diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h
index 461322b473b5..230b830e94d4 100644
--- a/arch/tile/include/asm/processor.h
+++ b/arch/tile/include/asm/processor.h
@@ -148,9 +148,10 @@ struct thread_struct {
 
 /*
  * Start with "sp" this many bytes below the top of the kernel stack.
- * This preserves the invariant that a called function may write to *sp.
+ * This allows us to be cache-aware when handling the initial save
+ * of the pt_regs value to the stack.
  */
-#define STACK_TOP_DELTA 8
+#define STACK_TOP_DELTA 64
 
 /*
  * When entering the kernel via a fault, start with the top of the
@@ -234,15 +235,15 @@ extern int do_work_pending(struct pt_regs *regs, u32 flags);
 unsigned long get_wchan(struct task_struct *p);
 
 /* Return initial ksp value for given task. */
-#define task_ksp0(task) ((unsigned long)(task)->stack + THREAD_SIZE)
+#define task_ksp0(task) \
+	((unsigned long)(task)->stack + THREAD_SIZE - STACK_TOP_DELTA)
 
 /* Return some info about the user process TASK. */
-#define KSTK_TOP(task)	(task_ksp0(task) - STACK_TOP_DELTA)
 #define task_pt_regs(task) \
-  ((struct pt_regs *)(task_ksp0(task) - KSTK_PTREGS_GAP) - 1)
+	((struct pt_regs *)(task_ksp0(task) - KSTK_PTREGS_GAP) - 1)
 #define current_pt_regs()                                   \
-  ((struct pt_regs *)((stack_pointer | (THREAD_SIZE - 1)) - \
-                      (KSTK_PTREGS_GAP - 1)) - 1)
+	((struct pt_regs *)((stack_pointer | (THREAD_SIZE - 1)) - \
+			    STACK_TOP_DELTA - (KSTK_PTREGS_GAP - 1)) - 1)
 #define task_sp(task)	(task_pt_regs(task)->sp)
 #define task_pc(task)	(task_pt_regs(task)->pc)
 /* Aliases for pc and sp (used in fs/proc/array.c) */
@@ -355,20 +356,38 @@ extern int kdata_huge;
 #define KERNEL_PL CONFIG_KERNEL_PL
 
 /* SYSTEM_SAVE_K_0 holds the current cpu number ORed with ksp0. */
-#define CPU_LOG_MASK_VALUE 12
-#define CPU_MASK_VALUE ((1 << CPU_LOG_MASK_VALUE) - 1)
-#if CONFIG_NR_CPUS > CPU_MASK_VALUE
-# error Too many cpus!
+#ifdef __tilegx__
+#define CPU_SHIFT 48
+#if CHIP_VA_WIDTH() > CPU_SHIFT
+# error Too many VA bits!
 #endif
+#define MAX_CPU_ID ((1 << (64 - CPU_SHIFT)) - 1)
 #define raw_smp_processor_id() \
-	((int)__insn_mfspr(SPR_SYSTEM_SAVE_K_0) & CPU_MASK_VALUE)
+	((int)(__insn_mfspr(SPR_SYSTEM_SAVE_K_0) >> CPU_SHIFT))
 #define get_current_ksp0() \
-	(__insn_mfspr(SPR_SYSTEM_SAVE_K_0) & ~CPU_MASK_VALUE)
+	((unsigned long)(((long)__insn_mfspr(SPR_SYSTEM_SAVE_K_0) << \
+			  (64 - CPU_SHIFT)) >> (64 - CPU_SHIFT)))
+#define next_current_ksp0(task) ({ \
+	unsigned long __ksp0 = task_ksp0(task) & ((1UL << CPU_SHIFT) - 1); \
+	unsigned long __cpu = (long)raw_smp_processor_id() << CPU_SHIFT; \
+	__ksp0 | __cpu; \
+})
+#else
+#define LOG2_NR_CPU_IDS 6
+#define MAX_CPU_ID ((1 << LOG2_NR_CPU_IDS) - 1)
+#define raw_smp_processor_id() \
+	((int)__insn_mfspr(SPR_SYSTEM_SAVE_K_0) & MAX_CPU_ID)
+#define get_current_ksp0() \
+	(__insn_mfspr(SPR_SYSTEM_SAVE_K_0) & ~MAX_CPU_ID)
 #define next_current_ksp0(task) ({ \
 	unsigned long __ksp0 = task_ksp0(task); \
 	int __cpu = raw_smp_processor_id(); \
-	BUG_ON(__ksp0 & CPU_MASK_VALUE); \
+	BUG_ON(__ksp0 & MAX_CPU_ID); \
 	__ksp0 | __cpu; \
 })
+#endif
+#if CONFIG_NR_CPUS > (MAX_CPU_ID + 1)
+# error Too many cpus!
+#endif
 
