Merge tag 'xtensa-20211105' of git://github.com/jcmvbkbc/linux-xtensa

Pull xtensa updates from Max Filippov:

 - add support for xtensa cores without windowed registers option

* tag 'xtensa-20211105' of git://github.com/jcmvbkbc/linux-xtensa:
  xtensa: move section symbols to asm/sections.h
  xtensa: remove unused variable wmask
  xtensa: only build windowed register support code when needed
  xtensa: use register window specific opcodes only when present
  xtensa: implement call0 ABI support in assembly
  xtensa: definitions for call0 ABI
  xtensa: don't use a12 in __xtensa_copy_user in call0 ABI
  xtensa: don't use a12 in strncpy_user
  xtensa: use a14 instead of a15 in inline assembly
  xtensa: move _SimulateUserKernelVectorException out of WindowVectors

10 files changed, 305 insertions, 189 deletions

diff --git a/arch/xtensa/kernel/align.S b/arch/xtensa/kernel/align.S
index 9301452e521e..d062c732ef18 100644
--- a/arch/xtensa/kernel/align.S
+++ b/arch/xtensa/kernel/align.S
@@ -58,7 +58,9 @@
  *  BE  shift left / mask 0 0 X X
  */
 
+#if XCHAL_HAVE_WINDOWED
 #define UNALIGNED_USER_EXCEPTION
+#endif
 
 #if XCHAL_HAVE_BE
 
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 647b162f959b..99ab3c1a3387 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -158,6 +158,7 @@ _user_exception:
 	/* Rotate ws so that the current windowbase is at bit0. */
 	/* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */
 
+#if defined(USER_SUPPORT_WINDOWED)
 	rsr	a2, windowbase
 	rsr	a3, windowstart
 	ssr	a2
@@ -167,24 +168,33 @@ _user_exception:
 	src	a2, a3, a2
 	srli	a2, a2, 32-WSBITS
 	s32i	a2, a1, PT_WMASK	# needed for restoring registers
+#else
+	movi	a2, 0
+	movi	a3, 1
+	s32i	a2, a1, PT_WINDOWBASE
+	s32i	a3, a1, PT_WINDOWSTART
+	s32i	a3, a1, PT_WMASK
+#endif
 
 	/* Save only live registers. */
 
-	_bbsi.l	a2, 1, 1f
+UABI_W	_bbsi.l	a2, 1, 1f
 	s32i	a4, a1, PT_AREG4
 	s32i	a5, a1, PT_AREG5
 	s32i	a6, a1, PT_AREG6
 	s32i	a7, a1, PT_AREG7
-	_bbsi.l	a2, 2, 1f
+UABI_W	_bbsi.l	a2, 2, 1f
 	s32i	a8, a1, PT_AREG8
 	s32i	a9, a1, PT_AREG9
 	s32i	a10, a1, PT_AREG10
 	s32i	a11, a1, PT_AREG11
-	_bbsi.l	a2, 3, 1f
+UABI_W	_bbsi.l	a2, 3, 1f
 	s32i	a12, a1, PT_AREG12
 	s32i	a13, a1, PT_AREG13
 	s32i	a14, a1, PT_AREG14
 	s32i	a15, a1, PT_AREG15
+
+#if defined(USER_SUPPORT_WINDOWED)
 	_bnei	a2, 1, 1f		# only one valid frame?
 
 	/* Only one valid frame, skip saving regs. */
@@ -239,7 +249,7 @@ _user_exception:
 	rsync
 
 	/* We are back to the original stack pointer (a1) */
-
+#endif
 2:	/* Now, jump to the common exception handler. */
 
 	j	common_exception
@@ -295,6 +305,7 @@ _kernel_exception:
 	s32i	a3, a1, PT_SAR
 	s32i	a2, a1, PT_ICOUNTLEVEL
 
+#if defined(__XTENSA_WINDOWED_ABI__)
 	/* Rotate ws so that the current windowbase is at bit0. */
 	/* Assume ws = xxwww1yyyy. Rotate ws right, so that a2 = yyyyxxwww1 */
 
@@ -305,27 +316,28 @@ _kernel_exception:
 	src	a2, a3, a2
 	srli	a2, a2, 32-WSBITS
 	s32i	a2, a1, PT_WMASK	# needed for kernel_exception_exit
+#endif
 
 	/* Save only the live window-frame */
 
-	_bbsi.l	a2, 1, 1f
+KABI_W	_bbsi.l	a2, 1, 1f
 	s32i	a4, a1, PT_AREG4
 	s32i	a5, a1, PT_AREG5
 	s32i	a6, a1, PT_AREG6
 	s32i	a7, a1, PT_AREG7
-	_bbsi.l	a2, 2, 1f
+KABI_W	_bbsi.l	a2, 2, 1f
 	s32i	a8, a1, PT_AREG8
 	s32i	a9, a1, PT_AREG9
 	s32i	a10, a1, PT_AREG10
 	s32i	a11, a1, PT_AREG11
-	_bbsi.l	a2, 3, 1f
+KABI_W	_bbsi.l	a2, 3, 1f
 	s32i	a12, a1, PT_AREG12
 	s32i	a13, a1, PT_AREG13
 	s32i	a14, a1, PT_AREG14
 	s32i	a15, a1, PT_AREG15
 
