linux-kernel - [PATCH 2/4] sparc: fix accurate exception reporting in copy_{from_to}

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Message-ID: <20250826160312.2070-3-kernel@mkarcher.dialup.fu-berlin.de>
Date: Tue, 26 Aug 2025 18:03:04 +0200
From: Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>
To: linux-kernel@...r.kernel.org
Cc: sparclinux@...r.kernel.org,
	Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>,
	Andreas Larsson <andreas@...sler.com>,
	John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
	Anthony Yznaga <anthony.yznaga@...cle.com>
Subject: [PATCH 2/4] sparc: fix accurate exception reporting in copy_{from_to}_user for UltraSPARC III

Based on a finding by Anthony Yznaga that the UltraSPARC III copy_from_user
returns invalid values breaking other parts of the kernel in case of a
fault, while the generic implementation is correct.

Fixes: ee841d0aff64 ("sparc64: Convert U3copy_{from,to}_user to accurate exception reporting.")
Signed-off-by: Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>
---
 arch/sparc/lib/U3memcpy.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sparc/lib/U3memcpy.S b/arch/sparc/lib/U3memcpy.S
index 9248d59c734c..bace3a18f836 100644
--- a/arch/sparc/lib/U3memcpy.S
+++ b/arch/sparc/lib/U3memcpy.S
@@ -267,6 +267,7 @@ FUNC_NAME:	/* %o0=dst, %o1=src, %o2=len */
 	faligndata	%f10, %f12, %f26
 	EX_LD_FP(LOAD(ldd, %o1 + 0x040, %f0), U3_retl_o2)
 
+	and		%o2, 0x3f, %o2
 	subcc		GLOBAL_SPARE, 0x80, GLOBAL_SPARE
 	add		%o1, 0x40, %o1
 	bgu,pt		%XCC, 1f
@@ -336,7 +337,6 @@ FUNC_NAME:	/* %o0=dst, %o1=src, %o2=len */
 	 * Also notice how this code is careful not to perform a
 	 * load past the end of the src buffer.
 	 */
-	and		%o2, 0x3f, %o2
 	andcc		%o2, 0x38, %g2
 	be,pn		%XCC, 2f
 	 subcc		%g2, 0x8, %g2
-- 
2.50.1