On 29 March 2014 02:53, Nicolas Pitre [off-list ref] wrote:

On Fri, 28 Mar 2014, Ard Biesheuvel wrote:

quoted

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.

This file is a rather bad choice for this pretty generic macro.  There
is nothing crypto specific about it, even if crypto might be the only
user for now.  This should live in include/asm/assembler.h, or a
separate file in that directory only if including <asm/asm-offsets.h>
from assembler.h is considered a nuisance.

True, there is nothing crypto specific about it,

@Catalin: would you object to adding this macro (and the #include
asm-offsets.h) to assembler.h?
Or would you prefer to have it in a separate file?

-- 
Ard.

quoted

Signed-off-by: Ard Biesheuvel <redacted>
---
 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@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


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