[Crash-utility] Check _PAGE_PROTNONE bit in uvtop()

[Dave Anderson]

----- Original Message -----
> Currently, some of uvtop() functions on x86, x86_64 and ia64 lacks
> checking whether in pte _PAGE_PROTNONE bit is set or not. The flag is
> set to pte when specifying to the corresponding memory space PROT_NONE
> using mprotect(), and then _PAGE_PRESENT bit in the pte is unset in
> order to make hardware cause segmentation fault
> intensionally. Important is the fact that besides _PAGE_PRESENT set,
> _PAGE_PROTNONE indicates the page is present (not swapped out).
> 
> The architectures fixed are x86, x86_64 and ia64 except for Xen.
> 
> The patchset based on crash 5.1.4 consists of 5 patches, which are
> divided into the ones extending machine dependent data on x86 and
> x86_64, and the ones actually adding _PAGE_PROTNONE checking into each
> uvtop().
> 
> defs.h | 6 ++++--
> ia64.c | 6 +++---
> x86.c | 10 ++++++++--
> x86_64.c | 11 +++++++++--
> 4 files changed, 24 insertions(+), 9 deletions(-)

Daisuke,

I have seen this "unknown swap location" on rare occasions when running
"vm -p" on the "ntpd" daemon.  I had determined that the task had done an 
mprotect(PROT_NONE), but never got around to fixing it.  Thanks for 
addressing this.
  
Also, I will add a display of the new page_protnone field in both the 
x86_dump_machdep_table() and x86_64_dump_machdep_table() functions.  

Queued for the next release.

Thanks,
  Dave

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