x86, um: switch to generic fork/vfork/clone

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

5 files changed, 29 insertions, 59 deletions

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 88b725aa1d5..c763116c535 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -739,30 +739,12 @@ ENTRY(ptregs_##name) ; \
 ENDPROC(ptregs_##name)
 
 PTREGSCALL1(iopl)
-PTREGSCALL0(fork)
-PTREGSCALL0(vfork)
 PTREGSCALL2(sigaltstack)
 PTREGSCALL0(sigreturn)
 PTREGSCALL0(rt_sigreturn)
 PTREGSCALL2(vm86)
 PTREGSCALL1(vm86old)
 
-/* Clone is an oddball.  The 4th arg is in %edi */
-ENTRY(ptregs_clone)
-	CFI_STARTPROC
-	leal 4(%esp),%eax
-	pushl_cfi %eax
-	pushl_cfi PT_EDI(%eax)
-	movl PT_EDX(%eax),%ecx
-	movl PT_ECX(%eax),%edx
-	movl PT_EBX(%eax),%eax
-	call sys_clone
-	addl $8,%esp
-	CFI_ADJUST_CFA_OFFSET -8
-	ret
-	CFI_ENDPROC
-ENDPROC(ptregs_clone)
-
 .macro FIXUP_ESPFIX_STACK
 /*
  * Switch back for ESPFIX stack to the normal zerobased stack
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 1328fe49a3f..2363e820ed6 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -845,9 +845,25 @@ ENTRY(\label)
 END(\label)
 	.endm
 
-	PTREGSCALL stub_clone, sys_clone, %r8
-	PTREGSCALL stub_fork, sys_fork, %rdi
-	PTREGSCALL stub_vfork, sys_vfork, %rdi
+	.macro FORK_LIKE func
+ENTRY(stub_\func)
+	CFI_STARTPROC
+	popq	%r11			/* save return address */
+	PARTIAL_FRAME 0
+	SAVE_REST
+	pushq	%r11			/* put it back on stack */
+	FIXUP_TOP_OF_STACK %r11, 8
+	DEFAULT_FRAME 0 8		/* offset 8: return address */
+	call sys_\func
+	RESTORE_TOP_OF_STACK %r11, 8
+	ret $REST_SKIP		/* pop extended registers */
+	CFI_ENDPROC
+END(stub_\func)
+	.endm
+
+	FORK_LIKE  clone
+	FORK_LIKE  fork
+	FORK_LIKE  vfork
 	PTREGSCALL stub_sigaltstack, sys_sigaltstack, %rdx
 	PTREGSCALL stub_iopl, sys_iopl, %rsi
 
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index b644e1c765d..fe945959325 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -262,36 +262,6 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
 	propagate_user_return_notify(prev_p, next_p);
 }
 
-int sys_fork(struct pt_regs *regs)
-{
-	return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
-}
-
-/*
- * This is trivial, and on the face of it looks like it
- * could equally well be done in user mode.
- *
- * Not so, for quite unobvious reasons - register pressure.
- * In user mode vfork() cannot have a stack frame, and if
- * done by calling the "clone()" system call directly, you
- * do not have enough call-clobbered registers to hold all
- * the information you need.
- */
-int sys_vfork(struct pt_regs *regs)
-{
-	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs, 0,
-		       NULL, NULL);
-}
-
-long
-sys_clone(unsigned long clone_flags, unsigned long newsp,
-	  void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
-{
-	if (!newsp)
-		newsp = regs->sp;
-	return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
-}
-
 /*
  * Idle related variables and functions
  */
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 44e0bff38e7..16efa974532 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -129,7 +129,7 @@ void release_thread(struct task_struct *dead_task)
 
 int copy_thread(unsigned long clone_flags, unsigned long sp,
 	unsigned long arg,
-	struct task_struct *p, struct pt_regs *regs)
+	struct task_struct *p, struct pt_regs *unused)
 {
 	struct pt_regs *childregs = task_pt_regs(p);
 	struct task_struct *tsk;
@@ -138,7 +138,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
 	p->thread.sp = (unsigned long) childregs;
 	p->thread.sp0 = (unsigned long) (childregs+1);
 
-	if (unlikely(!regs)) {
+	if (unlikely(p->flags & PF_KTHREAD)) {
 		/* kernel thread */
 		memset(childregs, 0, sizeof(struct pt_regs));
 		p->thread.ip = (unsigned long) ret_from_kernel_thread;
@@ -156,12 +156,13 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
 		memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 		return 0;
 	}
-	*childregs = *regs;
+	*childregs = *current_pt_regs();
 	childregs->ax = 0;
-	childregs->sp = sp;
+	if (sp)
+		childregs->sp = sp;
 
 	p->thread.ip = (unsigned long) ret_from_fork;
-	task_user_gs(p) = get_user_gs(regs);
+	task_user_gs(p) = get_user_gs(current_pt_regs());
 
 	p->fpu_counter = 0;
 	p->thread.io_bitmap_ptr = NULL;
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 16c6365e2b8..74aac76c6e3 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -169,7 +169,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
 	savesegment(ds, p->thread.ds);
 	memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
 
-	if (unlikely(!regs)) {
+	if (unlikely(p->flags & PF_KTHREAD)) {
 		/* kernel thread */
 		memset(childregs, 0, sizeof(struct pt_regs));
 		childregs->sp = (unsigned long)childregs;
@@ -181,10 +181,11 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
 		childregs->flags = X86_EFLAGS_IF | X86_EFLAGS_BIT1;
 		return 0;
 	}
-	*childregs = *regs;
+	*childregs = *current_pt_regs();
 
 	childregs->ax = 0;
-	childregs->sp = sp;
+	if (sp)
+		childregs->sp = sp;
 
 	err = -ENOMEM;
 	memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));