On some ARMs the memory can be mapped pgprot_noncached() and still
be working for atomic operations. As pointed out by Colin Cross
<ccross@android.com>, in some cases you do want to use
pgprot_noncached() if the SoC supports it to see a debug printk
just before a write hanging the system.
On ARMs, the atomic operations on strongly ordered memory are
implementation defined. So let's provide an optional kernel parameter
for configuring pgprot_noncached(), and use pgprot_writecombine() by
default.
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robherring2@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Olof Johansson <olof@lixom.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: stable@vger.kernel.org
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
With this patch we no longer reuse function tracer infrastructure, now
we register our own tracer back-end via a debugfs knob.
It's a bit more code, but that is the only downside. On the bright side we
have:
- Ability to make persistent_ram module removable (when needed, we can
move ftrace_ops struct into a module). Note that persistent_ram is still
not removable for other reasons, but with this patch it's just one
thing less to worry about;
- Pstore part is more isolated from the generic function tracer. We tried
it already by registering our own tracer in available_tracers, but that
way we're loosing ability to see the traces while we record them to
pstore. This solution is somewhere in the middle: we only register
"internal ftracer" back-end, but not the "front-end";
- When there is only pstore tracing enabled, the kernel will only write
to the pstore buffer, omitting function tracer buffer (which, of course,
still can be enabled via 'echo function > current_tracer').
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
The ftrace log size is configurable via ramoops.ftrace_size
module option, and the log itself is available via
<pstore-mount>/ftrace-ramoops file.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is now straightforward: just introduce a module parameter and pass
the needed value to persistent_ram_new().
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Marco Stornelli <marco.stornelli@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since ramoops was converted to pstore, it has nothing to do with character
devices nowadays. Instead, today it is just a RAM backend for pstore.
The patch just moves things around. There are a few changes were needed
because of the move:
1. Kconfig and Makefiles fixups, of course.
2. In pstore/ram.c we have to play a bit with MODULE_PARAM_PREFIX, this
is needed to keep user experience the same as with ramoops driver
(i.e. so that ramoops.foo kernel command line arguments would still
work).
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Marco Stornelli <marco.stornelli@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Instead of using /dev/mem directly and forcing userspace to know (or
extract) where the platform has defined persistent memory, how many slots
it has, the sizes, etc, use the common pstore infrastructure to handle
Oops gathering and extraction. This presents a much easier to use
filesystem-based view to the memory region. This also means that any
other tools that are written to understand pstore will automatically be
able to process ramoops too.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Marco Stornelli <marco.stornelli@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
