[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, 48 insertions, 34 deletions

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 5acfac654f9..11d9b019762 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -280,24 +280,26 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long new_stackp,
         return 0;
 }
 
-asmlinkage long sys_fork(struct pt_regs regs)
+asmlinkage long sys_fork(void)
 {
-	return do_fork(SIGCHLD, regs.gprs[15], &regs, 0, NULL, NULL);
+	struct pt_regs *regs = task_pt_regs(current);
+	return do_fork(SIGCHLD, regs->gprs[15], regs, 0, NULL, NULL);
 }
 
-asmlinkage long sys_clone(struct pt_regs regs)
+asmlinkage long sys_clone(void)
 {
-        unsigned long clone_flags;
-        unsigned long newsp;
+	struct pt_regs *regs = task_pt_regs(current);
+	unsigned long clone_flags;
+	unsigned long newsp;
 	int __user *parent_tidptr, *child_tidptr;
 
-        clone_flags = regs.gprs[3];
-        newsp = regs.orig_gpr2;
-	parent_tidptr = (int __user *) regs.gprs[4];
-	child_tidptr = (int __user *) regs.gprs[5];
-        if (!newsp)
-                newsp = regs.gprs[15];
-        return do_fork(clone_flags, newsp, &regs, 0,
+	clone_flags = regs->gprs[3];
+	newsp = regs->orig_gpr2;
+	parent_tidptr = (int __user *) regs->gprs[4];
+	child_tidptr = (int __user *) regs->gprs[5];
+	if (!newsp)
+		newsp = regs->gprs[15];
+	return do_fork(clone_flags, newsp, regs, 0,
 		       parent_tidptr, child_tidptr);
 }
 
@@ -311,40 +313,52 @@ asmlinkage long sys_clone(struct pt_regs regs)
  * do not have enough call-clobbered registers to hold all
  * the information you need.
  */
-asmlinkage long sys_vfork(struct pt_regs regs)
+asmlinkage long sys_vfork(void)
 {
+	struct pt_regs *regs = task_pt_regs(current);
 	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD,
-		       regs.gprs[15], &regs, 0, NULL, NULL);
+		       regs->gprs[15], regs, 0, NULL, NULL);
+}
+
+asmlinkage void execve_tail(void)
+{
+	task_lock(current);
+	current->ptrace &= ~PT_DTRACE;
+	task_unlock(current);
+	current->thread.fp_regs.fpc = 0;
+	if (MACHINE_HAS_IEEE)
+		asm volatile("sfpc %0,%0" : : "d" (0));
 }
 
 /*
  * sys_execve() executes a new program.
  */
-asmlinkage long sys_execve(struct pt_regs regs)
+asmlinkage long sys_execve(void)
 {
-        int error;
-        char * filename;
-
-        filename = getname((char __user *) regs.orig_gpr2);
-        error = PTR_ERR(filename);
-        if (IS_ERR(filename))
-                goto out;
-        error = do_execve(filename, (char __user * __user *) regs.gprs[3],
-			  (char __user * __user *) regs.gprs[4], &regs);
-	if (error == 0) {
-		task_lock(current);
-		current->ptrace &= ~PT_DTRACE;
-		task_unlock(current);
-		current->thread.fp_regs.fpc = 0;
-		if (MACHINE_HAS_IEEE)
-			asm volatile("sfpc %0,%0" : : "d" (0));
+	struct pt_regs *regs = task_pt_regs(current);
+	char *filename;
+	unsigned long result;
+	int rc;
+
+	filename = getname((char __user *) regs->orig_gpr2);
+	if (IS_ERR(filename)) {
+		result = PTR_ERR(filename);
+		goto out;
 	}
-        putname(filename);
+	rc = do_execve(filename, (char __user * __user *) regs->gprs[3],
+		       (char __user * __user *) regs->gprs[4], regs);
+	if (rc) {
+		result = rc;
+		goto out_putname;
+	}
+	execve_tail();
+	result = regs->gprs[2];
+out_putname:
+	putname(filename);
 out:
-        return error;
+	return result;
 }
 
-
 /*
  * fill in the FPU structure for a core dump.
  */