Call from 8-bytes aligned stack to functions that require 16-bytes stack alignment

Yuxuan Shui yshuiv7 at
Tue Sep 25 12:36:07 CEST 2018


L4Linux is compiled with -mpreferred-stack-boundary=3, but the "external
functions" it calls are usually compiled without this option, so defaults
to 16 bytes alignment. This causes potential unaligned memory access if the
compiler choose to generate instructions like movdqa.

QEMU without kvm seems to just let this pass, but with kvm enabled, this
could generate a GP.


Yuxuan Shui
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the l4-hackers mailing list