print_symbol() is a very old API that has been obsoleted by %pS format
specifier in a normal printk() call.

Replace print_symbol() with a direct printk("%pS") call and correctly
handle continuous lines.

Link: http://lkml.kernel.org/r/20171211125025.2270-9-sergey.senozhatsky@gmail.com
To: Andrew Morton <akpm@linux-foundation.org>
To: Russell King <linux@armlinux.org.uk>
To: Catalin Marinas <catalin.marinas@arm.com>
To: Mark Salter <msalter@redhat.com>
To: Tony Luck <tony.luck@intel.com>
To: David Howells <dhowells@redhat.com>
To: Yoshinori Sato <ysato@users.sourceforge.jp>
To: Guan Xuetao <gxt@mprc.pku.edu.cn>
To: Borislav Petkov <bp@alien8.de>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
To: Vineet Gupta <vgupta@synopsys.com>
To: Fengguang Wu <fengguang.wu@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-am33-list@redhat.com
Cc: linux-sh@vger.kernel.org
Cc: linux-edac@vger.kernel.org
Cc: x86@kernel.org
Cc: linux-snps-arc@lists.infradead.org
Signed-off-by: NSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Borislav Petkov <bp@suse.de> # mce.c part
[pmladek@suse.com: updated commit message]
Signed-off-by: NPetr Mladek <pmladek@suse.com>

In line with asm/e820/types.h, move the e820 API declarations to
asm/e820/api.h and update all usage sites.

This is just a mechanical, obviously correct move & replace patch,
there will be subsequent changes to clean up the code and to make
better use of the new header organization.

Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Jackson <pj@sgi.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends.  That changed
when we forked out support for the latter into the export.h file.

This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig.  The advantage
in doing so is that module.h itself sources about 15 other headers;
adding significantly to what we feed cpp, and it can obscure what
headers we are effectively using.

Since module.h was the source for init.h (for __init) and for
export.h (for EXPORT_SYMBOL) we consider each obj-y/bool instance
for the presence of either and replace accordingly where needed.

Note that some bool/obj-y instances remain since module.h is
the header for some exception table entry stuff, and for things
like __init_or_module (code that is tossed when MODULES=n).
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160714001901.31603-3-paul.gortmaker@windriver.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings.  In any case, they are temporary and harmless.

This removes all the arch/x86 uses of the __cpuinit macros from
all C files.  x86 only had the one __CPUINIT used in assembly files,
and it wasn't paired off with a .previous or a __FINIT, so we can
delete it directly w/o any corresponding additional change there.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Acked-by: NIngo Molnar <mingo@kernel.org>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NH. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>

module_param(bool) used to counter-intuitively take an int.  In
fddd5201 (mid-2009) we allowed bool or int/unsigned int using a messy
trick.

It's time to remove the int/unsigned int option.  For this version
it'll simply give a warning, but it'll break next kernel version.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

It was pointed out by 'make versioncheck' that the include of
linux/version.h is not needed in arch/x86/mm/mmio-mod.c .
This patch removes it.
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

It was pointed out by 'make versioncheck' that the include of
linux/version.h is not needed in arch/x86/mm/mmio-mod.c .
This patch removes it.
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1108012305570.31999@swampdragon.chaosbits.netSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

This allows us to move duplicated code in <asm/atomic.h>
(atomic_inc_not_zero() for now) to <linux/atomic.h>
Signed-off-by: NArun Sharma <asharma@fb.com>
Reviewed-by: NEric Dumazet <eric.dumazet@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Miller <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h

percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files.  percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.

percpu.h -> slab.h dependency is about to be removed.  Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability.  As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.

  http://userweb.kernel.org/~tj/misc/slabh-sweep.py

The script does the followings.

* Scan files for gfp and slab usages and update includes such that
  only the necessary includes are there.  ie. if only gfp is used,
  gfp.h, if slab is used, slab.h.

* When the script inserts a new include, it looks at the include
  blocks and try to put the new include such that its order conforms
  to its surrounding.  It's put in the include block which contains
  core kernel includes, in the same order that the rest are ordered -
  alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
  doesn't seem to be any matching order.

