Changes

==== Checkpoint ====

==== Checkpoint ====

We need to determine where the <code>struct rseq</code> is and dump its address length and signature.

CRIU locates the <code>struct rseq</code> instance and records its address, length, and signature using the <code>PTRACE_GET_RSEQ_CONFIGURATION</code> ptrace request (see <code>dump_thread_rseq</code>).

To achieve that we use special ptrace handle <code>PTRACE_GET_RSEQ_CONFIGURATION</code> (refer to the <code>dump_thread_rseq</code> function).

In addition, the instruction pointer is explicitly adjusted to point to the RSEQ abort handler.

 

We have to fix up IP to the abort handler.

==== Restore ====

==== Restore ====

We need to take data about the <code>struct rseq</code> from the image (see images/rseq.proto) and register it from the parasite context using the <code>rseq</code> syscall (take a look on <code>restore_rseq</code> in criu/pie/restorer.c)

During restore, CRIU reads data about the <code>struct rseq</code> state from the checkpoint image (<code>images/rseq.proto</code>) and re-register it from the restorer context using the <code>rseq</code> system call (see <code>restore_rseq</code> in <code>criu/pie/restorer.c</code>). No further action is required: the process resumes execution at the abort handler, outside of the RSEQ critical section.

 

No additional actions here. The process will be restored and will continue execution from the abort handler (not within the rseq CS!).

=== Executing non-abortable critical section ===

=== Executing inside non-abortable critical section ===

This is a relatively rare case, but it is fully supported by CRIU. When an RSEQ critical section is marked with the <code>RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL</code> flag, it is effectively non-abortable.

This is a relatively rare case, but it is fully supported by CRIU. When an RSEQ critical section is marked with the <code>RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL</code> flag, it is effectively non-abortable.

==== Restore ====

==== Restore ====

During restore, CRIU re-registers the <code>struct rseq</code> from the checkpoint image (<code>images/rseq.proto<code>) using the <code>rseq</code> system call from the restorer context (see <code>restore_rseq</code> in <code>criu/pie/restorer.c</code>). In addition, CRIU explicitly restores the <code>(struct rseq).rseq_cs</code> field using <code>PTRACE_POKEAREA</code> (see <code>restore_rseq_cs</code>) to reestablish the correct <code>rseq</code> execution context in the kernel.

During restore, CRIU re-registers the <code>struct rseq</code> from the checkpoint image (<code>images/rseq.proto</code>) using the <code>rseq</code> system call from the restorer context (see <code>restore_rseq</code> in <code>criu/pie/restorer.c</code>). In addition, CRIU explicitly restores the <code>(struct rseq).rseq_cs</code> field using <code>PTRACE_POKEAREA</code> (see <code>restore_rseq_cs</code>) to reestablish the correct <code>rseq</code> execution context in the kernel.

== TODO ==

== TODO ==