> Date: Mon, 7 Aug 2017 20:53:59 +0200
> From: Matthieu Herrb <matth...@herrb.eu>
>
> On Mon, Aug 07, 2017 at 05:04:46PM +0200, Mark Kettenis wrote:
> > > Date: Mon, 7 Aug 2017 16:46:42 +0200 (CEST)
> > > From: Mark Kettenis <mark.kette...@xs4all.nl>
> > >
> > > > Date: Sun, 6 Aug 2017 19:44:49 -0700
> > > > From: Max Parmer <m...@trystero.is>
> > > >
> > > > >Synopsis: X server segfaults in VESA driver as Linux KVM guest
> > > > >Category: system
> > > > >Environment:
> > > > System : OpenBSD 6.1
> > > > Details : OpenBSD 6.1-current (GENERIC.MP) #45: Sat Aug 5
> > > > 16:22:04 MDT 2017
> > > >
> > > > dera...@amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP
> > > >
> > > > Architecture: OpenBSD.amd64
> > > > Machine : amd64
> > > > >Description:
> > > > startx crashes with an illegal instruction leaving a jumble of
> > > > colors on screen.
> > > >
> > > > After enabling suid coredumps I retrieved this backtrace:
> > > > (gdb) bt
> > > > #0 0x0000169016f7e620 in xf86SlowBcopy () from
> > > > /usr/X11R6/bin/Xorg
> > > > #1 0x00001692b393238a in VESASaveRestore () from
> > > > /usr/X11R6/lib/modules/drivers/vesa_drv.so
> > > > #2 0x00001692b39314ea in VESAScreenInit () from
> > > > /usr/X11R6/lib/modules/drivers/vesa_drv.so
> > > > #3 0x0000169016f147d3 in AddScreen () from /usr/X11R6/bin/Xorg
> > > > #4 0x0000169016f5dcb2 in InitOutput () from /usr/X11R6/bin/Xorg
> > > > #5 0x0000169016f18774 in dix_main () from /usr/X11R6/bin/Xorg
> > > > #6 0x0000169016f01914 in _start () from /usr/X11R6/bin/Xorg
> > > > #7 0x0000169016f018c0 in ?? () from /usr/X11R6/bin/Xorg
> > > > #8 0x0000000000000000 in ?? ()
> > >
> > > Looks like clang is uptimizing xf86SlowBcopy() to use SSE
> > > instructions. I wouldn't be surprised that those are indeed
> > > unsupported on memory mapped device memory. Since the whole purpose
> > > of xf86SlowBcopy to do a bytewise unoptimized copy, we need to tell
> > > the compiler not to optimize this code.
> >
> > FreeBSD fixed this:
> >
> > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=202643
>
> Here's an adaptation of Dimitry's patch for xenocara (tested here).
The xf86Init.c bit isn't supposed to be in here is it?
The Makefile bits are ok kettenis@
> Index: hw/xfree86/common/xf86Init.c
> ===================================================================
> RCS file: /cvs/OpenBSD/xenocara/xserver/hw/xfree86/common/xf86Init.c,v
> retrieving revision 1.25
> diff -u -p -u -r1.25 xf86Init.c
> --- hw/xfree86/common/xf86Init.c 9 Aug 2016 18:59:52 -0000 1.25
> +++ hw/xfree86/common/xf86Init.c 6 Mar 2017 22:20:33 -0000
> @@ -945,6 +945,10 @@ InitOutput(ScreenInfo * pScreenInfo, int
>
> RegisterBlockAndWakeupHandlers((BlockHandlerProcPtr) NoopDDA, xf86Wakeup,
> NULL);
> +#ifdef X_PRIVSEP
> + ErrorF("enabling local access\n");
> + LocalAccessScopeUser();
> +#endif
> }
>
> /**
> Index: hw/xfree86/os-support/misc/Makefile.am
> ===================================================================
> RCS file:
> /cvs/OpenBSD/xenocara/xserver/hw/xfree86/os-support/misc/Makefile.am,v
> retrieving revision 1.4
> diff -u -p -u -r1.4 Makefile.am
> --- hw/xfree86/os-support/misc/Makefile.am 2 May 2014 19:27:49 -0000
> 1.4
> +++ hw/xfree86/os-support/misc/Makefile.am 7 Aug 2017 18:31:57 -0000
> @@ -7,6 +7,11 @@ libmisc_la_SOURCES = SlowBcopy.c
>
> AM_CPPFLAGS = $(XORG_INCS)
>
> -AM_CFLAGS = $(XORG_CFLAGS) $(DIX_CFLAGS)
> +if I386_VIDEO
> +NOSSE_CFLAGS = -mno-sse
> +endif
> +
> +AM_CFLAGS = $(XORG_CFLAGS) $(DIX_CFLAGS) $(NOSSE_CFLAGS)
> +
>
> EXTRA_DIST = $(I386_SRCS) $(PORTIO_SRCS)
> Index: hw/xfree86/os-support/misc/Makefile.in
> ===================================================================
> RCS file:
> /cvs/OpenBSD/xenocara/xserver/hw/xfree86/os-support/misc/Makefile.in,v
> retrieving revision 1.33
> diff -u -p -u -r1.33 Makefile.in
> --- hw/xfree86/os-support/misc/Makefile.in 11 Oct 2016 22:15:56 -0000
> 1.33
> +++ hw/xfree86/os-support/misc/Makefile.in 7 Aug 2017 18:37:58 -0000
> @@ -475,7 +475,8 @@ libmisc_la_SOURCES = SlowBcopy.c
>
> #AM_LDFLAGS = -r
> AM_CPPFLAGS = $(XORG_INCS)
> -AM_CFLAGS = $(XORG_CFLAGS) $(DIX_CFLAGS)
> +@I386_VIDEO_TRUE@NOSSE_CFLAGS = -mno-sse
> +AM_CFLAGS = $(XORG_CFLAGS) $(DIX_CFLAGS) $(NOSSE_CFLAGS)
> EXTRA_DIST = $(I386_SRCS) $(PORTIO_SRCS)
> all: all-am
>
>
> --
> Matthieu Herrb
>
