linux-toradex.git/arch/arc, branch v3.10.2 Linux kernel for Apalis and Colibri modules ARC: lazy dcache flush broke gdb in non-aliasing configs 2013-05-25T08:45:55+00:00 Vineet Gupta vgupta@synopsys.com 2013-05-25T08:34:25+00:00 7bb66f6e6eecdd8e10ed3a63bd28c1e9105adc79 gdbserver inserting a breakpoint ends up calling copy_user_page() for a code page. The generic version of which (non-aliasing config) didn't set the PG_arch_1 bit hence update_mmu_cache() didn't sync dcache/icache for corresponding dynamic loader code page - causing garbade to be executed. So now aliasing versions of copy_user_highpage()/clear_page() are made default. There is no significant overhead since all of special alias handling code is compiled out for non-aliasing build Signed-off-by: Vineet Gupta <vgupta@synopsys.com> 
gdbserver inserting a breakpoint ends up calling copy_user_page() for a
code page. The generic version of which (non-aliasing config) didn't set
the PG_arch_1 bit hence update_mmu_cache() didn't sync dcache/icache for
corresponding dynamic loader code page - causing garbade to be executed.

So now aliasing versions of copy_user_highpage()/clear_page() are made
default. There is no significant overhead since all of special alias
handling code is compiled out for non-aliasing build

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: Use enough bits for determining page's cache color 2013-05-23T08:55:09+00:00 Vineet Gupta vgupta@synopsys.com 2013-05-19T08:36:44+00:00 006dfb3c9c44192f06093d65b3a876fa5ad1319a The current code uses 2 bits for determining page's dcache color, thus sorting pages into 4 bins, whereas the aliasing dcache really has 2 bins (8k page, 64k dcache - 4 way-set-assoc). This can cause extraneous flushes - e.g. color 0 and 2. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> 
The current code uses 2 bits for determining page's dcache color, thus
sorting pages into 4 bins, whereas the aliasing dcache really has 2 bins
(8k page, 64k dcache - 4 way-set-assoc).
This can cause extraneous flushes - e.g. color 0 and 2.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: Brown paper bag bug in macro for checking cache color 2013-05-23T08:54:52+00:00 Vineet Gupta vgupta@synopsys.com 2013-05-22T13:08:10+00:00 3e87974dec5ec25a8a4852d9292db6be659164e6 The VM_EXEC check in update_mmu_cache() was getting optimized away because of a stupid error in definition of macro addr_not_cache_congruent() The intention was to have the equivalent of following: if (a || (1 ? b : 0)) but we ended up with following: if (a || 1 ? b : 0) And because precedence of '||' is more that that of '?', gcc was optimizing away evaluation of <a> Nasty Repercussions: 1. For non-aliasing configs it would mean some extraneous dcache flushes for non-code pages if U/K mappings were not congruent. 2. For aliasing config, some needed dcache flush for code pages might be missed if U/K mappings were congruent. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> 
The VM_EXEC check in update_mmu_cache() was getting optimized away
because of a stupid error in definition of macro addr_not_cache_congruent()

The intention was to have the equivalent of following:

	if (a || (1 ? b : 0))

but we ended up with following:

	if (a || 1 ? b : 0)

And because precedence of '||' is more that that of '?', gcc was optimizing
away evaluation of <a>

