diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index 046b44225623..e32d75fef068 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -707,8 +707,17 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
  * 63–48 all equal to bit 47, or else a page-fault exception will occur."
  */
 #ifdef CONFIG_64BIT
-#define TASK_SIZE      (PGDIR_SIZE * PTRS_PER_PGD / 2)
-#define TASK_SIZE_MIN  (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
+#define TASK_SIZE_64	(PGDIR_SIZE * PTRS_PER_PGD / 2)
+#define TASK_SIZE_MIN	(PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
+
+#ifdef CONFIG_COMPAT
+#define TASK_SIZE_32	(_AC(0x80000000, UL) - PAGE_SIZE)
+#define TASK_SIZE	(test_thread_flag(TIF_32BIT) ? \
+			 TASK_SIZE_32 : TASK_SIZE_64)
+#else
+#define TASK_SIZE	TASK_SIZE_64
+#endif
+
 #else
 #define TASK_SIZE	FIXADDR_START
 #define TASK_SIZE_MIN	TASK_SIZE
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 0749924d9e55..21c8072dce17 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -19,7 +19,11 @@
 #define TASK_UNMAPPED_BASE	PAGE_ALIGN(TASK_SIZE / 3)
 
 #define STACK_TOP		TASK_SIZE
-#define STACK_TOP_MAX		STACK_TOP
+#ifdef CONFIG_64BIT
+#define STACK_TOP_MAX		TASK_SIZE_64
+#else
+#define STACK_TOP_MAX		TASK_SIZE
+#endif
 #define STACK_ALIGN		16
 
 #ifndef __ASSEMBLY__