xref: /openbmc/linux/arch/s390/kernel/entry.S (revision d09a307fde1c943d23ccb9fecc9a0e1a569732ad)

/* SPDX-License-Identifier: GPL-2.0 */
/*
 *    S390 low-level entry points.
 *
 *    Copyright IBM Corp. 1999, 2012
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
 *		 Hartmut Penner (hp@de.ibm.com),
 *		 Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
 */

#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/asm-extable.h>
#include <asm/alternative-asm.h>
#include <asm/processor.h>
#include <asm/cache.h>
#include <asm/dwarf.h>
#include <asm/errno.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>
#include <asm/page.h>
#include <asm/sigp.h>
#include <asm/irq.h>
#include <asm/vx-insn.h>
#include <asm/setup.h>
#include <asm/nmi.h>
#include <asm/export.h>
#include <asm/nospec-insn.h>

__PT_R0      =	__PT_GPRS
__PT_R1      =	__PT_GPRS + 8
__PT_R2      =	__PT_GPRS + 16
__PT_R3      =	__PT_GPRS + 24
__PT_R4      =	__PT_GPRS + 32
__PT_R5      =	__PT_GPRS + 40
__PT_R6      =	__PT_GPRS + 48
__PT_R7      =	__PT_GPRS + 56
__PT_R8      =	__PT_GPRS + 64
__PT_R9      =	__PT_GPRS + 72
__PT_R10     =	__PT_GPRS + 80
__PT_R11     =	__PT_GPRS + 88
__PT_R12     =	__PT_GPRS + 96
__PT_R13     =	__PT_GPRS + 104
__PT_R14     =	__PT_GPRS + 112
__PT_R15     =	__PT_GPRS + 120

STACK_SHIFT = PAGE_SHIFT + THREAD_SIZE_ORDER
STACK_SIZE  = 1 << STACK_SHIFT
STACK_INIT = STACK_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE

_LPP_OFFSET	= __LC_LPP

	.macro STBEAR address
	ALTERNATIVE "", ".insn	s,0xb2010000,\address", 193
	.endm

	.macro LBEAR address
	ALTERNATIVE "", ".insn	s,0xb2000000,\address", 193
	.endm

	.macro LPSWEY address,lpswe
	ALTERNATIVE "b \lpswe", ".insn siy,0xeb0000000071,\address,0", 193
	.endm

	.macro MBEAR reg
	ALTERNATIVE "", __stringify(mvc __PT_LAST_BREAK(8,\reg),__LC_LAST_BREAK), 193
	.endm

	.macro	CHECK_STACK savearea
#ifdef CONFIG_CHECK_STACK
	tml	%r15,STACK_SIZE - CONFIG_STACK_GUARD
	lghi	%r14,\savearea
	jz	stack_overflow
#endif
	.endm

	.macro	CHECK_VMAP_STACK savearea,oklabel
#ifdef CONFIG_VMAP_STACK
	lgr	%r14,%r15
	nill	%r14,0x10000 - STACK_SIZE
	oill	%r14,STACK_INIT
	clg	%r14,__LC_KERNEL_STACK
	je	\oklabel
	clg	%r14,__LC_ASYNC_STACK
	je	\oklabel
	clg	%r14,__LC_MCCK_STACK
	je	\oklabel
	clg	%r14,__LC_NODAT_STACK
	je	\oklabel
	clg	%r14,__LC_RESTART_STACK
	je	\oklabel
	lghi	%r14,\savearea
	j	stack_overflow
#else
	j	\oklabel
#endif
	.endm

	.macro STCK savearea
	ALTERNATIVE ".insn	s,0xb2050000,\savearea", \
		    ".insn	s,0xb27c0000,\savearea", 25
	.endm

	/*
	 * The TSTMSK macro generates a test-under-mask instruction by
	 * calculating the memory offset for the specified mask value.
	 * Mask value can be any constant.  The macro shifts the mask
	 * value to calculate the memory offset for the test-under-mask
	 * instruction.
	 */
	.macro TSTMSK addr, mask, size=8, bytepos=0
		.if (\bytepos < \size) && (\mask >> 8)
			.if (\mask & 0xff)
				.error "Mask exceeds byte boundary"
			.endif
			TSTMSK \addr, "(\mask >> 8)", \size, "(\bytepos + 1)"
			.exitm
		.endif
		.ifeq \mask
			.error "Mask must not be zero"
		.endif
		off = \size - \bytepos - 1
		tm	off+\addr, \mask
	.endm