+#ifdef __XTENSA_WINDOWED_ABI__
 	_bnei	a2, 1, 1f
-
 	/* Copy spill slots of a0 and a1 to imitate movsp
 	 * in order to keep exception stack continuous
 	 */
@@ -333,6 +345,7 @@ _kernel_exception:
 	l32i	a0, a1, PT_SIZE + 4
 	s32e	a3, a1, -16
 	s32e	a0, a1, -12
+#endif
 1:
 	l32i	a0, a1, PT_AREG0	# restore saved a0
 	wsr	a0, depc
@@ -419,16 +432,16 @@ common_exception:
 	movi	a3, LOCKLEVEL
 
 .Lexception:
-	movi	a0, PS_WOE_MASK
-	or	a3, a3, a0
+KABI_W	movi	a0, PS_WOE_MASK
+KABI_W	or	a3, a3, a0
 #else
 	addi	a2, a2, -EXCCAUSE_LEVEL1_INTERRUPT
 	movi	a0, LOCKLEVEL
 	extui	a3, a3, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
 					# a3 = PS.INTLEVEL
 	moveqz	a3, a0, a2		# a3 = LOCKLEVEL iff interrupt
-	movi	a2, PS_WOE_MASK
-	or	a3, a3, a2
+KABI_W	movi	a2, PS_WOE_MASK
+KABI_W	or	a3, a3, a2
 	rsr	a2, exccause
 #endif
 
@@ -461,14 +474,14 @@ common_exception:
 	 */
 
 	rsr	a4, excsave1
-	mov	a6, a1			# pass stack frame
-	mov	a7, a2			# pass EXCCAUSE
 	addx4	a4, a2, a4
 	l32i	a4, a4, EXC_TABLE_DEFAULT		# load handler
+	mov	abi_arg1, a2			# pass EXCCAUSE
+	mov	abi_arg0, a1			# pass stack frame
 
 	/* Call the second-level handler */
 
-	callx4	a4
+	abi_callx	a4
 
 	/* Jump here for exception exit */
 	.global common_exception_return
@@ -482,15 +495,15 @@ common_exception_return:
 1:
 	irq_save a2, a3
 #ifdef CONFIG_TRACE_IRQFLAGS
-	call4	trace_hardirqs_off
+	abi_call	trace_hardirqs_off
 #endif
 
 	/* Jump if we are returning from kernel exceptions. */
 
-	l32i	a3, a1, PT_PS
+	l32i	abi_saved1, a1, PT_PS
 	GET_THREAD_INFO(a2, a1)
 	l32i	a4, a2, TI_FLAGS
-	_bbci.l	a3, PS_UM_BIT, 6f
+	_bbci.l	abi_saved1, PS_UM_BIT, 6f
 
 	/* Specific to a user exception exit:
 	 * We need to check some flags for signal handling and rescheduling,
@@ -509,20 +522,20 @@ common_exception_return:
 	/* Call do_signal() */
 
 #ifdef CONFIG_TRACE_IRQFLAGS
-	call4	trace_hardirqs_on
+	abi_call	trace_hardirqs_on
 #endif
 	rsil	a2, 0
-	mov	a6, a1
-	call4	do_notify_resume	# int do_notify_resume(struct pt_regs*)
+	mov	abi_arg0, a1
+	abi_call	do_notify_resume	# int do_notify_resume(struct pt_regs*)
 	j	1b
 
 3:	/* Reschedule */
 
 #ifdef CONFIG_TRACE_IRQFLAGS
-	call4	trace_hardirqs_on
+	abi_call	trace_hardirqs_on
 #endif
 	rsil	a2, 0
-	call4	schedule	# void schedule (void)
+	abi_call	schedule	# void schedule (void)
 	j	1b
 
 #ifdef CONFIG_PREEMPTION
@@ -533,33 +546,33 @@ common_exception_return:
 
 	l32i	a4, a2, TI_PRE_COUNT
 	bnez	a4, 4f
-	call4	preempt_schedule_irq
+	abi_call	preempt_schedule_irq
 	j	4f
 #endif
 
 #if XTENSA_FAKE_NMI
 .LNMIexit:
-	l32i	a3, a1, PT_PS
-	_bbci.l	a3, PS_UM_BIT, 4f
+	l32i	abi_saved1, a1, PT_PS
+	_bbci.l	abi_saved1, PS_UM_BIT, 4f
 #endif
 
 5:
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
 	_bbci.l	a4, TIF_DB_DISABLED, 7f
-	call4	restore_dbreak
+	abi_call	restore_dbreak
 7:
 #endif
 #ifdef CONFIG_DEBUG_TLB_SANITY
 	l32i	a4, a1, PT_DEPC
 	bgeui	a4, VALID_DOUBLE_EXCEPTION_ADDRESS, 4f
-	call4	check_tlb_sanity
+	abi_call	check_tlb_sanity
 #endif
 6:
 4:
 #ifdef CONFIG_TRACE_IRQFLAGS
-	extui	a4, a3, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
+	extui	a4, abi_saved1, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
 	bgei	a4, LOCKLEVEL, 1f
-	call4	trace_hardirqs_on
+	abi_call	trace_hardirqs_on
 1:
 #endif
 	/* Restore optional registers. */
@@ -572,14 +585,15 @@ common_exception_return:
 	l32i    a2, a1, PT_SCOMPARE1
 	wsr     a2, scompare1
 #endif
-	wsr	a3, ps		/* disable interrupts */
+	wsr	abi_saved1, ps		/* disable interrupts */
 
-	_bbci.l	a3, PS_UM_BIT, kernel_exception_exit
+	_bbci.l	abi_saved1, PS_UM_BIT, kernel_exception_exit
 
 user_exception_exit:
 
