<feed xmlns='http://www.w3.org/2005/Atom'>
<title>litmus-rt.git/arch/blackfin/kernel, branch master</title>
<subtitle>The LITMUS^RT kernel.</subtitle>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/'/>
<entry>
<title>Merge tag 'blackfin-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/realmz6/blackfin-linux</title>
<updated>2015-04-24T14:58:07+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2015-04-24T14:58:07+00:00</published>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/commit/?id=668b54a1c2c25bde34cd9c077b1c5f03b46bcb49'/>
<id>668b54a1c2c25bde34cd9c077b1c5f03b46bcb49</id>
<content type='text'>
Pull blackfin updates from Steven Miao.

* tag 'blackfin-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/realmz6/blackfin-linux:
  eth: bf609 eth clock: add pclk clock for stmmac driver probe
  blackfin: Wire up missing syscalls
  arch: blackfin: kernel: kgdb: Remove unused function
  dma: fix build error after update to v3.19
  blackfin: io: define __raw_readx/writex with bfin_readx/writex
  bf609: add resources for lcd nl8048
  pm: sometimes wake up from suspend to RAM would fail
  debug-mmrs: Eliminate all traces of the USB_PHY_TEST MMR
  bf609: remove softswitch i2c configuration from adv7842 and adv7511 platform data
  bf609: add platform data for soft switch devices on the video extenders
  bf609: enable soft switch gpio driver by default
  bf609: add gpio soft switch platform data for mcp23017 i2c devices
  bf609: use new SND_BF6XX_PCM to choose audio pcm driver
  bug[220] kgdb: change the smp cross core function entry
  arch: blackfin: kernel: setup.c: Cleaning up missing null-terminate in conjunction with strncpy
  blackfin: defconfigs: cleanup unused CONFIG_MTD_CHAR, add MTD_SPI_NOR for BF537-STAMP
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull blackfin updates from Steven Miao.

* tag 'blackfin-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/realmz6/blackfin-linux:
  eth: bf609 eth clock: add pclk clock for stmmac driver probe
  blackfin: Wire up missing syscalls
  arch: blackfin: kernel: kgdb: Remove unused function
  dma: fix build error after update to v3.19
  blackfin: io: define __raw_readx/writex with bfin_readx/writex
  bf609: add resources for lcd nl8048
  pm: sometimes wake up from suspend to RAM would fail
  debug-mmrs: Eliminate all traces of the USB_PHY_TEST MMR
  bf609: remove softswitch i2c configuration from adv7842 and adv7511 platform data
  bf609: add platform data for soft switch devices on the video extenders
  bf609: enable soft switch gpio driver by default
  bf609: add gpio soft switch platform data for mcp23017 i2c devices
  bf609: use new SND_BF6XX_PCM to choose audio pcm driver
  bug[220] kgdb: change the smp cross core function entry
  arch: blackfin: kernel: setup.c: Cleaning up missing null-terminate in conjunction with strncpy
  blackfin: defconfigs: cleanup unused CONFIG_MTD_CHAR, add MTD_SPI_NOR for BF537-STAMP
</pre>
</div>
</content>
</entry>
<entry>
<title>arch: blackfin: kernel: kgdb: Remove unused function</title>
<updated>2015-04-23T14:56:54+00:00</updated>
<author>
<name>Rickard Strandqvist</name>
<email>rickard_strandqvist@spectrumdigital.se</email>
</author>
<published>2015-01-01T17:54:26+00:00</published>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/commit/?id=b9061ef5d4da934cfc6e052a1e486077d29f267d'/>
<id>b9061ef5d4da934cfc6e052a1e486077d29f267d</id>
<content type='text'>
Remove the function kgdb_post_primary_code() that is not used anywhere.

This was partially found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist &lt;rickard_strandqvist@spectrumdigital.se&gt;
Acked-by: Sonic Zhang &lt;sonic.zhang@analog.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Remove the function kgdb_post_primary_code() that is not used anywhere.