	.macro BPOFF
	ALTERNATIVE "", ".long 0xb2e8c000", 82
	.endm

	.macro BPON
	ALTERNATIVE "", ".long 0xb2e8d000", 82
	.endm

	.macro BPENTER tif_ptr,tif_mask
	ALTERNATIVE "TSTMSK \tif_ptr,\tif_mask; jz .+8; .long 0xb2e8d000", \
		    "", 82
	.endm

	.macro BPEXIT tif_ptr,tif_mask
	TSTMSK	\tif_ptr,\tif_mask
	ALTERNATIVE "jz .+8;  .long 0xb2e8c000", \
		    "jnz .+8; .long 0xb2e8d000", 82
	.endm

	/*
	 * The CHKSTG macro jumps to the provided label in case the
	 * machine check interruption code reports one of unrecoverable
	 * storage errors:
	 * - Storage error uncorrected
	 * - Storage key error uncorrected
	 * - Storage degradation with Failing-storage-address validity
	 */
	.macro CHKSTG errlabel
	TSTMSK	__LC_MCCK_CODE,(MCCK_CODE_STG_ERROR|MCCK_CODE_STG_KEY_ERROR)
	jnz	\errlabel
	TSTMSK	__LC_MCCK_CODE,MCCK_CODE_STG_DEGRAD
	jz	.Loklabel\@
	TSTMSK	__LC_MCCK_CODE,MCCK_CODE_STG_FAIL_ADDR
	jnz	\errlabel
.Loklabel\@:
	.endm

#if IS_ENABLED(CONFIG_KVM)
	/*
	 * The OUTSIDE macro jumps to the provided label in case the value
	 * in the provided register is outside of the provided range. The
	 * macro is useful for checking whether a PSW stored in a register
	 * pair points inside or outside of a block of instructions.
	 * @reg: register to check
	 * @start: start of the range
	 * @end: end of the range
	 * @outside_label: jump here if @reg is outside of [@start..@end)
	 */
	.macro OUTSIDE reg,start,end,outside_label
	lgr	%r14,\reg
	larl	%r13,\start
	slgr	%r14,%r13
	lghi	%r13,\end - \start
	clgr	%r14,%r13
	jhe	\outside_label
	.endm

	.macro SIEEXIT
	lg	%r9,__SF_SIE_CONTROL(%r15)	# get control block pointer
	ni	__SIE_PROG0C+3(%r9),0xfe	# no longer in SIE
	lctlg	%c1,%c1,__LC_KERNEL_ASCE	# load primary asce
	larl	%r9,sie_exit			# skip forward to sie_exit
	.endm
#endif

	GEN_BR_THUNK %r14

	.section .kprobes.text, "ax"
.Ldummy:
	/*
	 * This nop exists only in order to avoid that __bpon starts at
	 * the beginning of the kprobes text section. In that case we would
	 * have several symbols at the same address. E.g. objdump would take
	 * an arbitrary symbol name when disassembling this code.
	 * With the added nop in between the __bpon symbol is unique
	 * again.
	 */
	nop	0

ENTRY(__bpon)
	.globl __bpon
	BPON
	BR_EX	%r14
ENDPROC(__bpon)

