- Define a new md function 'casuptr'. This atomically compares and sets

a pointer that is in user space.  It will be used as the basic primitive
   for a kernel supported user space lock implementation.
 - Implement this function in x86's support.s
 - Provide stubs that return -1 in all other architectures.  Implementations
   will follow along shortly.

Reviewed by:	jake

sys/alpha/alpha/machdep.c

@@ -2324,3 +2324,9 @@ cpu_pcpu_init(struct pcpu *pcpu, int cpuid, size_t sz)
 	pcpu->pc_idlepcb.apcb_ptbr = thread0.td_pcb->pcb_hw.apcb_ptbr;
 	pcpu->pc_current_asngen = 1;
 }
+
+intptr_t
+casuptr(intptr_t *p, intptr_t old, intptr_t new)
+{
+	return (-1);
+}

sys/amd64/amd64/support.S

@@ -1172,6 +1172,37 @@ fastmove_tail_fault:
 	ret
 #endif /* I586_CPU && defined(DEV_NPX) */
 
+/*
+ * casuptr.  Compare and set user pointer.  Returns -1 or the current value.
+ */
+ENTRY(casuptr)
+	movl	PCPU(CURPCB),%ecx
+	movl	$fusufault,PCB_ONFAULT(%ecx)
+	movl	4(%esp),%edx			/* dst */
+	movl	8(%esp),%eax			/* old */
+	movl	12(%esp),%ecx			/* new */
+
+	cmpl	$VM_MAXUSER_ADDRESS-4,%edx	/* verify address is valid */
+	ja	fusufault
+
+#if defined(SMP)
+	lock cmpxchgl %ecx, (%edx)		/* Compare and set. */
+#else	/* !SMP */
+	cmpxchgl %ecx, (%edx)
+#endif	/* !SMP */
+
+	/*
+	 * We store the current value regardless of the success of the
+	 * cmpxchg.  Calling code checks for new == return to determine
+	 * success.
+	 */
+	movl	(%edx), %eax
+	
+	movl	PCPU(CURPCB),%ecx
+	movl	$fusufault,PCB_ONFAULT(%ecx)
+	movl	$0,PCB_ONFAULT(%ecx)
+	ret
+
 /*
  * fu{byte,sword,word} - MP SAFE
  *

sys/amd64/amd64/support.s

@@ -1172,6 +1172,37 @@ fastmove_tail_fault:
 	ret
 #endif /* I586_CPU && defined(DEV_NPX) */
 
+/*
+ * casuptr.  Compare and set user pointer.  Returns -1 or the current value.
+ */
+ENTRY(casuptr)
+	movl	PCPU(CURPCB),%ecx
+	movl	$fusufault,PCB_ONFAULT(%ecx)
+	movl	4(%esp),%edx			/* dst */
+	movl	8(%esp),%eax			/* old */
+	movl	12(%esp),%ecx			/* new */
+
+	cmpl	$VM_MAXUSER_ADDRESS-4,%edx	/* verify address is valid */
+	ja	fusufault
+
+#if defined(SMP)
+	lock cmpxchgl %ecx, (%edx)		/* Compare and set. */
+#else	/* !SMP */
+	cmpxchgl %ecx, (%edx)
+#endif	/* !SMP */
+
+	/*
+	 * We store the current value regardless of the success of the
+	 * cmpxchg.  Calling code checks for new == return to determine
+	 * success.
+	 */
+	movl	(%edx), %eax
+	
+	movl	PCPU(CURPCB),%ecx
+	movl	$fusufault,PCB_ONFAULT(%ecx)
+	movl	$0,PCB_ONFAULT(%ecx)
+	ret
+
 /*
  * fu{byte,sword,word} - MP SAFE
  *

sys/i386/i386/support.s

@@ -1172,6 +1172,37 @@ fastmove_tail_fault:
 	ret
 #endif /* I586_CPU && defined(DEV_NPX) */
 
+/*
+ * casuptr.  Compare and set user pointer.  Returns -1 or the current value.
+ */
+ENTRY(casuptr)
+	movl	PCPU(CURPCB),%ecx
+	movl	$fusufault,PCB_ONFAULT(%ecx)
+	movl	4(%esp),%edx			/* dst */
+	movl	8(%esp),%eax			/* old */
+	movl	12(%esp),%ecx			/* new */
+
+	cmpl	$VM_MAXUSER_ADDRESS-4,%edx	/* verify address is valid */
+	ja	fusufault
+
+#if defined(SMP)
+	lock cmpxchgl %ecx, (%edx)		/* Compare and set. */
+#else	/* !SMP */
+	cmpxchgl %ecx, (%edx)
+#endif	/* !SMP */
+
+	/*
+	 * We store the current value regardless of the success of the
+	 * cmpxchg.  Calling code checks for new == return to determine
+	 * success.
+	 */
+	movl	(%edx), %eax
+	
+	movl	PCPU(CURPCB),%ecx
+	movl	$fusufault,PCB_ONFAULT(%ecx)
+	movl	$0,PCB_ONFAULT(%ecx)
+	ret
+
 /*
  * fu{byte,sword,word} - MP SAFE
  *

sys/ia64/ia64/machdep.c

@@ -1444,3 +1444,10 @@ ia64_rse_previous_frame(u_int64_t *bsp, int size)
 	return bsp - size - rnats;
 }
 
+
+intptr_t
+casuptr(intptr_t *p, intptr_t old, intptr_t new)
+{
+	return (-1);
+}
+

sys/pc98/i386/machdep.c

@@ -2803,3 +2803,11 @@ outb(u_int port, u_char data)
 }
 
 #endif /* DDB */
+
+
+intptr_t
+casuptr(intptr_t *p, intptr_t old, intptr_t new)
+{
+	return (-1);
+}
+

sys/pc98/pc98/machdep.c

@@ -2803,3 +2803,11 @@ outb(u_int port, u_char data)
 }
 
 #endif /* DDB */
+
+
+intptr_t
+casuptr(intptr_t *p, intptr_t old, intptr_t new)
+{
+	return (-1);
+}
+

sys/powerpc/aim/machdep.c

@@ -752,3 +752,11 @@ kcopy(const void *src, void *dst, size_t len)
 	td->td_pcb->pcb_onfault = oldfault;
 	return (0);
 }
+
+
+intptr_t
+casuptr(intptr_t *p, intptr_t old, intptr_t new)
+{
+	return (-1);
+}
+

sys/powerpc/powerpc/machdep.c

@@ -752,3 +752,11 @@ kcopy(const void *src, void *dst, size_t len)
 	td->td_pcb->pcb_onfault = oldfault;
 	return (0);
 }
+
+
+intptr_t
+casuptr(intptr_t *p, intptr_t old, intptr_t new)
+{
+	return (-1);
+}
+

sys/sparc64/sparc64/machdep.c

@@ -703,3 +703,10 @@ set_fpregs(struct thread *td, struct fpreg *fpregs)
 	tf->tf_gsr = fpregs->fr_gsr;
 	return (0);
 }
+
+intptr_t
+casuptr(intptr_t *p, intptr_t old, intptr_t new)
+{
+	return (-1);
+}
+

sys/sys/systm.h

@@ -197,6 +197,7 @@ int	suword(void *base, long word);
 int	suword16(void *base, int word);
 int	suword32(void *base, int32_t word);
 int	suword64(void *base, int64_t word);
+intptr_t casuptr(intptr_t *p, intptr_t old, intptr_t new);
 
 void	realitexpire(void *);