Give MPX a real config option. The CPUs that support it (referenced
here):

  https://software.intel.com/en-us/forums/topic/402393

are not available publicly yet. Right now only the software emulator
provides MPX for the general public.

[ tglx: Make it default off. There is no point in having it on right
        now as no hardware and no proper tooling support are available ]
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141212183836.2569D58D@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

I was writing some MPX test programs and realized that the
current design makes it tricky.  I did something like:

	bndcfgu |= bnd_dir | BNDCFGU_ENABLE;
	xrstor();
	printf("xrstor done");
	// #BR bounds exception here
	prctl(MPX_ENABLE_MANAGEMENT);

and then compiled the app with "-fcheck-pointer-bounds -mmpx"
to enable MPX instrumentation.

The problem is that there is MPX instrumentation inserted in
to the area of the printf().  The kernel gets a bounds exception
and since management isn't yet enabled, it SIGSEGV's.

Add a bit to the documentation to explain a way around this and
where apps need to be careful.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141212183835.8C581B3E@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

We should be checking IS_ERR() here.  PTR_ERR() is always true.

Fixes: fe3d197f ('x86, mpx: On-demand kernel allocation of
bounds tables')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Link: http://lkml.kernel.org/r/20141125172114.GA24535@mwandaSigned-off-by: Ingo Molnar <mingo@kernel.org>

This is a follow-on to commit 62e88b1c 'mm: Make
arch_unmap()/bprm_mm_init() available to all architectures'

I removed the asm-generic version of arch_unmap() in that patch,
but missed arch_bprm_mm_init().  So this broke the build for
architectures using asm-generic/mmu_context.h who actually have
an MMU.

Fixes: 62e88b1c 'mm: Make arch_unmap()/bprm_mm_init() available to all architectures'
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: linux-arch@vger.kernel.org
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20141122163711.0F037EE6@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

The x86 MPX patch set calls arch_unmap() and arch_bprm_mm_init()
from fs/exec.c, so we need at least a stub for them in all
architectures.  They are only called under an #ifdef for
CONFIG_MMU=y, so we can at least restict this to architectures
with MMU support.

blackfin/c6x have no MMU support, so do not call arch_unmap().
They also do not include mm_hooks.h or mmu_context.h at all and
do not need to be touched.

s390, um and unicore32 do not use asm-generic/mm_hooks.h, so got
their own arch_unmap() versions.  (I also moved um's
arch_dup_mmap() to be closer to the other mm_hooks.h functions).

xtensa only includes mm_hooks when MMU=y, which should be fine
since arch_unmap() is called only from MMU=y code.

For the rest, we use the stub copies of these functions in
asm-generic/mm_hook.h.

I cross compiled defconfigs for cris (to check NOMMU) and s390
to make sure that this works.  I also checked a 64-bit build
of UML and all my normal x86 builds including PARAVIRT on and
off.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: linux-arch@vger.kernel.org
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20141118182350.8B4AA2C2@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

asm-generic/mm_hooks.h provides some generic fillers for the 90%
of architectures that do not need to hook some mmap-manipulation
functions.  A comment inside says:

> Define generic no-op hooks for arch_dup_mmap and
> arch_exit_mmap, to be included in asm-FOO/mmu_context.h
> for any arch FOO which doesn't need to hook these.

So, does x86 need to hook these?  It depends on CONFIG_PARAVIRT.
We *conditionally* include this generic header if we have
CONFIG_PARAVIRT=n.  That's madness.

With this patch, x86 stops using asm-generic/mmu_hooks.h entirely.
We use our own copies of the functions.  The paravirt code
provides some stubs if it is disabled, and we always call those
stubs in our x86-private versions of arch_exit_mmap() and
arch_dup_mmap().
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20141118182349.14567FA5@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

get_reg_offset() used to return the register contents themselves
instead of the register offset.  When it did that, it was an
unsigned long.  I changed it to return an integer _offset_
instead of the register.  But, I neglected to change the return
type of the function or the variables in which we store the
result of the call.