/*
 * Scheduler resume function, called by switch_to
 *  gpr2 = (task_struct *) prev
 *  gpr3 = (task_struct *) next
 * Returns:
 *  gpr2 = prev
 */
ENTRY(__switch_to)
	stmg	%r6,%r15,__SF_GPRS(%r15)	# store gprs of prev task
	lghi	%r4,__TASK_stack
	lghi	%r1,__TASK_thread
	llill	%r5,STACK_INIT
	stg	%r15,__THREAD_ksp(%r1,%r2)	# store kernel stack of prev
	lg	%r15,0(%r4,%r3)			# start of kernel stack of next
	agr	%r15,%r5			# end of kernel stack of next
	stg	%r3,__LC_CURRENT		# store task struct of next
	stg	%r15,__LC_KERNEL_STACK		# store end of kernel stack
	lg	%r15,__THREAD_ksp(%r1,%r3)	# load kernel stack of next
	aghi	%r3,__TASK_pid
	mvc	__LC_CURRENT_PID(4,%r0),0(%r3)	# store pid of next
	lmg	%r6,%r15,__SF_GPRS(%r15)	# load gprs of next task
	ALTERNATIVE "", ".insn s,0xb2800000,_LPP_OFFSET", 40
	BR_EX	%r14
ENDPROC(__switch_to)

#if IS_ENABLED(CONFIG_KVM)
/*
 * sie64a calling convention:
 * %r2 pointer to sie control block
 * %r3 guest register save area
 */
ENTRY(sie64a)
	stmg	%r6,%r14,__SF_GPRS(%r15)	# save kernel registers
	lg	%r12,__LC_CURRENT
	stg	%r2,__SF_SIE_CONTROL(%r15)	# save control block pointer
	stg	%r3,__SF_SIE_SAVEAREA(%r15)	# save guest register save area
	xc	__SF_SIE_REASON(8,%r15),__SF_SIE_REASON(%r15) # reason code = 0
	mvc	__SF_SIE_FLAGS(8,%r15),__TI_flags(%r12) # copy thread flags
	lmg	%r0,%r13,0(%r3)			# load guest gprs 0-13
	lg	%r14,__LC_GMAP			# get gmap pointer
	ltgr	%r14,%r14
	jz	.Lsie_gmap
	lctlg	%c1,%c1,__GMAP_ASCE(%r14)	# load primary asce
.Lsie_gmap:
	lg	%r14,__SF_SIE_CONTROL(%r15)	# get control block pointer
	oi	__SIE_PROG0C+3(%r14),1		# we are going into SIE now
	tm	__SIE_PROG20+3(%r14),3		# last exit...
	jnz	.Lsie_skip
	TSTMSK	__LC_CPU_FLAGS,_CIF_FPU
	jo	.Lsie_skip			# exit if fp/vx regs changed
	BPEXIT	__SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
.Lsie_entry:
	sie	0(%r14)
	BPOFF
	BPENTER	__SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
.Lsie_skip:
	ni	__SIE_PROG0C+3(%r14),0xfe	# no longer in SIE
	lctlg	%c1,%c1,__LC_KERNEL_ASCE	# load primary asce
.Lsie_done:
# some program checks are suppressing. C code (e.g. do_protection_exception)
# will rewind the PSW by the ILC, which is often 4 bytes in case of SIE. There
# are some corner cases (e.g. runtime instrumentation) where ILC is unpredictable.
# Other instructions between sie64a and .Lsie_done should not cause program
# interrupts. So lets use 3 nops as a landing pad for all possible rewinds.
.Lrewind_pad6:
	nopr	7
.Lrewind_pad4:
	nopr	7
.Lrewind_pad2:
	nopr	7
	.globl sie_exit
sie_exit:
	lg	%r14,__SF_SIE_SAVEAREA(%r15)	# load guest register save area
	stmg	%r0,%r13,0(%r14)		# save guest gprs 0-13
	xgr	%r0,%r0				# clear guest registers to
	xgr	%r1,%r1				# prevent speculative use
	xgr	%r3,%r3
	xgr	%r4,%r4
	xgr	%r5,%r5
	lmg	%r6,%r14,__SF_GPRS(%r15)	# restore kernel registers
	lg	%r2,__SF_SIE_REASON(%r15)	# return exit reason code
	BR_EX	%r14
.Lsie_fault:
	lghi	%r14,-EFAULT
	stg	%r14,__SF_SIE_REASON(%r15)	# set exit reason code
	j	sie_exit

	EX_TABLE(.Lrewind_pad6,.Lsie_fault)
	EX_TABLE(.Lrewind_pad4,.Lsie_fault)
	EX_TABLE(.Lrewind_pad2,.Lsie_fault)
	EX_TABLE(sie_exit,.Lsie_fault)
ENDPROC(sie64a)
EXPORT_SYMBOL(sie64a)
EXPORT_SYMBOL(sie_exit)
#endif