Nasty Repercussions:
1. For non-aliasing configs it would mean some extraneous dcache flushes
   for non-code pages if U/K mappings were not congruent.
2. For aliasing config, some needed dcache flush for code pages might
   be missed if U/K mappings were congruent.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: copy_(to|from)_user() to honor usermode-access permissions 2013-05-23T05:03:03+00:00 Vineet Gupta vgupta@synopsys.com 2013-05-21T09:55:11+00:00 a950549c675f2c8c504469dec7d780da8a6433dc This manifested as grep failing psuedo-randomly: -------------->8--------------------- [ARCLinux]$ ip address show lo | grep inet [ARCLinux]$ ip address show lo | grep inet [ARCLinux]$ ip address show lo | grep inet [ARCLinux]$ [ARCLinux]$ ip address show lo | grep inet inet 127.0.0.1/8 scope host lo -------------->8--------------------- ARC700 MMU provides fully orthogonal permission bits per page: Ur, Uw, Ux, Kr, Kw, Kx The user mode page permission templates used to have all Kernel mode access bits enabled. This caused a tricky race condition observed with uClibc buffered file read and UNIX pipes. 1. Read access to an anon mapped page in libc .bss: write-protected zero_page mapped: TLB Entry installed with Ur + K[rwx] 2. grep calls libc:getc() -> buffered read layer calls read(2) with the internal read buffer in same .bss page. The read() call is on STDIN which has been redirected to a pipe. read(2) => sys_read() => pipe_read() => copy_to_user() 3. Since page has Kernel-write permission (despite being user-mode write-protected), copy_to_user() suceeds w/o taking a MMU TLB-Miss Exception (page-fault for ARC). core-MM is unaware that kernel erroneously wrote to the reserved read-only zero-page (BUG #1) 4. Control returns to userspace which now does a write to same .bss page Since Linux MM is not aware that page has been modified by kernel, it simply reassigns a new writable zero-init page to mapping, loosing the prior write by kernel - effectively zero'ing out the libc read buffer under the hood - hence grep doesn't see right data (BUG #2) The fix is to make all kernel-mode access permissions mirror the user-mode ones. Note that the kernel still has full access to pages, when accessed directly (w/o MMU) - this fix ensures that kernel-mode access in copy_to_from() path uses the same faulting access model as for pure user accesses to keep MM fully aware of page state. The issue is peudo-random because it only shows up if the TLB entry installed in #1 is present at the time of #3. If it is evicted out, due to TLB pressure or some-such, then copy_to_user() does take a TLB Miss Exception, with a routine write-to-anon COW processing installing a fresh page for kernel writes and also usable as it is in userspace. Further the issue was dormant for so long as it depends on where the libc internal read buffer (in .bss) is mapped at runtime. If it happens to reside in file-backed data mapping of libc (in the page-aligned slack space trailing the file backed data), loader zero padding the slack space, does the early cow page replacement, setting things up at the very beginning itself. With gcc 4.8 based builds, the libc buffer got pushed out to a real anon mapping which triggers the issue. Reported-by: Anton Kolesov <akolesov@synopsys.com> Cc: <stable@vger.kernel.org> # 3.9 Signed-off-by: Vineet Gupta <vgupta@synopsys.com> 
This manifested as grep failing psuedo-randomly:

-------------->8---------------------
[ARCLinux]$ ip address show lo | grep inet
[ARCLinux]$ ip address show lo | grep inet
[ARCLinux]$ ip address show lo | grep inet
[ARCLinux]$
[ARCLinux]$ ip address show lo | grep inet
    inet 127.0.0.1/8 scope host lo
-------------->8---------------------

ARC700 MMU provides fully orthogonal permission bits per page:
Ur, Uw, Ux, Kr, Kw, Kx

The user mode page permission templates used to have all Kernel mode
access bits enabled.
This caused a tricky race condition observed with uClibc buffered file
read and UNIX pipes.

1. Read access to an anon mapped page in libc .bss: write-protected
   zero_page mapped: TLB Entry installed with Ur + K[rwx]

2. grep calls libc:getc() -> buffered read layer calls read(2) with the
   internal read buffer in same .bss page.
   The read() call is on STDIN which has been redirected to a pipe.
   read(2) => sys_read() => pipe_read() => copy_to_user()

3. Since page has Kernel-write permission (despite being user-mode
   write-protected), copy_to_user() suceeds w/o taking a MMU TLB-Miss
   Exception (page-fault for ARC). core-MM is unaware that kernel
   erroneously wrote to the reserved read-only zero-page (BUG #1)

4. Control returns to userspace which now does a write to same .bss page
   Since Linux MM is not aware that page has been modified by kernel, it
   simply reassigns a new writable zero-init page to mapping, loosing the
   prior write by kernel - effectively zero'ing out the libc read buffer
   under the hood - hence grep doesn't see right data (BUG #2)

The fix is to make all kernel-mode access permissions mirror the
user-mode ones. Note that the kernel still has full access to pages,
when accessed directly (w/o MMU) - this fix ensures that kernel-mode
access in copy_to_from() path uses the same faulting access model as for
pure user accesses to keep MM fully aware of page state.

The issue is peudo-random because it only shows up if the TLB entry
installed in #1 is present at the time of #3. If it is evicted out, due
to TLB pressure or some-such, then copy_to_user() does take a TLB Miss
Exception, with a routine write-to-anon COW processing installing a
fresh page for kernel writes and also usable as it is in userspace.

Further the issue was dormant for so long as it depends on where the
libc internal read buffer (in .bss) is mapped at runtime.
If it happens to reside in file-backed data mapping of libc (in the
page-aligned slack space trailing the file backed data), loader zero
padding the slack space, does the early cow page replacement, setting
things up at the very beginning itself.

With gcc 4.8 based builds, the libc buffer got pushed out to a real
anon mapping which triggers the issue.