This fixes up the code to clear up the warnings from the smatch
bot:

New smatch warnings:
arch/x86/mm/mpx.c:178 mpx_get_addr_ref() warn: unsigned 'addr_offset' is never less than zero.
arch/x86/mm/mpx.c:184 mpx_get_addr_ref() warn: unsigned 'base_offset' is never less than zero.
arch/x86/mm/mpx.c:188 mpx_get_addr_ref() warn: unsigned 'indx_offset' is never less than zero.
arch/x86/mm/mpx.c:196 mpx_get_addr_ref() warn: unsigned 'addr_offset' is never less than zero.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20141118182343.C3E0C629@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

We no longer need mpx.h in exec.c.  This will obviously also
break the build for non-x86 builds.  We get the MPX includes that
we need from mmu_context.h now.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141118003608.837015B3@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

This patch adds the Documentation/x86/intel_mpx.txt file with some
information about Intel MPX.
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151832.7FDB1720@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

The previous patch allocates bounds tables on-demand.  As noted in
an earlier description, these can add up to *HUGE* amounts of
memory.  This has caused OOMs in practice when running tests.

This patch adds support for freeing bounds tables when they are no
longer in use.

There are two types of mappings in play when unmapping tables:
 1. The mapping with the actual data, which userspace is
    munmap()ing or brk()ing away, etc...
 2. The mapping for the bounds table *backing* the data
    (is tagged with VM_MPX, see the patch "add MPX specific
    mmap interface").

If userspace use the prctl() indroduced earlier in this patchset
to enable the management of bounds tables in kernel, when it
unmaps the first type of mapping with the actual data, the kernel
needs to free the mapping for the bounds table backing the data.
This patch hooks in at the very end of do_unmap() to do so.
We look at the addresses being unmapped and find the bounds
directory entries and tables which cover those addresses.  If
an entire table is unused, we clear associated directory entry
and free the table.

Once we unmap the bounds table, we would have a bounds directory
entry pointing at empty address space. That address space might
now be allocated for some other (random) use, and the MPX
hardware might now try to walk it as if it were a bounds table.
That would be bad.  So any unmapping of an enture bounds table
has to be accompanied by a corresponding write to the bounds
directory entry to invalidate it.  That write to the bounds
directory can fault, which causes the following problem:

Since we are doing the freeing from munmap() (and other paths
like it), we hold mmap_sem for write. If we fault, the page
fault handler will attempt to acquire mmap_sem for read and
we will deadlock.  To avoid the deadlock, we pagefault_disable()
when touching the bounds directory entry and use a
get_user_pages() to resolve the fault.

The unmapping of bounds tables happends under vm_munmap().  We
also (indirectly) call vm_munmap() to _do_ the unmapping of the
bounds tables.  We avoid unbounded recursion by disallowing
freeing of bounds tables *for* bounds tables.  This would not
occur normally, so should not have any practical impact.  Being
strict about it here helps ensure that we do not have an
exploitable stack overflow.
Based-on-patch-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151831.E4531C4A@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

This is really the meat of the MPX patch set.  If there is one patch to
review in the entire series, this is the one.  There is a new ABI here
and this kernel code also interacts with userspace memory in a
relatively unusual manner.  (small FAQ below).

Long Description:

This patch adds two prctl() commands to provide enable or disable the
management of bounds tables in kernel, including on-demand kernel
allocation (See the patch "on-demand kernel allocation of bounds tables")
and cleanup (See the patch "cleanup unused bound tables"). Applications
do not strictly need the kernel to manage bounds tables and we expect
some applications to use MPX without taking advantage of this kernel
support. This means the kernel can not simply infer whether an application
needs bounds table management from the MPX registers.  The prctl() is an
explicit signal from userspace.

PR_MPX_ENABLE_MANAGEMENT is meant to be a signal from userspace to
require kernel's help in managing bounds tables.

PR_MPX_DISABLE_MANAGEMENT is the opposite, meaning that userspace don't
want kernel's help any more. With PR_MPX_DISABLE_MANAGEMENT, the kernel
won't allocate and free bounds tables even if the CPU supports MPX.

