In the pstore compression part, we use zlib/lzo/lz4/lz4hc/842
compression algorithm API to implement pstore compression backends. But
there are many repeat codes in these implementations. This patch uses
crypto compress API to simplify these codes.

1) rewrite allocate_buf_for_compression, free_buf_for_compression,
pstore_compress, pstore_decompress functions using crypto compress API.
2) drop compress, decompress, allocate, free functions in pstore_zbackend,
and add zbufsize function to get each different compress buffer size.
3) use late_initcall to call ramoops_init later, to make sure the crypto
subsystem has already initialized.
4) use 'unsigned int' type instead of 'size_t' in pstore_compress,
pstore_decompress functions' length arguments.
5) rename 'zlib' to 'deflate' to follow the crypto API's name convention.
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
[kees: tweaked error messages on allocation failures and Kconfig help]
Signed-off-by: NKees Cook <keescook@chromium.org>

To allow for easier build test coverage and run-time testing, this allows
multiple compression algorithms to be built into pstore. Still only one
is supported to operate at a time (which can be selected at build time
or at boot time, similar to how LSMs are selected).
Signed-off-by: NKees Cook <keescook@chromium.org>

Currently, pstore has supported three compression algorithms: zlib,
lzo and lz4. This patch added two more compression algorithms: lz4hc
and 842.
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
[kees: tweaked Kconfig help text slightly]
Signed-off-by: NKees Cook <keescook@chromium.org>

The previous patch renamed several files that are cross-referenced
along the Kernel documentation. Adjust the links to point to
the right places.
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

Like zlib compression in pstore, this patch added lzo and lz4
compression support so that users can have more options and better
compression ratio.

The original code treats the compressed data together with the
uncompressed ECC correction notice by using zlib decompress. The
ECC correction notice is missing in the decompression process. The
treatment also makes lzo and lz4 not working. So I treat them
separately by using pstore_decompress() to treat the compressed
data, and memcpy() to treat the uncompressed ECC correction notice.
Signed-off-by: NGeliang Tang <geliangtang@163.com>
Signed-off-by: NKees Cook <keescook@chromium.org>

pstore doesn't support unregistering yet. It was marked as TODO.
This patch adds some code to fix it:
 1) Add functions to unregister kmsg/console/ftrace/pmsg.
 2) Add a function to free compression buffer.
 3) Unmap the memory and free it.
 4) Add a function to unregister pstore filesystem.
Signed-off-by: NGeliang Tang <geliangtang@163.com>
Acked-by: NKees Cook <keescook@chromium.org>
[Removed __exit annotation from ramoops_remove(). Reported by Arnd Bergmann]
Signed-off-by: NTony Luck <tony.luck@intel.com>

A secured user-space accessible pstore object. Writes
to /dev/pmsg0 are appended to the buffer, on reboot
the persistent contents are available in
/sys/fs/pstore/pmsg-ramoops-[ID].

One possible use is syslogd, or other daemon, can
write messages, then on reboot provides a means to
triage user-space activities leading up to a panic
as a companion to the pstore dmesg or console logs.
Signed-off-by: NMark Salyzyn <salyzyn@android.com>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NTony Luck <tony.luck@intel.com>

Pstore will make use of deflate and inflate algorithm to compress and decompress
the data. So when Pstore is enabled select zlib_deflate and zlib_inflate.
Signed-off-by: NAruna Balakrishnaiah <aruna@linux.vnet.ibm.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NTony Luck <tony.luck@intel.com>

With this patch we no longer reuse function tracer infrastructure, now
we register our own tracer back-end via a debugfs knob.

It's a bit more code, but that is the only downside. On the bright side we
have:

- Ability to make persistent_ram module removable (when needed, we can
  move ftrace_ops struct into a module). Note that persistent_ram is still
  not removable for other reasons, but with this patch it's just one
  thing less to worry about;

- Pstore part is more isolated from the generic function tracer. We tried
  it already by registering our own tracer in available_tracers, but that
  way we're loosing ability to see the traces while we record them to
  pstore. This solution is somewhere in the middle: we only register
  "internal ftracer" back-end, but not the "front-end";

- When there is only pstore tracing enabled, the kernel will only write
  to the pstore buffer, omitting function tracer buffer (which, of course,
  still can be enabled via 'echo function > current_tracer').
Suggested-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>

With this support kernel can save function call chain log into a
persistent ram buffer that can be decoded and dumped after reboot
through pstore filesystem. It can be used to determine what function
was last called before a reset or panic.

We store the log in a binary format and then decode it at read time.

p.s.
Mostly the code comes from trace_persistent.c driver found in the
Android git tree, written by Colin Cross <ccross@android.com>
(according to sign-off history). I reworked the driver a little bit,
and ported it to pstore.
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Pstore doesn't support logging kernel messages in run-time, it only
dumps dmesg when kernel oopses/panics. This makes pstore useless for
debugging hangs caused by HW issues or improper use of HW (e.g.
weird device inserted -> driver tried to write a reserved bits ->
SoC hanged. In that case we don't get any messages in the pstore.

Therefore, let's add a runtime logging support: PSTORE_TYPE_CONSOLE.
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>

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>

Since ramoops was converted to pstore, it has nothing to do with character
devices nowadays. Instead, today it is just a RAM backend for pstore.

The patch just moves things around. There are a few changes were needed
because of the move:

1. Kconfig and Makefiles fixups, of course.

2. In pstore/ram.c we have to play a bit with MODULE_PARAM_PREFIX, this
   is needed to keep user experience the same as with ramoops driver
   (i.e. so that ramoops.foo kernel command line arguments would still
   work).
Signed-off-by: NAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: NMarco Stornelli <marco.stornelli@gmail.com>
Acked-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Fixes generated by 'codespell' and manually reviewed.
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>

Some platforms have a small amount of non-volatile storage that
can be used to store information useful to diagnose the cause of
a system crash.  This is the generic part of a file system interface
that presents information from the crash as a series of files in
/dev/pstore.  Once the information has been seen, the underlying
storage is freed by deleting the files.
Signed-off-by: NTony Luck <tony.luck@intel.com>