make: Provide mandatory options in cflags-y variable

In case if CFLAGS is overriden from command line we don't
see our headers anymore. So provide mandatory options in
ccflags-y variable to fix that.

https://bugzilla.openvz.org/show_bug.cgi?id=2521

Reported-by: Jan Engelhardt <jengelh@inai.de>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Tested-by: Alexander Kartashov <alekskartashov@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
make: pie -- Drop -fno-strict-aliasing option

It's already defined in general Makefile

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Tested-by: Alexander Kartashov <alekskartashov@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
make: pie -- Add -fno-stack-protector

PIE code use own handmade stack so we need -fno-stack-protector
option to eliminate compilation warning if -fstack-protector
passed in command line CFLAGS.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Tested-by: Alexander Kartashov <alekskartashov@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
make: arm -- Use syscalls-asm-y-asmflags instead of CFLAGS

CFLAGS can be overriden, we need own flags here.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Tested-by: Alexander Kartashov <alekskartashov@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Move BUG_ONs to include/bug.h

We will need futexes to use in PIE code but futex.h
uses BUG_ON helper, so to diet inclusions move BUG_ONs
code to include/bug.h.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
lock: Include bug.h instead of big util.h

This makes it suitable to use in PIE code.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
pie: Pass CR_NOGLIBC in pie/Makefile

PIE code can't use glibc helpers so instead of passing
CR_NOGLIBC macro in every source file pie code uses just
pass it in pie/Makefile.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
parasite: Print unknown command number

Convenient for debugging

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
parasite-syscall: Use pr_perror on prctl call failure

This prints more detailed error report.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
parasite: Make parasite arguments variable size

Sometimes we don't know the exact amount of data we would want
to send to parasite via args area (e.g. -- while draining fds).

Fix this, by moving the args area behind the parasite blob and
mmap-ing it with the run-time calculated size.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
fd: Dynamically allocate args for the array of fds to drain

Just make use of previous patch. The creds dumping args are tuned to
fit one page (minimal static args size).

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
vma: Introduce list-of-vmas object

Right now when we collect list of vmas we need to know the
number of elements in it. In the future I will need to know
more, so it makes sense to create a vmas-list object for it.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
vma: Helper, that checks whether vma is dumped via parasite

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
vma: Keep track of lonest vma in list and sum of its lengths

I will have to push some sort of map of pages to dump into parasite.
For this, I need to have estimation of how much memory I'd need for
than in parasite args. These two values will help with it.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
parasite: Prepare to allocate args for page maps

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
page-pipe: Introduce object to collect pages within

The page-pipe is an object, that can accumulate pages inside it. It
consists of list of page-pipe-bufs, which in turn has a pipa, an
array of iovecs that describe the pages' locations and some stats.

Users of it are supposed to vmsplice pages into pipes to accumulate
then for later use, and vmsplice them from pipes when required.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
mem: Drain memory from parasite before dumping it into file

Currently we dump pages directly from parasite into image files. This
is bad for several reasons:

1. We cannot use any more-or-less custom format for pages easily, since
   parasite code cannot be linked with any libraries;
2. We will not be able to optimize migration with preliminary memory
   migration (a.k.a. iterative migration) with it -- if we send pages
   from parasite over network we are not able to let the task we dump
   continue running.

That said, what is done is -- pages from target task are put into a
page-pipe in one go, then (not in this patch) parasite can be released
and we can do with pages whatever we want. For now pages are just
spliced from pipe into image file.

Some numbers:
In order to drain 1Gb of memory from task we need 1.5M of shared map
in args (for iovecs) and 4 pipes (8 descriptors) each referencing 128Mb
of pages, which int turn requires 4 x 640K chunks of sequential kernel
memory (for pipe_buffer). Not that big I guess.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: Test HUGE mappings to dump/restore OK

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
arm: fixup the parasite arguments automatically

The ARM parasite head uses a pad of 228 bytes
to make the offset of the symbol __export_parasite_stack
representable in the ARM instruction set. This value
needs to be changed every time the value of the macro
PARASITE_STACK_SIZE changes.

This patch makes this manual interference redundant.

Signed-off-by: Alexander Kartashov <alekskartashov@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
arm: added the description of the syscall vmsplice

Signed-off-by: Alexander Kartashov <alekskartashov@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>