C-SKY Architecture Gets Fix For Its Own Speculative Execution Bug In Linux 5.7

C-SKY is a Chinese 32-bit CPU architecture intended for low-power devices from media boxes / DVRs to printers and other consumer electronics. C-SKY has also worked its way into a ~$6 development board. With its updates for the Linux 5.7 kernel are various additions to this maturing architecture support along with a speculative execution fix.

The C-SKY architecture was added back in 2018 to the Linux kernel and has continued seeing updates.

C-SKY for this Linux 5.7 cycle is seeing support for KProbes and UProbes and lockdep / RSEQ / GCOV support. There are also a number of fixes.

The CPU speculative execution fix affecting C-SKY is in regards to a gap between the end size of memory and the border of 1GB. In some cases the CPU could speculatively execute into that gap in memory. In turn speculating into that gap could result in the system to crash. This speculative execution issue for C-SKY was discovered and fixed by Alibaba.

This and the other C-SKY changes for Linux 5.7 are outlined via this pull request.

Linux 5.7 is yet another busy cycle.