Fix stack alignment problem for MIPS N32 ABI, and fix alignment problem in CharAttribute

Signed-off-by: Harry Chen <i@harrychen.xyz>

kernel/src/arch/mipsel/boot/context.S

@@ -11,7 +11,7 @@
 
 switch_context:
 	// save from's registers
-	addi  sp, sp, (-4*14)
+	addi  sp, sp, (-4*16)
 	sw sp, 0(a0)
 	sw ra, 0(sp)
 	sw s0, 4*4(sp)
@@ -60,7 +60,7 @@ switch_context:
 	lw s7, 11*4(sp)
 	lw s8, 12*4(sp)
 	lw gp, 13*4(sp)
-	addi sp, sp, (4*14)
+	addi sp, sp, (4*16)
 
 	sw zero, 0(a1)
 	jr ra

kernel/src/arch/mipsel/boot/trap.S

@@ -32,8 +32,8 @@ trap_from_kernel:
 	 *  k1 = old stack pointer
 	 *  sp = kernel stack */
 	
-	# allocate 38 words for trapframe + 4 extra words
-	addiu sp, sp, -168
+	# allocate 38 words for trapframe + 6 extra words
+	addiu sp, sp, -176
 
 	# save general registers
 	sw ra, 160(sp)
@@ -149,7 +149,7 @@ trap_return:
 
 	// save kernel stack
 	la k0, _cur_kstack_ptr
-	addiu k1, sp, 168
+	addiu k1, sp, 176
 	sw k1, 0(k0)
 	nop
 

kernel/src/arch/mipsel/context.rs

@@ -52,6 +52,7 @@ pub struct TrapFrame {
     pub ra: usize,
     /// Reserved
     pub reserved: usize,
+    pub __padding: [usize; 2],
 }
 
 impl TrapFrame {
@@ -135,6 +136,7 @@ struct ContextData {
     /// s[1] = reserved
     /// s[2..11] = Callee-saved registers
     s: [usize; 12],
+    __padding: [usize; 2],
 }
 
 impl ContextData {

kernel/src/drivers/console/mod.rs

@@ -19,6 +19,7 @@ mod color;
 mod fonts;
 
 #[derive(Debug, Clone, Copy, PartialEq)]
+#[repr(align(4))]
 pub struct ConsoleChar {
     ascii_char: u8,
     attr: CharacterAttribute,

kernel/src/util/escape_parser.rs

@@ -9,6 +9,7 @@ use heapless::Vec;
 
 
 #[derive(Debug, Clone, Copy, PartialEq)]
+#[repr(align(4))]
 pub struct CharacterAttribute {
     /// foreground color
     pub foreground: ConsoleColor,