[PATCH] s390: improved machine check handling

Improved machine check handling.  Kernel is now able to receive machine checks
while in kernel mode (system call, interrupt and program check handling).
Also register validation is now performed.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 93 insertions, 9 deletions

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index c0e09b33feb..5b262b5d869 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -7,6 +7,7 @@
  *    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/sys.h>
@@ -49,9 +50,9 @@ SP_ILC       =  STACK_FRAME_OVERHEAD + __PT_ILC
 SP_TRAP      =  STACK_FRAME_OVERHEAD + __PT_TRAP
 SP_SIZE      =  STACK_FRAME_OVERHEAD + __PT_SIZE
 
-_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
+_TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_MCCK_PENDING | \
 		 _TIF_RESTART_SVC | _TIF_SINGLE_STEP )
-_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NEED_RESCHED)
+_TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NEED_RESCHED | _TIF_MCCK_PENDING)
 
 STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
 STACK_SIZE  = 1 << STACK_SHIFT
@@ -121,7 +122,11 @@ STACK_SIZE  = 1 << STACK_SHIFT
 	bz	BASED(stack_overflow)
 3:
 #endif
-2:	s	%r15,BASED(.Lc_spsize)	# make room for registers & psw
+2:
+	.endm
+
+	.macro  CREATE_STACK_FRAME psworg,savearea
+	s	%r15,BASED(.Lc_spsize)	# make room for registers & psw
 	mvc	SP_PSW(8,%r15),0(%r12)	# move user PSW to stack
 	la	%r12,\psworg
 	st	%r2,SP_ORIG_R2(%r15)	# store original content of gpr 2
@@ -161,6 +166,13 @@ __switch_to_base:
         be      __switch_to_noper-__switch_to_base(%r1)	# we got away w/o bashing TLB's
         lctl    %c9,%c11,__THREAD_per(%r3)	# Nope we didn't
 __switch_to_noper:
+	l	%r4,__THREAD_info(%r2)		# get thread_info of prev
+	tm	__TI_flags+3(%r4),_TIF_MCCK_PENDING # machine check pending?
+	bz	__switch_to_no_mcck-__switch_to_base(%r1)
+	ni	__TI_flags+3(%r4),255-_TIF_MCCK_PENDING # clear flag in prev
+	l	%r4,__THREAD_info(%r3)		# get thread_info of next
+	oi	__TI_flags+3(%r4),_TIF_MCCK_PENDING # set it in next
+__switch_to_no_mcck:
         stm     %r6,%r15,__SF_GPRS(%r15)# store __switch_to registers of prev task
 	st	%r15,__THREAD_ksp(%r2)	# store kernel stack to prev->tss.ksp
 	l	%r15,__THREAD_ksp(%r3)	# load kernel stack from next->tss.ksp
@@ -185,6 +197,7 @@ system_call:
 sysc_saveall:
 	SAVE_ALL_BASE __LC_SAVE_AREA
         SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1
+	CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA
 	lh	%r7,0x8a	  # get svc number from lowcore
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 sysc_vtime:
@@ -234,6 +247,8 @@ sysc_work_loop:
 # One of the work bits is on. Find out which one.
 #
 sysc_work:
+	tm	__TI_flags+3(%r9),_TIF_MCCK_PENDING
+	bo	BASED(sysc_mcck_pending)
 	tm	__TI_flags+3(%r9),_TIF_NEED_RESCHED
 	bo	BASED(sysc_reschedule)
 	tm	__TI_flags+3(%r9),_TIF_SIGPENDING
@@ -253,6 +268,14 @@ sysc_reschedule:
 	br      %r1		       # call scheduler
 
