[S390] fix system call parameter functions.

syscall_get_nr() currently returns a valid result only if the call
chain of the traced process includes do_syscall_trace_enter(). But
collect_syscall() can be called for any sleeping task, the result of
syscall_get_nr() in general is completely bogus.

To make syscall_get_nr() work for any sleeping task the traps field
in pt_regs is replace with svcnr - the system call number the process
is executing. If svcnr == 0 the process is not on a system call path.

The syscall_get_arguments and syscall_set_arguments use regs->gprs[2]
for the first system call parameter. This is incorrect since gprs[2]
may have been overwritten with the system call number if the call
chain includes do_syscall_trace_enter. Use regs->orig_gprs2 instead.

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

8 files changed, 44 insertions, 42 deletions

diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h
index a7226f8143fb..fb0ca4796d3b 100644
--- a/arch/s390/include/asm/ptrace.h
+++ b/arch/s390/include/asm/ptrace.h
@@ -321,8 +321,8 @@ struct pt_regs
         psw_t psw;
         unsigned long gprs[NUM_GPRS];
         unsigned long orig_gpr2;
+        unsigned short svcnr;
         unsigned short ilc;
-        unsigned short trap;
 };
 #endif
 
diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
index 6e623971fbb9..2429b87eb28d 100644
--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -17,9 +17,7 @@
 static inline long syscall_get_nr(struct task_struct *task,
                                   struct pt_regs *regs)
 {
-        if (regs->trap != __LC_SVC_OLD_PSW)
-                return -1;
-        return regs->gprs[2];
+        return regs->svcnr ? regs->svcnr : -1;
 }
 
 static inline void syscall_rollback(struct task_struct *task,
@@ -52,18 +50,20 @@ static inline void syscall_get_arguments(struct task_struct *task,
                                          unsigned int i, unsigned int n,
                                          unsigned long *args)
 {
+        unsigned long mask = -1UL;
+
         BUG_ON(i + n > 6);
 #ifdef CONFIG_COMPAT
-        if (test_tsk_thread_flag(task, TIF_31BIT)) {
-                if (i + n == 6)
-                        args[--n] = (u32) regs->args[0];
-                while (n-- > 0)
-                        args[n] = (u32) regs->gprs[2 + i + n];
-        }
+        if (test_tsk_thread_flag(task, TIF_31BIT))
+                mask = 0xffffffff;
 #endif
         if (i + n == 6)
-                args[--n] = regs->args[0];
-        memcpy(args, &regs->gprs[2 + i], n * sizeof(args[0]));
+                args[--n] = regs->args[0] & mask;
+        while (n-- > 0)
+                if (i + n > 0)
+                        args[n] = regs->gprs[2 + i + n] & mask;
+        if (i == 0)
+                args[0] = regs->orig_gpr2 & mask;
 }
 
 static inline void syscall_set_arguments(struct task_struct *task,
@@ -74,7 +74,11 @@ static inline void syscall_set_arguments(struct task_struct *task,
         BUG_ON(i + n > 6);
         if (i + n == 6)
                 regs->args[0] = args[--n];
-        memcpy(&regs->gprs[2 + i], args, n * sizeof(args[0]));
+        while (n-- > 0)
+                if (i + n > 0)
+                        regs->gprs[2 + i + n] = args[n];
+        if (i == 0)
+                regs->orig_gpr2 = args[0];
 }
 
 #endif  /* _ASM_SYSCALL_H */
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index fa28ecae636b..3d144e6020c6 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -32,7 +32,7 @@ int main(void)
         DEFINE(__PT_GPRS, offsetof(struct pt_regs, gprs));
         DEFINE(__PT_ORIG_GPR2, offsetof(struct pt_regs, orig_gpr2));
         DEFINE(__PT_ILC, offsetof(struct pt_regs, ilc));
-        DEFINE(__PT_TRAP, offsetof(struct pt_regs, trap));
+        DEFINE(__PT_SVCNR, offsetof(struct pt_regs, svcnr));
         DEFINE(__PT_SIZE, sizeof(struct pt_regs));
         BLANK();
         DEFINE(__SF_BACKCHAIN, offsetof(struct stack_frame, back_chain));
diff --git a/arch/s390/kernel/compat_signal.c b/arch/s390/kernel/compat_signal.c
index c7f02e777af2..b537cb0e9b55 100644
--- a/arch/s390/kernel/compat_signal.c
+++ b/arch/s390/kernel/compat_signal.c
@@ -340,7 +340,7 @@ static int restore_sigregs32(struct pt_regs *regs,_sigregs32 __user *sregs)
                 return err;
 
         restore_fp_regs(&current->thread.fp_regs);
-        regs->trap = -1;        /* disable syscall checks */
+        regs->svcnr = 0;        /* disable syscall checks */
         return 0;
 }
 
