Removing a bounce buffer copy operation in the pmsg driver path is
always better. We also gain in overall performance by not requesting
a vmalloc on every write as this can cause precious RT tasks, such
as user facing media operation, to stall while memory is being
reclaimed. Added a write_buf_user to the pstore functions, a backup
platform write_buf_user that uses the small buffer that is part of
the instance, and implemented a ramoops write_buf_user that only
supports PSTORE_TYPE_PMSG.
Signed-off-by: NMark Salyzyn <salyzyn@android.com>
Signed-off-by: NKees Cook <keescook@chromium.org>

I have here a FPGA behind PCIe which exports SRAM which I use for
pstore. Now it seems that the FPGA no longer supports cmpxchg based
updates and writes back 0xff…ff and returns the same.  This leads to
crash during crash rendering pstore useless.
Since I doubt that there is much benefit from using cmpxchg() here, I am
dropping this atomic access and use the spinlock based version.

Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Rabin Vincent <rabinv@axis.com>
Tested-by: NRabin Vincent <rabinv@axis.com>
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: NGuenter Roeck <linux@roeck-us.net>
[kees: remove "_locked" suffix since it's the only option now]
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org

On some ARMs the memory can be mapped pgprot_noncached() and still
be working for atomic operations. As pointed out by Colin Cross
<ccross@android.com>, in some cases you do want to use
pgprot_noncached() if the SoC supports it to see a debug printk
just before a write hanging the system.

On ARMs, the atomic operations on strongly ordered memory are
implementation defined. So let's provide an optional kernel parameter
for configuring pgprot_noncached(), and use pgprot_writecombine() by
default.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robherring2@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: stable@vger.kernel.org
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

Currently trying to use pstore on at least ARMs can hang as we're
mapping the peristent RAM with pgprot_noncached().

On ARMs, pgprot_noncached() will actually make the memory strongly
ordered, and as the atomic operations pstore uses are implementation
defined for strongly ordered memory, they may not work. So basically
atomic operations have undefined behavior on ARM for device or strongly
ordered memory types.

Let's fix the issue by using write-combine variants for mappings. This
corresponds to normal, non-cacheable memory on ARM. For many other
architectures, this change does not change the mapping type as by
default we have:

#define pgprot_writecombine pgprot_noncached

The reason why pgprot_noncached() was originaly used for pstore
is because Colin Cross <ccross@android.com> had observed lost
debug prints right before a device hanging write operation on some
systems. For the platforms supporting pgprot_noncached(), we can
add a an optional configuration option to support that. But let's
get pstore working first before adding new features.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Anton Vorontsov <cbouatmailru@gmail.com>
Cc: Colin Cross <ccross@android.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NRob Herring <rob.herring@calxeda.com>
[tony@atomide.com: updated description]
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NTony Luck <tony.luck@intel.com>

kmalloc_array manages count*sizeof overflow.
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

- Define pr_fmt in plateform.c and ram_core.c for global prefix.

- Coalesce format fragments.

- Separate format/arguments on lines > 80 characters.

Note: Some pr_foo() were initially declared without prefix and therefore
this could break existing log analyzer.

[akpm@linux-foundation.org: missed a couple of prefix removals]
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: Joe Perches <joe@perches.com>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In case new offset is equal to prz->buffer_size, it won't wrap at this
time and will return old(overflow) value next time.
Signed-off-by: NLiu ShuoX <shuox.liu@intel.com>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NTony Luck <tony.luck@intel.com>

For persistent RAM outside of main memory, the memory may have limitations
on supported accesses. For internal RAM on highbank platform exclusive
accesses are not supported and will hang the system. So atomic_cmpxchg
cannot be used. This commit uses spinlock protection for buffer size and
start updates on ioremapped regions instead.
Signed-off-by: NRob Herring <rob.herring@calxeda.com>
Acked-by: NAnton Vorontsov <anton@enomsg.org>
Signed-off-by: NTony Luck <tony.luck@intel.com>

This was lost when proc/last_kmsg moved to pstore/console-ramoops.
Signed-off-by: NArve Hjønnevåg <arve@android.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NAnton Vorontsov <anton@enomsg.org>

