[S390] add breaking event address for user space

Copy the last breaking event address from the lowcore to a new
field in the thread_struct on each system entry. Add a new
ptrace request PTRACE_GET_LAST_BREAK and a new utrace regset
REGSET_LAST_BREAK to query the last breaking event.

This is useful for debugging wild branches in user space code.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

8 files changed, 223 insertions, 127 deletions

diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index fef9b33cdd59..e2c218dc68a6 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -328,8 +328,8 @@ struct pt_regs
         psw_t psw;
         unsigned long gprs[NUM_GPRS];
         unsigned long orig_gpr2;
-        unsigned short svcnr;
         unsigned short ilc;
+        unsigned short svcnr;
 };
 #endif
 
@@ -436,6 +436,7 @@ typedef struct
 #define PTRACE_PEEKDATA_AREA          0x5003
 #define PTRACE_POKETEXT_AREA          0x5004
 #define PTRACE_POKEDATA_AREA          0x5005
+#define PTRACE_GET_LAST_BREAK         0x5006
 
 /*
  * PT_PROT definition is loosely based on hppa bsd definition in
diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
index 34f0873d6525..be3d3f91d86c 100644
--- a/arch/s390/include/asm/thread_info.h
+++ b/arch/s390/include/asm/thread_info.h
@@ -50,6 +50,7 @@ struct thread_info {
         struct restart_block    restart_block;
         __u64                   user_timer;
         __u64                   system_timer;
+        unsigned long           last_break;     /* last breaking-event-address. */
 };
 
 /*
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 44a4336d9a33..d9b490a2716e 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -39,6 +39,7 @@ int main(void)
         DEFINE(__TI_precount, offsetof(struct thread_info, preempt_count));
         DEFINE(__TI_user_timer, offsetof(struct thread_info, user_timer));
         DEFINE(__TI_system_timer, offsetof(struct thread_info, system_timer));
+        DEFINE(__TI_last_break, offsetof(struct thread_info, last_break));
         BLANK();
         DEFINE(__PT_ARGS, offsetof(struct pt_regs, args));
         DEFINE(__PT_PSW, offsetof(struct pt_regs, psw));
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 0e2b16241dfa..d5e3e6007447 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -180,9 +180,9 @@ STACK_SIZE  = 1 << STACK_SHIFT
         s       %r15,BASED(.Lc_spsize)  # make room for registers & psw
         mvc     SP_PSW(8,%r15),0(%r12)  # move user PSW to stack
         st      %r2,SP_ORIG_R2(%r15)    # store original content of gpr 2
-        icm     %r12,3,__LC_SVC_ILC
+        icm     %r12,12,__LC_SVC_ILC
         stm     %r0,%r11,SP_R0(%r15)    # store gprs %r0-%r11 to kernel stack
-        st      %r12,SP_SVCNR(%r15)
+        st      %r12,SP_ILC(%r15)
         mvc     SP_R12(16,%r15),\savearea # move %r12-%r15 to stack
         la      %r12,0
         st      %r12,__SF_BACKCHAIN(%r15)       # clear back chain
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 829b759ba1e1..178d92536d90 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -126,31 +126,35 @@ _TIF_SYSCALL = (_TIF_SYSCALL_TRACE>>8 | _TIF_SYSCALL_AUDIT>>8 | \
  *    R15 - kernel stack pointer
  */
 
-        .macro  SAVE_ALL_BASE savearea
-        stmg    %r12,%r15,\savearea
-        larl    %r13,system_call
-        .endm
-
         .macro  SAVE_ALL_SVC psworg,savearea
-        la      %r12,\psworg
+        stmg    %r11,%r15,\savearea
         lg      %r15,__LC_KERNEL_STACK  # problem state -> load ksp
+        aghi    %r15,-SP_SIZE           # make room for registers & psw
+        lg      %r11,__LC_LAST_BREAK
         .endm
 
-        .macro  SAVE_ALL_SYNC psworg,savearea
-        la      %r12,\psworg
+        .macro  SAVE_ALL_PGM psworg,savearea
+        stmg    %r11,%r15,\savearea
         tm      \psworg+1,0x01          # test problem state bit
-        jz      2f                      # skip stack setup save
-        lg      %r15,__LC_KERNEL_STACK  # problem state -> load ksp
 #ifdef CONFIG_CHECK_STACK
-        j       3f
-2:      tml     %r15,STACK_SIZE - CONFIG_STACK_GUARD
-        jz      stack_overflow
-3:
+        jnz     1f
+        tml     %r15,STACK_SIZE - CONFIG_STACK_GUARD
+        jnz     2f
+        la      %r12,\psworg
+        j       stack_overflow
+#else
+        jz      2f
 #endif
-2:
+1:      lg      %r15,__LC_KERNEL_STACK  # problem state -> load ksp
+2:      aghi    %r15,-SP_SIZE           # make room for registers & psw
+        larl    %r13,system_call
+        lg      %r11,__LC_LAST_BREAK
         .endm
 
