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| author | Mark Rutland <mark.rutland@arm.com> | 2026-02-18 16:43:47 +0000 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2026-02-25 21:37:44 +0000 |
| commit | bfd9c931d19aa59fb8371d557774fa169b15db9a (patch) | |
| tree | 22bdb2a1274001810020deaa1af42ee6e3e7514f | |
| parent | 9d1a7c4a457eac8a7e07e1685f95e54fa551db5e (diff) | |
| download | lwn-bfd9c931d19aa59fb8371d557774fa169b15db9a.tar.gz lwn-bfd9c931d19aa59fb8371d557774fa169b15db9a.zip | |
arm64: tlb: Allow XZR argument to TLBI ops
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>
| -rw-r--r-- | arch/arm64/include/asm/tlbflush.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h index a2d65d7d6aae..bf1cc9949dc8 100644 --- a/arch/arm64/include/asm/tlbflush.h +++ b/arch/arm64/include/asm/tlbflush.h @@ -38,12 +38,12 @@ : : ) #define __TLBI_1(op, arg) asm (ARM64_ASM_PREAMBLE \ - "tlbi " #op ", %0\n" \ + "tlbi " #op ", %x0\n" \ ALTERNATIVE("nop\n nop", \ - "dsb ish\n tlbi " #op ", %0", \ + "dsb ish\n tlbi " #op ", %x0", \ ARM64_WORKAROUND_REPEAT_TLBI, \ CONFIG_ARM64_WORKAROUND_REPEAT_TLBI) \ - : : "r" (arg)) + : : "rZ" (arg)) #define __TLBI_N(op, arg, n, ...) __TLBI_##n(op, arg) |