PR_MPX_ENABLE_MANAGEMENT will fetch the base address of the bounds
directory out of a userspace register (bndcfgu) and then cache it into
a new field (->bd_addr) in  the 'mm_struct'.  PR_MPX_DISABLE_MANAGEMENT
will set "bd_addr" to an invalid address.  Using this scheme, we can
use "bd_addr" to determine whether the management of bounds tables in
kernel is enabled.

Also, the only way to access that bndcfgu register is via an xsaves,
which can be expensive.  Caching "bd_addr" like this also helps reduce
the cost of those xsaves when doing table cleanup at munmap() time.
Unfortunately, we can not apply this optimization to #BR fault time
because we need an xsave to get the value of BNDSTATUS.

==== Why does the hardware even have these Bounds Tables? ====

MPX only has 4 hardware registers for storing bounds information.
If MPX-enabled code needs more than these 4 registers, it needs to
spill them somewhere. It has two special instructions for this
which allow the bounds to be moved between the bounds registers
and some new "bounds tables".

They are similar conceptually to a page fault and will be raised by
the MPX hardware during both bounds violations or when the tables
are not present. This patch handles those #BR exceptions for
not-present tables by carving the space out of the normal processes
address space (essentially calling the new mmap() interface indroduced
earlier in this patch set.) and then pointing the bounds-directory
over to it.

The tables *need* to be accessed and controlled by userspace because
the instructions for moving bounds in and out of them are extremely
frequent. They potentially happen every time a register pointing to
memory is dereferenced. Any direct kernel involvement (like a syscall)
to access the tables would obviously destroy performance.

==== Why not do this in userspace? ====

This patch is obviously doing this allocation in the kernel.
However, MPX does not strictly *require* anything in the kernel.
It can theoretically be done completely from userspace. Here are
a few ways this *could* be done. I don't think any of them are
practical in the real-world, but here they are.

Q: Can virtual space simply be reserved for the bounds tables so
   that we never have to allocate them?
A: As noted earlier, these tables are *HUGE*. An X-GB virtual
   area needs 4*X GB of virtual space, plus 2GB for the bounds
   directory. If we were to preallocate them for the 128TB of
   user virtual address space, we would need to reserve 512TB+2GB,
   which is larger than the entire virtual address space today.
   This means they can not be reserved ahead of time. Also, a
   single process's pre-popualated bounds directory consumes 2GB
   of virtual *AND* physical memory. IOW, it's completely
   infeasible to prepopulate bounds directories.

Q: Can we preallocate bounds table space at the same time memory
   is allocated which might contain pointers that might eventually
   need bounds tables?
A: This would work if we could hook the site of each and every
   memory allocation syscall. This can be done for small,
   constrained applications. But, it isn't practical at a larger
   scale since a given app has no way of controlling how all the
   parts of the app might allocate memory (think libraries). The
   kernel is really the only place to intercept these calls.

Q: Could a bounds fault be handed to userspace and the tables
   allocated there in a signal handler instead of in the kernel?
A: (thanks to tglx) mmap() is not on the list of safe async
   handler functions and even if mmap() would work it still
   requires locking or nasty tricks to keep track of the
   allocation state there.

Having ruled out all of the userspace-only approaches for managing
bounds tables that we could think of, we create them on demand in
the kernel.
Based-on-patch-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151829.AD4310DE@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

This patch sets bound violation fields of siginfo struct in #BR
exception handler by decoding the user instruction and constructing
the faulting pointer.

We have to be very careful when decoding these instructions.  They
are completely controlled by userspace and may be changed at any
time up to and including the point where we try to copy them in to
the kernel.  They may or may not be MPX instructions and could be
completely invalid for all we know.

Note: This code is based on Qiaowei Ren's specialized MPX
decoder, but uses the generic decoder whenever possible.  It was
tested for robustness by generating a completely random data
stream and trying to decode that stream.  I also unmapped random
pages inside the stream to test the "partial instruction" short
read code.