         .macro  SAVE_ALL_ASYNC psworg,savearea
+        stmg    %r11,%r15,\savearea
+        larl    %r13,system_call
+        lg      %r11,__LC_LAST_BREAK
         la      %r12,\psworg
         tm      \psworg+1,0x01          # test problem state bit
         jnz     1f                      # from user -> load kernel stack
@@ -164,27 +168,23 @@ _TIF_SYSCALL = (_TIF_SYSCALL_TRACE>>8 | _TIF_SYSCALL_AUDIT>>8 | \
 0:      lg      %r14,__LC_ASYNC_STACK   # are we already on the async. stack ?
         slgr    %r14,%r15
         srag    %r14,%r14,STACK_SHIFT
-        jz      2f
-1:      lg      %r15,__LC_ASYNC_STACK   # load async stack
 #ifdef CONFIG_CHECK_STACK
-        j       3f
-2:      tml     %r15,STACK_SIZE - CONFIG_STACK_GUARD
-        jz      stack_overflow
-3:
+        jnz     1f
+        tml     %r15,STACK_SIZE - CONFIG_STACK_GUARD
+        jnz     2f
+        j       stack_overflow
+#else
+        jz      2f
 #endif
-2:
+1:      lg      %r15,__LC_ASYNC_STACK   # load async stack
+2:      aghi    %r15,-SP_SIZE           # make room for registers & psw
         .endm
 
-        .macro  CREATE_STACK_FRAME psworg,savearea
-        aghi    %r15,-SP_SIZE           # make room for registers & psw
-        mvc     SP_PSW(16,%r15),0(%r12) # move user PSW to stack
+        .macro  CREATE_STACK_FRAME savearea
+        xc      __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
         stg     %r2,SP_ORIG_R2(%r15)    # store original content of gpr 2
-        icm     %r12,3,__LC_SVC_ILC
-        stmg    %r0,%r11,SP_R0(%r15)    # store gprs %r0-%r11 to kernel stack
-        st      %r12,SP_SVCNR(%r15)
-        mvc     SP_R12(32,%r15),\savearea # move %r12-%r15 to stack
-        la      %r12,0
-        stg     %r12,__SF_BACKCHAIN(%r15)
+        mvc     SP_R11(40,%r15),\savearea # move %r11-%r15 to stack
+        stmg    %r0,%r10,SP_R0(%r15)    # store gprs %r0-%r10 to kernel stack
         .endm
 
         .macro  RESTORE_ALL psworg,sync
@@ -200,6 +200,13 @@ _TIF_SYSCALL = (_TIF_SYSCALL_TRACE>>8 | _TIF_SYSCALL_AUDIT>>8 | \
         lpswe   \psworg                 # back to caller
         .endm
 
+        .macro  LAST_BREAK
+        srag    %r10,%r11,23
+        jz      0f
+        stg     %r11,__TI_last_break(%r12)
+0:
+        .endm
+
 /*
  * Scheduler resume function, called by switch_to
  *  gpr2 = (task_struct *) prev
@@ -245,37 +252,38 @@ __critical_start:
 system_call:
         stpt    __LC_SYNC_ENTER_TIMER
 sysc_saveall:
-        SAVE_ALL_BASE __LC_SAVE_AREA
         SAVE_ALL_SVC __LC_SVC_OLD_PSW,__LC_SAVE_AREA
-        CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA
-        llgh    %r7,__LC_SVC_INT_CODE   # get svc number from lowcore
+        CREATE_STACK_FRAME __LC_SAVE_AREA
+        mvc     SP_PSW(16,%r15),__LC_SVC_OLD_PSW
+        mvc     SP_ILC(4,%r15),__LC_SVC_ILC
+        stg     %r7,SP_ARGS(%r15)
+        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
 sysc_vtime:
         UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
 sysc_stime:
         UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
 sysc_update:
         mvc     __LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
+        LAST_BREAK
 sysc_do_svc:
-        lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
-        ltgr    %r7,%r7         # test for svc 0
+        llgh    %r7,SP_SVCNR(%r15)
+        slag    %r7,%r7,2       # shift and test for svc 0
         jnz     sysc_nr_ok
         # svc 0: system call number in %r1
-        cl      %r1,BASED(.Lnr_syscalls)
+        llgfr   %r1,%r1         # clear high word in r1
+        cghi    %r1,NR_syscalls
         jnl     sysc_nr_ok
-        lgfr    %r7,%r1         # clear high word in r1
+        sth     %r1,SP_SVCNR(%r15)
+        slag    %r7,%r1,2       # shift and test for svc 0
 sysc_nr_ok:
-        mvc     SP_ARGS(8,%r15),SP_R7(%r15)
-sysc_do_restart:
-        sth     %r7,SP_SVCNR(%r15)
-        sllg    %r7,%r7,2       # svc number * 4
         larl    %r10,sys_call_table
 #ifdef CONFIG_COMPAT
-        tm      __TI_flags+5(%r9),(_TIF_31BIT>>16)  # running in 31 bit mode ?
+        tm      __TI_flags+5(%r12),(_TIF_31BIT>>16)  # running in 31 bit mode ?
         jno     sysc_noemu
         larl    %r10,sys_call_table_emu  # use 31 bit emulation system calls
 sysc_noemu:
 #endif
-        tm      __TI_flags+6(%r9),_TIF_SYSCALL
+        tm      __TI_flags+6(%r12),_TIF_SYSCALL
         lgf     %r8,0(%r7,%r10) # load address of system call routine
         jnz     sysc_tracesys
         basr    %r14,%r8        # call sys_xxxx
@@ -284,7 +292,7 @@ sysc_noemu:
 sysc_return:
         LOCKDEP_SYS_EXIT
 sysc_tif:
-        tm      __TI_flags+7(%r9),_TIF_WORK_SVC
+        tm      __TI_flags+7(%r12),_TIF_WORK_SVC
         jnz     sysc_work       # there is work to do (signals etc.)
 sysc_restore:
         RESTORE_ALL __LC_RETURN_PSW,1
@@ -301,17 +309,17 @@ sysc_work:
 # One of the work bits is on. Find out which one.
 #
 sysc_work_tif:
-        tm      __TI_flags+7(%r9),_TIF_MCCK_PENDING
+        tm      __TI_flags+7(%r12),_TIF_MCCK_PENDING
         jo      sysc_mcck_pending
-        tm      __TI_flags+7(%r9),_TIF_NEED_RESCHED
+        tm      __TI_flags+7(%r12),_TIF_NEED_RESCHED
         jo      sysc_reschedule
-        tm      __TI_flags+7(%r9),_TIF_SIGPENDING
+        tm      __TI_flags+7(%r12),_TIF_SIGPENDING
         jo      sysc_sigpending
-        tm      __TI_flags+7(%r9),_TIF_NOTIFY_RESUME
+        tm      __TI_flags+7(%r12),_TIF_NOTIFY_RESUME
         jo      sysc_notify_resume
-        tm      __TI_flags+7(%r9),_TIF_RESTART_SVC
+        tm      __TI_flags+7(%r12),_TIF_RESTART_SVC
         jo      sysc_restart
-        tm      __TI_flags+7(%r9),_TIF_SINGLE_STEP
+        tm      __TI_flags+7(%r12),_TIF_SINGLE_STEP
         jo      sysc_singlestep
         j       sysc_return             # beware of critical section cleanup
 