/*
 * SVC interrupt handler routine. System calls are synchronous events and
 * are entered with interrupts disabled.
 */

ENTRY(system_call)
	stpt	__LC_SYS_ENTER_TIMER
	stmg	%r8,%r15,__LC_SAVE_AREA_SYNC
	BPOFF
	lghi	%r14,0
.Lsysc_per:
	STBEAR	__LC_LAST_BREAK
	lctlg	%c1,%c1,__LC_KERNEL_ASCE
	lg	%r12,__LC_CURRENT
	lg	%r15,__LC_KERNEL_STACK
	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
	stmg	%r0,%r7,STACK_FRAME_OVERHEAD+__PT_R0(%r15)
	BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
	# clear user controlled register to prevent speculative use
	xgr	%r0,%r0
	xgr	%r1,%r1
	xgr	%r4,%r4
	xgr	%r5,%r5
	xgr	%r6,%r6
	xgr	%r7,%r7
	xgr	%r8,%r8
	xgr	%r9,%r9
	xgr	%r10,%r10
	xgr	%r11,%r11
	la	%r2,STACK_FRAME_OVERHEAD(%r15)	# pointer to pt_regs
	mvc	__PT_R8(64,%r2),__LC_SAVE_AREA_SYNC
	MBEAR	%r2
	lgr	%r3,%r14
	brasl	%r14,__do_syscall
	lctlg	%c1,%c1,__LC_USER_ASCE
	mvc	__LC_RETURN_PSW(16),STACK_FRAME_OVERHEAD+__PT_PSW(%r15)
	BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP
	LBEAR	STACK_FRAME_OVERHEAD+__PT_LAST_BREAK(%r15)
	lmg	%r0,%r15,STACK_FRAME_OVERHEAD+__PT_R0(%r15)
	stpt	__LC_EXIT_TIMER
	LPSWEY	__LC_RETURN_PSW,__LC_RETURN_LPSWE
ENDPROC(system_call)

#
# a new process exits the kernel with ret_from_fork
#
ENTRY(ret_from_fork)
	lgr	%r3,%r11
	brasl	%r14,__ret_from_fork
	lctlg	%c1,%c1,__LC_USER_ASCE
	mvc	__LC_RETURN_PSW(16),STACK_FRAME_OVERHEAD+__PT_PSW(%r15)
	BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP
	LBEAR	STACK_FRAME_OVERHEAD+__PT_LAST_BREAK(%r15)
	lmg	%r0,%r15,STACK_FRAME_OVERHEAD+__PT_R0(%r15)
	stpt	__LC_EXIT_TIMER
	LPSWEY	__LC_RETURN_PSW,__LC_RETURN_LPSWE
ENDPROC(ret_from_fork)

/*
 * Program check handler routine
 */

ENTRY(pgm_check_handler)
	stpt	__LC_SYS_ENTER_TIMER
	BPOFF
	stmg	%r8,%r15,__LC_SAVE_AREA_SYNC
	lg	%r12,__LC_CURRENT
	lghi	%r10,0
	lmg	%r8,%r9,__LC_PGM_OLD_PSW
	tmhh	%r8,0x0001		# coming from user space?
	jno	.Lpgm_skip_asce
	lctlg	%c1,%c1,__LC_KERNEL_ASCE
	j	3f			# -> fault in user space
.Lpgm_skip_asce:
#if IS_ENABLED(CONFIG_KVM)
	# cleanup critical section for program checks in sie64a
	OUTSIDE	%r9,.Lsie_gmap,.Lsie_done,1f
	SIEEXIT
	lghi	%r10,_PIF_GUEST_FAULT
#endif
1:	tmhh	%r8,0x4000		# PER bit set in old PSW ?
	jnz	2f			# -> enabled, can't be a double fault
	tm	__LC_PGM_ILC+3,0x80	# check for per exception
	jnz	.Lpgm_svcper		# -> single stepped svc
2:	CHECK_STACK __LC_SAVE_AREA_SYNC
	aghi	%r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
	# CHECK_VMAP_STACK branches to stack_overflow or 4f
	CHECK_VMAP_STACK __LC_SAVE_AREA_SYNC,4f
3:	BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
	lg	%r15,__LC_KERNEL_STACK
4:	la	%r11,STACK_FRAME_OVERHEAD(%r15)
	stg	%r10,__PT_FLAGS(%r11)
	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
	stmg	%r0,%r7,__PT_R0(%r11)
	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_SYNC
	mvc	__PT_LAST_BREAK(8,%r11),__LC_PGM_LAST_BREAK
	stmg	%r8,%r9,__PT_PSW(%r11)