We kzalloc() the siginfo instead of stack allocating it because
we need to memset() it anyway, and doing this makes it much more
clear when it got initialized by the MPX instruction decoder.

Changes from the old decoder:
 * Use the generic decoder instead of custom functions.  Saved
   ~70 lines of code overall.
 * Remove insn->addr_bytes code (never used??)
 * Make sure never to possibly overflow the regoff[] array, plus
   check the register range correctly in 32 and 64-bit modes.
 * Allow get_reg() to return an error and have mpx_get_addr_ref()
   handle when it sees errors.
 * Only call insn_get_*() near where we actually use the values
   instead if trying to call them all at once.
 * Handle short reads from copy_from_user() and check the actual
   number of read bytes against what we expect from
   insn_get_length().  If a read stops in the middle of an
   instruction, we error out.
 * Actually check the opcodes intead of ignoring them.
 * Dynamically kzalloc() siginfo_t so we don't leak any stack
   data.
 * Detect and handle decoder failures instead of ignoring them.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Based-on-patch-by: Qiaowei Ren <qiaowei.ren@intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151828.5BDD0915@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

We have chosen to perform the allocation of bounds tables in
kernel (See the patch "on-demand kernel allocation of bounds
tables") and to mark these VMAs with VM_MPX.

However, there is currently no suitable interface to actually do
this.  Existing interfaces, like do_mmap_pgoff(), have no way to
set a modified ->vm_ops or ->vm_flags and don't hold mmap_sem
long enough to let a caller do it.

This patch wraps mmap_region() and hold mmap_sem long enough to
make the modifications to the VMA which we need.

Also note the 32/64-bit #ifdef in the header.  We actually need
to do this at runtime eventually.  But, for now, we don't support
running 32-bit binaries on 64-bit kernels.  Support for this will
come in later patches.
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151827.CE440F67@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

MPX-enabled applications using large swaths of memory can
potentially have large numbers of bounds tables in process
address space to save bounds information. These tables can take
up huge swaths of memory (as much as 80% of the memory on the
system) even if we clean them up aggressively. In the worst-case
scenario, the tables can be 4x the size of the data structure
being tracked. IOW, a 1-page structure can require 4 bounds-table
pages.

Being this huge, our expectation is that folks using MPX are
going to be keen on figuring out how much memory is being
dedicated to it. So we need a way to track memory use for MPX.

If we want to specifically track MPX VMAs we need to be able to
distinguish them from normal VMAs, and keep them from getting
merged with normal VMAs. A new VM_ flag set only on MPX VMAs does
both of those things. With this flag, MPX bounds-table VMAs can
be distinguished from other VMAs, and userspace can also walk
/proc/$pid/smaps to get memory usage for MPX.

In addition to this flag, we also introduce a special ->vm_ops
specific to MPX VMAs (see the patch "add MPX specific mmap
interface"), but currently different ->vm_ops do not by
themselves prevent VMA merging, so we still need this flag.

We understand that VM_ flags are scarce and are open to other
options.
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151825.565625B3@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

This allows us to use cpu_feature_enabled(X86_FEATURE_MPX) as
both a runtime and compile-time check.

When CONFIG_X86_INTEL_MPX is disabled,
cpu_feature_enabled(X86_FEATURE_MPX) will evaluate at
compile-time to 0. If CONFIG_X86_INTEL_MPX=y, then the cpuid
flag will be checked at runtime.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Qiaowei Ren <qiaowei.ren@intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151823.B358EAD2@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

New fields about bound violation are added into general struct
siginfo. This will impact MIPS and IA64, which extend general
struct siginfo. This patch syncs this struct for IA64 with
general version.
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151822.82B3B486@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

New fields about bound violation are added into general struct
siginfo. This will impact MIPS and IA64, which extend general
struct siginfo. This patch syncs this struct for MIPS with
general version.
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151820.F7EDC3CC@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

This patch adds new fields about bound violation into siginfo
structure. si_lower and si_upper are respectively lower bound
and upper bound when bound violation is caused.
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141114151819.1908C900@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

According to Intel SDM extension, MPX configuration and status registers
should be BNDCFGU and BNDSTATUS. This patch renames cfg_reg_u and
status_reg to bndcfgu and bndstatus.