 	/* Restore the state of the task and return from the exception. */
 
+#if defined(USER_SUPPORT_WINDOWED)
 	/* Switch to the user thread WINDOWBASE. Save SP temporarily in DEPC */
 
 	l32i	a2, a1, PT_WINDOWBASE
@@ -634,8 +648,10 @@ user_exception_exit:
 	 *	 frame where we had loaded a2), or at least the lower 4 bits
 	 *	 (if we have restored WSBITS-1 frames).
 	 */
-
 2:
+#else
+	movi	a2, 1
+#endif
 #if XCHAL_HAVE_THREADPTR
 	l32i	a3, a1, PT_THREADPTR
 	wur	a3, threadptr
@@ -650,6 +666,7 @@ user_exception_exit:
 
 kernel_exception_exit:
 
+#if defined(__XTENSA_WINDOWED_ABI__)
 	/* Check if we have to do a movsp.
 	 *
 	 * We only have to do a movsp if the previous window-frame has
@@ -702,6 +719,9 @@ kernel_exception_exit:
 	 *
 	 * Note: We expect a2 to hold PT_WMASK
 	 */
+#else
+	movi	a2, 1
+#endif
 
 common_exception_exit:
 
@@ -920,14 +940,16 @@ unrecoverable_text:
 
 ENTRY(unrecoverable_exception)
 
+#if XCHAL_HAVE_WINDOWED
 	movi	a0, 1
 	movi	a1, 0
 
 	wsr	a0, windowstart
 	wsr	a1, windowbase
 	rsync
+#endif
 
-	movi	a1, PS_WOE_MASK | LOCKLEVEL
+	movi	a1, KERNEL_PS_WOE_MASK | LOCKLEVEL
 	wsr	a1, ps
 	rsync
 
@@ -935,8 +957,8 @@ ENTRY(unrecoverable_exception)
 	movi	a0, 0
 	addi	a1, a1, PT_REGS_OFFSET
 
-	movi	a6, unrecoverable_text
-	call4	panic
+	movi	abi_arg0, unrecoverable_text
+	abi_call	panic
 
 1:	j	1b
 
@@ -947,6 +969,7 @@ ENDPROC(unrecoverable_exception)
 	__XTENSA_HANDLER
 	.literal_position
 
+#ifdef SUPPORT_WINDOWED
 /*
  * Fast-handler for alloca exceptions
  *
@@ -1010,6 +1033,7 @@ ENTRY(fast_alloca)
 8:	j	_WindowUnderflow8
 4:	j	_WindowUnderflow4
 ENDPROC(fast_alloca)
+#endif
 
 #ifdef CONFIG_USER_ABI_CALL0_PROBE
 /*
@@ -1206,7 +1230,8 @@ ENDPROC(fast_syscall_xtensa)
  * Note: We assume the stack pointer is EXC_TABLE_KSTK in the fixup handler.
  */
 
-#ifdef CONFIG_FAST_SYSCALL_SPILL_REGISTERS
+#if defined(CONFIG_FAST_SYSCALL_SPILL_REGISTERS) && \
+		defined(USER_SUPPORT_WINDOWED)
 
 ENTRY(fast_syscall_spill_registers)
 
@@ -1403,12 +1428,12 @@ ENTRY(fast_syscall_spill_registers)
 	rsr	a3, excsave1
 	l32i	a1, a3, EXC_TABLE_KSTK
 
-	movi	a4, PS_WOE_MASK | LOCKLEVEL
+	movi	a4, KERNEL_PS_WOE_MASK | LOCKLEVEL
 	wsr	a4, ps
 	rsync
 
-	movi	a6, SIGSEGV
-	call4	do_exit
+	movi	abi_arg0, SIGSEGV
+	abi_call	do_exit
 
 	/* shouldn't return, so panic */
 
@@ -1887,57 +1912,77 @@ ENDPROC(fast_store_prohibited)
 
 ENTRY(system_call)
 
+#if defined(__XTENSA_WINDOWED_ABI__)
 	abi_entry_default
+#elif defined(__XTENSA_CALL0_ABI__)
+	abi_entry(12)
+
+	s32i	a0, sp, 0
+	s32i	abi_saved0, sp, 4
+	s32i	abi_saved1, sp, 8
+	mov	abi_saved0, a2
+#else
+#error Unsupported Xtensa ABI
+#endif
 
 	/* regs->syscall = regs->areg[2] */
 
-	l32i	a7, a2, PT_AREG2
-	s32i	a7, a2, PT_SYSCALL
+	l32i	a7, abi_saved0, PT_AREG2
+	s32i	a7, abi_saved0, PT_SYSCALL
 
 	GET_THREAD_INFO(a4, a1)
-	l32i	a3, a4, TI_FLAGS
+	l32i	abi_saved1, a4, TI_FLAGS
 	movi	a4, _TIF_WORK_MASK
-	and	a3, a3, a4
-	beqz	a3, 1f
+	and	abi_saved1, abi_saved1, a4
+	beqz	abi_saved1, 1f
 
-	mov	a6, a2
-	call4	do_syscall_trace_enter
-	beqz	a6, .Lsyscall_exit
-	l32i	a7, a2, PT_SYSCALL
+	mov	abi_arg0, abi_saved0
+	abi_call	do_syscall_trace_enter
+	beqz	abi_rv, .Lsyscall_exit
+	l32i	a7, abi_saved0, PT_SYSCALL
 
