On Mon, Aug 07, 2017 at 09:08:53PM +0200, Mark Kettenis wrote:
> > Date: Mon, 7 Aug 2017 20:53:59 +0200
> > From: Matthieu Herrb <[email protected]>
> >
> > 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 <[email protected]>
> > > >
> > > > > Date: Sun, 6 Aug 2017 19:44:49 -0700
> > > > > From: Max Parmer <[email protected]>
> > > > >
> > > > > >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
> > > > >
> > > > > [email protected]:/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?
Ooups no. Glad I only had this small change in this tree :)
>
> 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
> >
--
Matthieu Herrb
