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.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
CC: Russell King <li...@arm.linux.org.uk>
CC: Catalin Marinas <catalin.mari...@arm.com>
CC: Will Deacon <will.dea...@arm.com>
CC: Thomas Gleixner <t...@linutronix.de>
CC: Paul Turner <p...@google.com>
CC: Andrew Hunter <a...@google.com>
CC: Peter Zijlstra <pet...@infradead.org>
CC: Andy Lutomirski <l...@amacapital.net>
CC: Andi Kleen <a...@firstfloor.org>
CC: Dave Watson <davejwat...@fb.com>
CC: Chris Lameter <c...@linux.com>
CC: Ingo Molnar <mi...@redhat.com>
CC: Ben Maurer <bmau...@fb.com>
CC: Steven Rostedt <rost...@goodmis.org>
CC: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
CC: Josh Triplett <j...@joshtriplett.org>
CC: Linus Torvalds <torva...@linux-foundation.org>
CC: Andrew Morton <a...@linux-foundation.org>
CC: Boqun Feng <boqun.f...@gmail.com>
CC: linux-...@vger.kernel.org
---
arch/arm/include/uapi/asm/unistd.h | 1 +
arch/arm/kernel/calls.S | 1 +
2 files changed, 2 insertions(+)
diff --git a/arch/arm/include/uapi/asm/unistd.h
b/arch/arm/include/uapi/asm/unistd.h
index 2cb9dc7..8f61c79 100644
--- a/arch/arm/include/uapi/asm/unistd.h
+++ b/arch/arm/include/uapi/asm/unistd.h
@@ -420,6 +420,7 @@
#define __NR_copy_file_range (__NR_SYSCALL_BASE+391)
#define __NR_preadv2 (__NR_SYSCALL_BASE+392)
#define __NR_pwritev2 (__NR_SYSCALL_BASE+393)
+#define __NR_rseq (__NR_SYSCALL_BASE+394)
/*
* The following SWIs are ARM private.
diff --git a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
index 703fa0f..0865c04 100644
--- a/arch/arm/kernel/calls.S
+++ b/arch/arm/kernel/calls.S
@@ -403,6 +403,7 @@
CALL(sys_copy_file_range)
CALL(sys_preadv2)
CALL(sys_pwritev2)
+ CALL(sys_rseq)
#ifndef syscalls_counted
.equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls
#define syscalls_counted
--
2.1.4
