[PATCH v3 0/9] arm64: Work around for mismatched cache line size

Suzuki K Poulose suzuki.poulose at arm.com
Mon Sep 5 02:58:20 PDT 2016

This series adds a work around for systems with mismatched {I,D}-cache
line sizes. When a thread of execution gets migrated to a different CPU,
the cache line size it had cached could be larger than that of the new
CPU. This could cause data corruption issues. We work around this by

 - Dynamically patching the kernel to use the smallest line size on the
   system (from the CPU feature infrastructure)
 - Trapping the userspace access to CTR_EL0 (by clearing SCTLR_EL1.UCT) and
   emulating it with the system wide safe value of CTR.

The series also adds support for alternative code patching of adrp
instructions by adjusting the PC-relative address offset to reflect
the new PC.

The series has been tested on Juno with a hack to forced enabling
of the capability.

Applies on aarch64 for-next/core.
 The tree is avaiable at :
  git://linux-arm.org/linux-skp.git ctr-v3

Changes since V2:
 - Rebase to for-next/core which contains Ard's series for refactoring
   the arm64_ftr_reg [1]

Changes since V1:

 - Replace adr_adrp insn helper with seperate helpers for adr and adrp.
 - Add/use align_down() macro for adjusting the page address for adrp offsets.
 - Add comments for existing ISS field defintions.
 - Added a patch to disallow silent patching of unhandled pc relative
   instructions in alternative code patching.

[1] http://marc.info/?l=linux-arm-kernel&m=147263959504998&w=2

Suzuki K Poulose (9):
  arm64: Set the safe value for L1 icache policy
  arm64: Use consistent naming for errata handling
  arm64: Rearrange CPU errata workaround checks
  arm64: alternative: Disallow patching instructions using literals
  arm64: insn: Add helpers for adrp offsets
  arm64: alternative: Add support for patching adrp instructions
  arm64: Introduce raw_{d,i}cache_line_size
  arm64: Refactor sysinstr exception handling
  arm64: Work around systems with mismatched cache line sizes

 arch/arm64/include/asm/assembler.h  | 45 +++++++++++++++++--
 arch/arm64/include/asm/cpufeature.h | 13 +++---
 arch/arm64/include/asm/esr.h        | 84 +++++++++++++++++++++++++++++++----
 arch/arm64/include/asm/insn.h       | 11 ++++-
 arch/arm64/include/asm/sysreg.h     |  1 +
 arch/arm64/kernel/alternative.c     | 21 +++++++++
 arch/arm64/kernel/asm-offsets.c     |  2 +
 arch/arm64/kernel/cpu_errata.c      | 26 ++++++++++-
 arch/arm64/kernel/cpufeature.c      | 35 ++++++++++-----
 arch/arm64/kernel/cpuinfo.c         |  2 -
 arch/arm64/kernel/hibernate-asm.S   |  2 +-
 arch/arm64/kernel/insn.c            | 13 ++++++
 arch/arm64/kernel/relocate_kernel.S |  2 +-
 arch/arm64/kernel/smp.c             |  8 +++-
 arch/arm64/kernel/traps.c           | 87 ++++++++++++++++++++++++++-----------
 15 files changed, 287 insertions(+), 65 deletions(-)


More information about the linux-arm-kernel mailing list