@@ -333,12 +341,12 @@ sysc_mcck_pending:
 # _TIF_SIGPENDING is set, call do_signal
 #
 sysc_sigpending:
-        ni      __TI_flags+7(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
+        ni      __TI_flags+7(%r12),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
         la      %r2,SP_PTREGS(%r15)     # load pt_regs
         brasl   %r14,do_signal          # call do_signal
-        tm      __TI_flags+7(%r9),_TIF_RESTART_SVC
+        tm      __TI_flags+7(%r12),_TIF_RESTART_SVC
         jo      sysc_restart
-        tm      __TI_flags+7(%r9),_TIF_SINGLE_STEP
+        tm      __TI_flags+7(%r12),_TIF_SINGLE_STEP
         jo      sysc_singlestep
         j       sysc_return
 
@@ -354,17 +362,19 @@ sysc_notify_resume:
 # _TIF_RESTART_SVC is set, set up registers and restart svc
 #
 sysc_restart:
-        ni      __TI_flags+7(%r9),255-_TIF_RESTART_SVC # clear TIF_RESTART_SVC
+        ni      __TI_flags+7(%r12),255-_TIF_RESTART_SVC # clear TIF_RESTART_SVC
         lg      %r7,SP_R2(%r15)         # load new svc number
         mvc     SP_R2(8,%r15),SP_ORIG_R2(%r15) # restore first argument
         lmg     %r2,%r6,SP_R2(%r15)     # load svc arguments
-        j       sysc_do_restart         # restart svc
+        sth     %r7,SP_SVCNR(%r15)
+        slag    %r7,%r7,2
+        j       sysc_nr_ok              # restart svc
 
