<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/mips/include/asm/processor.h, branch v5.10</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>MIPS: process: Add prototype for function arch_dup_task_struct</title>
<updated>2020-09-30T19:52:42+00:00</updated>
<author>
<name>Pujin Shi</name>
<email>shipujin.t@gmail.com</email>
</author>
<published>2020-09-29T09:30:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=99419c310ee0f3f9aceff8966b2eeffc03ba76a5'/>
<id>99419c310ee0f3f9aceff8966b2eeffc03ba76a5</id>
<content type='text'>
This commit adds a prototype to fix warning at W=1:

  arch/mips/kernel/process.c:95:5: error: no previous prototype for 'arch_dup_task_struct' [-Werror=missing-prototypes]

Signed-off-by: Pujin Shi &lt;shipujin.t@gmail.com&gt;
Signed-off-by: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This commit adds a prototype to fix warning at W=1:

  arch/mips/kernel/process.c:95:5: error: no previous prototype for 'arch_dup_task_struct' [-Werror=missing-prototypes]

Signed-off-by: Pujin Shi &lt;shipujin.t@gmail.com&gt;
Signed-off-by: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'mips_5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux</title>
<updated>2020-03-31T15:51:45+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-03-31T15:51:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d71e064449a704a026fa032ec852d532f08aefa1'/>
<id>d71e064449a704a026fa032ec852d532f08aefa1</id>
<content type='text'>
Pull MIPS updates from Thomas Bogendoerfer:

 - loongson64 irq rework

 - dmi support loongson

 - replace setup_irq() by request_irq()

 - jazz cleanups

 - minor cleanups and fixes

* tag 'mips_5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: (44 commits)
  MIPS: ralink: mt7621: Fix soc_device introduction
  MIPS: Exclude more dsemul code when CONFIG_MIPS_FP_SUPPORT=n
  MIPS/tlbex: Fix LDDIR usage in setup_pw() for Loongson-3
  MIPS: do not compile generic functions for CONFIG_CAVIUM_OCTEON_SOC
  MAINTAINERS: Update Loongson64 entry
  MIPS: Loongson64: Load built-in dtbs
  MIPS: Loongson64: Add generic dts
  dt-bindings: mips: Add loongson boards
  MIPS: Loongson64: Drop legacy IRQ code
  dt-bindings: interrupt-controller: Add Loongson-3 HTPIC
  irqchip: Add driver for Loongson-3 HyperTransport PIC controller
  dt-bindings: interrupt-controller: Add Loongson LIOINTC
  irqchip: loongson-liointc: Workaround LPC IRQ Errata
  irqchip: Add driver for Loongson I/O Local Interrupt Controller
  docs: mips: remove no longer needed au1xxx_ide.rst documentation
  MIPS: Alchemy: remove no longer used au1xxx_ide.h header
  ide: remove no longer used au1xxx-ide driver
  MIPS: Add support for Desktop Management Interface (DMI)
  firmware: dmi: Add macro SMBIOS_ENTRY_POINT_SCAN_START
  MIPS: ralink: mt7621: introduce 'soc_device' initialization
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull MIPS updates from Thomas Bogendoerfer:

 - loongson64 irq rework

 - dmi support loongson

 - replace setup_irq() by request_irq()

 - jazz cleanups

 - minor cleanups and fixes

* tag 'mips_5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: (44 commits)
  MIPS: ralink: mt7621: Fix soc_device introduction
  MIPS: Exclude more dsemul code when CONFIG_MIPS_FP_SUPPORT=n
  MIPS/tlbex: Fix LDDIR usage in setup_pw() for Loongson-3
  MIPS: do not compile generic functions for CONFIG_CAVIUM_OCTEON_SOC
  MAINTAINERS: Update Loongson64 entry
  MIPS: Loongson64: Load built-in dtbs
  MIPS: Loongson64: Add generic dts
  dt-bindings: mips: Add loongson boards
  MIPS: Loongson64: Drop legacy IRQ code
  dt-bindings: interrupt-controller: Add Loongson-3 HTPIC
  irqchip: Add driver for Loongson-3 HyperTransport PIC controller
  dt-bindings: interrupt-controller: Add Loongson LIOINTC
  irqchip: loongson-liointc: Workaround LPC IRQ Errata
  irqchip: Add driver for Loongson I/O Local Interrupt Controller
  docs: mips: remove no longer needed au1xxx_ide.rst documentation
  MIPS: Alchemy: remove no longer used au1xxx_ide.h header
  ide: remove no longer used au1xxx-ide driver
  MIPS: Add support for Desktop Management Interface (DMI)
  firmware: dmi: Add macro SMBIOS_ENTRY_POINT_SCAN_START
  MIPS: ralink: mt7621: introduce 'soc_device' initialization
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>MIPS: Exclude more dsemul code when CONFIG_MIPS_FP_SUPPORT=n</title>
<updated>2020-03-25T15:07:14+00:00</updated>
<author>
<name>Yousong Zhou</name>
<email>yszhou4tech@gmail.com</email>
</author>
<published>2020-03-24T15:27:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=aebdc6ff3b2e79327d8eff7c0e2d835bb1d3221f'/>
<id>aebdc6ff3b2e79327d8eff7c0e2d835bb1d3221f</id>
<content type='text'>
This furthers what commit 42b10815d559 ("MIPS: Don't compile math-emu
when CONFIG_MIPS_FP_SUPPORT=n") has done

