[PATCH 0/7] Fix CLONE_SETTLS with clone3

[Amanieu d'Antras]

The clone3 syscall is currently broken when used with CLONE_SETTLS on all
architectures that don't have an implementation of copy_thread_tls. The old
copy_thread function handles CLONE_SETTLS by reading the new TLS value from
pt_regs containing the clone syscall parameters. Since clone3 passes the TLS
value in clone_args, this results in the TLS register being initialized to a
garbage value.

This patch series implements copy_thread_tls on all architectures that currently
define __ARCH_WANT_SYS_CLONE3 and adds a compile-time check to ensure that any
architecture that enables clone3 in the future also implements copy_thread_tls.

I have also included a minor fix for the arm64 uapi headers which caused
__NR_clone3 to be missing from the exported user headers.

I have only tested this on arm64, but the copy_thread_tls implementations for
the various architectures are fairly straightforward.

Amanieu d'Antras (7):
  arm64: Move __ARCH_WANT_SYS_CLONE3 definition to uapi headers
  arm64: Implement copy_thread_tls
  arm: Implement copy_thread_tls
  parisc: Implement copy_thread_tls
  riscv: Implement copy_thread_tls
  xtensa: Implement copy_thread_tls
  clone3: ensure copy_thread_tls is implemented

 arch/arm/Kconfig                     |  1 +
 arch/arm/kernel/process.c            |  6 +++---
 arch/arm64/Kconfig                   |  1 +
 arch/arm64/include/asm/unistd.h      |  1 -
 arch/arm64/include/uapi/asm/unistd.h |  1 +
 arch/arm64/kernel/process.c          | 10 +++++-----
 arch/parisc/Kconfig                  |  1 +
 arch/parisc/kernel/process.c         |  8 ++++----
 arch/riscv/Kconfig                   |  1 +
 arch/riscv/kernel/process.c          |  6 +++---
 arch/xtensa/Kconfig                  |  1 +
 arch/xtensa/kernel/process.c         |  8 ++++----
 kernel/fork.c                        | 10 ++++++++++
 13 files changed, 35 insertions(+), 20 deletions(-)

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2.24.1