Re: [PATCH 1/9] x86, pkeys: add fault handling for PF_PK page fault bit

On 07/07/2016 07:40 AM, Mel Gorman wrote:

On Thu, Jul 07, 2016 at 05:47:20AM -0700, Dave Hansen wrote:

quoted

From: Dave Hansen <dave.hansen@linux.intel.com>
PF_PK means that a memory access violated the protection key
access restrictions.  It is unconditionally an access_error()
because the permissions set on the VMA don't matter (the PKRU
value overrides it), and we never "resolve" PK faults (like
how a COW can "resolve write fault).

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>

An access fault gets propgated as SEGV_PKUERR. What happens if glibc
does not recognise it?

It passes it through to the handler without any side-effects.  I don't
think it does anything differently with SEGV_* codes that it knows about
vs. unknown ones.  The only negative side-effect that I can think of is
that it won't have a nice error message for it.

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