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Subject[PATCH AUTOSEL 4.4 4/9] parisc: Provide an extru_safe() macro to extract unsigned bits
Date
From: Helge Deller <deller@gmx.de>

[ Upstream commit 169d1a4a2adb2c246396c56aa2f9eec3868546f1 ]

The extru instruction leaves the most significant 32 bits of the
target register in an undefined state on PA 2.0 systems.
Provide a macro to safely use extru on 32- and 64-bit machines.

Suggested-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/parisc/include/asm/assembly.h | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/arch/parisc/include/asm/assembly.h b/arch/parisc/include/asm/assembly.h
index b3069fd83468c..a6784745c571e 100644
--- a/arch/parisc/include/asm/assembly.h
+++ b/arch/parisc/include/asm/assembly.h
@@ -153,6 +153,17 @@
extrd,u \r, 63-(\sa), 64-(\sa), \t
.endm

+ /* Extract unsigned for 32- and 64-bit
+ * The extru instruction leaves the most significant 32 bits of the
+ * target register in an undefined state on PA 2.0 systems. */
+ .macro extru_safe r, p, len, t
+#ifdef CONFIG_64BIT
+ extrd,u \r, 32+(\p), \len, \t
+#else
+ extru \r, \p, \len, \t
+#endif
+ .endm
+
/* load 32-bit 'value' into 'reg' compensating for the ldil
* sign-extension when running in wide mode.
* WARNING!! neither 'value' nor 'reg' can be expressions
--
2.33.0
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