	# clear user controlled registers to prevent speculative use
	xgr	%r0,%r0
	xgr	%r1,%r1
	xgr	%r3,%r3
	xgr	%r4,%r4
	xgr	%r5,%r5
	xgr	%r6,%r6
	xgr	%r7,%r7
	lgr	%r2,%r11
	brasl	%r14,__do_pgm_check
	tmhh	%r8,0x0001		# returning to user space?
	jno	.Lpgm_exit_kernel
	lctlg	%c1,%c1,__LC_USER_ASCE
	BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP
	stpt	__LC_EXIT_TIMER
.Lpgm_exit_kernel:
	mvc	__LC_RETURN_PSW(16),STACK_FRAME_OVERHEAD+__PT_PSW(%r15)
	LBEAR	STACK_FRAME_OVERHEAD+__PT_LAST_BREAK(%r15)
	lmg	%r0,%r15,STACK_FRAME_OVERHEAD+__PT_R0(%r15)
	LPSWEY	__LC_RETURN_PSW,__LC_RETURN_LPSWE

#
# single stepped system call
#
.Lpgm_svcper:
	mvc	__LC_RETURN_PSW(8),__LC_SVC_NEW_PSW
	larl	%r14,.Lsysc_per
	stg	%r14,__LC_RETURN_PSW+8
	lghi	%r14,1
	LBEAR	__LC_PGM_LAST_BREAK
	LPSWEY	__LC_RETURN_PSW,__LC_RETURN_LPSWE # branch to .Lsysc_per
ENDPROC(pgm_check_handler)

/*
 * Interrupt handler macro used for external and IO interrupts.
 */
.macro INT_HANDLER name,lc_old_psw,handler
ENTRY(\name)
	STCK	__LC_INT_CLOCK
	stpt	__LC_SYS_ENTER_TIMER
	STBEAR	__LC_LAST_BREAK
	BPOFF
	stmg	%r8,%r15,__LC_SAVE_AREA_ASYNC
	lg	%r12,__LC_CURRENT
	lmg	%r8,%r9,\lc_old_psw
	tmhh	%r8,0x0001			# interrupting from user ?
	jnz	1f
#if IS_ENABLED(CONFIG_KVM)
	OUTSIDE	%r9,.Lsie_gmap,.Lsie_done,0f
	BPENTER	__SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
	SIEEXIT
#endif
0:	CHECK_STACK __LC_SAVE_AREA_ASYNC
	aghi	%r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
	j	2f
1:	BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
	lctlg	%c1,%c1,__LC_KERNEL_ASCE
	lg	%r15,__LC_KERNEL_STACK
2:	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
	la	%r11,STACK_FRAME_OVERHEAD(%r15)
	stmg	%r0,%r7,__PT_R0(%r11)
	# clear user controlled registers to prevent speculative use
	xgr	%r0,%r0
	xgr	%r1,%r1
	xgr	%r3,%r3
	xgr	%r4,%r4
	xgr	%r5,%r5
	xgr	%r6,%r6
	xgr	%r7,%r7
	xgr	%r10,%r10
	xc	__PT_FLAGS(8,%r11),__PT_FLAGS(%r11)
	mvc	__PT_R8(64,%r11),__LC_SAVE_AREA_ASYNC
	MBEAR	%r11
	stmg	%r8,%r9,__PT_PSW(%r11)
	tm	%r8,0x0001		# coming from user space?
	jno	1f
	lctlg	%c1,%c1,__LC_KERNEL_ASCE
1:	lgr	%r2,%r11		# pass pointer to pt_regs
	brasl	%r14,\handler
	mvc	__LC_RETURN_PSW(16),__PT_PSW(%r11)
	tmhh	%r8,0x0001		# returning to user ?
	jno	2f
	lctlg	%c1,%c1,__LC_USER_ASCE
	BPEXIT	__TI_flags(%r12),_TIF_ISOLATE_BP
	stpt	__LC_EXIT_TIMER
2:	LBEAR	__PT_LAST_BREAK(%r11)
	lmg	%r0,%r15,__PT_R0(%r11)
	LPSWEY	__LC_RETURN_PSW,__LC_RETURN_LPSWE
ENDPROC(\name)
.endm