Allow specifying ecc parameters in platform data
Signed-off-by: NArve Hjønnevåg <arve@android.com>
[jstultz: Tweaked commit subject & add commit message]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NAnton Vorontsov <anton@enomsg.org>

Wastes less memory and allows using more memory for ecc than data.
Signed-off-by: NArve Hjønnevåg <arve@android.com>
[jstultz: Tweaked commit subject]
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NAnton Vorontsov <anton@enomsg.org>

CONFIG_HOTPLUG is going away as an option.  As a result, the __dev*
markings need to be removed.

This change removes the use of __devinit from the pstore filesystem.

Based on patches originally written by Bill Pemberton, but redone by me
in order to handle some of the coding style issues better, by hand.

Cc: Bill Pemberton <wfp5p@virginia.edu>
Cc: Anton Vorontsov <cbouatmailru@gmail.com>
Cc: Colin Cross <ccross@android.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Decoding the binary trace w/ a different kernel might be troublesome
since we convert addresses to symbols. For kernels with minimal changes,
the mappings would probably match, but it's not guaranteed at all.
(But still we could convert the addresses by hand, since we do print
raw addresses.)

If we use modules, the symbols could be loaded at different addresses
from the previously booted kernel, and so this would also fail, but
there's nothing we can do about it.

Also, the binary data format that pstore/ram is using in its ringbuffer
may change between the kernels, so here we too must ensure that we're
running the same kernel.

So, there are two questions really:

1. How to compute the unique kernel tag;
2. Where to store it.

In this patch we're using LINUX_VERSION_CODE, just as hibernation
(suspend-to-disk) does. This way we are protecting from the kernel
version mismatch, making sure that we're running the same kernel
version and patch level. We could use CRC of a symbol table (as
suggested by Tony Luck), but for now let's not be that strict.

And as for storing, we are using a small trick here. Instead of
allocating a dedicated buffer for the tag (i.e. another prz), or
hacking ram_core routines to "reserve" some control data in the
buffer, we are just encoding the tag into the buffer signature
(and XOR'ing it with the actual signature value, so that buffers
not needing a tag can just pass zero, which will result into the
plain old PRZ signature).
Suggested-by: NSteven Rostedt <rostedt@goodmis.org>
Suggested-by: NTony Luck <tony.luck@intel.com>
Suggested-by: NColin Cross <ccross@android.com>
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Nowadays we can use prz->ecc_size as a flag, no need for the special
member in the prz struct.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This is now pretty straightforward: instead of using bool, just pass
an integer. For backwards compatibility ramoops.ecc=1 means 16 bytes
ECC (using 1 byte for ECC isn't much of use anyway).
Suggested-by: NArve Hjønnevåg <arve@android.com>
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The struct members were never used anywhere outside of
persistent_ram_init_ecc(), so there's actually no need for them
to be in the struct.

If we ever want to make polynomial or symbol size configurable,
it would make more sense to just pass initialized rs_decoder
to the persistent_ram init functions.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

- Instead of exploiting unsigned overflows (which doesn't work for all
  sizes), use straightforward checking for ECC total size not exceeding
  initial buffer size;

- Printing overflowed buffer_size is not informative. Instead, print
  ecc_size and buffer_size;

- No need for buffer_size argument in persistent_ram_init_ecc(),
  we can address prz->buffer_size directly.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

We will implement variable-sized ECC buffers soon, so post_init routine
might fail much more likely, so we'd better check for its errors.

To make error handling simple, modify persistent_ram_free() to it be safe
at all times.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Registering the platform driver before module_init allows us to log oopses
that happen during device probing.

This requires changing module_init to postcore_initcall, and switching
from platform_driver_probe to platform_driver_register because the
platform device is not registered when the platform driver is registered;
and because we use driver_register, now can't use create_bundle() (since
it will try to register the same driver once again), so we have to switch
to platform_device_register_data().

Also, some __init -> __devinit changes were needed.