This was partially found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist &lt;rickard_strandqvist@spectrumdigital.se&gt;
Acked-by: Sonic Zhang &lt;sonic.zhang@analog.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>debug-mmrs: Eliminate all traces of the USB_PHY_TEST MMR</title>
<updated>2015-04-23T13:34:31+00:00</updated>
<author>
<name>Andre Wolokita</name>
<email>Andre.Wolokita@analog.com</email>
</author>
<published>2014-09-05T00:42:28+00:00</published>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/commit/?id=bb717b33aa6b01abcc78c7a18dec343a3bde9574'/>
<id>bb717b33aa6b01abcc78c7a18dec343a3bde9574</id>
<content type='text'>
Interacting with the USB_PHY_TEST MMR through debugfs was causing wide-spread
chaos in the realm (kernel panic). Expunge all references to this demonic
register.

Signed-off-by: Andre Wolokita &lt;Andre.Wolokita@analog.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Interacting with the USB_PHY_TEST MMR through debugfs was causing wide-spread
chaos in the realm (kernel panic). Expunge all references to this demonic
register.

Signed-off-by: Andre Wolokita &lt;Andre.Wolokita@analog.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>bug[220] kgdb: change the smp cross core function entry</title>
<updated>2015-04-23T13:34:26+00:00</updated>
<author>
<name>Sonic Zhang</name>
<email>sonic.zhang@analog.com</email>
</author>
<published>2014-07-29T08:41:10+00:00</published>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/commit/?id=a0f4207d03b40eee6338b51288849965ac2b94e2'/>
<id>a0f4207d03b40eee6338b51288849965ac2b94e2</id>
<content type='text'>
Signed-off-by: Sonic Zhang &lt;sonic.zhang@analog.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Signed-off-by: Sonic Zhang &lt;sonic.zhang@analog.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arch: blackfin: kernel: setup.c: Cleaning up missing null-terminate in conjunction with strncpy</title>
<updated>2015-04-23T13:34:25+00:00</updated>
<author>
<name>Rickard Strandqvist</name>
<email>rickard_strandqvist@spectrumdigital.se</email>
</author>
<published>2014-07-26T13:58:22+00:00</published>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/commit/?id=4eb147c83f34e00184557923d2bf93f593deb41c'/>
<id>4eb147c83f34e00184557923d2bf93f593deb41c</id>
<content type='text'>
Replacing strncpy with strlcpy to avoid strings that lacks null terminate.

Signed-off-by: Rickard Strandqvist &lt;rickard_strandqvist@spectrumdigital.se&gt;
Signed-off-by: Steven Miao &lt;realmz6@gmail.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Replacing strncpy with strlcpy to avoid strings that lacks null terminate.

Signed-off-by: Rickard Strandqvist &lt;rickard_strandqvist@spectrumdigital.se&gt;
Signed-off-by: Steven Miao &lt;realmz6@gmail.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>frv: Remove signal translation and exec_domain</title>
<updated>2015-04-12T18:58:24+00:00</updated>
<author>
<name>Richard Weinberger</name>
<email>richard@nod.at</email>
</author>
<published>2014-07-13T15:15:06+00:00</published>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/commit/?id=7bd8301084dfaf9210f66142fadb62a2bee7588b'/>
<id>7bd8301084dfaf9210f66142fadb62a2bee7588b</id>
<content type='text'>
As execution domain support is gone we can remove
signal translation from the signal code and remove
exec_domain from thread_info.

Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
As execution domain support is gone we can remove
signal translation from the signal code and remove
exec_domain from thread_info.

Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blackfin: Remove exec_domain usage</title>
<updated>2015-04-12T18:58:24+00:00</updated>
<author>
<name>Richard Weinberger</name>
<email>richard@nod.at</email>
</author>
<published>2015-04-03T16:58:10+00:00</published>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/commit/?id=61622aa399ecc65601331b946395ce095cb7c9d8'/>
<id>61622aa399ecc65601331b946395ce095cb7c9d8</id>
<content type='text'>
As execution domain support is gone we can remove
signal translation from the signal code and remove
exec_domain from thread_info.

Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
As execution domain support is gone we can remove
signal translation from the signal code and remove
exec_domain from thread_info.

Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blackfin: Autogenerate offsets in struct thread_info</title>
<updated>2015-04-12T18:58:24+00:00</updated>
<author>
<name>Richard Weinberger</name>
<email>richard@nod.at</email>
</author>
<published>2015-04-03T16:56:16+00:00</published>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/commit/?id=ede45dd302385007b7ee83148753654ab8453167'/>
<id>ede45dd302385007b7ee83148753654ab8453167</id>
<content type='text'>
Maintaining offsets by hand is no fun.

Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Maintaining offsets by hand is no fun.