* If the script can't find a place to put a new include (mostly
  because the file doesn't have fitting include block), it prints out
  an error message indicating which .h file needs to be added to the
  file.

The conversion was done in the following steps.

1. The initial automatic conversion of all .c files updated slightly
   over 4000 files, deleting around 700 includes and adding ~480 gfp.h
   and ~3000 slab.h inclusions.  The script emitted errors for ~400
   files.

2. Each error was manually checked.  Some didn't need the inclusion,
   some needed manual addition while adding it to implementation .h or
   embedding .c file was more appropriate for others.  This step added
   inclusions to around 150 files.

3. The script was run again and the output was compared to the edits
   from #2 to make sure no file was left behind.

4. Several build tests were done and a couple of problems were fixed.
   e.g. lib/decompress_*.c used malloc/free() wrappers around slab
   APIs requiring slab.h to be added manually.

5. The script was run on all .h files but without automatically
   editing them as sprinkling gfp.h and slab.h inclusions around .h
   files could easily lead to inclusion dependency hell.  Most gfp.h
   inclusion directives were ignored as stuff from gfp.h was usually
   wildly available and often used in preprocessor macros.  Each
   slab.h inclusion directive was examined and added manually as
   necessary.

6. percpu.h was updated not to include slab.h.

7. Build test were done on the following configurations and failures
   were fixed.  CONFIG_GCOV_KERNEL was turned off for all tests (as my
   distributed build env didn't work with gcov compiles) and a few
   more options had to be turned off depending on archs to make things
   build (like ipr on powerpc/64 which failed due to missing writeq).

   * x86 and x86_64 UP and SMP allmodconfig and a custom test config.
   * powerpc and powerpc64 SMP allmodconfig
   * sparc and sparc64 SMP allmodconfig
   * ia64 SMP allmodconfig
   * s390 SMP allmodconfig
   * alpha SMP allmodconfig
   * um on x86_64 SMP allmodconfig

8. percpu.h modifications were reverted so that it could be applied as
   a separate patch and serve as bisection point.

Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: NTejun Heo <tj@kernel.org>
Guess-its-ok-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>

Stephen Rothwell reported these warnings:

 arch/x86/mm/mmio-mod.c: In function 'print_pte':
 arch/x86/mm/mmio-mod.c:100: warning: too many arguments for format
 arch/x86/mm/mmio-mod.c:106: warning: too many arguments for format

The 'fmt' was left out accidentally.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus <torvalds@linux-foundation.org>
LKML-Reference: <1260775443.18538.16.camel@Joe-Laptop.home>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

- Add #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 - Remove #define NAME
 - Remove NAME from pr_<level>
Signed-off-by: NJoe Perches <joe@perches.com>
LKML-Reference: <009cb214c45ef932df0242856228f4739cc91408.1260383912.git.joe@perches.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Follow up to afcfe024 in Linus' tree
("x86: mmiotrace: quieten spurious warning message")
Signed-off-by: NStuart Bennett <stuart@freedesktop.org>
Acked-by: NPekka Paalanen <pq@iki.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1240946271-7083-5-git-send-email-stuart@freedesktop.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Impact: cleanup, reduce memory usage for CONFIG_CPUMASK_OFFSTACK=y

Part of the "getting rid of obsolete cpumask_t" patch:

 1) Use cpumask_var_t: this is a pointer if CONFIG_CPUMASK_OFFSTACK=y
 2) Call alloc_cpumask_var() on first entry into enter_uniprocessor()
 3) Use modern cpumask_* functions.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: Pekka Paalanen <pq@iki.fi>
LKML-Reference: <200903111633.55952.rusty@rustcorp.com.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NPekka Paalanen <pq@iki.fi>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Offer mmiotrace users a function to inject markers from inside the kernel.
This depends on the trace_vprintk() patch.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NPekka Paalanen <pq@iki.fi>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

