svn commit: r195535 - head/sys/amd64/amd64

[Konstantin Belousov]

Author: kib
Date: Fri Jul 10 10:29:16 2009
New Revision: 195535
URL: http://svn.freebsd.org/changeset/base/195535

Log:
  When amd64 CPU cannot load segment descriptor during trap return to
  usermode, it generates GPF, that is mirrored to user mode as SIGSEGV.
  The offending register in mcontext should contain the value loading of
  which generated the GPF, and it is so on i386. On amd64, we currently
  report segment descriptor in tf_err, while segment register contains the
  corrected value loaded by trap handler.
  
  Fix the issue by behaving like i386, reloading segment register in trap
  frame after signal frame is pushed onto user stack.
  
  Noted and tested by:	pho
  Approved by:	re (kensmith)

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

Modified: head/sys/amd64/amd64/exception.S
==============================================================================
--- head/sys/amd64/amd64/exception.S	Fri Jul 10 08:18:08 2009	(r195534)
+++ head/sys/amd64/amd64/exception.S	Fri Jul 10 10:29:16 2009	(r195535)
@@ -766,38 +766,38 @@ doreti_iret_fault:
 	.globl	ds_load_fault
 ds_load_fault:
 	movl	$T_PROTFLT,TF_TRAPNO(%rsp)
-	movzwl	TF_DS(%rsp),%edx
-	movl	%edx,TF_ERR(%rsp)
+	movq	%rsp, %rdi
+	call	trap
 	movw	$KUDSEL,TF_DS(%rsp)
-	jmp	calltrap
+	jmp	doreti
 
 	ALIGN_TEXT
 	.globl	es_load_fault
 es_load_fault:
 	movl	$T_PROTFLT,TF_TRAPNO(%rsp)
-	movzwl	TF_ES(%rsp),%edx
-	movl	%edx,TF_ERR(%rsp)
+	movq	%rsp, %rdi
+	call	trap
 	movw	$KUDSEL,TF_ES(%rsp)
-	jmp	calltrap
+	jmp	doreti
 
 	ALIGN_TEXT
 	.globl	fs_load_fault
 fs_load_fault:
 	movl	$T_PROTFLT,TF_TRAPNO(%rsp)
-	movzwl	TF_FS(%rsp),%edx
-	movl	%edx,TF_ERR(%rsp)
+	movq	%rsp, %rdi
+	call	trap
 	movw	$KUF32SEL,TF_FS(%rsp)
-	jmp	calltrap
+	jmp	doreti
 
 	ALIGN_TEXT
 	.globl	gs_load_fault
 gs_load_fault:
 	popfq
 	movl	$T_PROTFLT,TF_TRAPNO(%rsp)
-	movzwl	TF_GS(%rsp),%edx
-	movl	%edx,TF_ERR(%rsp)
+	movq	%rsp, %rdi
+	call	trap
 	movw	$KUG32SEL,TF_GS(%rsp)
-	jmp	calltrap
+	jmp	doreti
 #ifdef HWPMC_HOOKS
 	ENTRY(end_exceptions)
 #endif