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From: Mark Brown <broonie@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Dave Martin <dave.martin@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	Mark Brown <broonie@kernel.org>
Subject: [PATCH v1 2/3] arm64: Explicitly require that FPSIMD instructions do not trap
Date: Mon, 12 Apr 2021 16:19:54 +0100	[thread overview]
Message-ID: <20210412151955.16078-3-broonie@kernel.org> (raw)
In-Reply-To: <20210412151955.16078-1-broonie@kernel.org>

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: Mark Brown <broonie@kernel.org>
---
 Documentation/arm64/booting.rst | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/arm64/booting.rst b/Documentation/arm64/booting.rst
index b21049ab6c69..4d0e323c0a35 100644
--- a/Documentation/arm64/booting.rst
+++ b/Documentation/arm64/booting.rst
@@ -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
-- 
2.20.1


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  parent reply	other threads:[~2021-04-12 15:24 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-12 15:19 [PATCH v1 0/3] arm64: Boot requirements clarifications Mark Brown
2021-04-12 15:19 ` [PATCH v1 1/3] arm64: Relax booting requirements for configuration of traps Mark Brown
2021-04-12 15:19 ` Mark Brown [this message]
2021-04-12 15:19 ` [PATCH v1 3/3] arm64: Explicitly document boot requirements for SVE Mark Brown
2021-04-30 17:55 ` [PATCH v1 0/3] arm64: Boot requirements clarifications Catalin Marinas

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