 1:
 	/* syscall = sys_call_table[syscall_nr] */
 
 	movi	a4, sys_call_table
 	movi	a5, __NR_syscalls
-	movi	a6, -ENOSYS
+	movi	abi_rv, -ENOSYS
 	bgeu	a7, a5, 1f
 
 	addx4	a4, a7, a4
-	l32i	a4, a4, 0
+	l32i	abi_tmp0, a4, 0
 
 	/* Load args: arg0 - arg5 are passed via regs. */
 
-	l32i	a6, a2, PT_AREG6
-	l32i	a7, a2, PT_AREG3
-	l32i	a8, a2, PT_AREG4
-	l32i	a9, a2, PT_AREG5
-	l32i	a10, a2, PT_AREG8
-	l32i	a11, a2, PT_AREG9
+	l32i	abi_arg0, abi_saved0, PT_AREG6
+	l32i	abi_arg1, abi_saved0, PT_AREG3
+	l32i	abi_arg2, abi_saved0, PT_AREG4
+	l32i	abi_arg3, abi_saved0, PT_AREG5
+	l32i	abi_arg4, abi_saved0, PT_AREG8
+	l32i	abi_arg5, abi_saved0, PT_AREG9
 
-	callx4	a4
+	abi_callx	abi_tmp0
 
 1:	/* regs->areg[2] = return_value */
 
-	s32i	a6, a2, PT_AREG2
-	bnez	a3, 1f
+	s32i	abi_rv, abi_saved0, PT_AREG2
+	bnez	abi_saved1, 1f
 .Lsyscall_exit:
+#if defined(__XTENSA_WINDOWED_ABI__)
 	abi_ret_default
+#elif defined(__XTENSA_CALL0_ABI__)
+	l32i	a0, sp, 0
+	l32i	abi_saved0, sp, 4
+	l32i	abi_saved1, sp, 8
+	abi_ret(12)
+#else
+#error Unsupported Xtensa ABI
+#endif
 
 1:
-	mov	a6, a2
-	call4	do_syscall_trace_leave
-	abi_ret_default
+	mov	abi_arg0, abi_saved0
+	abi_call	do_syscall_trace_leave
+	j	.Lsyscall_exit
 
 ENDPROC(system_call)
 
@@ -1988,8 +2033,18 @@ ENDPROC(system_call)
 
 ENTRY(_switch_to)
 
+#if defined(__XTENSA_WINDOWED_ABI__)
 	abi_entry(XTENSA_SPILL_STACK_RESERVE)
+#elif defined(__XTENSA_CALL0_ABI__)
+	abi_entry(16)
 
+	s32i	a12, sp, 0
+	s32i	a13, sp, 4
+	s32i	a14, sp, 8
+	s32i	a15, sp, 12
+#else
+#error Unsupported Xtensa ABI
+#endif
 	mov	a11, a3			# and 'next' (a3)
 
 	l32i	a4, a2, TASK_THREAD_INFO
@@ -2033,7 +2088,9 @@ ENTRY(_switch_to)
 
 	/* Flush register file. */
 
+#if defined(__XTENSA_WINDOWED_ABI__)
 	spill_registers_kernel
+#endif
 
 	/* Set kernel stack (and leave critical section)
 	 * Note: It's save to set it here. The stack will not be overwritten
@@ -2055,34 +2112,43 @@ ENTRY(_switch_to)
 	wsr	a14, ps
 	rsync
 
+#if defined(__XTENSA_WINDOWED_ABI__)
 	abi_ret(XTENSA_SPILL_STACK_RESERVE)
+#elif defined(__XTENSA_CALL0_ABI__)
+	l32i	a12, sp, 0
+	l32i	a13, sp, 4
+	l32i	a14, sp, 8
+	l32i	a15, sp, 12
+	abi_ret(16)
+#else
+#error Unsupported Xtensa ABI
+#endif
 
 ENDPROC(_switch_to)
 
 ENTRY(ret_from_fork)
 
 	/* void schedule_tail (struct task_struct *prev)
-	 * Note: prev is still in a6 (return value from fake call4 frame)
+	 * Note: prev is still in abi_arg0 (return value from fake call frame)
 	 */
-	call4	schedule_tail
-
-	mov	a6, a1
-	call4	do_syscall_trace_leave
+	abi_call	schedule_tail
 
-	j	common_exception_return
+	mov		abi_arg0, a1
+	abi_call	do_syscall_trace_leave
+	j		common_exception_return
 
 ENDPROC(ret_from_fork)
 
 /*
  * Kernel thread creation helper
- * On entry, set up by copy_thread: a2 = thread_fn, a3 = thread_fn arg
- *           left from _switch_to: a6 = prev
+ * On entry, set up by copy_thread: abi_saved0 = thread_fn,
+ * abi_saved1 = thread_fn arg. Left from _switch_to: abi_arg0 = prev
  */
 ENTRY(ret_from_kernel_thread)
 
-	call4	schedule_tail
-	mov	a6, a3
-	callx4	a2
-	j	common_exception_return
+	abi_call	schedule_tail
+	mov		abi_arg0, abi_saved1
+	abi_callx	abi_saved0
+	j		common_exception_return
 
 ENDPROC(ret_from_kernel_thread)
diff --git a/arch/xtensa/kernel/head.S b/arch/xtensa/kernel/head.S
index b9b81e76beea..8484294bc623 100644
--- a/arch/xtensa/kernel/head.S
+++ b/arch/xtensa/kernel/head.S
@@ -15,6 +15,7 @@
  * Kevin Chea
  */
 
+#include <asm/asmmacro.h>
 #include <asm/processor.h>
 #include <asm/page.h>
 #include <asm/cacheasm.h>
@@ -66,11 +67,13 @@ _SetupOCD:
 	 * xt-gdb to single step via DEBUG exceptions received directly
 	 * by ocd.
 	 */
+#if XCHAL_HAVE_WINDOWED
 	movi	a1, 1
 	movi	a0, 0
 	wsr	a1, windowstart
 	wsr	a0, windowbase
 	rsync
+#endif
 
 	movi	a1, LOCKLEVEL
 	wsr	a1, ps
@@ -193,9 +196,10 @@ ENTRY(_startup)
 	movi	a1, start_info
 	l32i	a1, a1, 0
 