 #
 # _TIF_SINGLE_STEP is set, call do_single_step
 #
 sysc_singlestep:
-        ni      __TI_flags+7(%r9),255-_TIF_SINGLE_STEP  # clear TIF_SINGLE_STEP
+        ni      __TI_flags+7(%r12),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
         xc      SP_SVCNR(2,%r15),SP_SVCNR(%r15)         # clear svc number
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
         larl    %r14,sysc_return        # load adr. of system return
@@ -377,8 +387,8 @@ sysc_singlestep:
 sysc_tracesys:
         la      %r2,SP_PTREGS(%r15)     # load pt_regs
         la      %r3,0
-        srl     %r7,2
-        stg     %r7,SP_R2(%r15)
+        llgh    %r0,SP_SVCNR(%r15)
+        stg     %r0,SP_R2(%r15)
         brasl   %r14,do_syscall_trace_enter
         lghi    %r0,NR_syscalls
         clgr    %r0,%r2
@@ -391,7 +401,7 @@ sysc_tracego:
         basr    %r14,%r8                # call sys_xxx
         stg     %r2,SP_R2(%r15)         # store return value
 sysc_tracenogo:
-        tm      __TI_flags+6(%r9),_TIF_SYSCALL
+        tm      __TI_flags+6(%r12),_TIF_SYSCALL
         jz      sysc_return
         la      %r2,SP_PTREGS(%r15)     # load pt_regs
         larl    %r14,sysc_return        # return point is sysc_return
@@ -403,7 +413,7 @@ sysc_tracenogo:
         .globl  ret_from_fork
 ret_from_fork:
         lg      %r13,__LC_SVC_NEW_PSW+8
-        lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
+        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
         tm      SP_PSW+1(%r15),0x01     # forking a kernel thread ?
         jo      0f
         stg     %r15,SP_R15(%r15)       # store stack pointer for new kthread
@@ -437,8 +447,8 @@ kernel_execve:
         lg      %r15,__LC_KERNEL_STACK  # load ksp
         aghi    %r15,-SP_SIZE           # make room for registers & psw
         lg      %r13,__LC_SVC_NEW_PSW+8
-        lg      %r9,__LC_THREAD_INFO
         mvc     SP_PTREGS(__PT_SIZE,%r15),0(%r12)       # copy pt_regs
+        lg      %r12,__LC_THREAD_INFO
         xc      __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
 #       TRACE_IRQS_ON
         stosm   __SF_EMPTY(%r15),0x03   # reenable interrupts
@@ -465,21 +475,23 @@ pgm_check_handler:
  * for LPSW?).
  */
         stpt    __LC_SYNC_ENTER_TIMER
-        SAVE_ALL_BASE __LC_SAVE_AREA
         tm      __LC_PGM_INT_CODE+1,0x80 # check whether we got a per exception
         jnz     pgm_per                  # got per exception -> special case
-        SAVE_ALL_SYNC __LC_PGM_OLD_PSW,__LC_SAVE_AREA
-        CREATE_STACK_FRAME __LC_PGM_OLD_PSW,__LC_SAVE_AREA
+        SAVE_ALL_PGM __LC_PGM_OLD_PSW,__LC_SAVE_AREA
+        CREATE_STACK_FRAME __LC_SAVE_AREA
+        xc      SP_ILC(4,%r15),SP_ILC(%r15)
+        mvc     SP_PSW(16,%r15),__LC_PGM_OLD_PSW
+        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
         tm      SP_PSW+1(%r15),0x01     # interrupting from user ?
         jz      pgm_no_vtime
         UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
         UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
         mvc     __LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
+        LAST_BREAK
 pgm_no_vtime:
         HANDLE_SIE_INTERCEPT
         TRACE_IRQS_CHECK_OFF
-        lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
-        mvc     SP_ARGS(8,%r15),__LC_LAST_BREAK
+        stg     %r11,SP_ARGS(%r15)
         lgf     %r3,__LC_PGM_ILC        # load program interruption code
         lghi    %r8,0x7f
         ngr     %r8,%r3
@@ -503,31 +515,32 @@ pgm_per:
         clc     __LC_PGM_OLD_PSW(16),__LC_SVC_NEW_PSW
         je      pgm_svcper
 # no interesting special case, ignore PER event
-        lmg     %r12,%r15,__LC_SAVE_AREA
         lpswe   __LC_PGM_OLD_PSW
 
