Rest the FPU's fcw and mxcsr before initializing the "FPU reset state" area

problem discovered on bluhm@'s old opteron
ok deraadt@ kettenis@

diff --git a/sys/arch/amd64/amd64/cpu.c b/sys/arch/amd64/amd64/cpu.c
index 12489c0..4ad2069 100644 (file)
--- a/sys/arch/amd64/amd64/cpu.c
+++ b/sys/arch/amd64/amd64/cpu.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: cpu.c,v 1.123 2018/06/19 19:29:52 kettenis Exp $      */
+/*     $OpenBSD: cpu.c,v 1.124 2018/07/09 12:58:43 guenther Exp $      */
 /* $NetBSD: cpu.c,v 1.1 2003/04/26 18:39:26 fvdl Exp $ */
 
 /*-
@@ -571,6 +571,9 @@ cpu_init(struct cpu_info *ci)
        /* Give proc0 a clean FPU save area */
        sfp = &proc0.p_addr->u_pcb.pcb_savefpu;
        memset(sfp, 0, fpu_save_len);
+       sfp->fp_fxsave.fx_fcw = __INITIAL_NPXCW__;
+       sfp->fp_fxsave.fx_mxcsr = __INITIAL_MXCSR__;
+       fpureset();
        if (xsave_mask) {
                /* must not use xsaveopt here */
                xsave(sfp, xsave_mask);