4f62bb7cb1
To enable RELIABLE_STACKTRACE and LIVEPATCH on arm64, we need to substantially rework arm64's unwinding code. As part of this, we want to minimize the set of unwind interfaces we expose, and avoid open-coding of unwind logic outside of stacktrace.c. Currently, __get_wchan() walks the stack of a blocked task by calling start_backtrace() with the task's saved PC and FP values, and iterating unwind steps using unwind_frame(). The initialization is functionally equivalent to calling arch_stack_walk() with the blocked task, which will start with the task's saved PC and FP values. Currently __get_wchan() always performs an initial unwind step, which will stkip __switch_to(), but as this is now marked as a __sched function, this no longer needs special handling and will be skipped in the same way as other sched functions. Make __get_wchan() use arch_stack_walk(). This simplifies __get_wchan(), and in future will alow us to make unwind_frame() private to stacktrace.c. At the same time, we can simplify the try_get_task_stack() check and avoid the unnecessary `stack_page` variable. The change to the skipping logic means we may terminate one frame earlier than previously where there are an excessive number of sched functions in the trace, but this isn't seen in practice, and wchan is best-effort anyway, so this should not be a problem. Other than the above, there should be no functional change as a result of this patch. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> [Mark: rebase atop wchan changes, elaborate commit message, fix includes] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211129142849.3056714-6-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> |
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| arch | ||
| block | ||
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| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| .gitignore | ||
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| README | ||
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.