CVS commit: src/sys/arch/amd64

["Maxime Villard" <maxv%netbsd.org@localhost>]

Module Name:    src
Committed By:   maxv
Date:           Sat May 18 13:32:12 UTC 2019

Modified Files:
        src/sys/arch/amd64/amd64: amd64_trap.S locore.S
        src/sys/arch/amd64/include: frameasm.h

Log Message:
Two changes in the CPU mitigations:

 * Micro-optimize: put every mitigation in the same branch. This removes
   two branches in each exc/int return path, and removes all branches in
   the syscall return path.

 * Modify the SpectreV2 mitigation to be compatible with SpectreV4. I
   recently realized that both couldn't be enabled at the same time on
   Intel. This is because initially, when there was just SpectreV2, we
   could reset the whole IA32_SPEC_CTRL MSR. But then Intel added another
   bit in it for SpectreV4, so it isn't right to reset it entirely
   anymore. SSBD needs to stay.


To generate a diff of this commit:
cvs rdiff -u -r1.47 -r1.48 src/sys/arch/amd64/amd64/amd64_trap.S
cvs rdiff -u -r1.184 -r1.185 src/sys/arch/amd64/amd64/locore.S
cvs rdiff -u -r1.43 -r1.44 src/sys/arch/amd64/include/frameasm.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.