Overall, the registration logic is now much clearer, since we have only
one driver registration point, and just an optional dummy device, which
is created from the module parameters.
Suggested-by: NColin Cross <ccross@android.com>
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The code tried to maintain the global list of persistent ram zones,
which isn't a great idea overall, plus since Android's ram_console
is no longer there, we can remove some unused functions.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NColin Cross <ccross@android.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Since we use multiple regions, the messages are somewhat annoying.
We do print total mapped memory already, so no need to print the
information for each region in the library routines.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NColin Cross <ccross@android.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

A handy function that we will use outside of ram_core soon. But
so far just factor it out and start using it in post_init().
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Otherwise, the files will survive just one reboot, and on a subsequent
boot they will disappear.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Without the update, we'll only see the new dmesg buffer after the
reboot, but previously we could see it right away. Making an oops
visible in pstore filesystem before reboot is a somewhat dubious
feature, but removing it wasn't an intentional change, so let's
restore it.

For this we have to make persistent_ram_save_old() safe for calling
multiple times, and also extern it.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This is a first step for adding ECC support for pstore RAM backend: we
will use the persistent_ram routines, kindly provided by Google.

Basically, persistent_ram is a set of helper routines to deal with the
[optionally] ECC-protected persistent ram regions.

A bit of Makefile, Kconfig and header files adjustments were needed
because of the move.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This is a transition patch to keep things bisectable, just moves
some routines under '#ifndef MODULE'. The code inside the #ifndef
will go away soon, but so far we must support pstore and ram_console.

So, we are about to use persistent_ram with pstore, with the ability
to compile persistent_ram routines as modules. Some parts of
persistent_ram uses memblock_reserve() routine, which is should be
only used built-in code, and thus it is not exported.

These persistent_ram bits are only used by Android's ram_console,
which is always built-in.

Without this patch, we won't able to compile persistent_ram as a
module:

ERROR: "memblock_reserve" [fs/pstore/ramoops.ko] undefined!
make[1]: *** [__modpost] Error 1
make: *** [modules] Error 2

(As alternative, we could export memblock_reserve, but the thing
is: we won't need it later.)
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

A corresponding function to persistent_ram_new().
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This includes devices' memory (e.g. framebuffers or memory mapped
EEPROMs on a local bus), as well as the normal RAM that we don't use
for the main memory.

For the normal (but unused) ram we could use kmaps, but this assumes
highmem support, so we don't bother and just use the memory via
ioremap.

As a side effect, the following hack is possible: when used together
with pstore_ram (new ramoops) module, we can limit the normal RAM region
with mem= and then point ramoops to use the rest of the memory, e.g.

	mem=128M ramoops.mem_address=0x8000000

Sure, we could just reserve the region with memblock_reserve() early in
the arch/ code, and then register a pstore_ram platform device pointing
to the reserved region. It's still a viable option if platform wants
to do so.

Also, we might want to use IO accessors in case of a real device,
but for now we don't bother (the old ramoops wasn't using it either, so
at least we don't make things worse).
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Factor out vmap logic out of persistent_ram_buffer_map(), this will
make the code a bit more understandable when we'll add support for
non-bootmem memory.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The routine just creates a persistent ram zone at a specified address.

For persistent_ram_init_ringbuffer() we'd need to add a
'struct persistent_ram' to the global list, and associate it with a
device. We don't need all this complexity in pstore_ram, so we introduce
the simple function.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Factor post init logic out of __persistent_ram_init(), we'll need
it for the new persistent_ram_new() routine.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This is a longstanding bug, almost unnoticeable when calling
persistent_ram_write() for small buffers.

But when called for large data buffers, the write routine behaves
incorrectly, as the size may never update: instead of clamping
the size to the maximum buffer size, buffer_size_add_clamp() returns
an error (which is never checked by the write routine, btw).

To fix this, we now use buffer_size_add() that actually clamps the
size to the max value.

Also remove buffer_size_add_clamp(), it is no longer needed.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NColin Cross <ccross@android.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The 'node' struct member is unused, so remove it.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

If, in __persistent_ram_init(), the call to
persistent_ram_buffer_init() fails or the call to
persistent_ram_init_ecc() fails then we fail to free the memory we
allocated to 'prz' with kzalloc() - thus leaking it.

