[src/trunk]: src/sys/arch/x86/x86 Initialize xstate_bv with the structures th...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/846cb80a542c
branches:  trunk
changeset: 827516:846cb80a542c
user:      maxv <maxv%NetBSD.org@localhost>
date:      Tue Oct 31 15:16:10 2017 +0000

description:
Initialize xstate_bv with the structures that were just filled in,
otherwise xrstor does not restore them. This can happen only if userland
calls setcontext without having used the FPU before.

Until rev1.15 xstate_bv was implicitly initialized because the xsave area
was not zeroed out properly.

diffstat:

 sys/arch/x86/x86/fpu.c |  24 ++++++++++++++++++++++--
 1 files changed, 22 insertions(+), 2 deletions(-)

diffs (52 lines):

diff -r 47b554b17ede -r 846cb80a542c sys/arch/x86/x86/fpu.c
--- a/sys/arch/x86/x86/fpu.c    Tue Oct 31 15:10:28 2017 +0000
+++ b/sys/arch/x86/x86/fpu.c    Tue Oct 31 15:16:10 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fpu.c,v 1.17 2017/10/31 12:02:20 maxv Exp $    */
+/*     $NetBSD: fpu.c,v 1.18 2017/10/31 15:16:10 maxv Exp $    */
 
 /*
  * Copyright (c) 2008 The NetBSD Foundation, Inc.  All
@@ -96,7 +96,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: fpu.c,v 1.17 2017/10/31 12:02:20 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: fpu.c,v 1.18 2017/10/31 15:16:10 maxv Exp $");
 
 #include "opt_multiprocessor.h"
 
@@ -574,6 +574,16 @@
                memcpy(&fpu_save->sv_xmm, fpregs, sizeof(fpu_save->sv_xmm));
                /* Invalid bits in the mxcsr_mask will cause faults */
                fpu_save->sv_xmm.fx_mxcsr_mask &= __INITIAL_MXCSR_MASK__;
+
+               /*
+                * Make sure the x87 and SSE bits are set in xstate_bv.
+                * Otherwise xrstor will not restore them.
+                */
+               if (x86_fpu_save == FPU_SAVE_XSAVE ||
+                   x86_fpu_save == FPU_SAVE_XSAVEOPT) {
+                       fpu_save->sv_xsave_hdr.xsh_xstate_bv |=
+                           (XCR0_X87 | XCR0_SSE);
+               }
        } else {
                process_xmm_to_s87(fpregs, &fpu_save->sv_87);
        }
@@ -589,6 +599,16 @@
                fpusave_lwp(l, true);
                fpu_save = process_fpframe(l);
                process_s87_to_xmm(fpregs, &fpu_save->sv_xmm);
+
+               /*
+                * Make sure the x87 and SSE bits are set in xstate_bv.
+                * Otherwise xrstor will not restore them.
+                */
+               if (x86_fpu_save == FPU_SAVE_XSAVE ||
+                   x86_fpu_save == FPU_SAVE_XSAVEOPT) {
+                       fpu_save->sv_xsave_hdr.xsh_xstate_bv |=
+                           (XCR0_X87 | XCR0_SSE);
+               }
        } else {
                fpusave_lwp(l, false);
                fpu_save = process_fpframe(l);