[RFC PATCH v6 3/5] Thread-local ABI: wire up ARM system call

[Mathieu Desnoyers <mathieu.desnoyers@efficios.com>]

Wire up the thread-local ABI system call on 32-bit ARM.

This provides an ABI improving the speed of a getcpu operation
on ARM by skipping the getcpu system call on the fast path.

The thread-local ABI can be extended to add features in the future.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: Russell King <linux@arm.linux.org.uk>
CC: Catalin Marinas <catalin.marinas@arm.com>
CC: Will Deacon <will.deacon@arm.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Paul Turner <pjt@google.com>
CC: Andrew Hunter <ahh@google.com>
CC: Peter Zijlstra <peterz@infradead.org>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Andi Kleen <andi@firstfloor.org>
CC: Dave Watson <davejwatson@fb.com>
CC: Chris Lameter <cl@linux.com>
CC: Ingo Molnar <mingo@redhat.com>
CC: Ben Maurer <bmaurer@fb.com>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
CC: Josh Triplett <josh@joshtriplett.org>
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Boqun Feng <boqun.feng@gmail.com>
CC: linux-api@vger.kernel.org
---
 arch/arm/include/asm/unistd.h      | 2 +-
 arch/arm/include/uapi/asm/unistd.h | 1 +
 arch/arm/kernel/calls.S            | 3 ++-
 3 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/unistd.h b/arch/arm/include/asm/unistd.h
index 7b84657..194b699 100644
--- a/arch/arm/include/asm/unistd.h
+++ b/arch/arm/include/asm/unistd.h
@@ -19,7 +19,7 @@
  * This may need to be greater than __NR_last_syscall+1 in order to
  * account for the padding in the syscall table
  */
-#define __NR_syscalls  (392)
+#define __NR_syscalls  (396)
 
 #define __ARCH_WANT_STAT64
 #define __ARCH_WANT_SYS_GETHOSTNAME
diff --git a/arch/arm/include/uapi/asm/unistd.h b/arch/arm/include/uapi/asm/unistd.h
index 5dd2528..aaa9221 100644
--- a/arch/arm/include/uapi/asm/unistd.h
+++ b/arch/arm/include/uapi/asm/unistd.h
@@ -418,6 +418,7 @@
 #define __NR_membarrier			(__NR_SYSCALL_BASE+389)
 #define __NR_mlock2			(__NR_SYSCALL_BASE+390)
 #define __NR_copy_file_range		(__NR_SYSCALL_BASE+391)
+#define __NR_thread_local_abi		(__NR_SYSCALL_BASE+392)
 
 /*
  * The following SWIs are ARM private.
diff --git a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
index dfc7cd6..d6a0fe9 100644
--- a/arch/arm/kernel/calls.S
+++ b/arch/arm/kernel/calls.S
@@ -399,8 +399,9 @@
 		CALL(sys_execveat)
 		CALL(sys_userfaultfd)
 		CALL(sys_membarrier)
-		CALL(sys_mlock2)
+/* 390 */	CALL(sys_mlock2)
 		CALL(sys_copy_file_range)
+		CALL(sys_thread_local_abi)
 #ifndef syscalls_counted
 .equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls
 #define syscalls_counted
-- 
2.1.4