 #
+# _TIF_MCCK_PENDING is set, call handler
+#
+sysc_mcck_pending:
+	l	%r1,BASED(.Ls390_handle_mcck)
+	la	%r14,BASED(sysc_work_loop)
+	br	%r1			# TIF bit will be cleared by handler
+
+#
 # _TIF_SIGPENDING is set, call do_signal
 #
 sysc_sigpending:     
@@ -430,6 +453,7 @@ pgm_check_handler:
         tm      __LC_PGM_INT_CODE+1,0x80 # check whether we got a per exception
         bnz     BASED(pgm_per)           # got per exception -> special case
 	SAVE_ALL __LC_PGM_OLD_PSW,__LC_SAVE_AREA,1
+	CREATE_STACK_FRAME __LC_PGM_OLD_PSW,__LC_SAVE_AREA
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
 	bz	BASED(pgm_no_vtime)
@@ -468,6 +492,7 @@ pgm_per:
 #
 pgm_per_std:
 	SAVE_ALL __LC_PGM_OLD_PSW,__LC_SAVE_AREA,1
+	CREATE_STACK_FRAME __LC_PGM_OLD_PSW,__LC_SAVE_AREA
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
 	bz	BASED(pgm_no_vtime2)
@@ -493,6 +518,7 @@ pgm_no_vtime2:
 #
 pgm_svcper:
 	SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1
+	CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
 	bz	BASED(pgm_no_vtime3)
@@ -521,6 +547,7 @@ io_int_handler:
 	stck	__LC_INT_CLOCK
 	SAVE_ALL_BASE __LC_SAVE_AREA+16
         SAVE_ALL __LC_IO_OLD_PSW,__LC_SAVE_AREA+16,0
+	CREATE_STACK_FRAME __LC_IO_OLD_PSW,__LC_SAVE_AREA+16
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
 	bz	BASED(io_no_vtime)
@@ -578,9 +605,11 @@ io_work:
 	lr	%r15,%r1
 #
 # One of the work bits is on. Find out which one.
-# Checked are: _TIF_SIGPENDING and _TIF_NEED_RESCHED
+# Checked are: _TIF_SIGPENDING, _TIF_NEED_RESCHED and _TIF_MCCK_PENDING
 #
 io_work_loop:
+	tm	__TI_flags+3(%r9),_TIF_MCCK_PENDING
+	bo      BASED(io_mcck_pending)
 	tm	__TI_flags+3(%r9),_TIF_NEED_RESCHED
 	bo	BASED(io_reschedule)
 	tm	__TI_flags+3(%r9),_TIF_SIGPENDING
@@ -588,6 +617,14 @@ io_work_loop:
 	b	BASED(io_leave)
 
 #
+# _TIF_MCCK_PENDING is set, call handler
+#
+io_mcck_pending:
+	l	%r1,BASED(.Ls390_handle_mcck)
+	l	%r14,BASED(io_work_loop)
+	br	%r1		       # TIF bit will be cleared by handler
+
+#
 # _TIF_NEED_RESCHED is set, call schedule
 #	
 io_reschedule:        
@@ -621,6 +658,7 @@ ext_int_handler:
 	stck	__LC_INT_CLOCK
 	SAVE_ALL_BASE __LC_SAVE_AREA+16
         SAVE_ALL __LC_EXT_OLD_PSW,__LC_SAVE_AREA+16,0
+	CREATE_STACK_FRAME __LC_EXT_OLD_PSW,__LC_SAVE_AREA+16
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
 	bz	BASED(ext_no_vtime)
@@ -642,19 +680,62 @@ ext_no_vtime:
 
