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arm64: tlb: Allow XZR argument to TLBI ops

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commit bfd9c931d1 upstream.

The TLBI instruction accepts XZR as a register argument, and for TLBI
operations with a register argument, there is no functional difference
between using XZR or another GPR which contains zeroes. Operations
without a register argument are encoded as if XZR were used.

Allow the __TLBI_1() macro to use XZR when a register argument is all
zeroes.

Today this only results in a trivial code saving in
__do_compat_cache_op()'s workaround for Neoverse-N1 erratum #1542419. In
subsequent patches this pattern will be used more generally.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oupton@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[Mark: Backport to v5.15.y]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Mark Rutland 2026-06-11 14:47:05 +01:00 • committed by Greg Kroah-Hartman
commit e4e7fdfb85
1 changed files with 3 additions and 3 deletions
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