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

Message

Nick Chan Sept. 6, 2024, 5:13 p.m. UTC

Resending as the cc list was messed up.

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