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

Message

Nick Chan Sept. 6, 2024, 4:59 p.m. UTC

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.

Nick Chan

---

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

 arch/arm64/include/asm/cputype.h | 42 +++++++++++++++++++++++---------
 arch/arm64/kernel/cpufeature.c   | 25 +++++++++++++++++++
 2 files changed, 55 insertions(+), 12 deletions(-)


base-commit: 9aaeb87ce1e966169a57f53a02ba05b30880ffb8