Reported-by: Anton Kolesov <akolesov@synopsys.com>
Cc: <stable@vger.kernel.org> # 3.9
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: [mm] Prevent stray dcache lines after__sync_icache_dcach() 2013-05-23T04:56:33+00:00 Vineet Gupta vgupta@synopsys.com 2013-05-16T06:49:29+00:00 f538881cc672c1b049aa0a34a792d0953fcecba5 Flush and INVALIDATE the dcache page. This helper is only used for writeback of CODE pages to memory. So there's no value in keeping the dcache lines around. Infact it is risky as a writeback on natural eviction under pressure can cause un-needed writeback with weird issues on aliasing dcache configurations. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> 
Flush and INVALIDATE the dcache page.

This helper is only used for writeback of CODE pages to memory. So
there's no value in keeping the dcache lines around. Infact it is risky
as a writeback on natural eviction under pressure can cause un-needed
writeback with weird issues on aliasing dcache configurations.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
ARC: [TB10x] Remove redundant abilis,simple-pinctrl mechanism 2013-05-15T04:42:03+00:00 Christian Ruppert christian.ruppert@abilis.com 2013-05-10T14:05:50+00:00 7d19273cd0408f8520539d5d6b1f695cd311b109 The TB10x platform port includes a custom mechanism using to set up default pin controller configurations using abilis,simple-default pin configurations of nodes compatible with abilis,simple-pinctrl. This mechanism is redundant with the Linux standard "default" pin configuration, see commit ab78029ecc347debbd737f06688d788bd9d60c1d "drivers/pinctrl: grab default handles from device core". This patch removes the TB10x custom mechanism in favour of the Linux standard. Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com> Reviewed-by: Stephen Warren <swarren@nvidia.com> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Vineet Gupta <vgupta@synopsys.com> 
The TB10x platform port includes a custom mechanism using to set up
default pin controller configurations using abilis,simple-default
pin configurations of nodes compatible with abilis,simple-pinctrl. This
mechanism is redundant with the Linux standard "default" pin
configuration, see commit ab78029ecc347debbd737f06688d788bd9d60c1d
"drivers/pinctrl: grab default handles from device core".
This patch removes the TB10x custom mechanism in favour of the Linux
standard.

Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Merge tag 'arc-v3.10-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc 2013-05-10T14:24:14+00:00 Linus Torvalds torvalds@linux-foundation.org 2013-05-10T14:24:14+00:00 6019958d146a4f127dae727a930f902c92531e6e Pull second set of arc arch updates from Vineet Gupta: "Aliasing VIPT dcache support for ARC I'm satisified with testing, specially with fuse which has historically given grief to VIPT arches (ARM/PARISC...)" * tag 'arc-v3.10-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: ARC: [TB10x] Remove GENERIC_GPIO ARC: [mm] Aliasing VIPT dcache support 4/4 ARC: [mm] Aliasing VIPT dcache support 3/4 ARC: [mm] Aliasing VIPT dcache support 2/4 ARC: [mm] Aliasing VIPT dcache support 1/4 ARC: [mm] refactor the core (i|d)cache line ops loops ARC: [mm] serious bug in vaddr based icache flush 
Pull second set of arc arch updates from Vineet Gupta:
 "Aliasing VIPT dcache support for ARC

  I'm satisified with testing, specially with fuse which has
  historically given grief to VIPT arches (ARM/PARISC...)"

* tag 'arc-v3.10-rc1-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: [TB10x] Remove GENERIC_GPIO
  ARC: [mm] Aliasing VIPT dcache support 4/4
  ARC: [mm] Aliasing VIPT dcache support 3/4
  ARC: [mm] Aliasing VIPT dcache support 2/4
  ARC: [mm] Aliasing VIPT dcache support 1/4
  ARC: [mm] refactor the core (i|d)cache line ops loops
  ARC: [mm] serious bug in vaddr based icache flush
ARC: [TB10x] Remove GENERIC_GPIO 2013-05-10T04:20:33+00:00 Vineet Gupta Vineet.Gupta1@synopsys.com 2013-04-17T12:07:31+00:00 e7d5bab5efb94a82d80cab3ad68c357ce73ea596 This tracks Alexandre Courbot's mainline GPIO rework Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Acked-by: Alexandre Courbot <acourbot@nvidia.com> 
This tracks Alexandre Courbot's mainline GPIO rework

