On Thu, Mar 11, 2021 at 09:51:56AM -0500, Mathieu Desnoyers wrote: > > > ----- On Feb 26, 2021, at 8:51 AM, Piotr Figiel figiel@xxxxxxxxxx wrote: > > > 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@xxxxxxxxxx> > > Reviewed-by: Michal Miroslaw <emmir@xxxxxxxxxx> > > Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> How do we route this? Do I stick this in tip/sched/core as being an rseq patch?
