diff --git a/lib/proc.c b/lib/proc.c
index 66bca67..a55c8d6 100644
--- a/lib/proc.c
+++ b/lib/proc.c
@@ -2,20 +2,7 @@
 
 struct Cpu cpus[NCPU];
 
-/**
- * Must be called with interrupts disabled, to prevent race with process being
- * moved to a different CPU.
- */
-int cpuid() {
-    int id = read_tp();
-    return id;
-}
-
 /**
  * Return this CPU's cpu struct. Interrupts must be disabled.
  */
-struct Cpu *mycpu(void) {
-    int         id = cpuid();
-    struct Cpu *c = &cpus[id];
-    return c;
-}
+inline struct Cpu *mycpu(void) { return &cpus[read_tp()]; }
diff --git a/lib/spinlock.c b/lib/spinlock.c
index 6b1d89f..5277a8b 100644
--- a/lib/spinlock.c
+++ b/lib/spinlock.c
@@ -4,12 +4,10 @@
  */
 
 // #include <lib/stdio.h>
-#include "string.h"
 #include <panic.h>
 #include <proc.h>
 #include <riscv.h>
 #include <spinlock.h>
-#include <uart.h>
 
 /**
  * The aquire() and release() functions control ownership of the lock.
@@ -101,7 +99,6 @@ void push_off(void) {
     intr_off();
     if (mycpu()->noff == 0)
         mycpu()->intena = old;
-
     mycpu()->noff += 1;
 }
 
@@ -109,15 +106,8 @@ void pop_off(void) {
     struct Cpu *c = mycpu();
     if (intr_get())
         panic("pop_off - interruptible");
-    if (c->noff < 1) {
-        {
-            // TODO: Remove this block when fixed
-            char amt[100];
-            itoa(c->noff, amt, 10);
-            uart_puts(amt);
-        }
+    if (c->noff < 1)
         panic("pop_off");
-    }
     c->noff -= 1;
     if (c->noff == 0 && c->intena)
         intr_on();
diff --git a/riscv.h b/riscv.h
index d56bdce..3114b79 100644
--- a/riscv.h
+++ b/riscv.h
@@ -24,13 +24,51 @@ typedef u64 pte_t;
 /** Page Table Type */
 typedef u64 *pagetable_t; // 512 PTEs
 
-/** Returns the current hart id */
-static inline u64 read_mhartid() {
-    u64 x;
-    asm volatile("csrr %0, mhartid" : "=r"(x));
-    return x;
+// CSR numeric addresses
+#define CSR_MSTATUS    0x300
+#define CSR_MISA       0x301
+#define CSR_MIE        0x304
+#define CSR_MTVEC      0x305
+#define CSR_MCOUNTEREN 0x306
+
+#define CSR_MSCRATCH 0x340
+#define CSR_MEPC     0x341
+#define CSR_MCAUSE   0x342
+#define CSR_MTVAL    0x343
+#define CSR_MIP      0x344
+
+#define CSR_MHARTID 0xF14
+
+static inline u64 read_csr(u32 csr) {
+    u64 value;
+    asm volatile("csrr %0, %1" : "=r"(value) : "i"(csr));
+    return value;
 }
 
+static inline void write_csr(u32 csr, u64 value) {
+    asm volatile("csrw %0, %1" ::"i"(csr), "r"(value));
+}
+
+static inline u64  read_mstatus(void) { return read_csr(CSR_MSTATUS); }
+static inline void write_mstatus(u64 val) { write_csr(CSR_MSTATUS, val); }
+
+static inline u64  read_mcause(void) { return read_csr(CSR_MCAUSE); }
+static inline u64  read_mtval(void) { return read_csr(CSR_MTVAL); }
+static inline u64  read_mepc(void) { return read_csr(CSR_MEPC); }
+static inline void write_mepc(u64 val) { write_csr(CSR_MEPC, val); }
+
+static inline void write_mtvec(u64 val) { write_csr(CSR_MTVEC, val); }
+static inline u64  read_mtvec(void) { return read_csr(CSR_MTVEC); }
+
+/** Returns the current hart id */
+static inline u64 read_mhartid(void) { return read_csr(CSR_MHARTID); }
+
+// static inline u64 r_mhartid() {
+//     u64 x;
+//     asm volatile("csrr %0, mhartid" : "=r"(x));
+//     return x;
+// }
+
 /** Read thread pointer */
 static inline u64 read_tp() {
     u64 x;