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 08844fc24a2e..198ea18a534d 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -46,7 +46,7 @@ SP_R14	     =	STACK_FRAME_OVERHEAD + __PT_GPRS + 56
 SP_R15       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 60
 SP_ORIG_R2   =  STACK_FRAME_OVERHEAD + __PT_ORIG_GPR2
 SP_ILC       =  STACK_FRAME_OVERHEAD + __PT_ILC
-SP_TRAP      =  STACK_FRAME_OVERHEAD + __PT_TRAP
+SP_SVCNR     =  STACK_FRAME_OVERHEAD + __PT_SVCNR
 SP_SIZE      =  STACK_FRAME_OVERHEAD + __PT_SIZE
 
 _TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
@@ -183,11 +183,10 @@ STACK_SIZE  = 1 << STACK_SHIFT
         .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
-        icm     %r12,12,__LC_SVC_ILC
+        icm     %r12,3,__LC_SVC_ILC
         stm     %r0,%r11,SP_R0(%r15)    # store gprs %r0-%r11 to kernel stack
-        st      %r12,SP_ILC(%r15)
+        st      %r12,SP_SVCNR(%r15)
         mvc     SP_R12(16,%r15),\savearea # move %r12-%r15 to stack
         la      %r12,0
         st      %r12,__SF_BACKCHAIN(%r15)       # clear back chain
@@ -264,16 +263,17 @@ sysc_update:
 #endif
 sysc_do_svc:
         l       %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
-        sla     %r7,2                   # *4 and test for svc 0
+        ltr     %r7,%r7                 # test for svc 0
         bnz     BASED(sysc_nr_ok)       # svc number > 0
         # svc 0: system call number in %r1
         cl      %r1,BASED(.Lnr_syscalls)
         bnl     BASED(sysc_nr_ok)
         lr      %r7,%r1           # copy svc number to %r7
-        sla     %r7,2             # *4
 sysc_nr_ok:
         mvc     SP_ARGS(4,%r15),SP_R7(%r15)
 sysc_do_restart:
+        sth     %r7,SP_SVCNR(%r15)
+        sll     %r7,2             # svc number *4
         l       %r8,BASED(.Lsysc_table)
         tm      __TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
         l       %r8,0(%r7,%r8)    # get system call addr.
@@ -376,7 +376,6 @@ sysc_notify_resume:
 sysc_restart:
         ni      __TI_flags+3(%r9),255-_TIF_RESTART_SVC # clear TIF_RESTART_SVC
         l       %r7,SP_R2(%r15)         # load new svc number
-        sla     %r7,2
         mvc     SP_R2(4,%r15),SP_ORIG_R2(%r15) # restore first argument
         lm      %r2,%r6,SP_R2(%r15)     # load svc arguments
         b       BASED(sysc_do_restart)  # restart svc
@@ -386,7 +385,8 @@ sysc_restart:
 #
 sysc_singlestep:
         ni      __TI_flags+3(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
-        mvi     SP_TRAP+1(%r15),0x28    # set trap indication to pgm check
+        mvi     SP_SVCNR(%r15),0xff     # set trap indication to pgm check
+        mvi     SP_SVCNR+1(%r15),0xff
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
         l       %r1,BASED(.Lhandle_per) # load adr. of per handler
         la      %r14,BASED(sysc_return) # load adr. of system return
@@ -407,7 +407,7 @@ sysc_tracesys:
         bnl     BASED(sysc_tracenogo)
         l       %r8,BASED(.Lsysc_table)
         lr      %r7,%r2
-        sll     %r7,2                   # *4
+        sll     %r7,2                   # svc number *4
         l       %r8,0(%r7,%r8)
 sysc_tracego:
         lm      %r3,%r6,SP_R3(%r15)
@@ -586,7 +586,8 @@ pgm_svcper:
 # per was called from kernel, must be kprobes
 #
 kernel_per:
-        mvi     SP_TRAP+1(%r15),0x28    # set trap indication to pgm check
+        mvi     SP_SVCNR(%r15),0xff     # set trap indication to pgm check
+        mvi     SP_SVCNR+1(%r15),0xff
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
         l       %r1,BASED(.Lhandle_per) # load adr. of per handler
         la      %r14,BASED(sysc_restore)# load adr. of system return
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 41aca06682aa..89c121ae6339 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -46,7 +46,7 @@ SP_R14	     =	STACK_FRAME_OVERHEAD + __PT_GPRS + 112
 SP_R15       =  STACK_FRAME_OVERHEAD + __PT_GPRS + 120
 SP_ORIG_R2   =  STACK_FRAME_OVERHEAD + __PT_ORIG_GPR2
 SP_ILC       =  STACK_FRAME_OVERHEAD + __PT_ILC
-SP_TRAP      =  STACK_FRAME_OVERHEAD + __PT_TRAP
+SP_SVCNR      = STACK_FRAME_OVERHEAD + __PT_SVCNR
 SP_SIZE      =  STACK_FRAME_OVERHEAD + __PT_SIZE
 
 STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
@@ -171,11 +171,10 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
         .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
-        la      %r12,\psworg
         stg     %r2,SP_ORIG_R2(%r15)    # store original content of gpr 2
-        icm     %r12,12,__LC_SVC_ILC
+        icm     %r12,3,__LC_SVC_ILC
         stmg    %r0,%r11,SP_R0(%r15)    # store gprs %r0-%r11 to kernel stack
-        st      %r12,SP_ILC(%r15)
+        st      %r12,SP_SVCNR(%r15)
         mvc     SP_R12(32,%r15),\savearea # move %r12-%r15 to stack
         la      %r12,0
         stg     %r12,__SF_BACKCHAIN(%r15)
@@ -250,16 +249,17 @@ sysc_update:
 #endif
 sysc_do_svc:
         lg      %r9,__LC_THREAD_INFO    # load pointer to thread_info struct
-        slag    %r7,%r7,2       # *4 and test for svc 0
+        ltgr    %r7,%r7         # test for svc 0
         jnz     sysc_nr_ok
         # svc 0: system call number in %r1
         cl      %r1,BASED(.Lnr_syscalls)
         jnl     sysc_nr_ok
         lgfr    %r7,%r1         # clear high word in r1
-        slag    %r7,%r7,2       # svc 0: system call number in %r1
 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 ?
@@ -363,7 +363,6 @@ sysc_notify_resume:
 sysc_restart:
         ni      __TI_flags+7(%r9),255-_TIF_RESTART_SVC # clear TIF_RESTART_SVC
         lg      %r7,SP_R2(%r15)         # load new svc number
-        slag    %r7,%r7,2               # *4
         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
@@ -372,9 +371,8 @@ sysc_restart:
 # _TIF_SINGLE_STEP is set, call do_single_step
 #
 sysc_singlestep:
-        ni      __TI_flags+7(%r9),255-_TIF_SINGLE_STEP # clear TIF_SINGLE_STEP
-        lhi     %r0,__LC_PGM_OLD_PSW
-        sth     %r0,SP_TRAP(%r15)       # set trap indication to pgm check
+        ni      __TI_flags+7(%r9),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
         jg      do_single_step          # branch to do_sigtrap
@@ -392,7 +390,7 @@ sysc_tracesys:
         lghi    %r0,NR_syscalls
         clgr    %r0,%r2
         jnh     sysc_tracenogo
-        slag    %r7,%r2,2               # *4
+        sllg    %r7,%r2,2               # svc number *4
         lgf     %r8,0(%r7,%r10)
 sysc_tracego:
         lmg     %r3,%r6,SP_R3(%r15)
@@ -567,8 +565,7 @@ pgm_svcper:
 # per was called from kernel, must be kprobes
 #
 kernel_per:
-        lhi     %r0,__LC_PGM_OLD_PSW
-        sth     %r0,SP_TRAP(%r15)       # set trap indication to pgm check
+        xc      SP_SVCNR(2,%r15),SP_SVCNR(%r15) # clear svc number
         la      %r2,SP_PTREGS(%r15)     # address of register-save area
         larl    %r14,sysc_restore       # load adr. of system ret, no work
         jg      do_single_step          # branch to do_single_step
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 1f31be1ecc4b..38ff2bce1203 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -657,7 +657,7 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
                  * debugger stored an invalid system call number. Skip
                  * the system call and the system call restart handling.
                  */
-                regs->trap = -1;
+                regs->svcnr = 0;
                 ret = -1;
         }
 
diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 4f7fc3059a8e..8e6812a22670 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -160,7 +160,7 @@ static int restore_sigregs(struct pt_regs *regs, _sigregs __user *sregs)
         current->thread.fp_regs.fpc &= FPC_VALID_MASK;
 
         restore_fp_regs(&current->thread.fp_regs);
-        regs->trap = -1;        /* disable syscall checks */
+        regs->svcnr = 0;        /* disable syscall checks */
         return 0;
 }
 
@@ -445,7 +445,7 @@ void do_signal(struct pt_regs *regs)
                 oldset = &current->blocked;
 
         /* Are we from a system call? */
-        if (regs->trap == __LC_SVC_OLD_PSW) {
+        if (regs->svcnr) {
                 continue_addr = regs->psw.addr;
                 restart_addr = continue_addr - regs->ilc;
                 retval = regs->gprs[2];
@@ -462,7 +462,7 @@ void do_signal(struct pt_regs *regs)
                 case -ERESTART_RESTARTBLOCK:
                         regs->gprs[2] = -EINTR;
                 }
-                regs->trap = -1;        /* Don't deal with this again. */
+                regs->svcnr = 0;        /* Don't deal with this again. */
         }
 
         /* Get signal to deliver.  When running under ptrace, at this point