linux-kernel - [PATCH AUTOSEL 4.9 05/12] parisc: Provide an extru

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Date:   Tue, 30 Nov 2021 09:53:33 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Helge Deller <deller@....de>,
        John David Anglin <dave.anglin@...l.net>,
        Sasha Levin <sashal@...nel.org>,
        James.Bottomley@...senPartnership.com, svens@...ckframe.org,
        linux-parisc@...r.kernel.org
Subject: [PATCH AUTOSEL 4.9 05/12] parisc: Provide an extru_safe() macro to extract unsigned bits

From: Helge Deller <deller@....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@...l.net>
Signed-off-by: Helge Deller <deller@....de>
Signed-off-by: Sasha Levin <sashal@...nel.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 eb83d65153b83..2272cbeb65f22 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