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>
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: 9b4fffa149 ("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>
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>
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>
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>