Signed-off-by: Yousong Zhou &lt;yszhou4tech@gmail.com&gt;
Signed-off-by: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This furthers what commit 42b10815d559 ("MIPS: Don't compile math-emu
when CONFIG_MIPS_FP_SUPPORT=n") has done

Signed-off-by: Yousong Zhou &lt;yszhou4tech@gmail.com&gt;
Signed-off-by: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mips: vdso: Enable mips to use common headers</title>
<updated>2020-03-21T14:24:02+00:00</updated>
<author>
<name>Vincenzo Frascino</name>
<email>vincenzo.frascino@arm.com</email>
</author>
<published>2020-03-20T14:53:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c135fc875ce363ff8405a8e64408bca0aa2a865b'/>
<id>c135fc875ce363ff8405a8e64408bca0aa2a865b</id>
<content type='text'>
Enable mips to use only the common headers in the implementation of
the vDSO library.

Signed-off-by: Vincenzo Frascino &lt;vincenzo.frascino@arm.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Paul Burton &lt;paulburton@kernel.org&gt;
Link: https://lkml.kernel.org/r/20200320145351.32292-23-vincenzo.frascino@arm.com

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Enable mips to use only the common headers in the implementation of
the vDSO library.

Signed-off-by: Vincenzo Frascino &lt;vincenzo.frascino@arm.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Paul Burton &lt;paulburton@kernel.org&gt;
Link: https://lkml.kernel.org/r/20200320145351.32292-23-vincenzo.frascino@arm.com

</pre>
</div>
</content>
</entry>
<entry>
<title>MIPS: Loongson64: Rename CPU TYPES</title>
<updated>2019-10-31T22:03:10+00:00</updated>
<author>
<name>Jiaxun Yang</name>
<email>jiaxun.yang@flygoat.com</email>
</author>
<published>2019-10-20T14:43:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=268a2d60013049cfd9a0aada77284aa6ea8ad26a'/>
<id>268a2d60013049cfd9a0aada77284aa6ea8ad26a</id>
<content type='text'>
CPU_LOONGSON2 -&gt; CPU_LOONGSON2EF
CPU_LOONGSON3 -&gt; CPU_LOONGSON64

As newer loongson-2 products (2G/2H/2K1000) can share kernel
implementation with loongson-3 while 2E/2F are less similar with
other LOONGSON64 products.

Signed-off-by: Jiaxun Yang &lt;jiaxun.yang@flygoat.com&gt;
Signed-off-by: Paul Burton &lt;paulburton@kernel.org&gt;
Cc: linux-mips@vger.kernel.org
Cc: chenhc@lemote.com
Cc: paul.burton@mips.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
CPU_LOONGSON2 -&gt; CPU_LOONGSON2EF
CPU_LOONGSON3 -&gt; CPU_LOONGSON64

As newer loongson-2 products (2G/2H/2K1000) can share kernel
implementation with loongson-3 while 2E/2F are less similar with
other LOONGSON64 products.

Signed-off-by: Jiaxun Yang &lt;jiaxun.yang@flygoat.com&gt;
Signed-off-by: Paul Burton &lt;paulburton@kernel.org&gt;
Cc: linux-mips@vger.kernel.org
Cc: chenhc@lemote.com
Cc: paul.burton@mips.com
</pre>
</div>
</content>
</entry>
<entry>
<title>mips: use generic mmap top-down layout and brk randomization</title>
<updated>2019-09-24T22:54:12+00:00</updated>
<author>
<name>Alexandre Ghiti</name>
<email>alex@ghiti.fr</email>
</author>
<published>2019-09-23T22:39:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=9035bd29427921cd32d268a830aff78dcafb945b'/>
<id>9035bd29427921cd32d268a830aff78dcafb945b</id>
<content type='text'>
mips uses a top-down layout by default that exactly fits the generic
functions, so get rid of arch specific code and use the generic version by
selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT.

As ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects ARCH_HAS_ELF_RANDOMIZE,
use the generic version of arch_randomize_brk since it also fits.  Note
that this commit also removes the possibility for mips to have elf
randomization and no MMU: without MMU, the security added by randomization
is worth nothing.

Link: http://lkml.kernel.org/r/20190730055113.23635-14-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti &lt;alex@ghiti.fr&gt;
Acked-by: Paul Burton &lt;paul.burton@mips.com&gt;
Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Reviewed-by: Luis Chamberlain &lt;mcgrof@kernel.org&gt;
Cc: Albert Ou &lt;aou@eecs.berkeley.edu&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
Cc: Christoph Hellwig &lt;hch@lst.de&gt;
Cc: James Hogan &lt;jhogan@kernel.org&gt;
Cc: Palmer Dabbelt &lt;palmer@sifive.com&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Russell King &lt;linux@armlinux.org.uk&gt;
Cc: Will Deacon &lt;will.deacon@arm.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>
mips uses a top-down layout by default that exactly fits the generic
functions, so get rid of arch specific code and use the generic version by
selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT.

As ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects ARCH_HAS_ELF_RANDOMIZE,
use the generic version of arch_randomize_brk since it also fits.  Note
that this commit also removes the possibility for mips to have elf
randomization and no MMU: without MMU, the security added by randomization
is worth nothing.

Link: http://lkml.kernel.org/r/20190730055113.23635-14-alex@ghiti.fr
Signed-off-by: Alexandre Ghiti &lt;alex@ghiti.fr&gt;
Acked-by: Paul Burton &lt;paul.burton@mips.com&gt;
Reviewed-by: Kees Cook &lt;keescook@chromium.org&gt;
Reviewed-by: Luis Chamberlain &lt;mcgrof@kernel.org&gt;
Cc: Albert Ou &lt;aou@eecs.berkeley.edu&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
Cc: Christoph Hellwig &lt;hch@lst.de&gt;
Cc: James Hogan &lt;jhogan@kernel.org&gt;
Cc: Palmer Dabbelt &lt;palmer@sifive.com&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Russell King &lt;linux@armlinux.org.uk&gt;
Cc: Will Deacon &lt;will.deacon@arm.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>MIPS: Remove struct task_struct fpu state when CONFIG_MIPS_FP_SUPPORT=n</title>
<updated>2018-11-09T18:23:19+00:00</updated>
<author>
<name>Paul Burton</name>
<email>paul.burton@mips.com</email>
</author>
<published>2018-11-07T23:14:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=2725f3778fddb70526318824de63476aff816ab8'/>
<id>2725f3778fddb70526318824de63476aff816ab8</id>
<content type='text'>
When CONFIG_MIPS_FP_SUPPORT=n we don't support floating point &amp; so don't
need to preserve floating point context for tasks. Remove that context
from struct task_struct.

Signed-off-by: Paul Burton &lt;paul.burton@mips.com&gt;
Patchwork: https://patchwork.linux-mips.org/patch/21013/
Cc: linux-mips@linux-mips.org
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When CONFIG_MIPS_FP_SUPPORT=n we don't support floating point &amp; so don't
need to preserve floating point context for tasks. Remove that context
from struct task_struct.

Signed-off-by: Paul Burton &lt;paul.burton@mips.com&gt;
Patchwork: https://patchwork.linux-mips.org/patch/21013/
Cc: linux-mips@linux-mips.org
</pre>
</div>
</content>
</entry>
<entry>
<title>treewide: remove current_text_addr</title>
<updated>2018-10-31T15:54:12+00:00</updated>
<author>
<name>Nick Desaulniers</name>
<email>ndesaulniers@google.com</email>
</author>
<published>2018-10-30T22:04:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=de0d22e50cd3d57277f073ccf65d57aa519d6888'/>
<id>de0d22e50cd3d57277f073ccf65d57aa519d6888</id>
<content type='text'>
Prefer _THIS_IP_ defined in linux/kernel.h.

Most definitions of current_text_addr were the same as _THIS_IP_, but
a few archs had inline assembly instead.

This patch removes the final call site of current_text_addr, making all
of the definitions dead code.

[akpm@linux-foundation.org: fix arch/csky/include/asm/processor.h]
Link: http://lkml.kernel.org/r/20180911182413.180715-1-ndesaulniers@google.com
Signed-off-by: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&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>
Prefer _THIS_IP_ defined in linux/kernel.h.

Most definitions of current_text_addr were the same as _THIS_IP_, but
a few archs had inline assembly instead.

