d4a8e98621
Currently we set up the paca after parsing the device tree for CPU features. Prior to that, r13 contains random data, which means there is random data in r13 while we're running the generic dt parsing code. This random data varies depending on whether we boot through a vmlinux or a zImage: for the vmlinux case it's usually around zero, but for zImages we see random values like 912a72603d420015. This is poor practice, and can also lead to difficult-to-debug crashes. For example, when kcov is enabled, the kcov instrumentation attempts to read preempt_count out of the current task, which goes via the paca. This then crashes in the zImage case. Similarly stack protector can cause crashes if r13 is bogus, by reading from the stack canary in the paca. To resolve this: - move the paca setup to before the CPU feature parsing. - because we no longer have access to CPU feature flags in paca setup, change the HV feature test in the paca setup path to consider the actual value of the MSR rather than the CPU feature. Translations get switched on once we leave early_setup, so I think we'd already catch any other cases where the paca or task aren't set up. Boot tested on a P9 guest and host. Fixes: |
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.