Bug 397265

Summary:	[PATCH] Add (partial) support for userfaultfd syscall and related ioctl
Product:	[Developer tools] valgrind	Reporter:	Even Rouault <even.rouault>
Component:	general	Assignee:	Julian Seward <jseward>
Status:	REPORTED ---
Severity:	normal
Priority:	NOR
Version First Reported In:	unspecified
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Implements userfaultfd syscall and related ioctl

Description Even Rouault 2018-08-08 10:01:45 UTC

Created attachment 114371 [details]
Implements userfaultfd syscall and related ioctl

The attached patch adds partial support for userfaultfd syscall and related ioctl

This is just a start, since unfortunately full support for the userfaultfd mechanism would require deeper changes in Valgrind internals, which I don't master.

When trying on the demo program at the end of
http://man7.org/linux/man-pages/man2/userfaultfd.2.html,
Attaching gdb, it looks like Valgrind is stuck on the "char c = addr[l];" instruction that accesses a unmapped page. Apparently the fault-handling thread is not waken up