b2346a56f1
There is currently a fundamental flaw in the current cpu_info() implementation. It assumes that current stack is CONFIG_STACK_SIZE aligned. This assumption breaks down when performing SMM relocation. The first step in performing SMM relocation is changing the SMBASE. This is accomplished by installing the smmstub at 0x00038000, which is the default SMM entry point. The stub is configured to set up a new stack with the size of 1 KiB (CONFIG_SMM_STUB_STACK_SIZE), and an entry point of smm_do_relocation located in RAMSTAGE RAM. This means that when smm_do_relocation is executed, it is running in SMM with a different sized stack. When cpu_info() gets called it will be using CONFIG_STACK_SIZE to calculate the location of the cpu_info struct. This results in reading random memory. Since cpu_info() has to run in multiple environments, we can't use a compile time constant to locate the cpu_info struct. This CL introduces a new way of locating cpu_info. It uses a per-cpu segment descriptor that points to a per-cpu segment that is allocated on the stack. By using a segment descriptor to point to the per-cpu data, we no longer need to calculate the location of the cpu_info struct. This has the following advantages: * Stacks no longer need to be CONFIG_STACK_SIZE aligned. * Accessing an unconfigured segment will result in an exception. This ensures no one can call cpu_info() from an unsupported environment. * Segment selectors are cleared when entering SMM and restored when leaving SMM. * There is a 1:1 mapping between cpu and cpu_info. When using COOP_MULTITASKING, a new cpu_info is currently allocated at the top of each thread's stack. This no longer needs to happen. This CL guards most of the code with CONFIG(CPU_INFO_V2). I did this so reviewers can feel more comfortable knowing most of the CL is a no-op. I would eventually like to remove most of the guards though. This CL does not touch the LEGACY_SMP_INIT code path. I don't have any way of testing it. The %gs segment was chosen over the %fs segment because it's what the linux kernel uses for per-cpu data in x86_64 mode. BUG=b:194391185, b:179699789 TEST=Boot guybrush with CPU_INFO_V2 and verify BSP and APs have correct %gs segment. Verify cpu_info looks sane. Verify booting to the OS works correctly with COOP_MULTITASKING enabled. Signed-off-by: Raul E Rangel <rrangel@chromium.org> Change-Id: I79dce9597cb784acb39a96897fb3c2f2973bfd98 Reviewed-on: https://review.coreboot.org/c/coreboot/+/57627 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Eric Peers <epeers@google.com> Reviewed-by: Karthik Ramasubramanian <kramasub@google.com> |
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| configs | ||
| Documentation | ||
| LICENSES | ||
| payloads | ||
| spd | ||
| src | ||
| tests | ||
| util | ||
| .checkpatch.conf | ||
| .clang-format | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmodules | ||
| .gitreview | ||
| AUTHORS | ||
| COPYING | ||
| gnat.adc | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc | ||
| README.md | ||
| 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 https://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:
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_TOOLCHAINKconfig option if you're feeling lucky (no support in this case). - iasl (for targets with ACPI support)
- pkg-config
- libssl-dev (openssl)
Optional:
- doxygen (for generating/viewing documentation)
- gdb (for better debugging facilities on some targets)
- ncurses (for
make menuconfigandmake nconfig) - flex and bison (for regenerating parsers)
Building coreboot
Please consult https://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 https://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:
You can contact us directly on the coreboot mailing list:
https://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.