powerpc/opal: use default_groups in kobj_type

There are currently 2 ways to create a set of sysfs files for a
kobj_type, through the default_attrs field, and the default_groups
field. Move the powerpc opal dump and elog sysfs code to use
default_groups field which has been the preferred way since aa30f47cf666
("kobject: Add support for default attribute groups to kobj_type") so
that we can soon get rid of the obsolete default_attrs field.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220104161318.1306023-1-gregkh@linuxfoundation.org

powerpc/powernv: Rate limit opal-elog read failure message

Sometimes we can't read an error log from OPAL, and we print an error
message accordingly. But the OPAL userspace tools seem to like retrying a
lot, in which case we flood the kernel log with a lot of messages.

Change pr_err() to pr_err_ratelimited() to help with this.

Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201211021140.28402-1-ajd@linux.ibm.com

powerpc/opal_elog: Handle multiple writes to ack attribute

Even though we use self removing sysfs helper, we still need
to make sure we do the final kobject delete conditionally.
sysfs_remove_file_self() will handle parallel calls to remove
the sysfs attribute file and returns true only in the caller
that removed the attribute file. The other parallel callers
are returned false. Do the final kobject delete checking
the return value of sysfs_remove_file_self().

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201014064813.109515-1-aneesh.kumar@linux.ibm.com

powerpc/powernv/elog: Fix race while processing OPAL error log event.

Every error log reported by OPAL is exported to userspace through a
sysfs interface and notified using kobject_uevent(). The userspace
daemon (opal_errd) then reads the error log and acknowledges the error
log is saved safely to disk. Once acknowledged the kernel removes the
respective sysfs file entry causing respective resources to be
released including kobject.

However it's possible the userspace daemon may already be scanning
elog entries when a new sysfs elog entry is created by the kernel.
User daemon may read this new entry and ack it even before kernel can
notify userspace about it through kobject_uevent() call. If that
happens then we have a potential race between
elog_ack_store->kobject_put() and kobject_uevent which can lead to
use-after-free of a kernfs object resulting in a kernel crash. eg:

BUG: Unable to handle kernel data access on read at 0x6b6b6b6b6b6b6bfb
Faulting instruction address: 0xc0000000008ff2a0
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV
CPU: 27 PID: 805 Comm: irq/29-opal-elo Not tainted 5.9.0-rc2-gcc-8.2.0-00214-g6f56a67bcbb5-dirty #363
...
NIP kobject_uevent_env+0xa0/0x910
LR elog_event+0x1f4/0x2d0
Call Trace:
0x5deadbeef0000122 (unreliable)
elog_event+0x1f4/0x2d0
irq_thread_fn+0x4c/0xc0
irq_thread+0x1c0/0x2b0
kthread+0x1c4/0x1d0
ret_from_kernel_thread+0x5c/0x6c

This patch fixes this race by protecting the sysfs file
creation/notification by holding a reference count on kobject until we
safely send kobject_uevent().

The function create_elog_obj() returns the elog object which if used
by caller function will end up in use-after-free problem again.
However, the return value of create_elog_obj() function isn't being
used today and there is no need as well. Hence change it to return
void to make this fix complete.

Fixes: 774fea1a38c6 ("powerpc/powernv: Read OPAL error log and export it through sysfs")
Cc: stable@vger.kernel.org # v3.15+
Reported-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Oliver O'Halloran <oohall@gmail.com>
Reviewed-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
[mpe: Rework the logic to use a single return, reword comments, add oops]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201006122051.190176-1-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: Use octal numbers for file permissions

Symbolic macros are unintuitive and hard to read, whereas octal constants
are much easier to interpret. Replace macros for the basic permission
flags (user/group/other read/write/execute) with numeric constants
instead, across the whole powerpc tree.

Introducing a significant number of changes across the tree for no runtime
benefit isn't exactly desirable, but so long as these macros are still
used in the tree people will keep sending patches that add them. Not only
are they hard to parse at a glance, there are multiple ways of coming to
the same value (as you can see with 0444 and 0644 in this patch) which
hurts readability.

Signed-off-by: Russell Currey <ruscur@russell.cc>
Reviewed-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Replace <asm/uaccess.h> with <linux/uaccess.h> globally

This was entirely automated, using the script by Al:

PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.

Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

powerpc/powernv : Drop reference added by kset_find_obj()

In a situation, where Linux kernel gets notified about duplicate error log
from OPAL, it is been observed that kernel fails to remove sysfs entries
(/sys/firmware/opal/elog/0xXXXXXXXX) of such error logs. This is because,
we currently search the error log/dump kobject in the kset list via
'kset_find_obj()' routine. Which eventually increment the reference count
by one, once it founds the kobject.

So, unless we decrement the reference count by one after it found the kobject,
we would not be able to release the kobject properly later.

This patch adds the 'kobject_put()' which was missing earlier.

Signed-off-by: Mukesh Ojha <mukesh02@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Reviewed-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/powernv: Fix opal-elog interrupt handler

The conversion of opal events to a proper irqchip means that handlers
are called until the relevant opal event has been cleared by
processing it. Events that queue work should therefore use a threaded
handler to mask the event until processing is complete.

Signed-off-by: Alistair Popple <alistair@popple.id.au>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powernv/elog: Convert elog to opal irq domain

This patch converts the elog code to use the opal irq domain instead
of notifier events.

Signed-off-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/powernv: only call OPAL_ELOG_RESEND if firmware supports it

Otherwise firmware complains: "OPAL: Called with bad token 74 !"
as not all OPAL systems have the ability to resend error logs.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Acked-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/powernv: Check OPAL elog calls exist before using

Check that the OPAL_ELOG_READ token exists before initalising the elog
infrastructure.

This avoids littering the OPAL console with:
"OPAL: Called with bad token 74"

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/powernv/opal-elog.c: fix world-writable sysfs files

If you don't have a store function, you're not writable anyway!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Stewart Smith <stewart@linux.vnet.ibm.com>

powerpc/powernv: Change BUG_ON to WARN_ON in elog code

We can continue to read the error log (up to MAX size) even if
we get the elog size more than MAX size. Hence change BUG_ON to
WARN_ON.

Also updated error message.

Reported-by: Gopesh Kumar Chaudhary <gopchaud@in.ibm.com>
Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
Acked-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/powernv: Fix little endian issues in OPAL error log code

Fix little endian issues with the OPAL error log code.

Signed-off-by: Anton Blanchard <anton@samba.org>
Reviewed-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/powernv: Use uint64_t instead of size_t in OPAL APIs

Using size_t in our APIs is asking for trouble, especially
when some OPAL calls use size_t pointers.

Signed-off-by: Anton Blanchard <anton@samba.org>
Reviewed-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/powernv Adapt opal-elog and opal-dump to new sysfs_remove_file_self

We are currently using sysfs_schedule_callback() which is deprecated
and about to be removed. Switch to the new interface instead.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/powernv: Read OPAL error log and export it through sysfs

Based on a patch by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>

This patch adds support to read error logs from OPAL and export
them to userspace through a sysfs interface.

We export each log entry as a directory in /sys/firmware/opal/elog/

Currently, OPAL will buffer up to 128 error log records, we don't
need to have any knowledge of this limit on the Linux side as that
is actually largely transparent to us.

Each error log entry has the following files: id, type, acknowledge, raw.
Currently we just export the raw binary error log in the 'raw' attribute.
In a future patch, we may parse more of the error log to make it a bit
easier for userspace (e.g. to be able to display a brief summary in
petitboot without having to have a full parser).

If we have >128 logs from OPAL, we'll only be notified of 128 until
userspace starts acknowledging them. This limitation may be lifted in
the future and with this patch, that should "just work" from the linux side.

A userspace daemon should:
- wait for error log entries using normal mechanisms (we announce creation)
- read error log entry
- save error log entry safely to disk
- acknowledge the error log entry
- rinse, repeat.

On the Linux side, we read the error log when we're notified of it. This
possibly isn't ideal as it would be better to only read them on-demand.
However, this doesn't really work with current OPAL interface, so we
read the error log immediately when notified at the moment.

I've tested this pretty extensively and am rather confident that the
linux side of things works rather well. There is currently an issue with
the service processor side of things for >128 error logs though.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>