[v2] Disable 32-bit EL0 for Apple A10(X), T2

[PATCH v2 0/2] Disable 32-bit EL0 for Apple A10(X), T2

Nick Chan posted 2 patches 2 months, 3 weeks ago

Diff against v1 v1
Download series mbox

arch/arm64/include/asm/cputype.h | 42 +++++++++++++++++++++++---------
arch/arm64/kernel/cpufeature.c   | 27 ++++++++++++++++++++
2 files changed, 57 insertions(+), 12 deletions(-)

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[PATCH v2 0/2] Disable 32-bit EL0 for Apple A10(X), T2

Posted by Nick Chan 2 months, 3 weeks ago

Hi,

Apple's A10(X), T2 SoCs consists of pairs of performance and efficiency
cores. However, only one of the core types may be active at a given time,
and to software, it appears as logical cores that could switch between
P-mode and E-mode, depending on the p-state.

Unforunately, only the performance cores can execute 32-bit EL0. To
software, this results in logical cores that lose ability to execute
32-bit EL0 when the p-state is below a certain value.

Since these CPU cores only supported 16K pages, many AArch32
executables will not run anyways. This series disables 32-bit EL0 for
these SoCs.

Changes since v1:
  - Drop #ifdef CONFIG_ARCH_APPLE, the code to disable NV1 on M2 does
    not use it either.

  - Added comment to explain why 32-bit EL0 have to be disabled.

v1: https://lore.kernel.org/asahi/20240906171449.324354-1-towinchenmi@gmail.com

Nick Chan
---

Nick Chan (2):
  arm64: cputype: Add CPU types for A7-A11, T2 SoCs
  arm64: cpufeature: Pretend that Apple A10 family does not support
    32-bit EL0

 arch/arm64/include/asm/cputype.h | 42 +++++++++++++++++++++++---------
 arch/arm64/kernel/cpufeature.c   | 27 ++++++++++++++++++++
 2 files changed, 57 insertions(+), 12 deletions(-)


base-commit: 9aaeb87ce1e966169a57f53a02ba05b30880ffb8
-- 
2.46.0