In order to use arbitrary block devices as a pstore backend, provide a
new module param named "best_effort", which will allow using any block
device, even if it has not provided a panic_write callback.
Link: https://lore.kernel.org/lkml/20200511233229.27745-12-keescook@chromium.org/
Signed-off-by: Kees Cook <keescook@chromium.org>
Add support for non-block devices (e.g. MTD). A non-block driver calls
pstore_blk_register_device() to register iself.
In addition, pstore/zone is updated to handle non-block devices,
where an erase must be done before a write. Without this, there is no
way to remove records stored to an MTD.
Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com>
Link: https://lore.kernel.org/lkml/20200511233229.27745-10-keescook@chromium.org/
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
In order to configure itself, the MTD backend needs to be able to query
the current pstore configuration. Introduce pstore_blk_get_config() for
this purpose.
Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com>
Link: https://lore.kernel.org/lkml/20200511233229.27745-9-keescook@chromium.org/
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
One requirement to support MTD devices in pstore/zone is having a
way to declare certain regions as broken. Add this support to
pstore/zone.
The MTD driver should return -ENOMSG when encountering a bad region,
which tells pstore/zone to skip and try the next one.
Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com>
Link: https://lore.kernel.org/lkml/20200511233229.27745-8-keescook@chromium.org/
Co-developed-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: //lore.kernel.org/lkml/20200512173801.222666-1-colin.king@canonical.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Support backend for console. To enable console backend, just make
console_size be greater than 0 and a multiple of 4096.
Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com>
Link: https://lore.kernel.org/lkml/20200511233229.27745-5-keescook@chromium.org/
Signed-off-by: Kees Cook <keescook@chromium.org>
pstore/blk is similar to pstore/ram, but uses a block device as the
storage rather than persistent ram.
The pstore/blk backend solves two common use-cases that used to preclude
using pstore/ram:
- not all devices have a battery that could be used to persist
regular RAM across power failures.
- most embedded intelligent equipment have no persistent ram, which
increases costs, instead preferring cheaper solutions, like block
devices.
pstore/blk provides separate configurations for the end user and for the
block drivers. User configuration determines how pstore/blk operates, such
as record sizes, max kmsg dump reasons, etc. These can be set by Kconfig
and/or module parameters, but module parameter have priority over Kconfig.
Driver configuration covers all the details about the target block device,
such as total size of the device and how to perform read/write operations.
These are provided by block drivers, calling pstore_register_blkdev(),
including an optional panic_write callback used to bypass regular IO
APIs in an effort to avoid potentially destabilized kernel code during
a panic.
Signed-off-by: WeiXiong Liao <liaoweixiong@allwinnertech.com>
Link: https://lore.kernel.org/lkml/20200511233229.27745-3-keescook@chromium.org/
Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