To prevent the leaks I consolidated all error exits from the function
at a 'err:' label at the end and made all error cases jump to that
label where we can then make sure we always free 'prz'. This is safe
since all the situations where the code bails out happen before 'prz'
has been stored anywhere and although we'll do a redundant kfree(NULL)
call in the case of kzalloc() itself failing that's OK since kfree()
deals gracefully with NULL pointers and I felt it was more important
to keep all error exits at a single location than to avoid that one
harmless/redundant kfree() on a error path.
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Acked-by: NColin Cross <ccross@android.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix printk format warnings in android/persistent_ram.c:

drivers/staging/android/persistent_ram.c:426:4: warning: format '%ld' expects type 'long int', but argument 2 has type 'size_t'
drivers/staging/android/persistent_ram.c:426:4: warning: format '%ld' expects type 'long int', but argument 3 has type 'size_t'
drivers/staging/android/persistent_ram.c:430:4: warning: format '%ld' expects type 'long int', but argument 2 has type 'size_t'
drivers/staging/android/persistent_ram.c:430:4: warning: format '%ld' expects type 'long int', but argument 3 has type 'size_t'
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Cc: Brian Swetland <swetland@google.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Add the notrace attribute to persistent_ram_write and the
non-ecc functions that it calls to allow persistent_ram to
be used for ftracing (only when ecc is disabled).

CC: Greg KH <gregkh@linuxfoundation.org>
CC: Android Kernel Team <kernel-team@android.com>
Signed-off-by: NColin Cross <ccross@android.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Allow persistent_ram_write to be called on multiple cpus at
the same time, as long as ecc is not in use.  Uses atomics
for the buffer->start and buffer->size counters.

[jstultz: Fix up some pr_info casting issues on 64bit]
CC: Greg KH <gregkh@linuxfoundation.org>
CC: Android Kernel Team <kernel-team@android.com>
Signed-off-by: NColin Cross <ccross@android.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Replace the ioremapped memory passed in from the drivers with
a memblock_reserve and vmap.  Adds a new function,
persistent_ram_early_init, designed to be called from the machine
init_early callback, that calls memblock_remove and saves the
provided persistent ram area layout.

Drivers only pass in their struct device * and ecc settings.
Locating and mapping the memory is now handled entirely within
persistent_ram.

Also, convert ram_console to the new persistent_ram_init
parameters that only take a struct device * and ecc settings.

[jstultz: Fix pr_info casting issues on 64bit, folded two
patches as the build breaks if they are apart. Also replaced
phys_to_page() w/ pfn_to_page(addr>>PAGE_SHIFT), as phys_to_page
is only on a few arches.]
CC: Greg KH <gregkh@linuxfoundation.org>
CC: Android Kernel Team <kernel-team@android.com>
Signed-off-by: NColin Cross <ccross@android.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove CONFIG_ANDROID_RAM_CONSOLE_ERROR_CORRECTION and related
 #ifdefs.  Also allow persistent ram zones without ecc enabled.
For some use cases, like the data portion of the upcoming
persistent_vars patches, or a persistent ftrace ringbuffer,
ecc on every update is too expensive.

CC: Greg KH <gregkh@linuxfoundation.org>
CC: Android Kernel Team <kernel-team@android.com>
Signed-off-by: NColin Cross <ccross@android.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Split ram_console into two halves.

persistent_ram is a set of apis that handle a block of memory
that does not get erased across a reboot.  It provides functions
to fill it as a single buffer or a ring buffer, and to extract
the old data after a reboot.  It handles ecc on the data to
correct bit errors introduced during reboot.

ram_console is now a small wrapper around persistent_ram that
feeds console data into the ringbuffer, and exports the old
data to /proc/last_kmsg after a reboot.

[jstultz: Moved persistent_ram.h to staging dir]
CC: Greg KH <gregkh@linuxfoundation.org>
CC: Android Kernel Team <kernel-team@android.com>
Signed-off-by: NColin Cross <ccross@android.com>
Signed-off-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>