 #endif /* _ASM_TILE_PROCESSOR_H */
diff --git a/arch/tile/kernel/head_32.S b/arch/tile/kernel/head_32.S
index d1527fce2861..f3f17b0283ff 100644
--- a/arch/tile/kernel/head_32.S
+++ b/arch/tile/kernel/head_32.S
@@ -86,7 +86,7 @@ ENTRY(_start)
 	/*
 	 * Load up our per-cpu offset.  When the first (master) tile
 	 * boots, this value is still zero, so we will load boot_pc
-	 * with start_kernel, and boot_sp with init_stack + THREAD_SIZE.
+	 * with start_kernel, and boot_sp at the top of init_stack.
 	 * The master tile initializes the per-cpu offset array, so that
 	 * when subsequent (secondary) tiles boot, they will instead load
 	 * from their per-cpu versions of boot_sp and boot_pc.
@@ -126,7 +126,6 @@ ENTRY(_start)
 	lw sp, r1
 	or r4, sp, r4
 	mtspr SPR_SYSTEM_SAVE_K_0, r4  /* save ksp0 + cpu */
-	addi sp, sp, -STACK_TOP_DELTA
 	{
 	  move lr, zero   /* stop backtraces in the called function */
 	  jr r0
diff --git a/arch/tile/kernel/head_64.S b/arch/tile/kernel/head_64.S
index 969e4f81f3b3..652b81426158 100644
--- a/arch/tile/kernel/head_64.S
+++ b/arch/tile/kernel/head_64.S
@@ -158,7 +158,7 @@ ENTRY(_start)
 	/*
 	 * Load up our per-cpu offset.  When the first (master) tile
 	 * boots, this value is still zero, so we will load boot_pc
-	 * with start_kernel, and boot_sp with init_stack + THREAD_SIZE.
+	 * with start_kernel, and boot_sp with at the top of init_stack.
 	 * The master tile initializes the per-cpu offset array, so that
 	 * when subsequent (secondary) tiles boot, they will instead load
 	 * from their per-cpu versions of boot_sp and boot_pc.
@@ -202,9 +202,9 @@ ENTRY(_start)
 	}
 	ld r0, r0
 	ld sp, r1
-	or r4, sp, r4
+	shli r4, r4, CPU_SHIFT
+	bfins r4, sp, 0, CPU_SHIFT-1
 	mtspr SPR_SYSTEM_SAVE_K_0, r4  /* save ksp0 + cpu */
-	addi sp, sp, -STACK_TOP_DELTA
 	{
 	  move lr, zero   /* stop backtraces in the called function */
 	  jr r0
diff --git a/arch/tile/kernel/intvec_32.S b/arch/tile/kernel/intvec_32.S
index 9c0c3cb6aab0..f3d26f48e659 100644
--- a/arch/tile/kernel/intvec_32.S
+++ b/arch/tile/kernel/intvec_32.S
@@ -185,7 +185,7 @@ intvec_\vecname:
 	 * point sp at the top aligned address on the actual stack page.
 	 */
 	mfspr   r0, SPR_SYSTEM_SAVE_K_0
-	mm      r0, r0, zero, LOG2_THREAD_SIZE, 31
+	mm      r0, r0, zero, LOG2_NR_CPU_IDS, 31
 
 0:
 	/*
@@ -203,6 +203,9 @@ intvec_\vecname:
 	 *    cache line 1: r14...r29
 	 *    cache line 0: 2 x frame, r0..r13
 	 */
+#if STACK_TOP_DELTA != 64
+#error STACK_TOP_DELTA must be 64 for assumptions here and in task_pt_regs()
+#endif
 	andi    r0, r0, -64
 
 	/*
@@ -464,7 +467,7 @@ intvec_\vecname:
 	}
 	{
 	 auli   r21, r21, ha16(__per_cpu_offset)
-	 mm     r20, r20, zero, 0, LOG2_THREAD_SIZE-1
+	 mm     r20, r20, zero, 0, LOG2_NR_CPU_IDS-1
 	}
 	s2a     r20, r20, r21
 	lw      tp, r20
diff --git a/arch/tile/kernel/intvec_64.S b/arch/tile/kernel/intvec_64.S
index df19d4f3946e..3b35bb490d3e 100644
--- a/arch/tile/kernel/intvec_64.S
+++ b/arch/tile/kernel/intvec_64.S
@@ -132,13 +132,9 @@ intvec_\vecname:
 	mfspr   r3, SPR_SYSTEM_SAVE_K_0
 