[ tglx: Renamed 'struct bndscr_struct' to 'struct bndscr' ]
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-mm@kvack.org
Cc: linux-mips@linux-mips.org
Cc: Dave Hansen <dave@sr71.net>
Cc: Qiaowei Ren <qiaowei.ren@intel.com>
Link: http://lkml.kernel.org/r/20141114151817.031762AC@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Consider the bndX MPX registers.  There 4 registers each
containing a 64-bit lower and a 64-bit upper bound.  That's 8*64
bits and we declare it thusly:

	struct bndregs_struct {
		u64 bndregs[8];
	}
    
Let's say you want to read the upper bound from the MPX register
bnd2 out of the xsave buf.  You do:

	bndregno = 2;
	upper_bound = xsave_buf->bndregs.bndregs[2*bndregno+1];

That kinda sucks.  Every time you access it, you need to know:
1. Each bndX register is two entries wide in "bndregs"
2. The lower comes first followed by upper.  We do the +1 to get
   upper vs. lower.

This replaces the old definition.  You can now access them
indexed by the register number directly, and with a meaningful
name for the lower and upper bound:

	bndregno = 2;
	xsave_buf->bndreg[bndregno].upper_bound;

It's now *VERY* clear that there are 4 registers.  The programmer
now doesn't have to care what order the lower and upper bounds
are in, and it's harder to get it wrong.

[ tglx: Changed ub/lb to upper_bound/lower_bound and renamed struct
bndreg_struct to struct bndreg ]
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: Qiaowei Ren <qiaowei.ren@intel.com>
Cc: "Yu, Fenghua" <fenghua.yu@intel.com>
Cc: Dave Hansen <dave@sr71.net>
Link: http://lkml.kernel.org/r/20141031215820.5EA5E0EC@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

The current x86 instruction decoder steps along through the
instruction stream but always ensures that it never steps farther
than the largest possible instruction size (MAX_INSN_SIZE).

The MPX code is now going to be doing some decoding of userspace
instructions.  We copy those from userspace in to the kernel and
they're obviously completely untrusted coming from userspace.  In
addition to the constraint that instructions can only be so long,
we also have to be aware of how long the buffer is that came in
from userspace.  This _looks_ to be similar to what the perf and
kprobes is doing, but it's unclear to me whether they are
affected.

The whole reason we need this is that it is perfectly valid to be
executing an instruction within MAX_INSN_SIZE bytes of an
unreadable page. We should be able to gracefully handle short
reads in those cases.

This adds support to the decoder to record how long the buffer
being decoded is and to refuse to "validate" the instruction if
we would have gone over the end of the buffer to decode it.

The kprobes code probably needs to be looked at here a bit more
carefully.  This patch still respects the MAX_INSN_SIZE limit
there but the kprobes code does look like it might be able to
be a bit more strict than it currently is.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: x86@kernel.org
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Link: http://lkml.kernel.org/r/20141114153957.E6B01535@viggo.jf.intel.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>

Pull arm64 fixes from Catalin Marinas:
 - enable bpf syscall for compat
 - cpu_suspend fix when checking the idle state type
 - defconfig update

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: defconfig: update defconfig for 3.18
  arm64: compat: Enable bpf syscall
  arm64: psci: fix cpu_suspend to check idle state type for index

Pull ARM SoC fixes from Olof Johansson:
 "Another quiet week:

   - a fix to silence edma probe error on non-supported platforms from
     Arnd
   - a fix to enable the PL clock for Parallella, to make mainline
     usable with the SDK.
   - a somewhat verbose fix for the PLL clock tree on VF610
   - enabling of SD/MMC on one of the VF610-based boards (for testing)
   - a fix for i.MX where CONFIG_SPI used to be implicitly enabled and
     now needs to be added to the defconfig instead
   - another maintainer added for bcm2835: Lee Jones"

