diff --git a/arch/risc-v/src/common/riscv_percpu.c b/arch/risc-v/src/common/riscv_percpu.c
index 13072ff8cd..a74d114c35 100644
--- a/arch/risc-v/src/common/riscv_percpu.c
+++ b/arch/risc-v/src/common/riscv_percpu.c
@@ -42,10 +42,16 @@
 
 #define HART_CNT    (CONFIG_SMP_NCPUS)
 
+static_assert(RISCV_PERCPU_TCB == offsetof(riscv_percpu_t, tcb),
+              "RISCV_PERCPU_TCB offset is wrong");
 static_assert(RISCV_PERCPU_HARTID == offsetof(riscv_percpu_t, hartid),
               "RISCV_PERCPU_HARTID offset is wrong");
 static_assert(RISCV_PERCPU_IRQSTACK == offsetof(riscv_percpu_t, irq_stack),
               "RISCV_PERCPU_IRQSTACK offset is wrong");
+static_assert(RISCV_PERCPU_USP == offsetof(riscv_percpu_t, usp),
+              "RISCV_PERCPU_USP offset is wrong");
+static_assert(RISCV_PERCPU_KSP == offsetof(riscv_percpu_t, ksp),
+              "RISCV_PERCPU_KSP offset is wrong");
 
 /****************************************************************************
  * Private Data
@@ -223,3 +229,35 @@ void riscv_percpu_set_kstack(uintptr_t ksp)
   ((riscv_percpu_t *)scratch)->ksp = ksp;
   leave_critical_section(flags);
 }
+
+/****************************************************************************
+ * Name: riscv_percpu_set_thread
+ *
+ * Description:
+ *   Set current thread (tcb), so it can be found quickly when a trap is
+ *   taken.
+ *
+ * Input Parameters:
+ *   tcb - Pointer to the current thread's tcb
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void riscv_percpu_set_thread(struct tcb_s *tcb)
+{
+  irqstate_t flags;
+  uintptr_t scratch;
+
+  /* This must be done with interrupts disabled */
+
+  flags   = enter_critical_section();
+  scratch = READ_CSR(CSR_SCRATCH);
+
+  DEBUGASSERT(scratch >= (uintptr_t) &g_percpu &&
+              scratch <  (uintptr_t) &g_percpu + sizeof(g_percpu));
+
+  ((riscv_percpu_t *)scratch)->tcb = tcb;
+  leave_critical_section(flags);
+}
diff --git a/arch/risc-v/src/common/riscv_percpu.h b/arch/risc-v/src/common/riscv_percpu.h
index cc09fe0b24..147e6c143d 100644
--- a/arch/risc-v/src/common/riscv_percpu.h
+++ b/arch/risc-v/src/common/riscv_percpu.h
@@ -47,7 +47,7 @@
  * 2: REGLOAD a0, RISCV_PERCPU_HARTID(a0)
  */
 
-#define RISCV_PERCPU_LIST       (0 * INT_REG_SIZE)
+#define RISCV_PERCPU_TCB        (0 * INT_REG_SIZE)
 #define RISCV_PERCPU_HARTID     (1 * INT_REG_SIZE)
 #define RISCV_PERCPU_IRQSTACK   (2 * INT_REG_SIZE)
 #define RISCV_PERCPU_USP        (3 * INT_REG_SIZE)
@@ -65,16 +65,20 @@
  * will set up [m/s]scratch to point to the CPUs own area
  */
 
-struct riscv_percpu_s
+union riscv_percpu_s
 {
-  struct riscv_percpu_s *next;      /* For sl list linkage */
-  uintptr_t              hartid;    /* Hart ID */
-  uintptr_t              irq_stack; /* Interrupt stack */
-  uintptr_t              usp;       /* Area to store user sp */
-  uintptr_t              ksp;       /* Area to load kernel sp */
+  union riscv_percpu_s *next;      /* For sl list linkage */
+  struct
+  {
+    struct tcb_s       *tcb;       /* Current thread TCB */
+    uintptr_t           hartid;    /* Hart ID */
+    uintptr_t           irq_stack; /* Interrupt stack */
+    uintptr_t           usp;       /* Area to store user sp */
+    uintptr_t           ksp;       /* Area to load kernel sp */
+  };
 };
 
-typedef struct riscv_percpu_s riscv_percpu_t;
+typedef union riscv_percpu_s riscv_percpu_t;
 
 /****************************************************************************
  * Public Function Prototypes
@@ -137,5 +141,22 @@ uintptr_t riscv_percpu_get_irqstack(void);
 
 void riscv_percpu_set_kstack(uintptr_t ksp);
 
+/****************************************************************************
+ * Name: riscv_percpu_set_thread
+ *
+ * Description:
+ *   Set current thread (tcb), so it can be found quickly when a trap is
+ *   taken.
+ *
+ * Input Parameters:
+ *   tcb - Pointer to the current thread's tcb
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void riscv_percpu_set_thread(struct tcb_s *tcb);
+
 #endif /* __ASSEMBLY__ */
 #endif /* __ARCH_RISC_V_SRC_COMMON_RISCV_PERCPU_H */