Bug 95230

Summary:	linux kernel 4.5.0 gets SIGSEGV in latest intel_drv.so with xserver 1.18.3
Product:	xorg	Reporter:	Jason Vas Dias <jason.vas.dias>
Component:	Driver/intel	Assignee:	Chris Wilson <chris>
Status:	RESOLVED INVALID	QA Contact:	Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity:	normal
Priority:	medium
Version:	git
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:

Description Jason Vas Dias 2016-05-01 19:51:48 UTC

With 100% reproducibility, the latest xf86-video-intel driver from GIT (2.99.917) 
when built against the latest Xorg server from GIT ( 1.18.3 ), and all the
latest GIT versions of all Xorg modules as listed in  Bug #95140 :
https://bugs.freedesktop.org/attachment.cgi?id=123274 ,
the kernel gets a SIGSEGV and Xorg server quits and is restarted (by xdm) :

May  1 20:21:16 jvdlux kernel: [10675.162089] X[6342]: segfault at 7c ip 00007fcf2e4f1c2c sp 00007ffd0ec6ced0 error 6 in intel_drv.so[7fcf2e4cf000+174000]
May  1 20:21:16 jvdlux xdm[6348]: pam_unix(xdm:session): session closed for user jvd

I guess I'd have to know exactly were in memory the Xserver HAD 
intel_drv.so loaded to interpret the 00007ffd0ec6ced0 instruction pointer
address ?

This happens reliably by browsing to any long page with firefox 46 (latest version), clicking into the main window content, and holding down the <PageDown>
OR <DownArrow> keys ; it doesn't happen by holding down these keys in emacs or
xterm (Firefox does have problems with scrolling, but...)

I did have to patch uxa/intel_driver.c in order to compile against xserver
1.18.3 code (Bug #95140) and sna/kgem.c (Bug #95185) to avoid coredumping
during initialization . 
My machine hardware and xorg configuration is fully documented in those bug
reports.

If there is any further information you require, please let me know .

I'm happy to help maintain xf86-video-intel.c to work with latest Xorg 
server and Linux kernel - I really think it should be able to do so - 
but I'd need a few pointers / help to get started .
How is the kernel calling into intel_drv.so ?  How to map 
0x00007ffd0ec6ced0 to a source file name and line number ?

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