* tag 'armsoc-for-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: dts: zynq: Enable PL clocks for Parallella
  dma: edma: move device registration to platform code
  ARM: dts: vf610: add SD node to cosmic dts
  MAINTAINERS: update bcm2835 entry
  ARM: imx: Fix the removal of CONFIG_SPI option
  ARM: imx: clk-vf610: define PLL's clock tree

Pull devicetree bugfix from Grant Likely:
 "One buffer overflow bug that shouldn't be left around"

* 'devicetree/merge' of git://git.kernel.org/pub/scm/linux/kernel/git/glikely/linux:
  of: Fix overflow bug in string property parsing functions

Pull btrfs fix from Chris Mason:
 "It's a one liner for an error cleanup path that leads to crashes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: fix kfree on list_head in btrfs_lookup_csums_range error cleanup

Merge tag 'driver-core-3.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core fixes from Greg KH:
 "Here are 3 tiny fixes for 3.18-rc4.

  One fixes up a long-stading race condition in the driver core for
  removing directories in /sys/devices/virtual/ and the other 2 fix up
  the wording of a new Kconfig option that was added in 3.18-rc1"

* tag 'driver-core-3.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  tiny: rename ENABLE_DEV_COREDUMP to ALLOW_DEV_COREDUMP
  tiny: reverse logic for DISABLE_DEV_COREDUMP
  sysfs: driver core: Fix glue dir race condition by gdp_mutex

Pull staging driver fixes from Greg KH:
 "Here are some staging/iio fixes for 3.18-rc4.

  Nothing major, just a few bugfixes of things that have been reported"

* tag 'staging-3.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging:iio:ade7758: Remove "raw" from channel name
  staging:iio:ade7758: Fix check if channels are enabled in prenable
  staging:iio:ade7758: Fix NULL pointer deref when enabling buffer
  iio: as3935: allocate correct iio_device size
  io: accel: kxcjk-1013: Fix iio_event_spec direction
  iio: tsl4531: Fix compiler error when CONFIG_PM_OPS is not defined
  iio: adc: mxs-lradc: Disable the clock on probe failure
  iio: st_sensors: Fix buffer copy
  staging:iio:ad5933: Drop "raw" from channel names
  staging:iio:ad5933: Fix NULL pointer deref when enabling buffer

Pull tty/serial fixes from Greg KH:
 "Here are some tiny serial/tty fixes for 3.18-rc4 that resolve some
  reported issues"

* tag 'tty-3.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  tty: Fix pty master poll() after slave closes v2
  serial: of-serial: fix uninitialized kmalloc variable
  tty/vt: don't set font mappings on vc not supporting this
  tty: serial: 8250_mtk: Fix quot calculation
  tty: Prevent "read/write wait queue active!" log flooding
  tty: Fix high cpu load if tty is unreleaseable
  serial: Fix divide-by-zero fault in uart_get_divisor()

Pull USB fixes from Greg KH:
 "Here are some USB fixes for 3.18-rc4.

  Just a bunch of little fixes resolving reported issues and new device
  ids for existing drivers.  Full details are in the shortlog"

* tag 'usb-3.18-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (26 commits)
  USB: Update default usb-storage delay_use value in kernel-parameters.txt
  USB: cdc-acm: add quirk for control-line state requests
  phy: omap-usb2: Enable runtime PM of omap-usb2 phy properly
  USB: storage: Fix timeout in usb_stor_euscsi_init() and usb_stor_huawei_e220_init()
  USB: cdc-acm: only raise DTR on transitions from B0
  Revert "storage: Replace magic number with define in usb_stor_euscsi_init()"
  usb: core: notify disconnection when core detects disconnect
  usb: core: need to call usb_phy_notify_connect after device setup
  uas: Add US_FL_NO_ATA_1X quirk for 2 more Seagate models
  xhci: no switching back on non-ULT Haswell
  USB: quirks: enable device-qualifier quirk for yet another Elan touchscreen
  USB: quirks: enable device-qualifier quirk for another Elan touchscreen
  MAINTAINERS: Remove duplicate entry for usbip driver
  usb: storage: fix build warnings !CONFIG_PM
  usb: Remove references to non-existent PLAT_S5P symbol
  uas: Add NO_ATA_1X for VIA VL711 devices
  xhci: Disable streams on Asmedia 1042 xhci controllers
  USB: HWA: fix a warning message
  uas: Add US_FL_NO_ATA_1X quirk for 1 more Seagate model
  usb-storage: handle a skipped data phase
  ...

