sparc: fix accurate exception reporting in copy_{from_to}_user for Niagara

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[ Upstream commit 0b67c8fc10 ]

The referenced commit introduced exception handlers on user-space memory
references in copy_from_user and copy_to_user. These handlers return from
the respective function and calculate the remaining bytes left to copy
using the current register contents. This commit fixes a couple of bad
calculations and a broken epilogue in the exception handlers. This will
prevent crashes and ensure correct return values of copy_from_user and
copy_to_user in the faulting case. The behaviour of memcpy stays unchanged.

Fixes: 7ae3aaf53f ("sparc64: Convert NGcopy_{from,to}_user to accurate exception reporting.")
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> # on SPARC T4 with modified kernel to use Niagara 1 code
Tested-by: Magnus Lindholm <linmag7@gmail.com> # on Sun Fire T2000
Signed-off-by: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
Tested-by: Ethan Hawke <ehawk@ember.systems> # on Sun Fire T2000
Tested-by: Ken Link <iissmart@numberzero.org> # on Sun Fire T1000
Reviewed-by: Andreas Larsson <andreas@gaisler.com>
Link: https://lore.kernel.org/r/20250905-memcpy_series-v4-3-1ca72dda195b@mkarcher.dialup.fu-berlin.de
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

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Michael Karcher 2025-09-05 00:03:32 +02:00 • committed by Greg Kroah-Hartman

parent 1857cdca12

commit 37547d8e6e

1 changed files with 18 additions and 11 deletions

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arch/sparc/lib/NGmemcpy.S

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