No description
372d0ff1d1
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> |
||
|---|---|---|
| 3rdparty | ||
| Documentation | ||
| payloads | ||
| src | ||
| util | ||
| .clang-format | ||
| .gitignore | ||
| .gitmodules | ||
| .gitreview | ||
| COPYING | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc | ||
| README | ||
| toolchain.inc | ||
------------------------------------------------------------------------------- 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.