 #
 # Normal per exception
 #
 pgm_per_std:
-        SAVE_ALL_SYNC __LC_PGM_OLD_PSW,__LC_SAVE_AREA
-        CREATE_STACK_FRAME __LC_PGM_OLD_PSW,__LC_SAVE_AREA
+        SAVE_ALL_PGM __LC_PGM_OLD_PSW,__LC_SAVE_AREA
+        CREATE_STACK_FRAME __LC_SAVE_AREA
+        mvc     SP_PSW(16,%r15),__LC_PGM_OLD_PSW
+        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
         tm      SP_PSW+1(%r15),0x01     # interrupting from user ?
         jz      pgm_no_vtime2
         UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
         UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
         mvc     __LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
+        LAST_BREAK
 pgm_no_vtime2:
         HANDLE_SIE_INTERCEPT
         TRACE_IRQS_CHECK_OFF
-        lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
-        lg      %r1,__TI_task(%r9)
+        lg      %r1,__TI_task(%r12)
         tm      SP_PSW+1(%r15),0x01     # kernel per event ?
         jz      kernel_per
         mvc     __THREAD_per+__PER_atmid(2,%r1),__LC_PER_ATMID
         mvc     __THREAD_per+__PER_address(8,%r1),__LC_PER_ADDRESS
         mvc     __THREAD_per+__PER_access_id(1,%r1),__LC_PER_ACCESS_ID
-        oi      __TI_flags+7(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
+        oi      __TI_flags+7(%r12),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
         lgf     %r3,__LC_PGM_ILC        # load program interruption code
         lghi    %r8,0x7f
         ngr     %r8,%r3                 # clear per-event-bit and ilc
@@ -538,19 +551,21 @@ pgm_no_vtime2:
 # it was a single stepped SVC that is causing all the trouble
 #
 pgm_svcper:
-        SAVE_ALL_SYNC __LC_SVC_OLD_PSW,__LC_SAVE_AREA
-        CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA
+        SAVE_ALL_PGM __LC_SVC_OLD_PSW,__LC_SAVE_AREA
+        CREATE_STACK_FRAME __LC_SAVE_AREA
+        mvc     SP_PSW(16,%r15),__LC_SVC_OLD_PSW
+        mvc     SP_ILC(4,%r15),__LC_SVC_ILC
+        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
         UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
         UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
         mvc     __LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
-        llgh    %r7,__LC_SVC_INT_CODE   # get svc number from lowcore
-        lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
+        LAST_BREAK
         TRACE_IRQS_OFF
-        lg      %r8,__TI_task(%r9)
+        lg      %r8,__TI_task(%r12)
         mvc     __THREAD_per+__PER_atmid(2,%r8),__LC_PER_ATMID
         mvc     __THREAD_per+__PER_address(8,%r8),__LC_PER_ADDRESS
         mvc     __THREAD_per+__PER_access_id(1,%r8),__LC_PER_ACCESS_ID
-        oi      __TI_flags+7(%r9),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
+        oi      __TI_flags+7(%r12),_TIF_SINGLE_STEP # set TIF_SINGLE_STEP
         TRACE_IRQS_ON
         stosm   __SF_EMPTY(%r15),0x03   # reenable interrupts
         lmg     %r2,%r6,SP_R2(%r15)     # load svc arguments
@@ -572,16 +587,17 @@ kernel_per:
 io_int_handler:
         stck    __LC_INT_CLOCK
         stpt    __LC_ASYNC_ENTER_TIMER
-        SAVE_ALL_BASE __LC_SAVE_AREA+32
-        SAVE_ALL_ASYNC __LC_IO_OLD_PSW,__LC_SAVE_AREA+32
-        CREATE_STACK_FRAME __LC_IO_OLD_PSW,__LC_SAVE_AREA+32
+        SAVE_ALL_ASYNC __LC_IO_OLD_PSW,__LC_SAVE_AREA+40
+        CREATE_STACK_FRAME __LC_SAVE_AREA+40
+        mvc     SP_PSW(16,%r15),0(%r12) # move user PSW to stack
+        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
         tm      SP_PSW+1(%r15),0x01     # interrupting from user ?
         jz      io_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
+        LAST_BREAK
 io_no_vtime:
-        lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
         HANDLE_SIE_INTERCEPT
         TRACE_IRQS_OFF
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
@@ -590,7 +606,7 @@ io_return:
         LOCKDEP_SYS_EXIT
         TRACE_IRQS_ON
 io_tif:
-        tm      __TI_flags+7(%r9),_TIF_WORK_INT
+        tm      __TI_flags+7(%r12),_TIF_WORK_INT
         jnz     io_work                 # there is work to do (signals etc.)
 io_restore:
         RESTORE_ALL __LC_RETURN_PSW,0
@@ -610,7 +626,7 @@ io_work:
         jo      io_work_user            # yes -> do resched & signal
 #ifdef CONFIG_PREEMPT
         # check for preemptive scheduling
-        icm     %r0,15,__TI_precount(%r9)
+        icm     %r0,15,__TI_precount(%r12)
         jnz     io_restore              # preemption is disabled
         tm      __TI_flags+7(%r12),_TIF_NEED_RESCHED
         jno     io_restore
@@ -645,13 +661,13 @@ io_work_user:
 #              and _TIF_MCCK_PENDING
 #
 io_work_tif:
-        tm      __TI_flags+7(%r9),_TIF_MCCK_PENDING
+        tm      __TI_flags+7(%r12),_TIF_MCCK_PENDING
         jo      io_mcck_pending
-        tm      __TI_flags+7(%r9),_TIF_NEED_RESCHED
+        tm      __TI_flags+7(%r12),_TIF_NEED_RESCHED
         jo      io_reschedule
-        tm      __TI_flags+7(%r9),_TIF_SIGPENDING
+        tm      __TI_flags+7(%r12),_TIF_SIGPENDING
         jo      io_sigpending
-        tm      __TI_flags+7(%r9),_TIF_NOTIFY_RESUME
+        tm      __TI_flags+7(%r12),_TIF_NOTIFY_RESUME
         jo      io_notify_resume
         j       io_return               # beware of critical section cleanup
 