The Parallella board comes with a U-Boot bootloader that loads one of
two predefined FPGA bitstreams before booting the kernel. Both define an
AXI interface to the on-board Epiphany processor.

Enable clocks FCLK0..FCLK3 for the Programmable Logic by default.

Otherwise accessing, e.g., the ESYSRESET register freezes the board,
as seen with the Epiphany SDK tools e-reset and e-hw-rev, using /dev/mem.

Cc: <stable@vger.kernel.org> # 3.17.x
Signed-off-by: Andreas Färber <afaerber@suse.de>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

Pull i2c bugfixes from Wolfram Sang:
 "One bigger cleanup (FSF address removal) and two bugfixes for I2C"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: core: Dispose OF IRQ mapping at client removal time
  i2c: at91: don't account as iowait
  i2c: remove FSF address

Pull irq fixes from Thomas Gleixner:
 "Two fixlets for the armada SoC interrupt controller"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip: armada-370-xp: Fix MPIC interrupt handling
  irqchip: armada-370-xp: Fix MSI interrupt handling

Pull media fixes from Mauro Carvalho Chehab:
 "For:
   - some regression fixes at the Remote Controller core and imon driver
   - a build fix for certain randconfigs with ir-hix5hd2
   - don't feed power to satellite system at ds3000 driver init

  It also contains some fixes for drivers added for Kernel 3.18:
   - some fixes at the new ISDB-S driver, and the corresponding bits to
     fix some descriptors for this Japanese TV standard at the DVB core
   - two warning cleanups for sp2 driver if PM is disabled
   - change the default mode for the new vivid driver"

* git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
  [media] sp2: sp2_init() can be static
  [media] dvb:tc90522: fix always-false expression
  [media] dvb-core: set default properties of ISDB-S
  [media] dvb:tc90522: fix stats report
  [media] vivid: default to single planar device instances
  [media] imon: fix other RC type protocol support
  [media] ir-hix5hd2 fix build warning
  [media] ds3000: fix LNB supply voltage on Tevii S480 on initialization
  [media] rc5-decoder: BZ#85721: Fix RC5-SZ decoding
  [media] rc-core: fix protocol_change regression in ir_raw_event_register

Pull MIPS updates from Ralf Baechle:
 "This weeks' round of MIPS bug fixes for 3.18:

   - wire up the bpf syscall
   - fix TLB dump output for R3000 class TLBs
   - fix strnlen_user return value if no NUL character was found.
   - fix build with binutils 2.24.51+.  While there is no binutils 2.25
     release yet, toolchains derived from binutils 2.24.51+ are already
     in common use.
   - the Octeon GPIO code forgot to offline GPIO IRQs.
   - fix build error for XLP.
   - fix possible BUG assertion with EVA for CMA"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
  MIPS: Fix build with binutils 2.24.51+
  MIPS: R3000: Fix debug output for Virtual page number
  MIPS: Fix strnlen_user() return value in case of overlong strings.
  MIPS: CMA: Do not reserve memory if not required
  MIPS: Wire up bpf syscall.
  MIPS/Xlp: Remove the dead function destroy_irq() to fix build error
  MIPS: Octeon: Make Octeon GPIO IRQ chip CPU hotplug-aware

Pull xfs fixes from Dave Chinner:
 "This update fixes a warning in the new pagecache_isize_extended() and
  updates some related comments, another fix for zero-range
  misbehaviour, and an unforntuately large set of fixes for regressions
  in the bulkstat code.

  The bulkstat fixes are large but necessary.  I wouldn't normally push
  such a rework for a -rcX update, but right now xfsdump can silently
  create incomplete dumps on 3.17 and it's possible that even xfsrestore
  won't notice that the dumps were incomplete.  Hence we need to get
  this update into 3.17-stable kernels ASAP.

