path: root/arch/s390/kernel/entry.S

/* 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),
 *		 Heiko Carstens <heiko.carstens@de.ibm.com>
 */

#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/alternative-asm.h>
#include <asm/processor.h>
#include <asm/cache.h>
#include <asm/ctl_reg.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

_TIF_WORK	= (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
		   _TIF_UPROBE | _TIF_GUARDED_STORAGE | _TIF_PATCH_PENDING)
_TIF_TRACE	= (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \
		   _TIF_SYSCALL_TRACEPOINT)
_CIF_WORK	= (_CIF_MCCK_PENDING | _CIF_ASCE_PRIMARY | \
		   _CIF_ASCE_SECONDARY | _CIF_FPU)
_PIF_WORK	= (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART)

_LPP_OFFSET	= __LC_LPP

#define BASED(name) name-cleanup_critical(%r13)

	.macro	TRACE_IRQS_ON
#ifdef CONFIG_TRACE_IRQFLAGS
	basr	%r2,%r0
	brasl	%r14,trace_hardirqs_on_caller
#endif
	.endm

	.macro	TRACE_IRQS_OFF
#ifdef CONFIG_TRACE_IRQFLAGS
	basr	%r2,%r0
	brasl	%r14,trace_hardirqs_off_caller
#endif
	.endm

	.macro	LOCKDEP_SYS_EXIT
#ifdef CONFIG_LOCKDEP
	tm	__PT_PSW+1(%r11),0x01	# returning to user ?
	jz	.+10
	brasl	%r14,lockdep_sys_exit
#endif
	.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_NODAT_STACK
	je	\oklabel
	clg	%r14,__LC_RESTART_STACK
	je	\oklabel
	lghi	%r14,\savearea
	j	stack_overflow
#else
	j	\oklabel
#endif
	.endm

	.macro	SWITCH_ASYNC savearea,timer
	tmhh	%r8,0x0001		# interrupting from user ?
	jnz	1f
	lgr	%r14,%r9
	slg	%r14,BASED(.Lcritical_start)
	clg	%r14,BASED(.Lcritical_length)
	jhe	0f
	lghi	%r11,\savearea		# inside critical section, do cleanup
	brasl	%r14,cleanup_critical
	tmhh	%r8,0x0001		# retest problem state after cleanup
	jnz	1f
0:	lg	%r14,__LC_ASYNC_STACK	# are we already on the target stack?
	slgr	%r14,%r15
	srag	%r14,%r14,STACK_SHIFT
	jnz	2f
	CHECK_STACK \savearea
	aghi	%r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
	j	3f
1:	UPDATE_VTIME %r14,%r15,\timer
	BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
2:	lg	%r15,__LC_ASYNC_STACK	# load async stack
3:	la	%r11,STACK_FRAME_OVERHEAD(%r15)
	.endm

	.macro UPDATE_VTIME w1,w2,enter_timer
	lg	\w1,__LC_EXIT_TIMER
	lg	\w2,__LC_LAST_UPDATE_TIMER
	slg	\w1,\enter_timer
	slg	\w2,__LC_EXIT_TIMER
	alg	\w1,__LC_USER_TIMER
	alg	\w2,__LC_SYSTEM_TIMER
	stg	\w1,__LC_USER_TIMER
	stg	\w2,__LC_SYSTEM_TIMER
	mvc	__LC_LAST_UPDATE_TIMER(8),\enter_timer
	.endm

	.macro REENABLE_IRQS
	stg	%r8,__LC_RETURN_PSW
	ni	__LC_RETURN_PSW,0xbf
	ssm	__LC_RETURN_PSW
	.endm

	.macro STCK savearea
#ifdef CONFIG_HAVE_MARCH_Z9_109_FEATURES
	.insn	s,0xb27c0000,\savearea		# store clock fast
#else
	.insn	s,0xb2050000,\savearea		# store clock
#endif
	.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

	GEN_BR_THUNK %r9
	GEN_BR_THUNK %r14
	GEN_BR_THUNK %r14,%r11

	.section .kprobes.text, "ax"
.Ldummy:
	/*
	 * This nop exists only in order to avoid that __switch_to 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 __switch_to symbol is unique
	 * again.
	 */
	nop	0

ENTRY(__bpon)
	.globl __bpon
	BPON
	BR_EX	%r14

/*
 * 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

.L__critical_start:

#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
	TSTMSK	__LC_CPU_FLAGS,_CIF_FPU		# load guest fp/vx registers ?
	jno	.Lsie_load_guest_gprs
	brasl	%r14,load_fpu_regs		# load guest fp/vx regs
.Lsie_load_guest_gprs:
	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		# la