@@ -706,16 +722,17 @@ io_notify_resume:
 ext_int_handler:
         stck    __LC_INT_CLOCK
         stpt    __LC_ASYNC_ENTER_TIMER
-        SAVE_ALL_BASE __LC_SAVE_AREA+32
-        SAVE_ALL_ASYNC __LC_EXT_OLD_PSW,__LC_SAVE_AREA+32
-        CREATE_STACK_FRAME __LC_EXT_OLD_PSW,__LC_SAVE_AREA+32
+        SAVE_ALL_ASYNC __LC_EXT_OLD_PSW,__LC_SAVE_AREA+40
+        CREATE_STACK_FRAME __LC_SAVE_AREA+40
+        mvc     SP_PSW(16,%r15),0(%r12) # move user PSW to stack
+        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
         tm      SP_PSW+1(%r15),0x01     # interrupting from user ?
         jz      ext_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
+        LAST_BREAK
 ext_no_vtime:
-        lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
         HANDLE_SIE_INTERCEPT
         TRACE_IRQS_OFF
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
@@ -734,7 +751,9 @@ mcck_int_handler:
         la      %r1,4095                # revalidate r1
         spt     __LC_CPU_TIMER_SAVE_AREA-4095(%r1)      # revalidate cpu timer
         lmg     %r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r1)# revalidate gprs
-        SAVE_ALL_BASE __LC_SAVE_AREA+64
+        stmg    %r11,%r15,__LC_SAVE_AREA+80
+        larl    %r13,system_call
+        lg      %r11,__LC_LAST_BREAK
         la      %r12,__LC_MCK_OLD_PSW
         tm      __LC_MCCK_CODE,0x80     # system damage?
         jo      mcck_int_main           # yes -> rest of mcck code invalid
@@ -769,7 +788,10 @@ mcck_int_main:
         srag    %r14,%r14,PAGE_SHIFT
         jz      0f
         lg      %r15,__LC_PANIC_STACK   # load panic stack
-0:      CREATE_STACK_FRAME __LC_MCK_OLD_PSW,__LC_SAVE_AREA+64
+0:      aghi    %r15,-SP_SIZE           # make room for registers & psw
+        CREATE_STACK_FRAME __LC_SAVE_AREA+80
+        mvc     SP_PSW(16,%r15),0(%r12)
+        lg      %r12,__LC_THREAD_INFO   # load pointer to thread_info struct
         tm      __LC_MCCK_CODE+2,0x08   # mwp of old psw valid?
         jno     mcck_no_vtime           # no -> no timer update
         tm      SP_PSW+1(%r15),0x01     # interrupting from user ?
@@ -777,8 +799,8 @@ mcck_int_main:
         UPDATE_VTIME __LC_EXIT_TIMER,__LC_MCCK_ENTER_TIMER,__LC_USER_TIMER
         UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
         mvc     __LC_LAST_UPDATE_TIMER(8),__LC_MCCK_ENTER_TIMER
+        LAST_BREAK
 mcck_no_vtime:
-        lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
         la      %r2,SP_PTREGS(%r15)     # load pt_regs
         brasl   %r14,s390_do_machine_check
         tm      SP_PSW+1(%r15),0x01     # returning to user ?
@@ -789,7 +811,7 @@ mcck_no_vtime:
         xc      __SF_BACKCHAIN(8,%r1),__SF_BACKCHAIN(%r1) # clear back chain
         lgr     %r15,%r1
         stosm   __SF_EMPTY(%r15),0x04   # turn dat on
-        tm      __TI_flags+7(%r9),_TIF_MCCK_PENDING
+        tm      __TI_flags+7(%r12),_TIF_MCCK_PENDING
         jno     mcck_return
         HANDLE_SIE_INTERCEPT
         TRACE_IRQS_OFF
@@ -803,6 +825,7 @@ mcck_return:
         jno     0f
         stpt    __LC_EXIT_TIMER
 0:      lpswe   __LC_RETURN_MCCK_PSW    # back to caller
+mcck_done:
 
