firmware: coreboot: Replace tag with id table in driver struct

Switch the plain 'tag' field in struct coreboot_driver for the newly
created coreboot_device_id struct, which also contains a tag field and
has the benefit of allowing modalias generation, and update all coreboot
drivers accordingly.

While at it, also add the id table for each driver to the module device
table to allow automatically loading the module.

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Link: https://lore.kernel.org/r/20240212-coreboot-mod-defconfig-v4-3-d14172676f6d@collabora.com
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

firmware: google: make coreboot driver's remove callback return void

All coreboot drivers return 0 unconditionally in their remove callback.
Also the device core ignores the return value of the struct
bus_type::remove(), so make the coreboot remove callback return void
instead of giving driver authors the illusion they could return an error
code here.

All drivers are adapted accordingly.

Signed-off-by: Uwe Kleine-König <uwe@kleine-koenig.org>
Link: https://lore.kernel.org/r/20210126215339.706021-1-uwe@kleine-koenig.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: google: memconsole: Replace zero-length array with flexible-array member

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 287

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 v2 0 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 23 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.115786599@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: google: coreboot: Drop unnecessary headers

These headers aren't used by the files they're included in, so drop
them. The memconsole file uses memremap() though, so include io.h there
so that the include is explicit.

Cc: Wei-Ning Huang <wnhuang@chromium.org>
Cc: Julius Werner <jwerner@chromium.org>
Cc: Brian Norris <briannorris@chromium.org>
Cc: Samuel Holland <samuel@sholland.org>
Cc: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: google: memconsole: Drop __iomem on memremap memory

memremap() doesn't return __iomem marked memory, so drop the marking
here. This makes static analysis tools like sparse happy again.

Cc: Wei-Ning Huang <wnhuang@chromium.org>
Cc: Julius Werner <jwerner@chromium.org>
Cc: Brian Norris <briannorris@chromium.org>
Cc: Samuel Holland <samuel@sholland.org>
Cc: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: google: memconsole: Use devm_memremap()

Use the devm version of memremap so that we can delete the unmapping
code in driver remove, but more importantly so that we can unmap this
memory region if memconsole_sysfs_init() errors out for some reason.

Cc: Wei-Ning Huang <wnhuang@chromium.org>
Cc: Julius Werner <jwerner@chromium.org>
Cc: Brian Norris <briannorris@chromium.org>
Cc: Samuel Holland <samuel@sholland.org>
Cc: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: google: Add a module_coreboot_driver() macro and use it

Remove some boiler plate code we have in three drivers with a single
line each time. This also gets us a free assignment of the driver .owner
field, making these drivers work better as modules.

Cc: Wei-Ning Huang <wnhuang@chromium.org>
Cc: Julius Werner <jwerner@chromium.org>
Cc: Brian Norris <briannorris@chromium.org>
Cc: Samuel Holland <samuel@sholland.org>
Cc: Guenter Roeck <groeck@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: memconsole: Probe via coreboot bus

Remove the ad-hoc coreboot table search. Now the driver will only be
probed when the necessary coreboot table entry has already been found.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: google: memconsole: Prevent overrun attack on coreboot console

The recent coreboot memory console update (firmware: google: memconsole:
Adapt to new coreboot ring buffer format) introduced a small security
issue in the driver: The new driver implementation parses the memory
console structure again on every access. This is intentional so that
additional lines added concurrently by runtime firmware can be read out.

However, if an attacker can write to the structure, they could increase
the size value to a point where the driver would read potentially
sensitive memory areas from outside the original console buffer during
the next access. This can be done through /dev/mem, since the console
buffer usually resides in firmware-reserved memory that is not covered
by STRICT_DEVMEM.

This patch resolves that problem by reading the buffer's size value only
once during boot (where we can still trust the structure). Other parts
of the structure can still be modified at runtime, but the driver's
bounds checks make sure that it will never read outside the buffer.

Fixes: a5061d028 ("firmware: google: memconsole: Adapt to new coreboot ring buffer format")
Signed-off-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: google: memconsole: Adapt to new coreboot ring buffer format

The upstream coreboot implementation of memconsole was enhanced from a
single-boot console to a persistent ring buffer
(https://review.coreboot.org/#/c/18301). This patch changes the kernel
memconsole driver to be able to read the new format in all cases.

Signed-off-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: google: memconsole: Make memconsole interface more flexible

This patch redesigns the interface between the generic memconsole driver
and its implementations to become more flexible than a flat memory
buffer with unchanging bounds. This allows memconsoles like coreboot's
to include lines that were added by runtime firmware after the driver
was initialized. Since the console log size is thus no longer static,
this means that the /sys/firmware/log file has to become unseekable.

Signed-off-by: Julius Werner <jwerner@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: google memconsole: Fix return value check in platform_memconsole_init()

In case of error, the function platform_device_register_simple() returns
ERR_PTR() and never returns NULL. The NULL test in the return value
check should be replaced with IS_ERR().

Fixes: d384d6f43d1e ("firmware: google memconsole: Add coreboot support")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

firmware: google memconsole: Add coreboot support

Coreboot (http://www.coreboot.org) allows to save the firmware console
output in a memory buffer. With this patch, the address of this memory
buffer is obtained from coreboot tables on x86 chromebook devices
declaring an ACPI device with name matching GOOGCB00 or BOOT0000.

If the memconsole-coreboot driver is able to find the coreboot table,
the memconsole driver sets the cbmem_console address and initializes the
memconsole sysfs entries.

The coreboot_table-acpi driver is responsible for setting the address of
the coreboot table header when probed. If this address is not yet set
when memconsole-coreboot is probed, then the probe is deferred by
returning -EPROBE_DEFER.

This patch is a rework/split/merge of patches from the chromeos v4.4
kernel tree originally authored by:
Vadim Bendebury <vbendeb@chromium.org>
Wei-Ning Huang <wnhuang@google.com>
Yuji Sasaki <sasakiy@google.com>
Duncan Laurie <dlaurie@chromium.org>
Julius Werner <jwerner@chromium.org>
Brian Norris <briannorris@chromium.org>

Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>