svn commit: r322763 - head/lib/libc/amd64/sys

[Shawn Webb]

On Mon, Aug 21, 2017 at 05:39:13PM +0000, Konstantin Belousov wrote:
> Author: kib
> Date: Mon Aug 21 17:39:12 2017
> New Revision: 322763
> URL: https://svnweb.freebsd.org/changeset/base/322763
> 
> Log:
>   Optimize libc to get and set TLS using the RDFSBASE and RDGSBASE
>   instructions, if supported both by CPU and kernel.
>   
>   Reviewed by:	jhb (previous version)
>   Tested by:	pho (previous version)
>   Sponsored by:	The FreeBSD Foundation
>   MFC after:	3 weeks
>   Differential revision:	https://reviews.freebsd.org/D12023
> 
> Added:
>   head/lib/libc/amd64/sys/amd64_detect_rdfsgsbase.c   (contents, props changed)
>   head/lib/libc/amd64/sys/amd64_detect_rdfsgsbase.h   (contents, props changed)
> Modified:
>   head/lib/libc/amd64/sys/Makefile.inc
>   head/lib/libc/amd64/sys/amd64_get_fsbase.c
>   head/lib/libc/amd64/sys/amd64_get_gsbase.c
>   head/lib/libc/amd64/sys/amd64_set_fsbase.c
>   head/lib/libc/amd64/sys/amd64_set_gsbase.c

Hey kib,

This commit breaks booting in UEFI mode under bhyve. The VM gets stuck
when the kernel launches /sbin/init. Here's a screenshot of a verbose
boot at a recent HEAD: https://imgur.com/PiJhfll

Note, the screenshot depicts HardenedBSD, not FreeBSD. Another user
attempting to boot a recent vanilla FreeBSD 12-CURRENT/amd64 snapshot
reported to me the same behavior, though, so the issue is certainly not
specific to HardenedBSD.

Reverting just this commit enabled booting in a bhyve VM again.

Thanks,

-- 
Shawn Webb
Cofounder and Security Engineer
HardenedBSD

GPG Key ID:          0x6A84658F52456EEE
GPG Key Fingerprint: 2ABA B6BD EF6A F486 BE89  3D9E 6A84 658F 5245 6EEE
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