[PATCH RFC 1/3] arm64/crypto: add shared macro to test for NEED_RESCHED

[Ard Biesheuvel]

This adds arch/arm64/crypto/preempt.h, currently containing just a single
asm macro definition 'b_if_no_resched' that will be shared between multiple
crypto algorithm implementations that need to test for preemption in the
inner loop.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
---
 arch/arm64/crypto/preempt.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 arch/arm64/crypto/preempt.h

diff --git a/arch/arm64/crypto/preempt.h b/arch/arm64/crypto/preempt.h
new file mode 100644
index 000000000000..94302d5b5ae9
--- /dev/null
+++ b/arch/arm64/crypto/preempt.h
@@ -0,0 +1,28 @@
+/*
+ * preempt.h - shared macros to check preempt state
+ *
+ * Copyright (C) 2014 Linaro Ltd <ard.biesheuvel at linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
+
+	/*
+	 * Branch to 'lb' but only if we have not been tagged for preemption.
+	 *
+	 * Expects current->thread_info in ti, or NULL if running in interrupt
+	 * context. reg is a scratch x register.
+	 */
+	.macro		b_if_no_resched, ti, reg, lb
+#if defined(CONFIG_PREEMPT) || defined(CONFIG_PREEMPT_VOLUNTARY)
+	cbz		\ti, \lb			// have thread_info?
+	ldr		\reg, [\ti, #TI_FLAGS]		// get flags
+	tbz	 	\reg, #TIF_NEED_RESCHED, \lb	// needs rescheduling?
+#else
+	b		\lb
+#endif
+	.endm
-- 
1.8.3.2