Re: [GIT PULL] ARM: support THREAD_INFO_IN_TASK

On Mon, 27 Sept 2021 at 17:06, Ard Biesheuvel [off-list ref] wrote:

The following changes since commit 6880fa6c56601bb8ed59df6c30fd390cc5f6dd8f:

  Linux 5.15-rc1 (2021-09-12 16:28:37 -0700)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git tags/pr-arm32-ti-in-task

for you to fetch changes up to 18ed1c01a7dd3d7c780b06a49124da237a4c1790:

  ARM: smp: Enable THREAD_INFO_IN_TASK (2021-09-27 16:54:02 +0200)

----------------------------------------------------------------
ARM: support THREAD_INFO_IN_TASK

Move thread_info off the stack and into the task struct, as is done by
many other architectures. This requires a method to find the task struct
of the task currently running on the CPU, which is provided in this case
by the user space TLS (Thread Local Storage) register. This implies that
the feature is only supported on CPUs that implement this register,
i.e., ARM v6k or later.

Kindly tested by Amit and reviewed by Linus. The first patch is against
the GCC plugins subsystem, but was reviewed by the maintainer and can be
taken through the ARM tree.

----------------------------------------------------------------

Ping?

Cc: Keith Packard <redacted>
Cc: Kees Cook <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Amit Daniel Kachhap <redacted>
Cc: Linus Walleij <redacted>

Ard Biesheuvel (4):
      gcc-plugins: arm-ssp: Prepare for THREAD_INFO_IN_TASK support
      ARM: smp: Free up the TLS register while running in the kernel
      ARM: smp: Store current pointer in TPIDRURO register if available
      ARM: smp: Enable THREAD_INFO_IN_TASK

Keith Packard (1):
      ARM: smp: Pass task to secondary_start_kernel

 arch/arm/Kconfig                              |  8 ++++-
 arch/arm/Makefile                             |  9 ++---
 arch/arm/include/asm/assembler.h              | 29 ++++++++++++++++
 arch/arm/include/asm/current.h                | 50 +++++++++++++++++++++++++++
 arch/arm/include/asm/smp.h                    |  3 +-
 arch/arm/include/asm/stackprotector.h         |  2 --
 arch/arm/include/asm/switch_to.h              | 16 +++++++++
 arch/arm/include/asm/thread_info.h            | 15 +++++---
 arch/arm/include/asm/tls.h                    | 10 ++++--
 arch/arm/kernel/asm-offsets.c                 |  6 ++--
 arch/arm/kernel/entry-armv.S                  |  5 +++
 arch/arm/kernel/entry-common.S                |  1 +
 arch/arm/kernel/entry-header.S                |  8 +++++
 arch/arm/kernel/head-common.S                 |  5 +++
 arch/arm/kernel/head-nommu.S                  |  1 +
 arch/arm/kernel/head.S                        |  5 +--
 arch/arm/kernel/process.c                     |  8 ++---
 arch/arm/kernel/smp.c                         | 13 +++++--
 arch/arm/mm/proc-macros.S                     |  3 +-
 scripts/gcc-plugins/arm_ssp_per_task_plugin.c | 27 ++++-----------
 20 files changed, 174 insertions(+), 50 deletions(-)
 create mode 100644 arch/arm/include/asm/current.h

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