Linux 4.4 Continues Moving x86 Assembly Code Into C

The past few kernel cycles we've seen a fair amount of x86 Assembly changes with a goal of turning more Assembly into C code for the Linux kernel. That process has continued with the in-development Linux 4.4 kernel.

Ingo Molnar sent in the x86 ASM changes this morning for the Linux 4.4 merge window. He noted:

The main change in this cycle is another step in the big x86 system call interface rework by Andy Lutomirski, which moves most of the low level x86 entry code from assembly to C, for all syscall entries except native 64-bit system calls:

arch/x86/entry/entry_32.S | 182 +++----
arch/x86/entry/entry_64_compat.S | 547 +++++----------------

... our hope is that the final remaining step (converting native 64-bit system calls) will be less painful as all the previous steps, given that most of the legacies and quirks are concentrated around native 32-bit and compat environments.