 	/* Get &thread_info->unalign_jit_tmp[0] in r3. */
+	bfexts  r3, r3, 0, CPU_SHIFT-1
 	mm      r3, zero, LOG2_THREAD_SIZE, 63
-#if THREAD_SIZE < 65536
-	addli   r3, r3, -(PAGE_SIZE - THREAD_INFO_UNALIGN_JIT_TMP_OFFSET)
-#else
-	addli   r3, r3, -(PAGE_SIZE/2)
-	addli   r3, r3, -(PAGE_SIZE/2 - THREAD_INFO_UNALIGN_JIT_TMP_OFFSET)
-#endif
+	addli   r3, r3, THREAD_INFO_UNALIGN_JIT_TMP_OFFSET
 
 	/*
 	 * Save r0, r1, r2 into thread_info array r3 points to
@@ -365,13 +361,13 @@ intvec_\vecname:
 
 2:
 	/*
-	 * SYSTEM_SAVE_K_0 holds the cpu number in the low bits, and
-	 * the current stack top in the higher bits.  So we recover
-	 * our stack top by just masking off the low bits, then
+	 * SYSTEM_SAVE_K_0 holds the cpu number in the high bits, and
+	 * the current stack top in the lower bits.  So we recover
+	 * our starting stack value by sign-extending the low bits, then
 	 * point sp at the top aligned address on the actual stack page.
 	 */
 	mfspr   r0, SPR_SYSTEM_SAVE_K_0
-	mm      r0, zero, LOG2_THREAD_SIZE, 63
+	bfexts  r0, r0, 0, CPU_SHIFT-1
 
 0:
 	/*
@@ -393,6 +389,9 @@ intvec_\vecname:
 	 *    cache line 1: r6...r13
 	 *    cache line 0: 2 x frame, r0..r5
 	 */
+#if STACK_TOP_DELTA != 64
+#error STACK_TOP_DELTA must be 64 for assumptions here and in task_pt_regs()
+#endif
 	andi    r0, r0, -64
 
 	/*
@@ -690,7 +689,7 @@ intvec_\vecname:
 	}
 	{
 	 shl16insli r21, r21, hw1(__per_cpu_offset)
-	 bfextu r20, r20, 0, LOG2_THREAD_SIZE-1
+	 bfextu r20, r20, CPU_SHIFT, 63
 	}
 	shl16insli r21, r21, hw0(__per_cpu_offset)
 	shl3add r20, r20, r21
diff --git a/arch/tile/kernel/stack.c b/arch/tile/kernel/stack.c
index a9db923bb9eb..24fd223df65d 100644
--- a/arch/tile/kernel/stack.c
+++ b/arch/tile/kernel/stack.c
@@ -197,19 +197,19 @@ static void validate_stack(struct pt_regs *regs)
 {
 	int cpu = raw_smp_processor_id();
 	unsigned long ksp0 = get_current_ksp0();
-	unsigned long ksp0_base = ksp0 - THREAD_SIZE;
+	unsigned long ksp0_base = ksp0 & -THREAD_SIZE;
 	unsigned long sp = stack_pointer;
 
 	if (EX1_PL(regs->ex1) == KERNEL_PL && regs->sp >= ksp0) {
-		pr_err("WARNING: cpu %d: kernel stack page %#lx underrun!\n"
+		pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx underrun!\n"
 		       "  sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
-		       cpu, ksp0_base, sp, regs->sp, regs->pc, regs->lr);
+		       cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
 	}
 
 	else if (sp < ksp0_base + sizeof(struct thread_info)) {
-		pr_err("WARNING: cpu %d: kernel stack page %#lx overrun!\n"
+		pr_err("WARNING: cpu %d: kernel stack %#lx..%#lx overrun!\n"
 		       "  sp %#lx (%#lx in caller), caller pc %#lx, lr %#lx\n",
-		       cpu, ksp0_base, sp, regs->sp, regs->pc, regs->lr);
+		       cpu, ksp0_base, ksp0, sp, regs->sp, regs->pc, regs->lr);
 	}
 }