linux/drivers/lguest
Rusty Russell e27d90e8be lguest: Map switcher text R/O
Pavel noted that lguest maps the switcher code executable and
read-write.  This is a bad idea for any kernel text, but
particularly for text mapped at a fixed address.

Create two vmas, one for the text (PAGE_KERNEL_RX) and another
for the stacks (PAGE_KERNEL).  Use VM_NO_GUARD to map them
adjacent (as expected by the rest of the code).

Reported-by: Pavel Machek <pavel@ucw.cz>
Tested-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-01-12 12:17:28 +01:00
..
x86 x86/fpu: Pass 'struct fpu' to fpu__restore() 2015-05-19 15:48:11 +02:00
core.c lguest: Map switcher text R/O 2016-01-12 12:17:28 +01:00
hypercalls.c lguest: suppress interrupts for single insn, not range. 2015-03-24 11:52:08 +10:30
interrupts_and_traps.c x86/asm/entry: Fix remaining use of SYSCALL_VECTOR 2015-05-11 07:17:04 +02:00
Kconfig lguest: now needs PCI_DIRECT. 2015-04-01 10:29:05 -07:00
lg.h lguest: suppress interrupts for single insn, not range. 2015-03-24 11:52:08 +10:30
lguest_user.c lguest: explicitly set miscdevice's private_data NULL 2015-03-24 11:52:06 +10:30
Makefile lguest: remove support for lguest bus. 2015-02-11 16:47:41 +10:30
page_tables.c lguest: add iomem region, where guest page faults get sent to userspace. 2015-02-11 16:47:33 +10:30
README lguest: documentation I: Preparation 2007-07-26 11:35:16 -07:00
segments.c lguest: switch segment-voodoo-numbers to readable symbols 2012-01-12 15:44:47 +10:30

Welcome, friend reader, to lguest.

Lguest is an adventure, with you, the reader, as Hero.  I can't think of many
5000-line projects which offer both such capability and glimpses of future
potential; it is an exciting time to be delving into the source!

But be warned; this is an arduous journey of several hours or more!  And as we
know, all true Heroes are driven by a Noble Goal.  Thus I offer a Beer (or
equivalent) to anyone I meet who has completed this documentation.

So get comfortable and keep your wits about you (both quick and humorous).
Along your way to the Noble Goal, you will also gain masterly insight into
lguest, and hypervisors and x86 virtualization in general.

Our Quest is in seven parts: (best read with C highlighting turned on)

I) Preparation
	- In which our potential hero is flown quickly over the landscape for a
	  taste of its scope.  Suitable for the armchair coders and other such
	  persons of faint constitution.

II) Guest
	- Where we encounter the first tantalising wisps of code, and come to
	  understand the details of the life of a Guest kernel.

III) Drivers
	- Whereby the Guest finds its voice and become useful, and our
	  understanding of the Guest is completed.

IV) Launcher
	- Where we trace back to the creation of the Guest, and thus begin our
	  understanding of the Host.

V) Host
	- Where we master the Host code, through a long and tortuous journey.
	  Indeed, it is here that our hero is tested in the Bit of Despair.

VI) Switcher
	- Where our understanding of the intertwined nature of Guests and Hosts
	  is completed.

VII) Mastery
	- Where our fully fledged hero grapples with the Great Question:
	  "What next?"

make Preparation!
Rusty Russell.