svn commit: r275833 - head/sys/amd64/amd64

[Konstantin Belousov]

Author: kib
Date: Tue Dec 16 18:28:33 2014
New Revision: 275833
URL: https://svnweb.freebsd.org/changeset/base/275833

Log:
  The iret instruction may generate #np and #ss fault, besides #gp.
  When returning to usermode, the handler for that exceptions is also
  executed with wrong gs base.  Handle all three possible faults in the
  same way, checking for iret fault, and performing full iret.
  
  Sponsored by:	The FreeBSD Foundation
  MFC after:	3 days

Modified:
  head/sys/amd64/amd64/exception.S

Modified: head/sys/amd64/amd64/exception.S
==============================================================================
--- head/sys/amd64/amd64/exception.S	Tue Dec 16 17:59:05 2014	(r275832)
+++ head/sys/amd64/amd64/exception.S	Tue Dec 16 18:28:33 2014	(r275833)
@@ -153,9 +153,13 @@ IDTVEC(xmm)
 IDTVEC(tss)
 	TRAP_ERR(T_TSSFLT)
 IDTVEC(missing)
-	TRAP_ERR(T_SEGNPFLT)
+	subq	$TF_ERR,%rsp
+	movl	$T_SEGNPFLT,TF_TRAPNO(%rsp)
+	jmp	prot_addrf
 IDTVEC(stk)
-	TRAP_ERR(T_STKFLT)
+	subq	$TF_ERR,%rsp
+	movl	$T_STKFLT,TF_TRAPNO(%rsp)
+	jmp	prot_addrf
 IDTVEC(align)
 	TRAP_ERR(T_ALIGNFLT)
 
@@ -318,6 +322,7 @@ IDTVEC(page)
 IDTVEC(prot)
 	subq	$TF_ERR,%rsp
 	movl	$T_PROTFLT,TF_TRAPNO(%rsp)
+prot_addrf:
 	movq	$0,TF_ADDR(%rsp)
 	movq	%rdi,TF_RDI(%rsp)	/* free up a GP register */
 	leaq	doreti_iret(%rip),%rdi