-	movi	a2, PS_WOE_MASK | LOCKLEVEL
-					# WOE=1, INTLEVEL=LOCKLEVEL, UM=0
-	wsr	a2, ps			# (enable reg-windows; progmode stack)
+	/* Disable interrupts. */
+	/* Enable window exceptions if kernel is built with windowed ABI. */
+	movi	a2, KERNEL_PS_WOE_MASK | LOCKLEVEL
+	wsr	a2, ps
 	rsync
 
 #ifdef CONFIG_SMP
@@ -267,13 +271,13 @@ ENTRY(_startup)
 	l32i	a1, a1, 0
 #endif
 
-	movi	a6, 0
-	xsr	a6, excsave1
+	movi	abi_arg0, 0
+	xsr	abi_arg0, excsave1
 
 	/* init_arch kick-starts the linux kernel */
 
-	call4	init_arch
-	call4	start_kernel
+	abi_call	init_arch
+	abi_call	start_kernel
 
 should_never_return:
 	j	should_never_return
@@ -297,10 +301,10 @@ should_never_return:
 	s32i	a3, a2, 0
 	memw
 
-	movi	a6, 0
-	wsr	a6, excsave1
+	movi	abi_arg0, 0
+	wsr	abi_arg0, excsave1
 
-	call4	secondary_start_kernel
+	abi_call	secondary_start_kernel
 	j	should_never_return
 
 #endif  /* CONFIG_SMP */
diff --git a/arch/xtensa/kernel/mcount.S b/arch/xtensa/kernel/mcount.S
index 5e4619f52858..51daaf4e0b82 100644
--- a/arch/xtensa/kernel/mcount.S
+++ b/arch/xtensa/kernel/mcount.S
@@ -17,11 +17,16 @@
 /*
  * Entry condition:
  *
- *   a2:	a0 of the caller
+ *   a2:	a0 of the caller in windowed ABI
+ *   a10:	a0 of the caller in call0 ABI
+ *
+ * In call0 ABI the function _mcount is called with the special ABI:
+ * its argument is in a10 and all the usual argument registers (a2 - a7)
+ * must be preserved in addition to callee-saved a12 - a15.
  */
 
 ENTRY(_mcount)
-
+#if defined(__XTENSA_WINDOWED_ABI__)
 	abi_entry_default
 
 	movi	a4, ftrace_trace_function
@@ -42,7 +47,36 @@ ENTRY(_mcount)
 	callx4	a4
 
 	abi_ret_default
+#elif defined(__XTENSA_CALL0_ABI__)
+	abi_entry_default
+
+	movi	a9, ftrace_trace_function
+	l32i	a9, a9, 0
+	movi	a11, ftrace_stub
+	bne	a9, a11, 1f
+	abi_ret_default
 
+1:	abi_entry(28)
+	s32i	a0, sp, 0
+	s32i	a2, sp, 4
+	s32i	a3, sp, 8
+	s32i	a4, sp, 12
+	s32i	a5, sp, 16
+	s32i	a6, sp, 20
+	s32i	a7, sp, 24
+	addi	a2, a10, -MCOUNT_INSN_SIZE
+	callx0	a9
+	l32i	a0, sp, 0
+	l32i	a2, sp, 4
+	l32i	a3, sp, 8
+	l32i	a4, sp, 12
+	l32i	a5, sp, 16
+	l32i	a6, sp, 20
+	l32i	a7, sp, 24
+	abi_ret(28)
+#else
+#error Unsupported Xtensa ABI
+#endif
 ENDPROC(_mcount)
 
 ENTRY(ftrace_stub)
diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 47f933fed870..bd80df890b1e 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -211,11 +211,18 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
 	struct thread_info *ti;
 #endif
 
+#if defined(__XTENSA_WINDOWED_ABI__)
 	/* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
 	SPILL_SLOT(childregs, 1) = (unsigned long)childregs;
 	SPILL_SLOT(childregs, 0) = 0;
 
 	p->thread.sp = (unsigned long)childregs;
+#elif defined(__XTENSA_CALL0_ABI__)
+	/* Reserve 16 bytes for the _switch_to stack frame. */
+	p->thread.sp = (unsigned long)childregs - 16;
+#else
+#error Unsupported Xtensa ABI
+#endif
 
 	if (!(p->flags & (PF_KTHREAD | PF_IO_WORKER))) {
 		struct pt_regs *regs = current_pt_regs();
@@ -272,11 +279,25 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
 		p->thread.ra = MAKE_RA_FOR_CALL(
 				(unsigned long)ret_from_kernel_thread, 1);
 
-		/* pass parameters to ret_from_kernel_thread:
-		 * a2 = thread_fn, a3 = thread_fn arg
+		/* pass parameters to ret_from_kernel_thread: */
+#if defined(__XTENSA_WINDOWED_ABI__)
+		/*
+		 * a2 = thread_fn, a3 = thread_fn arg.
+		 * Window underflow will load registers from the
+		 * spill slots on the stack on return from _switch_to.
 		 */
-		SPILL_SLOT(childregs, 3) = thread_fn_arg;
 		SPILL_SLOT(childregs, 2) = usp_thread_fn;
+		SPILL_SLOT(childregs, 3) = thread_fn_arg;
+#elif defined(__XTENSA_CALL0_ABI__)
+		/*
+		 * a12 = thread_fn, a13 = thread_fn arg.
+		 * _switch_to epilogue will load registers from the stack.
+		 */
+		((unsigned long *)p->thread.sp)[0] = usp_thread_fn;
+		((unsigned long *)p->thread.sp)[1] = thread_fn_arg;
+#else
+#error Unsupported Xtensa ABI
+#endif
 
