[RFC PATCH v2 00/13] nommu UML

[Hajime Tazaki]

This is a series of patches of nommu arch addition to UML.  It would
be nice to ask comments/opinions on this.

There are still several limitations/issues which we already found;
here is the list of those issues.

- prompt configured with /etc/profile is broken (variables are not
  expanded, ${HOSTNAME%%.*}:$PWD#)
- there are no mechanism implemented to cache for mapped memory of
  exec(2) thus, always read files from filesystem upon every exec,
  which makes slow on some benchmark (lmbench).

-- Hajime


RFC v2:
- base branch is now uml/linux.git instead of torvalds/linux.git.
- reorganize the patch series to clean up
- fixed various coding styles issues
- clean up exec code path [07/13]
- fixed the crash/SIGSEGV case on userspace programs [10/13]
- add seccomp filter to limit syscall caller address [06/13]
- detect fsgsbase availability with sigsetjmp/siglongjmp [08/13]
- removes unrelated changes
- removes unneeded ifndef CONFIG_MMU
- convert UML_CONFIG_MMU to CONFIG_MMU as using uml/linux.git
- proposed a patch of maple-tree issue (resolving a limitation in RFC v1)
  https://lore.kernel.org/linux-mm/20241108222834.3625217-1-thehajime@gmail.com/

RFC:
- https://lore.kernel.org/linux-um/cover.1729770373.git.thehajime@gmail.com/

Hajime Tazaki (13):
  fs: binfmt_elf_efpic: add architecture hook elf_arch_finalize_exec
  x86/um: nommu: elf loader for fdpic
  um: nommu: memory handling
  x86/um: nommu: syscall handling
  x86/um: nommu: syscall translation by zpoline
  um: nommu: prevent host syscalls from userspace by seccomp filter
  x86/um: nommu: process/thread handling
  um: nommu: configure fs register on host syscall invocation
  x86/um/vdso: nommu: vdso memory update
  x86/um: nommu: signal handling
  um: change machine name for uname output
  um: nommu: add documentation of nommu UML
  um: nommu: plug nommu code into build system

 Documentation/virt/uml/nommu-uml.rst    | 221 +++++++++++++++++++++++
 arch/um/Kconfig                         |  14 +-
 arch/um/Makefile                        |   6 +
 arch/um/configs/x86_64_nommu_defconfig  |  64 +++++++
 arch/um/include/asm/Kbuild              |   1 +
 arch/um/include/asm/futex.h             |   4 +
 arch/um/include/asm/mmu.h               |   8 +
 arch/um/include/asm/mmu_context.h       |  13 +-
 arch/um/include/asm/ptrace-generic.h    |   6 +
 arch/um/include/asm/tlbflush.h          |  22 +++
 arch/um/include/asm/uaccess.h           |   7 +-
 arch/um/include/shared/kern_util.h      |   3 +
 arch/um/include/shared/os.h             |  14 ++
 arch/um/kernel/Makefile                 |   3 +-
 arch/um/kernel/mem.c                    |  12 +-
 arch/um/kernel/physmem.c                |   6 +
 arch/um/kernel/process.c                |  33 +++-
 arch/um/kernel/skas/Makefile            |   4 +-
 arch/um/kernel/trap.c                   |  14 ++
 arch/um/kernel/um_arch.c                |   4 +
 arch/um/os-Linux/Makefile               |   5 +-
 arch/um/os-Linux/cpu.c                  |  50 ++++++
 arch/um/os-Linux/internal.h             |   5 +
 arch/um/os-Linux/main.c                 |   5 +
 arch/um/os-Linux/process.c              |  94 +++++++++-
 arch/um/os-Linux/signal.c               |  18 +-
 arch/um/os-Linux/skas/process.c         |   4 +
 arch/um/os-Linux/start_up.c             |   3 +
 arch/um/os-Linux/util.c                 |   3 +-
 arch/x86/um/Makefile                    |  18 ++
 arch/x86/um/asm/elf.h                   |  11 +-
 arch/x86/um/asm/module.h                |  24 ---
 arch/x86/um/asm/processor.h             |  12 ++
 arch/x86/um/do_syscall_64.c             | 108 ++++++++++++
 arch/x86/um/entry_64.S                  | 108 ++++++++++++
 arch/x86/um/shared/sysdep/syscalls_64.h |   6 +
 arch/x86/um/signal.c                    |  37 +++-
 arch/x86/um/syscalls_64.c               |  69 ++++++++
 arch/x86/um/vdso/um_vdso.c              |  20 +++
 arch/x86/um/vdso/vma.c                  |  14 ++
 arch/x86/um/zpoline.c                   | 223 ++++++++++++++++++++++++
 fs/Kconfig.binfmt                       |   2 +-
 fs/binfmt_elf_fdpic.c                   |  10 ++
 43 files changed, 1262 insertions(+), 46 deletions(-)
 create mode 100644 Documentation/virt/uml/nommu-uml.rst
 create mode 100644 arch/um/configs/x86_64_nommu_defconfig
 create mode 100644 arch/um/os-Linux/cpu.c
 delete mode 100644 arch/x86/um/asm/module.h
 create mode 100644 arch/x86/um/do_syscall_64.c
 create mode 100644 arch/x86/um/entry_64.S
 create mode 100644 arch/x86/um/zpoline.c

-- 
2.43.0