Signed-off-by: Richard Weinberger &lt;richard@nod.at&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>all arches, signal: move restart_block to struct task_struct</title>
<updated>2015-02-13T02:54:12+00:00</updated>
<author>
<name>Andy Lutomirski</name>
<email>luto@amacapital.net</email>
</author>
<published>2015-02-12T23:01:14+00:00</published>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/commit/?id=f56141e3e2d9aabf7e6b89680ab572c2cdbb2a24'/>
<id>f56141e3e2d9aabf7e6b89680ab572c2cdbb2a24</id>
<content type='text'>
If an attacker can cause a controlled kernel stack overflow, overwriting
the restart block is a very juicy exploit target.  This is because the
restart_block is held in the same memory allocation as the kernel stack.

Moving the restart block to struct task_struct prevents this exploit by
making the restart_block harder to locate.

Note that there are other fields in thread_info that are also easy
targets, at least on some architectures.

It's also a decent simplification, since the restart code is more or less
identical on all architectures.

[james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
Signed-off-by: Andy Lutomirski &lt;luto@amacapital.net&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: David Miller &lt;davem@davemloft.net&gt;
Acked-by: Richard Weinberger &lt;richard@nod.at&gt;
Cc: Richard Henderson &lt;rth@twiddle.net&gt;
Cc: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Vineet Gupta &lt;vgupta@synopsys.com&gt;
Cc: Russell King &lt;rmk@arm.linux.org.uk&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Will Deacon &lt;will.deacon@arm.com&gt;
Cc: Haavard Skinnemoen &lt;hskinnemoen@gmail.com&gt;
Cc: Hans-Christian Egtvedt &lt;egtvedt@samfundet.no&gt;
Cc: Steven Miao &lt;realmz6@gmail.com&gt;
Cc: Mark Salter &lt;msalter@redhat.com&gt;
Cc: Aurelien Jacquiot &lt;a-jacquiot@ti.com&gt;
Cc: Mikael Starvik &lt;starvik@axis.com&gt;
Cc: Jesper Nilsson &lt;jesper.nilsson@axis.com&gt;
Cc: David Howells &lt;dhowells@redhat.com&gt;
Cc: Richard Kuo &lt;rkuo@codeaurora.org&gt;
Cc: "Luck, Tony" &lt;tony.luck@intel.com&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Michal Simek &lt;monstr@monstr.eu&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Jonas Bonn &lt;jonas@southpole.se&gt;
Cc: "James E.J. Bottomley" &lt;jejb@parisc-linux.org&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Acked-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt; (powerpc)
Tested-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt; (powerpc)
Cc: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Chen Liqin &lt;liqin.linux@gmail.com&gt;
Cc: Lennox Wu &lt;lennox.wu@gmail.com&gt;
Cc: Chris Metcalf &lt;cmetcalf@ezchip.com&gt;
Cc: Guan Xuetao &lt;gxt@mprc.pku.edu.cn&gt;
Cc: Chris Zankel &lt;chris@zankel.net&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Oleg Nesterov &lt;oleg@redhat.com&gt;
Cc: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: James Hogan &lt;james.hogan@imgtec.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
If an attacker can cause a controlled kernel stack overflow, overwriting
the restart block is a very juicy exploit target.  This is because the
restart_block is held in the same memory allocation as the kernel stack.

Moving the restart block to struct task_struct prevents this exploit by
making the restart_block harder to locate.

Note that there are other fields in thread_info that are also easy
targets, at least on some architectures.

It's also a decent simplification, since the restart code is more or less
identical on all architectures.

