[Bug 219399] System panics after several hours of 14-threads-compilation orgies using poudriere on AMD Ryzen...

[bugzilla-noreply at freebsd.org]

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=219399

--- Comment #190 from rozhuk.im at gmail.com ---
    "On AMD, the tool discovered that some processors generate
    a #UD (undefined opcode) exception prior to completing the
    instruction fetch. Per AMD specifications, a #PF (page fault)
    exception occurring during an instruction fetch should
    supersede a #UD exception, but in the instruction search,
    which places the last bytes of the instruction on a non
    -
    executable page, some processors generate the #UD before the
    final bytes are moved off of the read/write page. It appears
    that AMD discovered this at around the same time as this
    research; the newest AMD Architecture Programmer’s
    Manual (March 2017) was updated to allow this situation."
From:
https://github.com/xoreaxeaxeax/sandsifter/blob/master/references/domas_breaking_the_x86_isa_wp.pdf
Tool: https://github.com/xoreaxeaxeax/sandsifter

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