 		/* Childregs are only used when we're going to userspace
 		 * in which case start_thread will set them up.
diff --git a/arch/xtensa/kernel/setup.c b/arch/xtensa/kernel/setup.c
index ee9082a142fe..8db20cfb44ab 100644
--- a/arch/xtensa/kernel/setup.c
+++ b/arch/xtensa/kernel/setup.c
@@ -37,14 +37,15 @@
 #include <asm/bootparam.h>
 #include <asm/kasan.h>
 #include <asm/mmu_context.h>
-#include <asm/processor.h>
-#include <asm/timex.h>
-#include <asm/platform.h>
 #include <asm/page.h>
-#include <asm/setup.h>
 #include <asm/param.h>
+#include <asm/platform.h>
+#include <asm/processor.h>
+#include <asm/sections.h>
+#include <asm/setup.h>
 #include <asm/smp.h>
 #include <asm/sysmem.h>
+#include <asm/timex.h>
 
 #if defined(CONFIG_VGA_CONSOLE) || defined(CONFIG_DUMMY_CONSOLE)
 struct screen_info screen_info = {
@@ -271,49 +272,6 @@ void __init init_arch(bp_tag_t *bp_start)
  * Initialize system. Setup memory and reserve regions.
  */
 
-extern char _end[];
-extern char _stext[];
-extern char _WindowVectors_text_start;
-extern char _WindowVectors_text_end;
-extern char _DebugInterruptVector_text_start;
-extern char _DebugInterruptVector_text_end;
-extern char _KernelExceptionVector_text_start;
-extern char _KernelExceptionVector_text_end;
-extern char _UserExceptionVector_text_start;
-extern char _UserExceptionVector_text_end;
-extern char _DoubleExceptionVector_text_start;
-extern char _DoubleExceptionVector_text_end;
-extern char _exception_text_start;
-extern char _exception_text_end;
-#if XCHAL_EXCM_LEVEL >= 2
-extern char _Level2InterruptVector_text_start;
-extern char _Level2InterruptVector_text_end;
-#endif
-#if XCHAL_EXCM_LEVEL >= 3
-extern char _Level3InterruptVector_text_start;
-extern char _Level3InterruptVector_text_end;
-#endif
-#if XCHAL_EXCM_LEVEL >= 4
-extern char _Level4InterruptVector_text_start;
-extern char _Level4InterruptVector_text_end;
-#endif
-#if XCHAL_EXCM_LEVEL >= 5
-extern char _Level5InterruptVector_text_start;
-extern char _Level5InterruptVector_text_end;
-#endif
-#if XCHAL_EXCM_LEVEL >= 6
-extern char _Level6InterruptVector_text_start;
-extern char _Level6InterruptVector_text_end;
-#endif
-#ifdef CONFIG_SMP
-extern char _SecondaryResetVector_text_start;
-extern char _SecondaryResetVector_text_end;
-#endif
-#ifdef CONFIG_XIP_KERNEL
-extern char _xip_start[];
-extern char _xip_end[];
-#endif
-
 static inline int __init_memblock mem_reserve(unsigned long start,
 					      unsigned long end)
 {
@@ -349,49 +307,51 @@ void __init setup_arch(char **cmdline_p)
 #endif
 
 #ifdef CONFIG_VECTORS_ADDR
-	mem_reserve(__pa(&_WindowVectors_text_start),
-		    __pa(&_WindowVectors_text_end));
+#ifdef SUPPORT_WINDOWED
+	mem_reserve(__pa(_WindowVectors_text_start),
+		    __pa(_WindowVectors_text_end));
+#endif
 
-	mem_reserve(__pa(&_DebugInterruptVector_text_start),
-		    __pa(&_DebugInterruptVector_text_end));
+	mem_reserve(__pa(_DebugInterruptVector_text_start),
+		    __pa(_DebugInterruptVector_text_end));
 
-	mem_reserve(__pa(&_KernelExceptionVector_text_start),
-		    __pa(&_KernelExceptionVector_text_end));
+	mem_reserve(__pa(_KernelExceptionVector_text_start),
+		    __pa(_KernelExceptionVector_text_end));
 
-	mem_reserve(__pa(&_UserExceptionVector_text_start),
-		    __pa(&_UserExceptionVector_text_end));
+	mem_reserve(__pa(_UserExceptionVector_text_start),
+		    __pa(_UserExceptionVector_text_end));
 
-	mem_reserve(__pa(&_DoubleExceptionVector_text_start),
-		    __pa(&_DoubleExceptionVector_text_end));
+	mem_reserve(__pa(_DoubleExceptionVector_text_start),
+		    __pa(_DoubleExceptionVector_text_end));
 
