90f093fa8e
For userspace checkpoint and restore (C/R) a way of getting process state containing RSEQ configuration is needed. There are two ways this information is going to be used: - to re-enable RSEQ for threads which had it enabled before C/R - to detect if a thread was in a critical section during C/R Since C/R preserves TLS memory and addresses RSEQ ABI will be restored using the address registered before C/R. Detection whether the thread is in a critical section during C/R is needed to enforce behavior of RSEQ abort during C/R. Attaching with ptrace() before registers are dumped itself doesn't cause RSEQ abort. Restoring the instruction pointer within the critical section is problematic because rseq_cs may get cleared before the control is passed to the migrated application code leading to RSEQ invariants not being preserved. C/R code will use RSEQ ABI address to find the abort handler to which the instruction pointer needs to be set. To achieve above goals expose the RSEQ ABI address and the signature value with the new ptrace request PTRACE_GET_RSEQ_CONFIGURATION. This new ptrace request can also be used by debuggers so they are aware of stops within restartable sequences in progress. Signed-off-by: Piotr Figiel <figiel@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Michal Miroslaw <emmir@google.com> Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Link: https://lkml.kernel.org/r/20210226135156.1081606-1-figiel@google.com
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.