powerpc/powernv: Add __init attribute to eligible functions

Some functions defined in 'arch/powerpc/platforms/powernv' are
deserving of an `__init` macro attribute. These functions are only
called by other initialization functions and therefore should inherit
the attribute.
Also, change function declarations in header files to include `__init`.

Signed-off-by: Nick Child <nick.child@ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211216220035.605465-12-nick.child@ibm.com

powerpc/powernv: Include asm/powernv.h from the local powernv.h

The asm/powernv.h header provides prototypes for functions which need to be
called by non-powernv platform code. Also include it in the powernv.h
that's local to the platform directory to squash some warnings about
non-static functions missing prototypes.

Also include powernv.h since from opal-memcons.c since it has the
prototypes for the memcons wrangling functions which are used for the opal
and ultravisor msglog.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200804005410.146094-3-oohall@gmail.com

powerpc/powernv/opal-msglog: Refactor memcons code

This patch refactors the code in opal-msglog that operates on the OPAL
memory console in order to make it cleaner and also allow the reuse of
the new memcons_* functions.

Signed-off-by: Claudio Carvalho <cclaudio@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Claudio Carvalho <cclaudio@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190828130521.26764-1-mpe@ellerman.id.au

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

powerpc/powernv: Make opal log only readable by root

Currently the opal log is globally readable. It is kernel policy to
limit the visibility of physical addresses / kernel pointers to root.
Given this and the fact the opal log may contain this information it
would be better to limit the readability to root.

Fixes: bfc36894a48b ("powerpc/powernv: Add OPAL message log interface")
Cc: stable@vger.kernel.org # v3.15+
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Reviewed-by: Stewart Smith <stewart@linux.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()

Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.

For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.

However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:

----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()

// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch

virtual patch

@ depends on patch @
expression E1, E2;
@@

- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)

@ depends on patch @
expression E;
@@

- ACCESS_ONCE(E)
+ READ_ONCE(E)
----

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

powerpc/powernv: Report size of OPAL memcons log

The OPAL memory console is reported to be size zero, as we do not
initialise the struct attr with any size information due to the size
being variable. This leads users to think that the console is empty.

Instead report the maximum size.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/powernv: don't create OPAL msglog sysfs entry if memcons init fails

When initialising OPAL interfaces, there is a possibility that
opal_msglog_init() may fail to initialise the msglog/memory console.

Fix opal_msglog_sysfs_init() so it doesn't try to create sysfs entry for
the msglog if this occurs.

Suggested-by: Joel Stanley <joel@jms.id.au>
Fixes: 9b4fffa14906 ("powerpc/powernv: new function to access OPAL msglog")
Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/powernv: new function to access OPAL msglog

Currently, the OPAL msglog/console buffer is exposed as a sysfs file, with
the sysfs read handler responsible for retrieving the log from the OPAL
buffer. We'd like to be able to use it in xmon as well.

Refactor the OPAL msglog code to create a new function, opal_msglog_copy(),
that copies to an arbitrary buffer. Separate the initialisation code into
generic memcons init and sysfs file creation.

Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/powernv: Fix reading of OPAL msglog

memory_return_from_buffer returns a signed value, so ret should be
ssize_t.

Fixes the following issue reported by David Binderman:

[linux-3.15/arch/powerpc/platforms/powernv/opal-msglog.c:65]: (style)
Checking if unsigned variable 'ret' is less than zero.
[linux-3.15/arch/powerpc/platforms/powernv/opal-msglog.c:82]: (style)
Checking if unsigned variable 'ret' is less than zero.

Local variable "ret" is of type size_t. This is always unsigned,
so it is pointless to check if it is less than zero.

https://bugzilla.kernel.org/show_bug.cgi?id=77551

Fixing this exposes a real bug for the case where the entire count
bytes is successfully read from the POS_WRAP case. The second
memory_read_from_buffer will return EINVAL, causing the entire read to
return EINVAL to userspace, despite the data being copied correctly. The
fix is to test for the case where the data has been read and return
early.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/powernv: Add OPAL message log interface

OPAL provides an in-memory circular buffer containing a message log
populated with various runtime messages produced by the firmware.

Provide a sysfs interface /sys/firmware/opal/msglog for userspace to
view the messages.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>