[S390] System call cleanup.

Remove system call glue for sys_clone, sys_fork, sys_vfork, sys_execve,
sys_sigreturn, sys_rt_sigreturn and sys_sigaltstack. Call do_execve from
kernel_execve directly, move pt_regs to the right place and branch to
sysc_return to start the user space program. This removes the last
in-kernel system call.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 28 insertions, 72 deletions

diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 0f758c329a5d..93745fd8f555 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -244,8 +244,6 @@ sysc_noemu:
         jnz     sysc_tracesys
         basr    %r14,%r8        # call sys_xxxx
         stg     %r2,SP_R2(%r15) # store return value (change R2 on stack)
-                                # ATTENTION: check sys_execve_glue before
-                                # changing anything here !!
 
 sysc_return:
         tm      SP_PSW+1(%r15),0x01     # returning to user ?
@@ -371,77 +369,35 @@ ret_from_fork:
         j       sysc_return
 
 #
-# clone, fork, vfork, exec and sigreturn need glue,
-# because they all expect pt_regs as parameter,
-# but are called with different parameter.
-# return-address is set up above
+# kernel_execve function needs to deal with pt_regs that is not
+# at the usual place
 #
-sys_clone_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs
-        jg      sys_clone               # branch to sys_clone
-
-#ifdef CONFIG_COMPAT
-sys32_clone_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs
-        jg      sys32_clone             # branch to sys32_clone
-#endif
-
-sys_fork_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs
-        jg      sys_fork                # branch to sys_fork
-
-sys_vfork_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs
-        jg      sys_vfork               # branch to sys_vfork
-
-sys_execve_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs
-        lgr     %r12,%r14               # save return address
-        brasl   %r14,sys_execve         # call sys_execve
-        ltgr    %r2,%r2                 # check if execve failed
-        bnz     0(%r12)                 # it did fail -> store result in gpr2
-        b       6(%r12)                 # SKIP STG 2,SP_R2(15) in
-                                        # system_call/sysc_tracesys
-#ifdef CONFIG_COMPAT
-sys32_execve_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs
-        lgr     %r12,%r14               # save return address
-        brasl   %r14,sys32_execve       # call sys32_execve
-        ltgr    %r2,%r2                 # check if execve failed
-        bnz     0(%r12)                 # it did fail -> store result in gpr2
-        b       6(%r12)                 # SKIP STG 2,SP_R2(15) in
-                                        # system_call/sysc_tracesys
-#endif
-
-sys_sigreturn_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs as parameter
-        jg      sys_sigreturn           # branch to sys_sigreturn
-
-#ifdef CONFIG_COMPAT
-sys32_sigreturn_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs as parameter
-        jg      sys32_sigreturn         # branch to sys32_sigreturn
-#endif
-
-sys_rt_sigreturn_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs as parameter
-        jg      sys_rt_sigreturn        # branch to sys_sigreturn
-
-#ifdef CONFIG_COMPAT
-sys32_rt_sigreturn_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs as parameter
-        jg      sys32_rt_sigreturn      # branch to sys32_sigreturn
-#endif
-
-sys_sigaltstack_glue:
-        la      %r4,SP_PTREGS(%r15)     # load pt_regs as parameter
-        jg      sys_sigaltstack         # branch to sys_sigreturn
-
-#ifdef CONFIG_COMPAT
-sys32_sigaltstack_glue:
-        la      %r4,SP_PTREGS(%r15)     # load pt_regs as parameter
-        jg      sys32_sigaltstack_wrapper # branch to sys_sigreturn
-#endif
+        .globl  kernel_execve
+kernel_execve:
+        stmg    %r12,%r15,96(%r15)
+        lgr     %r14,%r15
+        aghi    %r15,-SP_SIZE
+        stg     %r14,__SF_BACKCHAIN(%r15)
+        la      %r12,SP_PTREGS(%r15)
+        xc      0(__PT_SIZE,%r12),0(%r12)
+        lgr     %r5,%r12
+        brasl   %r14,do_execve
+        ltgfr   %r2,%r2
+        je      0f
+        aghi    %r15,SP_SIZE
+        lmg     %r12,%r15,96(%r15)
+        br      %r14
+        # execve succeeded.
+0:      stnsm   __SF_EMPTY(%r15),0xfc   # disable interrupts
+        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
+        xc      __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
+        stosm   __SF_EMPTY(%r15),0x03   # reenable interrupts
+        brasl   %r14,execve_tail
+        j       sysc_return
 
 /*
  * Program check handler routine