 /*
  * Restart interruption handler, kick starter for additional CPUs
@@ -858,14 +881,14 @@ stack_overflow:
         lg      %r15,__LC_PANIC_STACK   # change to panic stack
         aghi    %r15,-SP_SIZE
         mvc     SP_PSW(16,%r15),0(%r12) # move user PSW to stack
-        stmg    %r0,%r11,SP_R0(%r15)    # store gprs %r0-%r11 to kernel stack
+        stmg    %r0,%r10,SP_R0(%r15)    # store gprs %r0-%r10 to kernel stack
         la      %r1,__LC_SAVE_AREA
         chi     %r12,__LC_SVC_OLD_PSW
         je      0f
         chi     %r12,__LC_PGM_OLD_PSW
         je      0f
-        la      %r1,__LC_SAVE_AREA+32
-0:      mvc     SP_R12(32,%r15),0(%r1)  # move %r12-%r15 to stack
+        la      %r1,__LC_SAVE_AREA+40
+0:      mvc     SP_R11(40,%r15),0(%r1)  # move %r11-%r15 to stack
         mvc     SP_ARGS(8,%r15),__LC_LAST_BREAK
         xc      __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15) # clear back chain
         la      %r2,SP_PTREGS(%r15)     # load pt_regs
@@ -920,21 +943,23 @@ cleanup_system_call:
         je      0f
         mvc     __LC_SYNC_ENTER_TIMER(8),__LC_ASYNC_ENTER_TIMER
 0:      cghi    %r12,__LC_MCK_OLD_PSW
-        la      %r12,__LC_SAVE_AREA+64
+        la      %r12,__LC_SAVE_AREA+80
         je      0f
-        la      %r12,__LC_SAVE_AREA+32
+        la      %r12,__LC_SAVE_AREA+40
 0:      clc     __LC_RETURN_PSW+8(8),BASED(cleanup_system_call_insn+16)
         jhe     cleanup_vtime
         clc     __LC_RETURN_PSW+8(8),BASED(cleanup_system_call_insn)
         jh      0f
-        mvc     __LC_SAVE_AREA(32),0(%r12)
-0:      stg     %r13,8(%r12)
-        stg     %r12,__LC_SAVE_AREA+96  # argh
-        SAVE_ALL_SYNC __LC_SVC_OLD_PSW,__LC_SAVE_AREA
-        CREATE_STACK_FRAME __LC_SVC_OLD_PSW,__LC_SAVE_AREA
-        lg      %r12,__LC_SAVE_AREA+96  # argh
-        stg     %r15,24(%r12)
-        llgh    %r7,__LC_SVC_INT_CODE
+        mvc     __LC_SAVE_AREA(40),0(%r12)
+0:      lg      %r15,__LC_KERNEL_STACK  # problem state -> load ksp
+        aghi    %r15,-SP_SIZE           # make room for registers & psw
+        stg     %r15,32(%r12)
+        stg     %r11,0(%r12)
+        CREATE_STACK_FRAME __LC_SAVE_AREA
+        mvc     SP_PSW(16,%r15),__LC_SVC_OLD_PSW
+        mvc     SP_ILC(4,%r15),__LC_SVC_ILC
+        stg     %r7,SP_ARGS(%r15)
+        mvc     8(8,%r12),__LC_THREAD_INFO
 cleanup_vtime:
         clc     __LC_RETURN_PSW+8(8),BASED(cleanup_system_call_insn+24)
         jhe     cleanup_stime
@@ -945,7 +970,11 @@ cleanup_stime:
         UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER
 cleanup_update:
         mvc     __LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
-        mvc     __LC_RETURN_PSW+8(8),BASED(cleanup_table_system_call+8)
+        srag    %r12,%r11,23
+        lg      %r12,__LC_THREAD_INFO
+        jz      0f
+        stg     %r11,__TI_last_break(%r12)
+0:      mvc     __LC_RETURN_PSW+8(8),BASED(cleanup_table_system_call+8)
         la      %r12,__LC_RETURN_PSW
         br      %r14
 cleanup_system_call_insn:
@@ -972,11 +1001,11 @@ cleanup_sysc_restore:
         mvc     __LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER
 0:      mvc     __LC_RETURN_PSW(16),SP_PSW(%r15)
         cghi    %r12,__LC_MCK_OLD_PSW
-        la      %r12,__LC_SAVE_AREA+64
+        la      %r12,__LC_SAVE_AREA+80
         je      1f
-        la      %r12,__LC_SAVE_AREA+32
-1:      mvc     0(32,%r12),SP_R12(%r15)
-        lmg     %r0,%r11,SP_R0(%r15)
+        la      %r12,__LC_SAVE_AREA+40
+1:      mvc     0(40,%r12),SP_R11(%r15)
+        lmg     %r0,%r10,SP_R0(%r15)
         lg      %r15,SP_R15(%r15)
 2:      la      %r12,__LC_RETURN_PSW
         br      %r14
@@ -997,8 +1026,8 @@ cleanup_io_restore:
         jhe     0f
         mvc     __LC_EXIT_TIMER(8),__LC_MCCK_ENTER_TIMER
 0:      mvc     __LC_RETURN_PSW(16),SP_PSW(%r15)
-        mvc     __LC_SAVE_AREA+64(32),SP_R12(%r15)
-        lmg     %r0,%r11,SP_R0(%r15)
+        mvc     __LC_SAVE_AREA+80(40),SP_R11(%r15)
+        lmg     %r0,%r10,SP_R0(%r15)
         lg      %r15,SP_R15(%r15)
 1:      la      %r12,__LC_RETURN_PSW
         br      %r14
@@ -1010,13 +1039,6 @@ cleanup_io_restore_insn:
  * Integer constants
  */
                 .align  4
-.Lconst:
-.Lnr_syscalls:  .long   NR_syscalls
-.L0x0130:       .short  0x130
-.L0x0140:       .short  0x140
-.L0x0150:       .short  0x150
-.L0x0160:       .short  0x160
-.L0x0170:       .short  0x170
 .Lcritical_start:
                 .quad   __critical_start
 .Lcritical_end:
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 9f654da4cecc..83339d33c4b1 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -57,6 +57,7 @@
 enum s390_regset {
         REGSET_GENERAL,
         REGSET_FP,
+        REGSET_LAST_BREAK,
         REGSET_GENERAL_EXTENDED,
 };
 
