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Julius Werner 372d0ff1d1 arch/arm64: mmu: Spot check TTB memory attributes
On ARM64, the memory type for accessing page table descriptors during
address translation is governed by the Translation Control Register
(TCR). When the MMU code accesses the same descriptors to change page
mappings, it uses the standard memory type rules (defined by the page
table descriptor for the page that contains that table, or 'device' if
the MMU is off).

Accessing the same memory with different memory types can lead to all
kinds of fun and hard to debug effects. In particular, if the TCR says
"cacheable" and the page tables say "uncacheable", page table walks will
pull stale entries into the cache and later mmu_config_range() calls
will write directly to memory, bypassing those cache lines. This means
the translations will not get updated even after a TLB flush, and later
cache flushes/evictions may write the stale entries back to memory.

Since page table configuration is currently always done from SoC code,
we can't generally ensure that the TTB is always mapped as cacheable.
We can however save developers of future SoCs a lot of headaches and
time by spot checking the attributes when the MMU gets enabled, as this
patch does.

BRANCH=None
BUG=None
TEST=Booted Oak. Manually tested get_pte() with a few addresses.

Change-Id: I3afd29dece848c4b5f759ce2f00ca2b7433374da
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: f3947f4bb0abf4466006d5e3a962bbcb8919b12d
Original-Change-Id: I1008883e5ed4cc37d30cae5777a60287d3d01af0
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/323862
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/13595
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
2016-02-10 09:39:23 +01:00
3rdparty 3rdparty/chromeec: Add Chrome EC firmware sources 2016-02-05 10:34:17 +01:00
Documentation Documentation: Add Quark EDK2 build instructions for Linux 2016-02-09 19:22:06 +01:00
payloads SeaBIOS: Disable serial console if serial is memory mapped 2016-02-09 22:31:12 +01:00
src arch/arm64: mmu: Spot check TTB memory attributes 2016-02-10 09:39:23 +01:00
util sandybridge: Set all native gfx-related options in northbridge code. 2016-02-09 22:35:09 +01:00
.clang-format Provide coreboot coding style formalisation file for clang-format 2015-11-10 00:49:03 +01:00
.gitignore .gitignore: add output files for various make targets 2015-11-24 22:35:34 +01:00
.gitmodules 3rdparty/chromeec: Add Chrome EC firmware sources 2016-02-05 10:34:17 +01:00
.gitreview
COPYING
MAINTAINERS MAINTAINERS: Designate Intel maintainers for FSP 1.0 Baytrail 2015-12-30 20:06:52 +01:00
Makefile build system: avoid setting HOSTCC to " gcc" 2016-02-02 14:35:11 +01:00
Makefile.inc build system: Add another post-processing step 2016-02-03 18:51:50 +01:00
README
toolchain.inc toolchain.inc: Update comments 2016-01-18 03:58:33 +01:00

README

-------------------------------------------------------------------------------
coreboot README
-------------------------------------------------------------------------------

coreboot is a Free Software project aimed at replacing the proprietary BIOS
(firmware) found in most computers.  coreboot performs a little bit of
hardware initialization and then executes additional boot logic, called a
payload.

With the separation of hardware initialization and later boot logic,
coreboot can scale from specialized applications that run directly
firmware, run operating systems in flash, load custom
bootloaders, or implement firmware standards, like PC BIOS services or
UEFI. This allows for systems to only include the features necessary
in the target application, reducing the amount of code and flash space
required.

coreboot was formerly known as LinuxBIOS.


Payloads
--------

After the basic initialization of the hardware has been performed, any
desired "payload" can be started by coreboot.

See http://www.coreboot.org/Payloads for a list of supported payloads.


Supported Hardware
------------------

coreboot supports a wide range of chipsets, devices, and mainboards.

For details please consult:

 * http://www.coreboot.org/Supported_Motherboards
 * http://www.coreboot.org/Supported_Chipsets_and_Devices


Build Requirements
------------------

 * make
 * gcc / g++
   Because Linux distribution compilers tend to use lots of patches. coreboot
   does lots of "unusual" things in its build system, some of which break due
   to those patches, sometimes by gcc aborting, sometimes - and that's worse -
   by generating broken object code.
   Two options: use our toolchain (eg. make crosstools-i386) or enable the
   ANY_TOOLCHAIN Kconfig option if you're feeling lucky (no support in this
   case).
 * iasl (for targets with ACPI support)

Optional:

 * doxygen (for generating/viewing documentation)
 * gdb (for better debugging facilities on some targets)
 * ncurses (for 'make menuconfig' and 'make nconfig')
 * flex and bison (for regenerating parsers)


Building coreboot
-----------------

Please consult http://www.coreboot.org/Build_HOWTO for details.


Testing coreboot Without Modifying Your Hardware
------------------------------------------------

If you want to test coreboot without any risks before you really decide
to use it on your hardware, you can use the QEMU system emulator to run
coreboot virtually in QEMU.

Please see http://www.coreboot.org/QEMU for details.


Website and Mailing List
------------------------

Further details on the project, a FAQ, many HOWTOs, news, development
guidelines and more can be found on the coreboot website:

  http://www.coreboot.org

You can contact us directly on the coreboot mailing list:

  http://www.coreboot.org/Mailinglist


Copyright and License
---------------------

The copyright on coreboot is owned by quite a large number of individual
developers and companies. Please check the individual source files for details.

coreboot is licensed under the terms of the GNU General Public License (GPL).
Some files are licensed under the "GPL (version 2, or any later version)",
and some files are licensed under the "GPL, version 2". For some parts, which
were derived from other projects, other (GPL-compatible) licenses may apply.
Please check the individual source files for details.

This makes the resulting coreboot images licensed under the GPL, version 2.