WARNING: vmlinux.o(.text+0x180af): Section mismatch in reference from the function leave_uniprocessor() to the function .cpuinit.text:cpu_up()
The function leave_uniprocessor() references
the function __cpuinit cpu_up().
This is often because leave_uniprocessor lacks a __cpuinit
annotation or the annotation of cpu_up is wrong.

leave_uniprocessor calls cpu_up only when CONFIG_HOTPLUG_CPU is set,
so it can be safely annotated as __ref
Signed-off-by: NMarcin Slusarz <marcin.slusarz@gmail.com>
Cc: Pekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pekka Paalanen <pq@iki.fi>

Fixes some sparse warnings.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

mmiotrace_ioremap() expects to receive the original unaligned map phys address
and size. Also fix {un,}register_kmmio_probe() to deal properly with
unaligned size.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

From c2da03771e29159627c5c7b9509ec70bce9f91ee Mon Sep 17 00:00:00 2001
From: Pekka Paalanen <pq@iki.fi>
Date: Mon, 28 Apr 2008 21:25:22 +0300
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

From 8979ee55cb6a429c4edd72ebec2244b849f6a79a Mon Sep 17 00:00:00 2001
From: Pekka Paalanen <pq@iki.fi>
Date: Sat, 12 Apr 2008 00:18:57 +0300

Mmiotrace is not reliable with multiple CPUs and may
miss events. Drop to single CPU when mmiotrace is activated.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Fix gcc printk format warnings:

next-20080415/arch/x86/mm/mmio-mod.c: In function 'print_pte':
next-20080415/arch/x86/mm/mmio-mod.c:154: warning: format '%lx' expects type 'long unsigned int', but argument 3 has type 'pteval_t'
next-20080415/arch/x86/mm/mmio-mod.c:154: warning: format '%lx' expects type 'long unsigned int', but argument 4 has type 'pteval_t'
next-20080415/arch/x86/mm/mmio-mod.c: At top level:
next-20080415/arch/x86/mm/mmio-mod.c:403: warning: 'downed_cpus' defined but not used
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

This had become a no-op.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

another weekend, another patch. This should apply on top of my previous patch
from March 23rd.

Summary of changes:
- Print PCI device list in output header
- work around recursive probe hits on SMP
- refactor dis/arm_kmmio_fault_page() and add check for page levels
- remove un/reference_kmmio(), the die notifier hook is registered
permanently into the list
- explicitly check for single stepping in die notifier callback

I have tested this version on my UP Athlon64 desktop with Nouveau, and
SMP Core 2 Duo laptop with the proprietary nvidia driver. Both systems
are 64-bit. One previously unknown bug crept into daylight: the ftrace
framework's output routines print the first entry last after buffer has
wrapped around.

The most important regressions compared to non-ftrace mmiotrace at this
time are:
- failure of trace_pipe file
- illegal lines in output file
- unaware of losing data due to buffer full

Personally I'd like to see these three solved before submitting to
mainline. Other issues may come up once we know when we lose events.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

here is a patch that makes mmiotrace work almost well within the tracing
framework. The patch applies on top of my previous patch. I have my own
output formatting in place now.

Summary of changes:
- fix the NULL dereference that was due to not calling tracing_reset()
- add print_line() callback into struct tracer
- implement print_line() for mmiotrace, producing up-to-spec text
- add my output header, but that is not really called in the right place
- rewrote the main structs in mmiotrace
- added two new trace entry types: TRACE_MMIO_RW and TRACE_MMIO_MAP
- made some functions in trace.c non-static
- check current==NULL in tracing_generic_entry_update()
- fix(?) comparison in trace_seq_printf()

Things seem to work fine except a few issues. Markers (text lines injected
into mmiotrace log) are missing, I did not feel hacking them in before we
have variable length entries. My output header is printed only for 'trace'
file, but not 'trace_pipe'. For some reason, despite my quick fix,
iter->trace is NULL in print_trace_line() when called from 'trace_pipe'
file, which means I don't get proper output formatting.

I only tried by loading nouveau.ko, which just detects the card, and that
is traced fine. I didn't try further. Map, two reads and unmap. Works
perfectly.

I am missing the information about overflows, I'd prefer to have a
counter for lost events. I didn't try, but I guess currently there is no
way of knowning when it overflows?