  In more detail, the refactoring work I committed in 3.17 has exposed a
  major hole in our QA coverage.  With both xfsdump (the major user of
  bulkstat) and xfsrestore silently ignoring missing files in the
  dump/restore process, incomplete dumps were going unnoticed if they
  were being triggered.  Many of the dump/restore filesets were so small
  that they didn't evenhave a chance of triggering the loop iteration
  bugs we introduced in 3.17, so we didn't exercise the code
  sufficiently, either.

  We have already taken steps to improve QA coverage in xfstests to
  avoid this happening again, and I've done a lot of manual verification
  of dump/restore on very large data sets (tens of millions of inodes)
  of the past week to verify this patch set results in bulkstat behaving
  the same way as it does on 3.16.

  Unfortunately, the fixes are not exactly simple - in tracking down the
  problem historic API warts were discovered (e.g xfsdump has been
  working around a 20 year old bug in the bulkstat API for the past 10
  years) and so that complicated the process of diagnosing and fixing
  the problems.  i.e. we had to fix bugs in the code as well as
  discover and re-introduce the userspace visible API bugs that we
  unwittingly "fixed" in 3.17 that xfsdump relied on to work correctly.

  Summary:

   - incorrect warnings about i_mutex locking in pagecache_isize_extended()
     and updates comments to match expected locking
   - another zero-range bug fix for stray file size updates
   - a bunch of fixes for regression in the bulkstat code introduced in
     3.17"

* tag 'xfs-for-linus-3.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs:
  xfs: track bulkstat progress by agino
  xfs: bulkstat error handling is broken
  xfs: bulkstat main loop logic is a mess
  xfs: bulkstat chunk-formatter has issues
  xfs: bulkstat chunk formatting cursor is broken
  xfs: bulkstat btree walk doesn't terminate
  mm: Fix comment before truncate_setsize()
  xfs: rework zero range to prevent invalid i_size updates
  mm: Remove false WARN_ON from pagecache_isize_extended()
  xfs: Check error during inode btree iteration in xfs_bulkstat()
  xfs: bulkstat doesn't release AGI buffer on error

Pull regulator fixes from Mark Brown:
 "More changes than I'd like here, most of them for a single bug
  repeated in a bunch of drivers with data not being initialized
  correctly, plus a fix to lower the severity of a warning introduced in
  the last merge window which can legitimately go off so we don't want
  to alarm users excessively"

* tag 'regulator-v3.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
  regulator: s2mpa01: zero-initialize regulator match table array
  regulator: max8660: zero-initialize regulator match table array
  regulator: max77802: zero-initialize regulator match table
  regulator: max77686: zero-initialize regulator match table
  regulator: max1586: zero-initialize regulator match table array
  regulator: max77693: Fix use of uninitialized regulator config
  regulator: of: Lower the severity of the error with no container

Pull spi bugfixes from Mark Brown:
 "A couple of small driver fixes for v3.18, both quite problematic if
  you hit a use case that's affected"

* tag 'spi-v3.18-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: pxa2xx: toggle clocks on suspend if not disabled by runtime PM
  spi: fsl-dspi: Fix CTAR selection

The ENABLE_DEV_COREDUMP option is misleading as it implies that
it gets the framework enabled, this isn't true it just allows it
to get enabled if a driver needs it.

Rename it to ALLOW_DEV_COREDUMP to better capture its semantics.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

It's desirable for allnconfig and tinyconfig targets to result in the
least amount of code possible. DISABLE_DEV_COREDUMP exists as a way to
switch off DEV_COREDUMP regardless if any drivers select
WANT_DEV_COREDUMP.

This patch renames the option to ENABLE_DEV_COREDUMP and setting it to
'n' (as in allnconfig or tinyconfig) will effectively disable device
coredump.

Cc: Josh Triplett <josh@joshtriplett.org>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Aristeu Rozanski <arozansk@redhat.com>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>