1, t2 # a + VPN[0] * PTESIZE.
|
|
|
|
j .Limem_map_at_leaf
|
|
|
|
.Limem_map_at_super:
|
|
# Calculate PPN[1] (10 most significant bits of the physical address
|
|
# and map it to 12 bits of the table page entry.
|
|
li t1, 0xfff00000
|
|
and t4, t4, t1
|
|
|
|
.Limem_map_at_leaf:
|
|
ori t4, t4, 0b1111 # Execute, write, read and valid.
|
|
sw t4, (t2)
|
|
ret
|
|
|
|
# Activates paging and creates root page table.
|
|
# Allocates enough pages for the kernel and its stack.
|
|
#
|
|
# Parameters:
|
|
#
|
|
# a0 - Start (base) address of the kernel.
|
|
# a1 - Page aligned address following the kernel (kernel end).
|
|
.type imem_initialize, @function
|
|
imem_initialize:
|
|
# Prologue.
|
|
addi sp, sp, -32
|
|
sw ra, 28(sp)
|
|
sw s0, 24(sp)
|
|
addi s0, sp, 32
|
|
|
|
li t0, 64 * 1024
|
|
add t0, a1, t0
|
|
sw t0, 20(sp)
|
|
sw a1, 16(sp)
|
|
|
|
srli t0, a1, 12
|
|
csrw satp, t0
|
|
|
|
.Limem_initialize_loop:
|
|
lw t0, 20(sp)
|
|
lw a1, 16(sp)
|
|
|
|
bge a0, t0, .Limem_initialize_activate
|
|
|
|
li t0, 4096
|
|
add a1, a1, t0
|
|
li a2, 1
|
|
call imem_map_at
|
|
|
|
li t0, 4096
|
|
add a0, a0, t0
|
|
|
|
j .Limem_initialize_loop
|
|
|
|
.Limem_initialize_activate:
|
|
csrr t0, satp
|
|
li t1, 0x80000000
|
|
or t0, t0, t1
|
|
|
|
sfence.vma
|
|
csrw satp, t0
|
|
sfence.vma
|
|
|
|
# Epilogue.
|
|
lw ra, 28(sp)
|
|
lw s0, 24(sp)
|
|
addi sp, sp, 32
|
|
ret
|
|
|
|
.type kernel_main, @function
|
|
kernel_main:
|
|
# Prologue.
|
|
addi sp, sp, -32
|
|
sw ra, 28(sp)
|
|
sw s0, 24(sp)
|
|
addi s0, sp, 32
|
|
|
|
sw a0, 20(sp)
|
|
sw a1, 16(sp)
|
|
|
|
la t0, kernel_entry
|
|
csrw stvec, t0
|
|
|
|
# Map flat device tree to the virtual memory.
|
|
lw a0, 16(sp)
|
|
lw a1, 20(sp)
|
|
li a2, 0
|
|
call imem_map_at
|
|
|
|
lw a0, 16(sp)
|
|
call device_tree
|
|
|
|
# Do nothing in a loop.
|
|
.Lkernel_main:
