x86/entry/64: Migrate the 64-bit syscall slow path to C
authorAndy Lutomirski <luto@kernel.org>
Thu, 28 Jan 2016 23:11:28 +0000 (15:11 -0800)
committerIngo Molnar <mingo@kernel.org>
Fri, 29 Jan 2016 08:46:38 +0000 (09:46 +0100)
commit1e423bff959e48166f5b7efca01fdb0dbdf05846
tree9bfdea82ed42920fbc2806e51a9a7281324db888
parent24d978b76ffd20ecff8a8d1c21b16fe740f8b119
x86/entry/64: Migrate the 64-bit syscall slow path to C

This is more complicated than the 32-bit and compat cases
because it preserves an asm fast path for the case where the
callee-saved regs aren't needed in pt_regs and no entry or exit
work needs to be done.

This appears to slow down fastpath syscalls by no more than one
cycle on my Skylake laptop.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/ce2335a4d42dc164b24132ee5e8c7716061f947b.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/entry/common.c
arch/x86/entry/entry_64.S