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[0/4] efi: Clean up runtime wrapper and wire it up for PRM

Message ID 20230804160359.228901-1-ardb@kernel.org (mailing list archive)
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Series efi: Clean up runtime wrapper and wire it up for PRM | expand

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Ard Biesheuvel Aug. 4, 2023, 4:03 p.m. UTC 
ACPI PRM uses the EFI runtime services infrastructure, but currently, it
issues the firmware calls directly, instead of going through the
wrappers and handing off the call to the EFI workqueue.

Given that ACPI PRM is used for vendor code rather than core EFI runtime
services, it would be nice if these calls get sandboxed in the same way
as EFI runtime services calls are. This ensures that any faults
occurring in the firmware are handled gracefully and don't bring down
the kernel.

Another reason for using the work queue is the fact that on some
platforms, the EFI memory regions are remapping into the lower address
space, and this means that sampling the instruction pointer in a perf
interrupt may cause confusion about whether the task is running in user
space or in the firmware.

So let's move the ACPI PRM calls into the EFI runtime wrapper
infrastructure. Before that, let's clean it up a bit.

Ard Biesheuvel (4):
  efi/runtime-wrappers: Use type safe encapsulation of call arguments
  efi/runtime-wrapper: Move workqueue manipulation out of line
  efi/runtime-wrappers: Remove duplicated macro for service returning
    void
  acpi/prmt: Use EFI runtime sandbox to invoke PRM handlers

 drivers/acpi/prmt.c                     |   8 +-
 drivers/firmware/efi/runtime-wrappers.c | 201 +++++++++++---------
 include/linux/efi.h                     | 110 ++++++++---
 3 files changed, 198 insertions(+), 121 deletions(-)