Commit b30dbf4d authored by Mark Brown's avatar Mark Brown Committed by Catalin Marinas
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arm64: Explicitly require that FPSIMD instructions do not trap 



We do not explicitly require that systems with FPSIMD support and EL3 have
disabled EL3 traps when the kernel is started, while it is unlikely that
systems will get this wrong for the sake of completeness let's spell it
out.

Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20210412151955.16078-3-broonie@kernel.org


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent ee61f36d

Documentation/arm64/booting.rst

+10 −0
Original line number Diff line number Diff line
@@ -277,6 +277,16 @@ Before jumping into the kernel, the following conditions must be met: 


    - SCR_EL3.FGTEn (bit 27) must be initialised to 0b1.



  For CPUs with Advanced SIMD and floating point support:



  - If EL3 is present:



    - CPTR_EL3.TFP (bit 10) must be initialised to 0b0.



  - If EL2 is present and the kernel is entered at EL1:



    - CPTR_EL2.TFP (bit 10) must be initialised to 0b0.



The requirements described above for CPU mode, caches, MMUs, architected

timers, coherency and system registers apply to all CPUs.  All CPUs must

enter the kernel in the same exception level.  Where the values documented