|
|
j .Lkernel_main
|
|
|
|
# Epilogue.
|
|
lw ra, 28(sp)
|
|
lw s0, 24(sp)
|
|
addi sp, sp, 32
|
|
ret
|
|
|
|
.balign 4
|
|
.type kernel_entry, @function
|
|
kernel_entry:
|
|
csrw sscratch, sp
|
|
addi sp, sp, -4 * 31
|
|
|
|
sw ra, 0(sp)
|
|
sw gp, 4(sp)
|
|
sw tp, 8(sp)
|
|
sw t0, 12(sp)
|
|
sw t1, 16(sp)
|
|
sw t2, 20(sp)
|
|
sw t3, 24(sp)
|
|
sw t4, 28(sp)
|
|
sw t5, 32(sp)
|
|
sw t6, 36(sp)
|
|
sw a0, 40(sp)
|
|
sw a1, 44(sp)
|
|
sw a2, 48(sp)
|
|
sw a3, 52(sp)
|
|
sw a4, 56(sp)
|
|
sw a5, 60(sp)
|
|
sw a6, 64(sp)
|
|
sw a7, 68(sp)
|
|
sw s0, 72(sp)
|
|
sw s1, 76(sp)
|
|
sw s2, 80(sp)
|
|
sw s3, 84(sp)
|
|
sw s4, 88(sp)
|
|
sw s5, 92(sp)
|
|
sw s6, 96(sp)
|
|
sw s7, 100(sp)
|
|
sw s8, 104(sp)
|
|
sw s9, 108(sp)
|
|
sw s10, 112(sp)
|
|
sw s11, 116(sp)
|
|
|
|
csrr a0, sscratch
|
|
sw a0, 120(sp)
|
|
|
|
mv a0, sp
|
|
call handle_trap
|
|
|
|
lw ra, 0(sp)
|
|
lw gp, 4(sp)
|
|
lw tp, 8(sp)
|
|
lw t0, 12(sp)
|
|
lw t1, 16(sp)
|
|
lw t2, 20(sp)
|
|
lw t3, 24(sp)
|
|
lw t4, 28(sp)
|
|
lw t5, 32(sp)
|
|
lw t6, 36(sp)
|
|
lw a0, 40(sp)
|
|
lw a1, 44(sp)
|
|
lw a2, 48(sp)
|
|
lw a3, 52(sp)
|
|
lw a4, 56(sp)
|
|
lw a5, 60(sp)
|
|
lw a6, 64(sp)
|
|
lw a7, 68(sp)
|
|
lw s0, 72(sp)
|
|
lw s1, 76(sp)
|
|
lw s2, 80(sp)
|
|
lw s3, 84(sp)
|
|
lw s4, 88(sp)
|
|
lw s5, 92(sp)
|
|
lw s6, 96(sp)
|
|
lw s7, 100(sp)
|
|
lw s8, 104(sp)
|
|
lw s9, 108(sp)
|
|
lw s10, 112(sp)
|
|
lw s11, 116(sp)
|
|
lw sp, 120(sp)
|
|
|
|
sret
|
|
|
|
.type handle_trap, @function
|
|
handle_trap:
|
|
# Prologue.
|
|
addi sp, sp, -32
|
|
sw ra, 28(sp)
|
|
sw s0, 24(sp)
|
|
addi s0, sp, 32
|
|
|
|
csrr t0, scause
|
|
csrr t1, stval
|
|
csrr t2, sepc
|
|
|
|
li a1, PANIC_MESSAGE_SIZE
|
|
la a0, panic_message
|
|
call write_s
|
|
|
|
li a0, ' '
|
|
call write_c
|
|
|
|
csrr a0, scause
|
|
la a1, write_c
|
|
call print_i
|
|
|
|
call separator
|
|
call write_c
|
|
|
|
csrr a0, stval
|
|
la a1, write_c
|
|
call print_i
|
|
|
|
call separator
|
|
call write_c
|
|
|
|
csrr a0, sepc
|
|
la a1, write_c
|
|
call print_i
|
|
|
|
call panic
|
|
|
|
# Epilogue.
|
|
lw ra, 28(sp)
|
|
lw s0, 24(sp)
|
|
addi sp, sp, 32
|
|
ret
|
|
|
|
.type panic, @function
|
|
panic:
|
|
# Prologue.
|
|
addi sp, sp, -32
|
|
sw ra, 28(sp)
|
|
sw s0, 24(sp)
|
|
addi s0, sp, 32
|
|
|
|
li a0, '\n'
|
|
call write_c
|
|
.Lpanic:
|
|
j .Lpanic
|
|
|
|
# Epilogue.
|
|
lw ra, 28(sp)
|
|
lw s0, 24(sp)
|
|
addi sp, sp, 32
|
|
ret
|
|
|
|
.section .text.boot
|
|
_entry:
|
|
# Set the stack pointer.
|
|
la t0, end
|
|
li t1, 64 * 1024
|
|
add sp, t0, t1
|
|
|
|
mv s1, a1
|
|
|
|
la a0, .text.boot
|
|
mv a1, sp
|
|
call imem_initialize
|
|
|
|
lw t0, (end)
|
|
la t1, next_paddr
|
|
sw t0, (t1)
|
|
|
|
call bzero
|
|
mv a0, sp
|
|
mv a1, s1
|
|
j kernel_main
|