[james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
Signed-off-by: Andy Lutomirski &lt;luto@amacapital.net&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: David Miller &lt;davem@davemloft.net&gt;
Acked-by: Richard Weinberger &lt;richard@nod.at&gt;
Cc: Richard Henderson &lt;rth@twiddle.net&gt;
Cc: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Vineet Gupta &lt;vgupta@synopsys.com&gt;
Cc: Russell King &lt;rmk@arm.linux.org.uk&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Will Deacon &lt;will.deacon@arm.com&gt;
Cc: Haavard Skinnemoen &lt;hskinnemoen@gmail.com&gt;
Cc: Hans-Christian Egtvedt &lt;egtvedt@samfundet.no&gt;
Cc: Steven Miao &lt;realmz6@gmail.com&gt;
Cc: Mark Salter &lt;msalter@redhat.com&gt;
Cc: Aurelien Jacquiot &lt;a-jacquiot@ti.com&gt;
Cc: Mikael Starvik &lt;starvik@axis.com&gt;
Cc: Jesper Nilsson &lt;jesper.nilsson@axis.com&gt;
Cc: David Howells &lt;dhowells@redhat.com&gt;
Cc: Richard Kuo &lt;rkuo@codeaurora.org&gt;
Cc: "Luck, Tony" &lt;tony.luck@intel.com&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Michal Simek &lt;monstr@monstr.eu&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Jonas Bonn &lt;jonas@southpole.se&gt;
Cc: "James E.J. Bottomley" &lt;jejb@parisc-linux.org&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Acked-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt; (powerpc)
Tested-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt; (powerpc)
Cc: Martin Schwidefsky &lt;schwidefsky@de.ibm.com&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Chen Liqin &lt;liqin.linux@gmail.com&gt;
Cc: Lennox Wu &lt;lennox.wu@gmail.com&gt;
Cc: Chris Metcalf &lt;cmetcalf@ezchip.com&gt;
Cc: Guan Xuetao &lt;gxt@mprc.pku.edu.cn&gt;
Cc: Chris Zankel &lt;chris@zankel.net&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Oleg Nesterov &lt;oleg@redhat.com&gt;
Cc: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: James Hogan &lt;james.hogan@imgtec.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blackfin: Replace __get_cpu_var uses</title>
<updated>2014-08-26T17:45:55+00:00</updated>
<author>
<name>Christoph Lameter</name>
<email>cl@linux.com</email>
</author>
<published>2014-08-17T17:30:52+00:00</published>
<link rel='alternate' type='text/html' href='http://rtsrv.cs.unc.edu/cgit/cgit.cgi/litmus-rt.git/commit/?id=7e788ab11d73fbb617973c12a9b3f84f93721e67'/>
<id>7e788ab11d73fbb617973c12a9b3f84f93721e67</id>
<content type='text'>
__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &amp;__get_cpu_var(x).  This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

#define __get_cpu_var(var) (*this_cpu_ptr(&amp;(var)))

__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset.  Thereby address calculations are avoided and less registers
are used when code is generated.

At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.

The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e.  using a global
register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &amp;__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&amp;y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

	DEFINE_PER_CPU(int, y);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(&amp;x, this_cpu_ptr(&amp;y), sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	__this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	__this_cpu_inc(y)

CC: Mike Frysinger &lt;vapier@gentoo.org&gt;
Signed-off-by: Christoph Lameter &lt;cl@linux.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &amp;__get_cpu_var(x).  This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.

Other use cases are for storing and retrieving data from the current
processors percpu area.  __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.

__get_cpu_var() is defined as :

#define __get_cpu_var(var) (*this_cpu_ptr(&amp;(var)))

__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.

this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.

This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset.  Thereby address calculations are avoided and less registers
are used when code is generated.

At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.

The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e.  using a global
register that may be set to the per cpu base.

Transformations done to __get_cpu_var()

1. Determine the address of the percpu instance of the current processor.

	DEFINE_PER_CPU(int, y);
	int *x = &amp;__get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(&amp;y);

2. Same as #1 but this time an array structure is involved.

	DEFINE_PER_CPU(int, y[20]);
	int *x = __get_cpu_var(y);

    Converts to

	int *x = this_cpu_ptr(y);

3. Retrieve the content of the current processors instance of a per cpu
variable.

	DEFINE_PER_CPU(int, y);
	int x = __get_cpu_var(y)

   Converts to

	int x = __this_cpu_read(y);

4. Retrieve the content of a percpu struct

	DEFINE_PER_CPU(struct mystruct, y);
	struct mystruct x = __get_cpu_var(y);

   Converts to

	memcpy(&amp;x, this_cpu_ptr(&amp;y), sizeof(x));

5. Assignment to a per cpu variable

	DEFINE_PER_CPU(int, y)
	__get_cpu_var(y) = x;

   Converts to

	__this_cpu_write(y, x);

6. Increment/Decrement etc of a per cpu variable

	DEFINE_PER_CPU(int, y);
	__get_cpu_var(y)++

   Converts to

	__this_cpu_inc(y)

CC: Mike Frysinger &lt;vapier@gentoo.org&gt;
Signed-off-by: Christoph Lameter &lt;cl@linux.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
</pre>
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