s390: switch to saner kernel_execve() semantics

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

4 files changed, 11 insertions, 49 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 3f3d9ca7a5b6..3cdc0f1978ad 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -136,6 +136,7 @@ config S390
         select KTIME_SCALAR if 32BIT
         select HAVE_ARCH_SECCOMP_FILTER
         select GENERIC_KERNEL_THREAD
+        select GENERIC_KERNEL_EXECVE
         select HAVE_MOD_ARCH_SPECIFIC
         select MODULES_USE_ELF_RELA
 
diff --git a/arch/s390/include/asm/unistd.h b/arch/s390/include/asm/unistd.h
index bbbae41fa9a5..ccbcab7742cd 100644
--- a/arch/s390/include/asm/unistd.h
+++ b/arch/s390/include/asm/unistd.h
@@ -54,7 +54,6 @@
 #   define __ARCH_WANT_COMPAT_SYS_RT_SIGSUSPEND
 # endif
 #define __ARCH_WANT_SYS_EXECVE
-#define __ARCH_WANT_KERNEL_EXECVE
 
 /*
  * "Conditional" syscalls
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index ef46f66bc0d6..aa8f2ba6289b 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -330,40 +330,18 @@ ENTRY(ret_from_fork)
         la      %r11,STACK_FRAME_OVERHEAD(%r15)
         l       %r12,__LC_THREAD_INFO
         l       %r13,__LC_SVC_NEW_PSW+4
-        tm      __PT_PSW+1(%r11),0x01   # forking a kernel thread ?
-        je      1f
         l       %r1,BASED(.Lschedule_tail)
         basr    %r14,%r1                # call schedule_tail
         TRACE_IRQS_ON
         ssm     __LC_SVC_NEW_PSW        # reenable interrupts
-        j       sysc_tracenogo
-
-1:      # it's a kernel thread
-        st      %r15,__PT_R15(%r11)     # store stack pointer for new kthread
-        l       %r1,BASED(.Lschedule_tail)
-        basr    %r14,%r1                # call schedule_tail
-        TRACE_IRQS_ON
-        ssm     __LC_SVC_NEW_PSW        # reenable interrupts
-        lm      %r9,%r11,__PT_R9(%r11)  # load gprs
+        tm      __PT_PSW+1(%r11),0x01   # forking a kernel thread ?
+        jne     sysc_tracenogo
+        # it's a kernel thread
+        lm      %r9,%r10,__PT_R9(%r11)  # load gprs
 ENTRY(kernel_thread_starter)
         la      %r2,0(%r10)
         basr    %r14,%r9
-        la      %r2,0
-        br      %r11                    # do_exit
-
-#
-# kernel_execve function needs to deal with pt_regs that is not
-# at the usual place
-#
-ENTRY(ret_from_kernel_execve)
-        ssm     __LC_PGM_NEW_PSW        # disable I/O and ext. interrupts
-        lr      %r15,%r2
-        lr      %r11,%r2
-        ahi     %r15,-STACK_FRAME_OVERHEAD
-        xc      __SF_BACKCHAIN(4,%r15),__SF_BACKCHAIN(%r15)
-        l       %r12,__LC_THREAD_INFO
-        ssm     __LC_SVC_NEW_PSW        # reenable interrupts
-        j       sysc_return
+        j       sysc_tracenogo
 
 /*
  * Program check handler routine
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 07d8de353984..499e95e90f38 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -352,33 +352,17 @@ sysc_tracenogo:
 ENTRY(ret_from_fork)
         la      %r11,STACK_FRAME_OVERHEAD(%r15)
         lg      %r12,__LC_THREAD_INFO
-        tm      __PT_PSW+1(%r11),0x01   # forking a kernel thread ?
-        je      1f
         brasl   %r14,schedule_tail
         TRACE_IRQS_ON
         ssm     __LC_SVC_NEW_PSW        # reenable interrupts
-        j       sysc_tracenogo
-1:      # it's a kernel thread
-        stg     %r15,__PT_R15(%r11)     # store stack pointer for new kthread
-        brasl   %r14,schedule_tail
-        TRACE_IRQS_ON
-        ssm     __LC_SVC_NEW_PSW        # reenable interrupts
-        lmg     %r9,%r11,__PT_R9(%r11)  # load gprs
+        tm      __PT_PSW+1(%r11),0x01   # forking a kernel thread ?
+        jne     sysc_tracenogo
+        # it's a kernel thread
+        lmg     %r9,%r10,__PT_R9(%r11)  # load gprs
 ENTRY(kernel_thread_starter)
         la      %r2,0(%r10)
         basr    %r14,%r9
-        la      %r2,0
-        br      %r11                    # do_exit
-
-ENTRY(ret_from_kernel_execve)
-        ssm     __LC_PGM_NEW_PSW        # disable I/O and ext. interrupts
-        lgr     %r15,%r2
-        lgr     %r11,%r2
-        aghi    %r15,-STACK_FRAME_OVERHEAD
-        xc      __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
-        lg      %r12,__LC_THREAD_INFO
-        ssm     __LC_SVC_NEW_PSW        # reenable interrupts
-        j       sysc_return
+        j       sysc_tracenogo
 
 /*
  * Program check handler routine