         .globl mcck_int_handler
 mcck_int_handler:
-	STORE_TIMER __LC_ASYNC_ENTER_TIMER
+	spt	__LC_CPU_TIMER_SAVE_AREA	# revalidate cpu timer
+	lm	%r0,%r15,__LC_GPREGS_SAVE_AREA	# revalidate gprs
 	SAVE_ALL_BASE __LC_SAVE_AREA+32
-        SAVE_ALL __LC_MCK_OLD_PSW,__LC_SAVE_AREA+32,0
+	la	%r12,__LC_MCK_OLD_PSW
+	tm	__LC_MCCK_CODE,0x80     # system damage?
+	bo	BASED(mcck_int_main)	# yes -> rest of mcck code invalid
+	tm	__LC_MCCK_CODE+5,0x02   # stored cpu timer value valid?
+	bo	BASED(0f)
+	spt	__LC_LAST_UPDATE_TIMER	# revalidate cpu timer
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
-	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?
+	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_ASYNC_ENTER_TIMER
+	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
+	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_EXIT_TIMER
+0:	tm	__LC_MCCK_CODE+2,0x08   # mwp of old psw valid?
+	bno	BASED(mcck_no_vtime)	# no -> skip cleanup critical
+	tm	__LC_MCK_OLD_PSW+1,0x01 # interrupting from user ?
 	bz	BASED(mcck_no_vtime)
 	UPDATE_VTIME __LC_EXIT_TIMER,__LC_ASYNC_ENTER_TIMER,__LC_USER_TIMER
 	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
 	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_ASYNC_ENTER_TIMER
 mcck_no_vtime:
 #endif
+0:
+	tm	__LC_MCCK_CODE+2,0x09   # mwp + ia of old psw valid?
+	bno	BASED(mcck_int_main)	# no -> skip cleanup critical
+	tm	__LC_MCK_OLD_PSW+1,0x01	# test problem state bit
+	bnz	BASED(mcck_int_main)	# from user -> load async stack
+	clc	__LC_MCK_OLD_PSW+4(4),BASED(.Lcritical_end)
+	bhe	BASED(mcck_int_main)
+	clc	__LC_MCK_OLD_PSW+4(4),BASED(.Lcritical_start)
+	bl	BASED(mcck_int_main)
+	l	%r14,BASED(.Lcleanup_critical)
+	basr	%r14,%r14
+mcck_int_main:
+	l	%r14,__LC_PANIC_STACK	# are we already on the panic stack?
+	slr	%r14,%r15
+	sra	%r14,PAGE_SHIFT
+	be	BASED(0f)
+	l	%r15,__LC_PANIC_STACK	# load panic stack
+0:	CREATE_STACK_FRAME __LC_MCK_OLD_PSW,__LC_SAVE_AREA+32
+	l	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct
+	la	%r2,SP_PTREGS(%r15)	# load pt_regs
 	l       %r1,BASED(.Ls390_mcck)
-	basr    %r14,%r1	  # call machine check handler
+	basr    %r14,%r1		# call machine check handler
+	tm      SP_PSW+1(%r15),0x01	# returning to user ?
+	bno	BASED(mcck_return)
+	l	%r1,__LC_KERNEL_STACK   # switch to kernel stack
+	s	%r1,BASED(.Lc_spsize)
+	mvc	SP_PTREGS(__PT_SIZE,%r1),SP_PTREGS(%r15)
+	xc      __SF_BACKCHAIN(4,%r1),__SF_BACKCHAIN(%r1) # clear back chain
+	lr	%r15,%r1
+	stosm	__SF_EMPTY(%r15),0x04	# turn dat on
+	tm	__TI_flags+3(%r9),_TIF_MCCK_PENDING
+	bno	BASED(mcck_return)
+	l	%r1,BASED(.Ls390_handle_mcck)
+	basr	%r14,%r1		# call machine check handler
 mcck_return:
         RESTORE_ALL 0
 
@@ -742,7 +823,7 @@ cleanup_critical:
 	clc	4(4,%r12),BASED(cleanup_table_sysc_work_loop)
 	bl	BASED(0f)
 	clc	4(4,%r12),BASED(cleanup_table_sysc_work_loop+4)
-	bl	BASED(cleanup_sysc_leave)
+	bl	BASED(cleanup_sysc_return)
 0:
 	br	%r14
 
@@ -760,6 +841,7 @@ cleanup_system_call:
 	mvc	__LC_SAVE_AREA(16),__LC_SAVE_AREA+16
 0:	st	%r13,__LC_SAVE_AREA+20
 	SAVE_ALL __LC_SVC_OLD_PSW,__LC_SAVE_AREA,1
+	CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA
 	st	%r15,__LC_SAVE_AREA+28
 	lh	%r7,0x8a
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
@@ -834,6 +916,8 @@ cleanup_sysc_leave_insn:
  * Symbol constants
  */
 .Ls390_mcck:   .long  s390_do_machine_check
+.Ls390_handle_mcck:
+	       .long  s390_handle_mcck
 .Ldo_IRQ:      .long  do_IRQ
 .Ldo_extint:   .long  do_extint
 .Ldo_signal:   .long  do_signal