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>,
linux-arm-kernel@lists.infradead.org,
Mark Brown <broonie@kernel.org>
Subject: [PATCH v2 1/4] arm64: Document requirements for fine grained traps at boot
Date: Thu, 1 Apr 2021 19:09:39 +0100 [thread overview]
Message-ID: <20210401180942.35815-2-broonie@kernel.org> (raw)
In-Reply-To: <20210401180942.35815-1-broonie@kernel.org>
The arm64 FEAT_FGT extension introduces a set of traps to EL2 for accesses
to small sets of registers and instructions from EL1 and EL0, access to
which is controlled by EL3. Require access to it so that it is
available to us in future and so that we can ensure these traps are
disabled during boot.
Signed-off-by: Mark Brown <broonie@kernel.org>
---
Documentation/arm64/booting.rst | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/Documentation/arm64/booting.rst b/Documentation/arm64/booting.rst
index 7552dbc1cc54..92ec0bea1af5 100644
--- a/Documentation/arm64/booting.rst
+++ b/Documentation/arm64/booting.rst
@@ -270,6 +270,12 @@ Before jumping into the kernel, the following conditions must be met:
having 0b1 set for the corresponding bit for each of the auxiliary
counters present.
+ For CPUs with the Fine Grained Traps (FEAT_FGT) extension present:
+
+ - If EL3 is present and the kernel is entered at EL2:
+
+ - SCR_EL3.FGTEn (bit 27) must be initialised to 0b1.
+
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.
--
2.20.1
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next prev parent reply other threads:[~2021-04-01 18:13 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 18:09 [PATCH v2 0/4] arm64: Booting clarifications and fine grained traps setup Mark Brown
2021-04-01 18:09 ` Mark Brown [this message]
2021-04-08 17:00 ` [PATCH v2 1/4] arm64: Document requirements for fine grained traps at boot Marc Zyngier
2021-04-01 18:09 ` [PATCH v2 2/4] arm64: Disable fine grained traps on boot Mark Brown
2021-04-08 17:00 ` Marc Zyngier
2021-04-01 18:09 ` [PATCH v2 3/4] arm64: Require that system registers at all visible ELs be initialized Mark Brown
2021-04-08 17:02 ` Marc Zyngier
2021-04-01 18:09 ` [PATCH v2 4/4] arm64: Document values for system registers on boot Mark Brown
2021-04-08 17:16 ` Marc Zyngier
2021-04-08 17:33 ` Mark Brown
2021-04-08 17:59 ` (subset) [PATCH v2 0/4] arm64: Booting clarifications and fine grained traps setup Catalin Marinas
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