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CVS commit: src/sys/arch/amd64/amd64

Module Name:    src
Committed By:   maxv
Date:           Wed Jan 10 20:51:11 UTC 2018

Modified Files:
        src/sys/arch/amd64/amd64: trap.c

Log Message:
Restrict the check: SMAP faults are always protection violations, as the
SDM points out, so make sure we have PGEX_P. This way NULL dereferences -
which are caused by an unmapped VA, and therefore are not protection
violations - don't take this branch, and don't display a misleading
"SMAP" in ddb.

Adding a PGEX_P check, or not, does not essentially change anything from
a security point of view, it's just a matter of what gets displayed when
a fatal fault comes in.

I didn't put PGEX_P until now, because initially when I wrote the SMAP
implementation Qemu did not always receive the fault if the PGEX_P check
was there, while a native i5 would. I'm unable to reproduce this issue
with a recent Qemu, so I assume I did something wrong when testing in the
first place.

To generate a diff of this commit:
cvs rdiff -u -r1.109 -r1.110 src/sys/arch/amd64/amd64/trap.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

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