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Subject: [Bug 219399] System panics after several hours of
 14-threads-compilation orgies using poudriere on AMD Ryzen...
Date: Mon, 07 Aug 2017 23:23:43 +0000
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D219399

--- Comment #216 from Don Lewis <truckman@FreeBSD.org> ---
LOL ...=20

Prior to the fix in r321899, the top page of user memory for amd64 executab=
les
was used by the shared page, the contents of which are controlled by the
kernel.  This page does contain the signal trampoline, which contains a SYS=
CALL
instruction, which made me very suspicious based on my experiments with
executing code in this page.  The SYSCALL instruction is located well away =
from
the top of the page, though.  I may try playing with this instruction if I =
ever
have the time.

After r321899, the shared page is moved lower and we don't allow the top pa=
ge
to be used at all, similar to Linux.  CloudABI64 got a similar fix.

--=20
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