This patch removes the final call site of current_text_addr, making all
of the definitions dead code.

[akpm@linux-foundation.org: fix arch/csky/include/asm/processor.h]
Link: http://lkml.kernel.org/r/20180911182413.180715-1-ndesaulniers@google.com
Signed-off-by: Nick Desaulniers &lt;ndesaulniers@google.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&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>MIPS: VDSO: Reduce VDSO_RANDOMIZE_SIZE to 64MB for 64bit</title>
<updated>2018-10-16T16:47:18+00:00</updated>
<author>
<name>Huacai Chen</name>
<email>chenhc@lemote.com</email>
</author>
<published>2018-10-16T01:20:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c61c7def1fa0a722610d89790e0255b74f3c07dd'/>
<id>c61c7def1fa0a722610d89790e0255b74f3c07dd</id>
<content type='text'>
Commit ea7e0480a4b6 ("MIPS: VDSO: Always map near top of user memory")
set VDSO_RANDOMIZE_SIZE to 256MB for 64bit kernel. But take a look at
arch/mips/mm/mmap.c we can see that MIN_GAP is 128MB, which means the
mmap_base may be at (user_address_top - 128MB). This make the stack be
surrounded by mmaped areas, then stack expanding fails and causes a
segmentation fault. Therefore, VDSO_RANDOMIZE_SIZE should be less than
MIN_GAP and this patch reduce it to 64MB.

Signed-off-by: Huacai Chen &lt;chenhc@lemote.com&gt;
Signed-off-by: Paul Burton &lt;paul.burton@mips.com&gt;
Fixes: ea7e0480a4b6 ("MIPS: VDSO: Always map near top of user memory")
Patchwork: https://patchwork.linux-mips.org/patch/20910/
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: James Hogan &lt;jhogan@kernel.org&gt;
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang &lt;zhangfx@lemote.com&gt;
Cc: Zhangjin Wu &lt;wuzhangjin@gmail.com&gt;
Cc: Huacai Chen &lt;chenhuacai@gmail.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Commit ea7e0480a4b6 ("MIPS: VDSO: Always map near top of user memory")
set VDSO_RANDOMIZE_SIZE to 256MB for 64bit kernel. But take a look at
arch/mips/mm/mmap.c we can see that MIN_GAP is 128MB, which means the
mmap_base may be at (user_address_top - 128MB). This make the stack be
surrounded by mmaped areas, then stack expanding fails and causes a
segmentation fault. Therefore, VDSO_RANDOMIZE_SIZE should be less than
MIN_GAP and this patch reduce it to 64MB.

Signed-off-by: Huacai Chen &lt;chenhc@lemote.com&gt;
Signed-off-by: Paul Burton &lt;paul.burton@mips.com&gt;
Fixes: ea7e0480a4b6 ("MIPS: VDSO: Always map near top of user memory")
Patchwork: https://patchwork.linux-mips.org/patch/20910/
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: James Hogan &lt;jhogan@kernel.org&gt;
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang &lt;zhangfx@lemote.com&gt;
Cc: Zhangjin Wu &lt;wuzhangjin@gmail.com&gt;
Cc: Huacai Chen &lt;chenhuacai@gmail.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>MIPS: VDSO: Always map near top of user memory</title>
<updated>2018-09-28T19:09:00+00:00</updated>
<author>
<name>Paul Burton</name>
<email>paul.burton@mips.com</email>
</author>
<published>2018-09-25T22:51:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ea7e0480a4b695d0aa6b3fa99bd658a003122113'/>
<id>ea7e0480a4b695d0aa6b3fa99bd658a003122113</id>
<content type='text'>
When using the legacy mmap layout, for example triggered using ulimit -s
unlimited, get_unmapped_area() fills memory from bottom to top starting
from a fairly low address near TASK_UNMAPPED_BASE.

This placement is suboptimal if the user application wishes to allocate
large amounts of heap memory using the brk syscall. With the VDSO being
located low in the user's virtual address space, the amount of space
available for access using brk is limited much more than it was prior to
the introduction of the VDSO.

For example:

  # ulimit -s unlimited; cat /proc/self/maps
  00400000-004ec000 r-xp 00000000 08:00 71436      /usr/bin/coreutils
  004fc000-004fd000 rwxp 000ec000 08:00 71436      /usr/bin/coreutils
  004fd000-0050f000 rwxp 00000000 00:00 0
  00cc3000-00ce4000 rwxp 00000000 00:00 0          [heap]
  2ab96000-2ab98000 r--p 00000000 00:00 0          [vvar]
  2ab98000-2ab99000 r-xp 00000000 00:00 0          [vdso]
  2ab99000-2ab9d000 rwxp 00000000 00:00 0
  ...