-	mem_reserve(__pa(&_exception_text_start),
-		    __pa(&_exception_text_end));
+	mem_reserve(__pa(_exception_text_start),
+		    __pa(_exception_text_end));
 #if XCHAL_EXCM_LEVEL >= 2
-	mem_reserve(__pa(&_Level2InterruptVector_text_start),
-		    __pa(&_Level2InterruptVector_text_end));
+	mem_reserve(__pa(_Level2InterruptVector_text_start),
+		    __pa(_Level2InterruptVector_text_end));
 #endif
 #if XCHAL_EXCM_LEVEL >= 3
-	mem_reserve(__pa(&_Level3InterruptVector_text_start),
-		    __pa(&_Level3InterruptVector_text_end));
+	mem_reserve(__pa(_Level3InterruptVector_text_start),
+		    __pa(_Level3InterruptVector_text_end));
 #endif
 #if XCHAL_EXCM_LEVEL >= 4
-	mem_reserve(__pa(&_Level4InterruptVector_text_start),
-		    __pa(&_Level4InterruptVector_text_end));
+	mem_reserve(__pa(_Level4InterruptVector_text_start),
+		    __pa(_Level4InterruptVector_text_end));
 #endif
 #if XCHAL_EXCM_LEVEL >= 5
-	mem_reserve(__pa(&_Level5InterruptVector_text_start),
-		    __pa(&_Level5InterruptVector_text_end));
+	mem_reserve(__pa(_Level5InterruptVector_text_start),
+		    __pa(_Level5InterruptVector_text_end));
 #endif
 #if XCHAL_EXCM_LEVEL >= 6
-	mem_reserve(__pa(&_Level6InterruptVector_text_start),
-		    __pa(&_Level6InterruptVector_text_end));
+	mem_reserve(__pa(_Level6InterruptVector_text_start),
+		    __pa(_Level6InterruptVector_text_end));
 #endif
 
 #endif /* CONFIG_VECTORS_ADDR */
 
 #ifdef CONFIG_SMP
-	mem_reserve(__pa(&_SecondaryResetVector_text_start),
-		    __pa(&_SecondaryResetVector_text_end));
+	mem_reserve(__pa(_SecondaryResetVector_text_start),
+		    __pa(_SecondaryResetVector_text_end));
 #endif
 	parse_early_param();
 	bootmem_init();
diff --git a/arch/xtensa/kernel/signal.c b/arch/xtensa/kernel/signal.c
index c4d77dbfb61a..f6c949895b3e 100644
--- a/arch/xtensa/kernel/signal.c
+++ b/arch/xtensa/kernel/signal.c
@@ -45,12 +45,13 @@ struct rt_sigframe
 	unsigned int window[4];
 };
 
-/* 
+#if defined(USER_SUPPORT_WINDOWED)
+/*
  * Flush register windows stored in pt_regs to stack.
  * Returns 1 for errors.
  */
 
-int
+static int
 flush_window_regs_user(struct pt_regs *regs)
 {
 	const unsigned long ws = regs->windowstart;
@@ -121,6 +122,13 @@ flush_window_regs_user(struct pt_regs *regs)
 errout:
 	return err;
 }
+#else
+static int
+flush_window_regs_user(struct pt_regs *regs)
+{
+	return 0;
+}
+#endif
 
 /*
  * Note: We don't copy double exception 'regs', we have to finish double exc. 
diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c
index 874b6efc6fb3..35a7d47f28cf 100644
--- a/arch/xtensa/kernel/traps.c
+++ b/arch/xtensa/kernel/traps.c
@@ -97,7 +97,9 @@ static dispatch_init_table_t __initdata dispatch_init_table[] = {
 /* EXCCAUSE_INSTRUCTION_FETCH unhandled */
 /* EXCCAUSE_LOAD_STORE_ERROR unhandled*/
 { EXCCAUSE_LEVEL1_INTERRUPT,	0,	   do_interrupt },
+#ifdef SUPPORT_WINDOWED
 { EXCCAUSE_ALLOCA,		USER|KRNL, fast_alloca },
+#endif
 /* EXCCAUSE_INTEGER_DIVIDE_BY_ZERO unhandled */
 /* EXCCAUSE_PRIVILEGED unhandled */
 #if XCHAL_UNALIGNED_LOAD_EXCEPTION || XCHAL_UNALIGNED_STORE_EXCEPTION
@@ -462,12 +464,10 @@ void secondary_trap_init(void)
 
 void show_regs(struct pt_regs * regs)
 {
-	int i, wmask;
+	int i;
 
 	show_regs_print_info(KERN_DEFAULT);
 
-	wmask = regs->wmask & ~1;
-
 	for (i = 0; i < 16; i++) {
 		if ((i % 8) == 0)
 			pr_info("a%02d:", i);
diff --git a/arch/xtensa/kernel/vectors.S b/arch/xtensa/kernel/vectors.S
index 1a7538ccfc5a..407ece204e7c 100644
--- a/arch/xtensa/kernel/vectors.S
+++ b/arch/xtensa/kernel/vectors.S
@@ -226,6 +226,7 @@ ENTRY(_DoubleExceptionVector)
 
 	xsr	a0, depc		# get DEPC, save a0
 
+#ifdef SUPPORT_WINDOWED
 	movi	a2, WINDOW_VECTORS_VADDR
 	_bltu	a0, a2, .Lfixup
 	addi	a2, a2, WINDOW_VECTORS_SIZE
@@ -275,6 +276,10 @@ _DoubleExceptionVector_WindowUnderflow:
 	l32i	a0, a0, EXC_TABLE_FAST_USER
 	jx	a0
 
+#else
+	j	.Lfixup
+#endif
+
 	/*
 	 * We only allow the ITLB miss exception if we are in kernel space.
 	 * All other exceptions are unexpected and thus unrecoverable!
@@ -343,6 +348,7 @@ _DoubleExceptionVector_WindowUnderflow:
 	l32i	a0, a0, EXC_TABLE_FAST_USER
 	jx	a0
 