INT_HANDLER ext_int_handler,__LC_EXT_OLD_PSW,do_ext_irq
INT_HANDLER io_int_handler,__LC_IO_OLD_PSW,do_io_irq

/*
 * Load idle PSW.
 */
ENTRY(psw_idle)
	stg	%r14,(__SF_GPRS+8*8)(%r15)
	stg	%r3,__SF_EMPTY(%r15)
	larl	%r1,psw_idle_exit
	stg	%r1,__SF_EMPTY+8(%r15)
	larl	%r1,smp_cpu_mtid
	llgf	%r1,0(%r1)
	ltgr	%r1,%r1
	jz	.Lpsw_idle_stcctm
	.insn	rsy,0xeb0000000017,%r1,5,__MT_CYCLES_ENTER(%r2)
.Lpsw_idle_stcctm:
	oi	__LC_CPU_FLAGS+7,_CIF_ENABLED_WAIT
	BPON
	STCK	__CLOCK_IDLE_ENTER(%r2)
	stpt	__TIMER_IDLE_ENTER(%r2)
	lpswe	__SF_EMPTY(%r15)
.globl psw_idle_exit
psw_idle_exit:
	BR_EX	%r14
ENDPROC(psw_idle)

/*
 * Machine check handler routines
 */
ENTRY(mcck_int_handler)
	STCK	__LC_MCCK_CLOCK
	BPOFF
	la	%r1,4095		# validate r1
	spt	__LC_CPU_TIMER_SAVE_AREA-4095(%r1)	# validate cpu timer
	LBEAR	__LC_LAST_BREAK_SAVE_AREA-4095(%r1)		# validate bear
	lmg	%r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r1)# validate gprs
	lg	%r12,__LC_CURRENT
	lmg	%r8,%r9,__LC_MCK_OLD_PSW
	TSTMSK	__LC_MCCK_CODE,MCCK_CODE_SYSTEM_DAMAGE
	jo	.Lmcck_panic		# yes -> rest of mcck code invalid
	TSTMSK	__LC_MCCK_CODE,MCCK_CODE_CR_VALID
	jno	.Lmcck_panic		# control registers invalid -> panic
	la	%r14,4095
	lctlg	%c0,%c15,__LC_CREGS_SAVE_AREA-4095(%r14) # validate ctl regs
	ptlb
	lghi	%r14,__LC_CPU_TIMER_SAVE_AREA
	mvc	__LC_MCCK_ENTER_TIMER(8),0(%r14)
	TSTMSK	__LC_MCCK_CODE,MCCK_CODE_CPU_TIMER_VALID
	jo	3f
	la	%r14,__LC_SYS_ENTER_TIMER
	clc	0(8,%r14),__LC_EXIT_TIMER
	jl	1f
	la	%r14,__LC_EXIT_TIMER
1:	clc	0(8,%r14),__LC_LAST_UPDATE_TIMER
	jl	2f
	la	%r14,__LC_LAST_UPDATE_TIMER
2:	spt	0(%r14)
	mvc	__LC_MCCK_ENTER_TIMER(8),0(%r14)
3:	TSTMSK	__LC_MCCK_CODE,MCCK_CODE_PSW_MWP_VALID
	jno	.Lmcck_panic
	tmhh	%r8,0x0001		# interrupting from user ?
	jnz	6f
	TSTMSK	__LC_MCCK_CODE,MCCK_CODE_PSW_IA_VALID
	jno	.Lmcck_panic
#if IS_ENABLED(CONFIG_KVM)
	OUTSIDE	%r9,.Lsie_gmap,.Lsie_done,6f
	OUTSIDE	%r9,.Lsie_entry,.Lsie_skip,4f
	oi	__LC_CPU_FLAGS+7, _CIF_MCCK_GUEST
	j	5f
4:	CHKSTG	.Lmcck_panic
5:	larl	%r14,.Lstosm_tmp
	stosm	0(%r14),0x04		# turn dat on, keep irqs off
	BPENTER	__SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
	SIEEXIT
	j	.Lmcck_stack
#endif
6:	CHKSTG	.Lmcck_panic
	larl	%r14,.Lstosm_tmp
	stosm	0(%r14),0x04		# turn dat on, keep irqs off
