[RFC PATCH v7 6/7] Restartable sequences: wire up x86 32/64 system call

Wire up the rseq system call on x86 32/64.

This provides an ABI improving the speed of a user-space getcpu
operation on x86 by removing the need to perform a function call, "lsl"
instruction, or system call on the fast path, as well as improving the
speed of user-space operations on per-cpu data.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: Russell King <redacted>
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Will Deacon <redacted>
CC: Thomas Gleixner <redacted>
CC: Paul Turner <redacted>
CC: Andrew Hunter <redacted>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Andi Kleen <redacted>
CC: Dave Watson <redacted>
CC: Chris Lameter <redacted>
CC: Ingo Molnar <mingo@redhat.com>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Ben Maurer <redacted>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: "Paul E. McKenney" <redacted>
CC: Josh Triplett <josh@joshtriplett.org>
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Boqun Feng <redacted>
CC: linux-api@vger.kernel.org
---
 arch/x86/entry/syscalls/syscall_32.tbl | 1 +
 arch/x86/entry/syscalls/syscall_64.tbl | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 4cddd17..15fb98c 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl

@@ -386,3 +386,4 @@
 377	i386	copy_file_range		sys_copy_file_range
 378	i386	preadv2			sys_preadv2			compat_sys_preadv2
 379	i386	pwritev2		sys_pwritev2			compat_sys_pwritev2
+380	i386	rseq			sys_rseq

diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 555263e..c7f3c7e 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl

@@ -335,6 +335,7 @@
 326	common	copy_file_range		sys_copy_file_range
 327	64	preadv2			sys_preadv2
 328	64	pwritev2		sys_pwritev2
+329	common	rseq			sys_rseq
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact

-- 
2.1.4