[PATCH 04/14] arm: Wire up restartable sequences system call

Wire up the rseq system call on 32-bit ARM.

This provides an ABI improving the speed of a user-space getcpu
operation on ARM by skipping the getcpu system call on the fast path, as
well as improving the speed of user-space operations on per-cpu data
compared to using load-linked/store-conditional.

TODO: wire up rseq_syscall() on return from system call. It is used with
CONFIG_DEBUG_RSEQ=y to ensure system calls are not issued within rseq critical
section

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: 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/arm/tools/syscall.tbl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
index 0bb0e9c6376c..fbc74b5fa3ed 100644
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl

@@ -412,3 +412,4 @@
 395	common	pkey_alloc		sys_pkey_alloc
 396	common	pkey_free		sys_pkey_free
 397	common	statx			sys_statx
+398	common	rseq			sys_rseq

-- 
2.11.0