linux-toradex.git/include/linux/pstore_ram.h, branch v4.16-rc4

ramoops: Split ftrace buffer space into per-CPU zones

2016-11-16T00:34:26+00:00

If the RAMOOPS_FLAG_FTRACE_PER_CPU flag is passed to ramoops pdata, split
the ftrace space into multiple zones depending on the number of CPUs.

This speeds up the performance of function tracing by about 280% in my
tests as we avoid the locking. The trade off being lesser space available
per CPU. Let the ramoops user decide which option they want based on pdata
flag.

Signed-off-by: Joel Fernandes 
[kees: added max_ftrace_cnt to track size, added DT logic and docs]
Signed-off-by: Kees Cook

pstore: Allow prz to control need for locking

2016-11-16T00:34:25+00:00

In preparation of not locking at all for certain buffers depending on if
there's contention, make locking optional depending on the initialization
of the prz.

Signed-off-by: Joel Fernandes 
[kees: moved locking flag into prz instead of via caller arguments]
Signed-off-by: Kees Cook

pstore: Make spinlock per zone instead of global

2016-11-11T18:35:37+00:00

Currently pstore has a global spinlock for all zones. Since the zones
are independent and modify different areas of memory, there's no need
to have a global lock, so we should use a per-zone lock as introduced
here. Also, when ramoops's ftrace use-case has a FTRACE_PER_CPU flag
introduced later, which splits the ftrace memory area into a single zone
per CPU, it will eliminate the need for locking. In preparation for this,
make the locking optional.

Signed-off-by: Joel Fernandes 
[kees: updated commit message]
Signed-off-by: Kees Cook

pstore/pmsg: drop bounce buffer

2016-09-08T22:01:10+00:00

Removing a bounce buffer copy operation in the pmsg driver path is
always better. We also gain in overall performance by not requesting
a vmalloc on every write as this can cause precious RT tasks, such
as user facing media operation, to stall while memory is being
reclaimed. Added a write_buf_user to the pstore functions, a backup
platform write_buf_user that uses the small buffer that is part of
the instance, and implemented a ramoops write_buf_user that only
supports PSTORE_TYPE_PMSG.

Signed-off-by: Mark Salyzyn 
Signed-off-by: Kees Cook

pstore: Add support for 64 Bit address space

2016-03-10T17:43:36+00:00

Some architectures have their reserved RAM in 64 Bit address space.
Therefore convert mem_address module parameter to ullong.

Signed-off-by: Wladislav Wiebe 
Acked-by: Kees Cook 
Signed-off-by: Tony Luck

pstore: Add pmsg - user-space accessible pstore object

2015-01-17T00:01:10+00:00

A secured user-space accessible pstore object. Writes
to /dev/pmsg0 are appended to the buffer, on reboot
the persistent contents are available in
/sys/fs/pstore/pmsg-ramoops-[ID].

One possible use is syslogd, or other daemon, can
write messages, then on reboot provides a means to
triage user-space activities leading up to a panic
as a companion to the pstore dmesg or console logs.

Signed-off-by: Mark Salyzyn 
Acked-by: Kees Cook 
Signed-off-by: Tony Luck

pstore-ram: Allow optional mapping with pgprot_noncached

2014-12-11T21:38:31+00:00

On some ARMs the memory can be mapped pgprot_noncached() and still
be working for atomic operations. As pointed out by Colin Cross
, 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 
Cc: Rob Herring 
Cc: Randy Dunlap 
Cc: Anton Vorontsov 
Cc: Colin Cross 
Cc: Olof Johansson 
Cc: Russell King 
Cc: stable@vger.kernel.org
Acked-by: Kees Cook 
Signed-off-by: Tony Lindgren 
Signed-off-by: Tony Luck

pstore/ram: Allow specifying ecc parameters in platform data

2013-04-04T04:50:00+00:00

Allow specifying ecc parameters in platform data

Signed-off-by: Arve Hjønnevåg 
[jstultz: Tweaked commit subject & add commit message]
Signed-off-by: John Stultz 
Acked-by: Kees Cook 
Signed-off-by: Anton Vorontsov

pstore: remove __dev* attributes.

2013-01-03T23:57:14+00:00

CONFIG_HOTPLUG is going away as an option.  As a result, the __dev*
markings need to be removed.

This change removes the use of __devinit from the pstore filesystem.

Based on patches originally written by Bill Pemberton, but redone by me
in order to handle some of the coding style issues better, by hand.

Cc: Bill Pemberton 
Cc: Anton Vorontsov 
Cc: Colin Cross 
Cc: Kees Cook 
Cc: Tony Luck 
Signed-off-by: Greg Kroah-Hartman

pstore/ram: Make tracing log versioned

2012-07-17T23:48:09+00:00

Decoding the binary trace w/ a different kernel might be troublesome
since we convert addresses to symbols. For kernels with minimal changes,
the mappings would probably match, but it's not guaranteed at all.
(But still we could convert the addresses by hand, since we do print
raw addresses.)

If we use modules, the symbols could be loaded at different addresses
from the previously booted kernel, and so this would also fail, but
there's nothing we can do about it.

Also, the binary data format that pstore/ram is using in its ringbuffer
may change between the kernels, so here we too must ensure that we're
running the same kernel.

So, there are two questions really:

1. How to compute the unique kernel tag;
2. Where to store it.

In this patch we're using LINUX_VERSION_CODE, just as hibernation
(suspend-to-disk) does. This way we are protecting from the kernel
version mismatch, making sure that we're running the same kernel
version and patch level. We could use CRC of a symbol table (as
suggested by Tony Luck), but for now let's not be that strict.

And as for storing, we are using a small trick here. Instead of
allocating a dedicated buffer for the tag (i.e. another prz), or
hacking ram_core routines to "reserve" some control data in the
buffer, we are just encoding the tag into the buffer signature
(and XOR'ing it with the actual signature value, so that buffers
not needing a tag can just pass zero, which will result into the
plain old PRZ signature).

Suggested-by: Steven Rostedt 
Suggested-by: Tony Luck 
Suggested-by: Colin Cross 
Signed-off-by: Anton Vorontsov 
Signed-off-by: Greg Kroah-Hartman