On 01/31/2018 03:19 PM, Florian Weimer wrote:
We are currently emitting additional multi-byte NOPs in Fedora 28, to
support the Intel CET feature in future processors. There are some
concerns that older CPUs treat these as UD. Pentium Pro and later
(i696) are supposed to be fine, but it would be better to double-check.
Would those who care about old CPUs please run this test?
/* endbr32 */
asm volatile (".byte 0xf3, 0x0f, 0x1e, 0xfb");
/* rdsspd %eax */
asm volatile (".byte 0xf3, 0x0f, 0x1e, 0xc8" ::: "eax");
The test passes if running the program does not segfault.
You can report he results here or on the redhat-rpm-config bug:
No segfaults for me, neither my PIII nor on my Atom N270.