Re: [PATCH] pkeys: Introduce PKEY_ALLOC_SIGNALINHERIT and change signal semantics

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On Wed, May 2, 2018 at 2:13 PM Ram Pai <linuxram@xxxxxxxxxx> wrote:


> > Ram, would you please comment?

> on POWER the pkey behavior will remain the same at entry or at exit from
> the signal handler.  For eg:  if a key is read-disabled on entry into
> the signal handler, and gets read-enabled in the signal handler, than it
> will continue to be read-enabled on return from the signal handler.

> In other words, changes to key permissions persist across signal
> boundaries.

I don't know about POWER's ISA, but this is crappy behavior.  If a thread
temporarily grants itself access to a restrictive memory key and then gets
a signal, the signal handler should *not* have access to that key.
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