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Merge tag 'arc-v3.10-rc1-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc 2013-05-09T21:36:27+00:00 Linus Torvalds torvalds@linux-foundation.org 2013-05-09T21:36:27+00:00 e30f4192456971623b40c97a027346b69457ef69 Pull ARC port updates from Vineet Gupta: "Support for two new platforms based on ARC700: - Abilis TB10x SoC [Chritisian/Pierrick] - Simulator only System-C Model [Mischa] ARC specific MM improvements: - Avoid full TLB flush (ASID increment) on munmap (even single page) - VIPT Cache Flushing improvements + Delayed dcache flush for non-aliasing dcache (big performance boost) + icache flush aliasing agnostic (no need to kill all possible aliases) Others: - Avoid needless rebuild of DTB files for every kernel build - Remove builtin cmdline as that is already provided by DeviceTree/bootargs - Fixing unaligned access emulation corner case - checkpatch fixes [Sachin] - Various fixlets [Noam] - Minor build failures/cleanups" * tag 'arc-v3.10-rc1-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: (35 commits) ARC: [mm] Lazy D-cache flush (non aliasing VIPT) ARC: [mm] micro-optimize page size icache invalidate ARC: [mm] remove the pessimistic all-alias-invalidate icache helpers ARC: [mm] consolidate icache/dcache sync code ARC: [mm] optimise icache flush for kernel mappings ARC: [mm] optimise icache flush for user mappings ARC: [mm] optimize needless full mm TLB flush on munmap ARC: Add support for nSIM OSCI System C model ARC: [TB10x] Adapt device tree to new compatible string ARC: [TB10x] Add support for TB10x platform ARC: [TB10x] Device tree of TB100 and TB101 Development Kits ARC: Prepare interrupt code for external controllers ARC: Allow embedded arc-intc to be properly placed in DT intc hierarchy ARC: [cmdline] Don't overwrite u-boot provided bootargs ARC: [cmdline] Remove CONFIG_CMDLINE ARC: [plat-arcfpga] defconfig update ARC: unaligned access emulation broken if callee-reg dest of LD/ST ARC: unaligned access emulation error handling consolidation ARC: Debug/crash-printing Improvements ARC: fix typo with clock speed ... 
Pull ARC port updates from Vineet Gupta:
 "Support for two new platforms based on ARC700:
   - Abilis TB10x SoC [Chritisian/Pierrick]
   - Simulator only System-C Model [Mischa]

  ARC specific MM improvements:
   - Avoid full TLB flush (ASID increment) on munmap (even single page)
   - VIPT Cache Flushing improvements
     + Delayed dcache flush for non-aliasing dcache (big performance boost)
     + icache flush aliasing agnostic (no need to kill all possible aliases)

  Others:
   - Avoid needless rebuild of DTB files for every kernel build
   - Remove builtin cmdline as that is already provided by DeviceTree/bootargs
   - Fixing unaligned access emulation corner case
   - checkpatch fixes [Sachin]
   - Various fixlets [Noam]
   - Minor build failures/cleanups"

* tag 'arc-v3.10-rc1-part1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc: (35 commits)
  ARC: [mm] Lazy D-cache flush (non aliasing VIPT)
  ARC: [mm] micro-optimize page size icache invalidate
  ARC: [mm] remove the pessimistic all-alias-invalidate icache helpers
  ARC: [mm] consolidate icache/dcache sync code
  ARC: [mm] optimise icache flush for kernel mappings
  ARC: [mm] optimise icache flush for user mappings
  ARC: [mm] optimize needless full mm TLB flush on munmap
  ARC: Add support for nSIM OSCI System C model
  ARC: [TB10x] Adapt device tree to new compatible string
  ARC: [TB10x] Add support for TB10x platform
  ARC: [TB10x] Device tree of TB100 and TB101 Development Kits
  ARC: Prepare interrupt code for external controllers
  ARC: Allow embedded arc-intc to be properly placed in DT intc hierarchy
  ARC: [cmdline] Don't overwrite u-boot provided bootargs
  ARC: [cmdline] Remove CONFIG_CMDLINE
  ARC: [plat-arcfpga] defconfig update
  ARC: unaligned access emulation broken if callee-reg dest of LD/ST
  ARC: unaligned access emulation error handling consolidation
  ARC: Debug/crash-printing Improvements
  ARC: fix typo with clock speed
  ...
ARC: [mm] Aliasing VIPT dcache support 4/4 2013-05-09T16:30:57+00:00 Vineet Gupta vgupta@synopsys.com 2013-05-09T13:50:43+00:00 5bba49f5397c012d873c73860ad7b50c526e613b Enforce congruency of userspace shared mappings Signed-off-by: Vineet Gupta <vgupta@synopsys.com> 
Enforce congruency of userspace shared mappings

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>