So, not too far from being fully operational, it seems :-)
And looking at the diffstat, there also is some 700-900 lines of user space
code that just became obsolete.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

On Sat, 22 Mar 2008 13:07:47 +0100
Ingo Molnar <mingo@elte.hu> wrote:

> > > i'd suggest the following: pull x86.git and sched-devel.git into a
> > > single tree [the two will combine without rejects]. Then try to add a
> > > kernel/tracing/trace_mmiotrace.c ftrace plugin. The trace_sysprof.c
> > > plugin might be a good example.
> >
> > I did this and now I have mmiotrace enabled/disabled via the tracing
> > framework (what do we call this, since ftrace is one of the tracers?).
>
> cool! could you send the patches for that? (even if they are not fully
> functional yet)

Patch attached in the end. Nice to see how much code disappeared. I tried
to mark all the features I had to break with XXX-comments.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Kconfig.debug, Makefile and testmmiotrace.c style fixes.
Use real mutex instead of mutex.
Fix failure path in register probe func.
kmmio: RCU read-locked over single stepping.
Generate mapping id's.
Make mmio-mod.c built-in and rewrite its locking.
Add debugfs file to enable/disable mmiotracing.
kmmio: use irqsave spinlocks.
Lots of cleanups in mmio-mod.c
Marker file moved from /proc into debugfs.
Call mmiotrace entrypoints directly from ioremap.c.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

kmmio.c handles the list of mmio probes with callbacks, list of traced
pages, and attaching into the page fault handler and die notifier. It
arms, traps and disarms the given pages, this is the core of mmiotrace.

mmio-mod.c is a user interface, hooking into ioremap functions and
registering the mmio probes. It also decodes the required information
from trapped mmio accesses via the pre and post callbacks in each probe.
Currently, hooking into ioremap functions works by redefining the symbols
of the target (binary) kernel module, so that it calls the traced
versions of the functions.

The most notable changes done since the last discussion are:
- kmmio.c is a built-in, not part of the module
- direct call from fault.c to kmmio.c, removing all dynamic hooks
- prepare for unregistering probes at any time
- make kmmio re-initializable and accessible to more than one user
- rewrite kmmio locking to remove all spinlocks from page fault path

Can I abuse call_rcu() like I do in kmmio.c:unregister_kmmio_probe()
or is there a better way?

The function called via call_rcu() itself calls call_rcu() again,
will this work or break? There I need a second grace period for RCU
after the first grace period for page faults.

Mmiotrace itself (mmio-mod.c) is still a module, I am going to attack
that next. At some point I will start looking into how to make mmiotrace
a tracer component of ftrace (thanks for the hint, Ingo). Ftrace should
make the user space part of mmiotracing as simple as
'cat /debug/trace/mmio > dump.txt'.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Signed-off-by: NPekka Paalanen <pq@iki.fi>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: pq@iki.fi
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Relay has per-cpu buffers, but mmiotrace was using only a single flag
for detecting buffer full/not-full transitions. The new code makes
this per-cpu and actually counts missed events.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Use lookup_address() from pageattr.c instead of doing the same
manually. Also had to EXPORT_SYMBOL_GPL(lookup_address) to make this
work for modules. This also fixes "undefined symbol 'init_mm'"
compile error for x86_32.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Mmiotrace is a tool for trapping memory mapped IO (MMIO) accesses within
the kernel. It is used for debugging and especially for reverse
engineering evil binary drivers.

Mmiotrace works by wrapping the ioremap family of kernel functions and
marking the returned pages as not present. Access to the IO memory
triggers a page fault, which will be handled by mmiotrace's custom page
fault handler. This will single-step the faulted instruction with the
MMIO page marked as present. Access logs are directed to user space via
relay and debug_fs.

This page fault approach is necessary, because binary drivers have
readl/writel etc. calls inlined and therefore extremely difficult to
trap with with e.g. kprobes.

This patch depends on the custom page fault handlers patch.
Signed-off-by: NPekka Paalanen <pq@iki.fi>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>