svn commit: r190237 - in head/sys: amd64/amd64 i386/i386

[Alan Cox]

Author: alc
Date: Sun Mar 22 02:33:48 2009
New Revision: 190237
URL: http://svn.freebsd.org/changeset/base/190237

Log:
  Eliminate the recomputation of pcb_cr3 from cpu_set_upcall().  The
  bcopy()ed value from the old thread is the correct value because the new
  thread and the old thread will share a page table.

Modified:
  head/sys/amd64/amd64/vm_machdep.c
  head/sys/i386/i386/vm_machdep.c

Modified: head/sys/amd64/amd64/vm_machdep.c
==============================================================================
--- head/sys/amd64/amd64/vm_machdep.c	Sun Mar 22 01:24:32 2009	(r190236)
+++ head/sys/amd64/amd64/vm_machdep.c	Sun Mar 22 02:33:48 2009	(r190237)
@@ -287,7 +287,6 @@ cpu_set_upcall(struct thread *td, struct
 	 * Set registers for trampoline to user mode.  Leave space for the
 	 * return address on stack.  These are the kernel mode register values.
 	 */
-	pcb2->pcb_cr3 = vtophys(vmspace_pmap(td->td_proc->p_vmspace)->pm_pml4);
 	pcb2->pcb_r12 = (register_t)fork_return;	    /* trampoline arg */
 	pcb2->pcb_rbp = 0;
 	pcb2->pcb_rsp = (register_t)td->td_frame - sizeof(void *);	/* trampoline arg */
@@ -295,6 +294,7 @@ cpu_set_upcall(struct thread *td, struct
 	pcb2->pcb_rip = (register_t)fork_trampoline;
 	/*
 	 * If we didn't copy the pcb, we'd need to do the following registers:
+	 * pcb2->pcb_cr3:	cloned above.
 	 * pcb2->pcb_dr*:	cloned above.
 	 * pcb2->pcb_savefpu:	cloned above.
 	 * pcb2->pcb_onfault:	cloned above (always NULL here?).

Modified: head/sys/i386/i386/vm_machdep.c
==============================================================================
--- head/sys/i386/i386/vm_machdep.c	Sun Mar 22 01:24:32 2009	(r190236)
+++ head/sys/i386/i386/vm_machdep.c	Sun Mar 22 02:33:48 2009	(r190237)
@@ -424,11 +424,6 @@ cpu_set_upcall(struct thread *td, struct
 	 * Set registers for trampoline to user mode.  Leave space for the
 	 * return address on stack.  These are the kernel mode register values.
 	 */
-#ifdef PAE
-	pcb2->pcb_cr3 = vtophys(vmspace_pmap(td->td_proc->p_vmspace)->pm_pdpt);
-#else
-	pcb2->pcb_cr3 = vtophys(vmspace_pmap(td->td_proc->p_vmspace)->pm_pdir);
-#endif
 	pcb2->pcb_edi = 0;
 	pcb2->pcb_esi = (int)fork_return;		    /* trampoline arg */
 	pcb2->pcb_ebp = 0;
@@ -439,6 +434,7 @@ cpu_set_upcall(struct thread *td, struct
 	pcb2->pcb_gs = rgs();
 	/*
 	 * If we didn't copy the pcb, we'd need to do the following registers:
+	 * pcb2->pcb_cr3:	cloned above.
 	 * pcb2->pcb_dr*:	cloned above.
 	 * pcb2->pcb_savefpu:	cloned above.
 	 * pcb2->pcb_flags:	cloned above.