@@ -381,6 +382,10 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data)
                         copied += sizeof(unsigned long);
                 }
                 return 0;
+        case PTRACE_GET_LAST_BREAK:
+                put_user(task_thread_info(child)->last_break,
+                         (unsigned long __user *) data);
+                return 0;
         default:
                 /* Removing high order bit from addr (only for 31 bit). */
                 addr &= PSW_ADDR_INSN;
@@ -633,6 +638,10 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
                         copied += sizeof(unsigned int);
                 }
                 return 0;
+        case PTRACE_GET_LAST_BREAK:
+                put_user(task_thread_info(child)->last_break,
+                         (unsigned int __user *) data);
+                return 0;
         }
         return compat_ptrace_request(child, request, addr, data);
 }
@@ -797,6 +806,28 @@ static int s390_fpregs_set(struct task_struct *target,
         return rc;
 }
 
+#ifdef CONFIG_64BIT
+
+static int s390_last_break_get(struct task_struct *target,
+                               const struct user_regset *regset,
+                               unsigned int pos, unsigned int count,
+                               void *kbuf, void __user *ubuf)
+{
+        if (count > 0) {
+                if (kbuf) {
+                        unsigned long *k = kbuf;
+                        *k = task_thread_info(target)->last_break;
+                } else {
+                        unsigned long  __user *u = ubuf;
+                        if (__put_user(task_thread_info(target)->last_break, u))
+                                return -EFAULT;
+                }
+        }
+        return 0;
+}
+
+#endif
+
 static const struct user_regset s390_regsets[] = {
         [REGSET_GENERAL] = {
                 .core_note_type = NT_PRSTATUS,
@@ -814,6 +845,15 @@ static const struct user_regset s390_regsets[] = {
                 .get = s390_fpregs_get,
                 .set = s390_fpregs_set,
         },
+#ifdef CONFIG_64BIT
+        [REGSET_LAST_BREAK] = {
+                .core_note_type = NT_S390_LAST_BREAK,
+                .n = 1,
+                .size = sizeof(long),
+                .align = sizeof(long),
+                .get = s390_last_break_get,
+        },
+#endif
 };
 
 static const struct user_regset_view user_s390_view = {
@@ -948,6 +988,27 @@ static int s390_compat_regs_high_set(struct task_struct *target,
         return rc;
 }
 
+static int s390_compat_last_break_get(struct task_struct *target,
+                                      const struct user_regset *regset,
+                                      unsigned int pos, unsigned int count,
+                                      void *kbuf, void __user *ubuf)
+{
+        compat_ulong_t last_break;
+
+        if (count > 0) {
+                last_break = task_thread_info(target)->last_break;
+                if (kbuf) {
+                        unsigned long *k = kbuf;
+                        *k = last_break;
+                } else {
+                        unsigned long  __user *u = ubuf;
+                        if (__put_user(last_break, u))
+                                return -EFAULT;
+                }
+        }
+        return 0;
+}
+
 static const struct user_regset s390_compat_regsets[] = {
         [REGSET_GENERAL] = {
                 .core_note_type = NT_PRSTATUS,
@@ -965,6 +1026,13 @@ static const struct user_regset s390_compat_regsets[] = {
                 .get = s390_fpregs_get,
                 .set = s390_fpregs_set,
         },
+        [REGSET_LAST_BREAK] = {
+                .core_note_type = NT_S390_LAST_BREAK,
+                .n = 1,
+                .size = sizeof(long),
+                .align = sizeof(long),
+                .get = s390_compat_last_break_get,
+        },
         [REGSET_GENERAL_EXTENDED] = {
                 .core_note_type = NT_S390_HIGH_GPRS,
                 .n = sizeof(s390_compat_regs_high) / sizeof(compat_long_t),
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 6289945562b0..ee7ac8b11782 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -313,6 +313,7 @@ static int setup_frame(int sig, struct k_sigaction *ka,
            To avoid breaking binary compatibility, they are passed as args. */
         regs->gprs[4] = current->thread.trap_no;
         regs->gprs[5] = current->thread.prot_addr;
+        regs->gprs[6] = task_thread_info(current)->last_break;
 
         /* Place signal number on stack to allow backtrace from handler.  */
         if (__put_user(regs->gprs[2], (int __user *) &frame->signo))
@@ -376,6 +377,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
         regs->gprs[2] = map_signal(sig);
         regs->gprs[3] = (unsigned long) &frame->info;
         regs->gprs[4] = (unsigned long) &frame->uc;
+        regs->gprs[5] = task_thread_info(current)->last_break;
         return 0;
 
 give_sigsegv:
diff --git a/include/linux/elf.h b/include/linux/elf.h
index 597858418051..4d608014753a 100644
--- a/include/linux/elf.h
+++ b/include/linux/elf.h
@@ -394,6 +394,7 @@ typedef struct elf64_shdr {
 #define NT_S390_TODPREG 0x303           /* s390 TOD programmable register */
 #define NT_S390_CTRS    0x304           /* s390 control registers */
 #define NT_S390_PREFIX  0x305           /* s390 prefix register */
+#define NT_S390_LAST_BREAK      0x306   /* s390 breaking event address */
 
 
 /* Note header in a PT_NOTE section */