	tmhh	%r8,0x0001		# interrupting from user ?
	jz	.Lmcck_stack
	BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
.Lmcck_stack:
	lg	%r15,__LC_MCCK_STACK
	la	%r11,STACK_FRAME_OVERHEAD(%r15)
	stctg	%c1,%c1,__PT_CR1(%r11)
	lctlg	%c1,%c1,__LC_KERNEL_ASCE
	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
	lghi	%r14,__LC_GPREGS_SAVE_AREA+64
	stmg	%r0,%r7,__PT_R0(%r11)
	# clear user controlled registers to prevent speculative use
	xgr	%r0,%r0
	xgr	%r1,%r1
	xgr	%r3,%r3
	xgr	%r4,%r4
	xgr	%r5,%r5
	xgr	%r6,%r6
	xgr	%r7,%r7
	xgr	%r10,%r10
	mvc	__PT_R8(64,%r11),0(%r14)
	stmg	%r8,%r9,__PT_PSW(%r11)
	xc	__PT_FLAGS(8,%r11),__PT_FLAGS(%r11)
	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
	lgr	%r2,%r11		# pass pointer to pt_regs
	brasl	%r14,s390_do_machine_check
	cghi	%r2,0
	je	.Lmcck_return
	lg	%r1,__LC_KERNEL_STACK	# switch to kernel stack
	mvc	STACK_FRAME_OVERHEAD(__PT_SIZE,%r1),0(%r11)
	xc	__SF_BACKCHAIN(8,%r1),__SF_BACKCHAIN(%r1)
	la	%r11,STACK_FRAME_OVERHEAD(%r1)
	lgr	%r15,%r1
	brasl	%r14,s390_handle_mcck
.Lmcck_return:
	lctlg	%c1,%c1,__PT_CR1(%r11)
	lmg	%r0,%r10,__PT_R0(%r11)
	mvc	__LC_RETURN_MCCK_PSW(16),__PT_PSW(%r11) # move return PSW
	tm	__LC_RETURN_MCCK_PSW+1,0x01 # returning to user ?
	jno	0f
	BPEXIT	__TI_flags(%r12),_TIF_ISOLATE_BP
	stpt	__LC_EXIT_TIMER
0:	ALTERNATIVE "", __stringify(lghi %r12,__LC_LAST_BREAK_SAVE_AREA),193
	LBEAR	0(%r12)
	lmg	%r11,%r15,__PT_R11(%r11)
	LPSWEY	__LC_RETURN_MCCK_PSW,__LC_RETURN_MCCK_LPSWE

.Lmcck_panic:
	/*
	 * Iterate over all possible CPU addresses in the range 0..0xffff
	 * and stop each CPU using signal processor. Use compare and swap
	 * to allow just one CPU-stopper and prevent concurrent CPUs from
	 * stopping each other while leaving the others running.
	 */
	lhi	%r5,0
	lhi	%r6,1
	larl	%r7,.Lstop_lock
	cs	%r5,%r6,0(%r7)		# single CPU-stopper only
	jnz	4f
	larl	%r7,.Lthis_cpu
	stap	0(%r7)			# this CPU address
	lh	%r4,0(%r7)
	nilh	%r4,0
	lhi	%r0,1
	sll	%r0,16			# CPU counter
	lhi	%r3,0			# next CPU address
0:	cr	%r3,%r4
	je	2f
1:	sigp	%r1,%r3,SIGP_STOP	# stop next CPU
	brc	SIGP_CC_BUSY,1b
2:	ahi	%r3,1
	brct	%r0,0b
3:	sigp	%r1,%r4,SIGP_STOP	# stop this CPU
	brc	SIGP_CC_BUSY,3b
4:	j	4b
ENDPROC(mcck_int_handler)