Resolve this by adjusting STACK_TOP to reserve space for the VDSO &amp;
providing an address hint to get_unmapped_area() causing it to use this
space even when using the legacy mmap layout.

We reserve enough space for the VDSO, plus 1MB or 256MB for 32 bit &amp; 64
bit systems respectively within which we randomize the VDSO base
address. Previously this randomization was taken care of by the mmap
base address randomization performed by arch_mmap_rnd(). The 1MB &amp; 256MB
sizes are somewhat arbitrary but chosen such that we have some
randomization without taking up too much of the user's virtual address
space, which is often in short supply for 32 bit systems.

With this the VDSO is always mapped at a high address, leaving lots of
space for statically linked programs to make use of brk:

  # ulimit -s unlimited; cat /proc/self/maps
  00400000-004ec000 r-xp 00000000 08:00 71436      /usr/bin/coreutils
  004fc000-004fd000 rwxp 000ec000 08:00 71436      /usr/bin/coreutils
  004fd000-0050f000 rwxp 00000000 00:00 0
  00c28000-00c49000 rwxp 00000000 00:00 0          [heap]
  ...
  7f67c000-7f69d000 rwxp 00000000 00:00 0          [stack]
  7f7fc000-7f7fd000 rwxp 00000000 00:00 0
  7fcf1000-7fcf3000 r--p 00000000 00:00 0          [vvar]
  7fcf3000-7fcf4000 r-xp 00000000 00:00 0          [vdso]

Signed-off-by: Paul Burton &lt;paul.burton@mips.com&gt;
Reported-by: Huacai Chen &lt;chenhc@lemote.com&gt;
Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
Cc: Huacai Chen &lt;chenhc@lemote.com&gt;
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org # v4.4+
</content>
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<pre>
When using the legacy mmap layout, for example triggered using ulimit -s
unlimited, get_unmapped_area() fills memory from bottom to top starting
from a fairly low address near TASK_UNMAPPED_BASE.

This placement is suboptimal if the user application wishes to allocate
large amounts of heap memory using the brk syscall. With the VDSO being
located low in the user's virtual address space, the amount of space
available for access using brk is limited much more than it was prior to
the introduction of the VDSO.

For example:

  # ulimit -s unlimited; cat /proc/self/maps
  00400000-004ec000 r-xp 00000000 08:00 71436      /usr/bin/coreutils
  004fc000-004fd000 rwxp 000ec000 08:00 71436      /usr/bin/coreutils
  004fd000-0050f000 rwxp 00000000 00:00 0
  00cc3000-00ce4000 rwxp 00000000 00:00 0          [heap]
  2ab96000-2ab98000 r--p 00000000 00:00 0          [vvar]
  2ab98000-2ab99000 r-xp 00000000 00:00 0          [vdso]
  2ab99000-2ab9d000 rwxp 00000000 00:00 0
  ...

Resolve this by adjusting STACK_TOP to reserve space for the VDSO &amp;
providing an address hint to get_unmapped_area() causing it to use this
space even when using the legacy mmap layout.

We reserve enough space for the VDSO, plus 1MB or 256MB for 32 bit &amp; 64
bit systems respectively within which we randomize the VDSO base
address. Previously this randomization was taken care of by the mmap
base address randomization performed by arch_mmap_rnd(). The 1MB &amp; 256MB
sizes are somewhat arbitrary but chosen such that we have some
randomization without taking up too much of the user's virtual address
space, which is often in short supply for 32 bit systems.

With this the VDSO is always mapped at a high address, leaving lots of
space for statically linked programs to make use of brk:

  # ulimit -s unlimited; cat /proc/self/maps
  00400000-004ec000 r-xp 00000000 08:00 71436      /usr/bin/coreutils
  004fc000-004fd000 rwxp 000ec000 08:00 71436      /usr/bin/coreutils
  004fd000-0050f000 rwxp 00000000 00:00 0
  00c28000-00c49000 rwxp 00000000 00:00 0          [heap]
  ...
  7f67c000-7f69d000 rwxp 00000000 00:00 0          [stack]
  7f7fc000-7f7fd000 rwxp 00000000 00:00 0
  7fcf1000-7fcf3000 r--p 00000000 00:00 0          [vvar]
  7fcf3000-7fcf4000 r-xp 00000000 00:00 0          [vdso]

Signed-off-by: Paul Burton &lt;paul.burton@mips.com&gt;
Reported-by: Huacai Chen &lt;chenhc@lemote.com&gt;
Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
Cc: Huacai Chen &lt;chenhc@lemote.com&gt;
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org # v4.4+
</pre>
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