[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, 32 insertions, 55 deletions

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index dddc3de30401..c8a2212014e0 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -249,8 +249,6 @@ sysc_do_restart:
         bnz     BASED(sysc_tracesys)
         basr    %r14,%r8          # call sys_xxxx
         st      %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 ?
@@ -381,50 +379,37 @@ ret_from_fork:
         b       BASED(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
-        l       %r1,BASED(.Lclone)
-        br      %r1                     # branch to sys_clone
-
-sys_fork_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs
-        l       %r1,BASED(.Lfork)
-        br      %r1                     # branch to sys_fork
-
-sys_vfork_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs
-        l       %r1,BASED(.Lvfork)
-        br      %r1                     # branch to sys_vfork
-
-sys_execve_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs
-        l       %r1,BASED(.Lexecve)
-        lr      %r12,%r14               # save return address
-        basr    %r14,%r1                # call sys_execve
-        ltr     %r2,%r2                 # check if execve failed
-        bnz     0(%r12)                 # it did fail -> store result in gpr2
-        b       4(%r12)                 # SKIP ST 2,SP_R2(15) after BASR 14,8
-                                        # in system_call/sysc_tracesys
-
-sys_sigreturn_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs as parameter
-        l       %r1,BASED(.Lsigreturn)
-        br      %r1                     # branch to sys_sigreturn
-
-sys_rt_sigreturn_glue:
-        la      %r2,SP_PTREGS(%r15)     # load pt_regs as parameter
-        l       %r1,BASED(.Lrt_sigreturn)
-        br      %r1                     # branch to sys_sigreturn
-
-sys_sigaltstack_glue:
-        la      %r4,SP_PTREGS(%r15)     # load pt_regs as parameter
-        l       %r1,BASED(.Lsigaltstack)
-        br      %r1                     # branch to sys_sigreturn
+        .globl  kernel_execve
+kernel_execve:
+        stm     %r12,%r15,48(%r15)
+        lr      %r14,%r15
+        l       %r13,__LC_SVC_NEW_PSW+4
+        s       %r15,BASED(.Lc_spsize)
+        st      %r14,__SF_BACKCHAIN(%r15)
+        la      %r12,SP_PTREGS(%r15)
+        xc      0(__PT_SIZE,%r12),0(%r12)
+        l       %r1,BASED(.Ldo_execve)
+        lr      %r5,%r12
+        basr    %r14,%r1
+        ltr     %r2,%r2
+        be      BASED(0f)
+        a       %r15,BASED(.Lc_spsize)
+        lm      %r12,%r15,48(%r15)
+        br      %r14
+        # execve succeeded.
+0:      stnsm   __SF_EMPTY(%r15),0xfc   # disable interrupts
+        l       %r15,__LC_KERNEL_STACK  # load ksp
+        s       %r15,BASED(.Lc_spsize)  # make room for registers & psw
+        l       %r9,__LC_THREAD_INFO
+        mvc     SP_PTREGS(__PT_SIZE,%r15),0(%r12)       # copy pt_regs
+        xc      __SF_BACKCHAIN(4,%r15),__SF_BACKCHAIN(%r15)
+        stosm   __SF_EMPTY(%r15),0x03   # reenable interrupts
+        l       %r1,BASED(.Lexecve_tail)
+        basr    %r14,%r1
+        b       BASED(sysc_return)
 
 /*
  * Program check handler routine
@@ -1031,19 +1016,11 @@ cleanup_io_leave_insn:
 .Ldo_extint:    .long   do_extint
 .Ldo_signal:    .long   do_signal
 .Lhandle_per:   .long   do_single_step
+.Ldo_execve:    .long   do_execve
+.Lexecve_tail:  .long   execve_tail
 .Ljump_table:   .long   pgm_check_table
 .Lschedule:     .long   schedule
-.Lclone:        .long   sys_clone
-.Lexecve:       .long   sys_execve
-.Lfork:         .long   sys_fork
-.Lrt_sigreturn: .long   sys_rt_sigreturn
-.Lrt_sigsuspend:
-                .long   sys_rt_sigsuspend
-.Lsigreturn:    .long   sys_sigreturn
-.Lsigsuspend:   .long   sys_sigsuspend
-.Lsigaltstack:  .long   sys_sigaltstack
 .Ltrace:        .long   syscall_trace
-.Lvfork:        .long   sys_vfork
 .Lschedtail:    .long   schedule_tail
 .Lsysc_table:   .long   sys_call_table
 #ifdef CONFIG_TRACE_IRQFLAGS