+#ifdef SUPPORT_WINDOWED
 	/*
 	 * Restart window OVERFLOW exception.
 	 * Currently:
@@ -475,9 +481,12 @@ _DoubleExceptionVector_handle_exception:
 	rsr	a0, depc
 	rotw	-3
 	j	1b
+#endif
 
 ENDPROC(_DoubleExceptionVector)
 
+#ifdef SUPPORT_WINDOWED
+
 /*
  * Fixup handler for TLB miss in double exception handler for window owerflow.
  * We get here with windowbase set to the window that was being spilled and
@@ -590,6 +599,8 @@ ENTRY(window_overflow_restore_a0_fixup)
 
 ENDPROC(window_overflow_restore_a0_fixup)
 
+#endif
+
 /*
  * Debug interrupt vector
  *
@@ -650,6 +661,25 @@ ENTRY(_Level\level\()InterruptVector)
 	irq_entry_level 5
 	irq_entry_level 6
 
+#if XCHAL_EXCM_LEVEL >= 2
+	/*
+	 *  Continuation of medium priority interrupt dispatch code.
+	 *  On entry here, a0 contains PS, and EPC2 contains saved a0:
+	 */
+	__XTENSA_HANDLER
+	.align 4
+_SimulateUserKernelVectorException:
+	addi	a0, a0, (1 << PS_EXCM_BIT)
+#if !XTENSA_FAKE_NMI
+	wsr	a0, ps
+#endif
+	bbsi.l	a0, PS_UM_BIT, 1f	# branch if user mode
+	xsr	a0, excsave2		# restore a0
+	j	_KernelExceptionVector	# simulate kernel vector exception
+1:	xsr	a0, excsave2		# restore a0
+	j	_UserExceptionVector	# simulate user vector exception
+#endif
+
 
 /* Window overflow and underflow handlers.
  * The handlers must be 64 bytes apart, first starting with the underflow
@@ -668,6 +698,8 @@ ENTRY(_Level\level\()InterruptVector)
 	.section		.WindowVectors.text, "ax"
 
 
+#ifdef SUPPORT_WINDOWED
+
 /* 4-Register Window Overflow Vector (Handler) */
 
 ENTRY_ALIGN64(_WindowOverflow4)
@@ -680,27 +712,6 @@ ENTRY_ALIGN64(_WindowOverflow4)
 
 ENDPROC(_WindowOverflow4)
 
-
-#if XCHAL_EXCM_LEVEL >= 2
-	/*  Not a window vector - but a convenient location
-	 *  (where we know there's space) for continuation of
-	 *  medium priority interrupt dispatch code.
-	 *  On entry here, a0 contains PS, and EPC2 contains saved a0:
-	 */
-	.align 4
-_SimulateUserKernelVectorException:
-	addi	a0, a0, (1 << PS_EXCM_BIT)
-#if !XTENSA_FAKE_NMI
-	wsr	a0, ps
-#endif
-	bbsi.l	a0, PS_UM_BIT, 1f	# branch if user mode
-	xsr	a0, excsave2		# restore a0
-	j	_KernelExceptionVector	# simulate kernel vector exception
-1:	xsr	a0, excsave2		# restore a0
-	j	_UserExceptionVector	# simulate user vector exception
-#endif
-
-
 /* 4-Register Window Underflow Vector (Handler) */
 
 ENTRY_ALIGN64(_WindowUnderflow4)
@@ -789,4 +800,6 @@ ENTRY_ALIGN64(_WindowUnderflow12)
 
 ENDPROC(_WindowUnderflow12)
 
+#endif
+
 	.text
diff --git a/arch/xtensa/kernel/vmlinux.lds.S b/arch/xtensa/kernel/vmlinux.lds.S
index d23a6e38f062..eee270a039a4 100644
--- a/arch/xtensa/kernel/vmlinux.lds.S
+++ b/arch/xtensa/kernel/vmlinux.lds.S
@@ -94,7 +94,9 @@ SECTIONS
     . = ALIGN(PAGE_SIZE);
     _vecbase = .;
 
+#ifdef SUPPORT_WINDOWED
     SECTION_VECTOR2 (.WindowVectors.text, WINDOW_VECTORS_VADDR)
+#endif
 #if XCHAL_EXCM_LEVEL >= 2
     SECTION_VECTOR2 (.Level2InterruptVector.text, INTLEVEL2_VECTOR_VADDR)
 #endif
@@ -166,8 +168,10 @@ SECTIONS
     __boot_reloc_table_start = ABSOLUTE(.);
 
 #if !MERGED_VECTORS
+#ifdef SUPPORT_WINDOWED
     RELOCATE_ENTRY(_WindowVectors_text,
 		   .WindowVectors.text);
+#endif
 #if XCHAL_EXCM_LEVEL >= 2
     RELOCATE_ENTRY(_Level2InterruptVector_text,
 		   .Level2InterruptVector.text);
@@ -229,14 +233,18 @@ SECTIONS
 #if !MERGED_VECTORS
   /* The vectors are relocated to the real position at startup time */
 
+#ifdef SUPPORT_WINDOWED
   SECTION_VECTOR4 (_WindowVectors_text,
 		  .WindowVectors.text,
 		  WINDOW_VECTORS_VADDR,
-		  .dummy)
+		  LAST)
+#undef LAST
+#define LAST	.WindowVectors.text
+#endif
   SECTION_VECTOR4 (_DebugInterruptVector_text,
 		  .DebugInterruptVector.text,
 		  DEBUG_VECTOR_VADDR,
-		  .WindowVectors.text)
+		  LAST)
 #undef LAST
 #define LAST	.DebugInterruptVector.text
 #if XCHAL_EXCM_LEVEL >= 2