ENTRY(restart_int_handler)
	ALTERNATIVE "", ".insn s,0xb2800000,_LPP_OFFSET", 40
	stg	%r15,__LC_SAVE_AREA_RESTART
	TSTMSK	__LC_RESTART_FLAGS,RESTART_FLAG_CTLREGS,4
	jz	0f
	la	%r15,4095
	lctlg	%c0,%c15,__LC_CREGS_SAVE_AREA-4095(%r15)
0:	larl	%r15,.Lstosm_tmp
	stosm	0(%r15),0x04			# turn dat on, keep irqs off
	lg	%r15,__LC_RESTART_STACK
	xc	STACK_FRAME_OVERHEAD(__PT_SIZE,%r15),STACK_FRAME_OVERHEAD(%r15)
	stmg	%r0,%r14,STACK_FRAME_OVERHEAD+__PT_R0(%r15)
	mvc	STACK_FRAME_OVERHEAD+__PT_R15(8,%r15),__LC_SAVE_AREA_RESTART
	mvc	STACK_FRAME_OVERHEAD+__PT_PSW(16,%r15),__LC_RST_OLD_PSW
	xc	0(STACK_FRAME_OVERHEAD,%r15),0(%r15)
	lg	%r1,__LC_RESTART_FN		# load fn, parm & source cpu
	lg	%r2,__LC_RESTART_DATA
	lgf	%r3,__LC_RESTART_SOURCE
	ltgr	%r3,%r3				# test source cpu address
	jm	1f				# negative -> skip source stop
0:	sigp	%r4,%r3,SIGP_SENSE		# sigp sense to source cpu
	brc	10,0b				# wait for status stored
1:	basr	%r14,%r1			# call function
	stap	__SF_EMPTY(%r15)		# store cpu address
	llgh	%r3,__SF_EMPTY(%r15)
2:	sigp	%r4,%r3,SIGP_STOP		# sigp stop to current cpu
	brc	2,2b
3:	j	3b
ENDPROC(restart_int_handler)

	.section .kprobes.text, "ax"

#if defined(CONFIG_CHECK_STACK) || defined(CONFIG_VMAP_STACK)
/*
 * The synchronous or the asynchronous stack overflowed. We are dead.
 * No need to properly save the registers, we are going to panic anyway.
 * Setup a pt_regs so that show_trace can provide a good call trace.
 */
ENTRY(stack_overflow)
	lg	%r15,__LC_NODAT_STACK	# change to panic stack
	la	%r11,STACK_FRAME_OVERHEAD(%r15)
	stmg	%r0,%r7,__PT_R0(%r11)
	stmg	%r8,%r9,__PT_PSW(%r11)
	mvc	__PT_R8(64,%r11),0(%r14)
	stg	%r10,__PT_ORIG_GPR2(%r11) # store last break to orig_gpr2
	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
	lgr	%r2,%r11		# pass pointer to pt_regs
	jg	kernel_stack_overflow
ENDPROC(stack_overflow)
#endif

	.section .data, "aw"
		.align	4
.Lstop_lock:	.long	0
.Lthis_cpu:	.short	0
.Lstosm_tmp:	.byte	0
	.section .rodata, "a"
#define SYSCALL(esame,emu)	.quad __s390x_ ## esame
	.globl	sys_call_table
sys_call_table:
#include "asm/syscall_table.h"
#undef SYSCALL

#ifdef CONFIG_COMPAT

#define SYSCALL(esame,emu)	.quad __s390_ ## emu
	.globl	sys_call_table_emu
sys_call_table_emu:
#include "asm/syscall_table.h"
#undef SYSCALL
#endif