Re: [RFC PATCH 00/23] aarch64-gnu port

[H.J. Lu]

On Wed, Jan 3, 2024 at 9:15 AM Sergey Bugaev <bugaevc@gmail.com> wrote:
>
> Hello!
>
> This is my work on the aarch64-gnu port, aka GNU/Hurd on 64-bit ARM.
>
> To build this, you need an aarch64-gnu toolchain (binutils, GCC, MIG),
> and GNU Mach headers for AArch64. I have posted the patches for
> binutils, GCC, and GNU Mach to the bug-hurd mailing list; no patches
> are required to build aarch64-gnu-mig.
>
> glibc fully builds and produces all the exepected libraries (including
> libmvec) and binaries. It can then be used to build other programs, in
> particular many core Hurd servers seem to build just fine.
>
> There is no AArch64 port of GNU Mach yet; I'm trying to get the ball
> rolling by making this port of glibc. I have only added some AArch64
> headers to GNU Mach, but no actual runnable code. My versions of
> <mach/aarch64/exception.h>, <mach/aarch64/thread_status.h> (and others)
> are by no means final, they are more of preliminary sketches of the API
> so I have something to port glibc against. If there are changes
> resulting from discussions and (hopefully) an eventual Mach AArch64
> port, we'll need to make corresponding changes to glibc.
>
> There not being a Mach build means that it's not currently possible to
> run or test any of this port on a real Mach. It is possible to run
> simple statically linked executables on Linux (or, I guess, other
> kernels which use ELF and similar enough ABI wrt how the arguments are
> placed on the stack) as long as you emulate the syscalls and RPCs in
> some way. I have done that, and verified that simple statically linked
> executables in the bootstrap configuration (i.e. without a Hurd exec
> server, with arguments already placed on the stack by Mach) start up
> fine.
>
> I have also done a quick i686-gnu build (to see if static-start.S or
> init-first.c changes have broken something), and a statically linked
> hello world seems to still work as expected.
>
> As usual, the disclaimer about me not knowing what I'm doing: I don't!
> I especially am not at all familiar with AArch64, even less so than with
> x86_64. I could have done something incredibly stupid; please do review!
>
> That being said, these changes seem smaller and a lot less radical than
> the x86_64 port patchset; they're mostly adding things rather than
> reworking them, so there is less of a chance to break the x86 targets.
> Evidently, we've done enough rewrokings and portability fixes (notably,
> various 64-bit fixes) during the x86_64 port to make it easier to add
> new ports. This port itself continues this trend somewhat too, with
> init-first.c now finally becoming only sysdeps/mach/hurd -specific, and
> HTL gaining support for TLS_DTV_AT_TP.
>
> As I said in the previous letter on bug-hurd, the hardware hardening
> features (BTI, MTE, PAC) are currently "not really supported", but I do
> want to support them in the future. I'm extremely interested in getting
> feedback or suggestions about these. For example: what should our API
> for controlling PAC keys look like, should we just allow userland to
> read and write all the keys? Are there, for example, any gotchas with
> BTI that we need to be aware of? Is it possible to start using PAC after
> initial start-up (once /dev/random becomes available, so PAC keys can be
> initialized) — how would we do that without crashing on e.g. ret
> pointers that have not been encrypted?
>
> Finally, a couple of words about the page size. My plan is for userland
> to not assume any static value of page size, and always query it
> dynamically, unlike on x86, even though GNU Mach will likely be compiled
> with some fixed value of page size; my understanding is this is also how
> things are done on GNU/Linux. To that end, I've tried to reduce the
> reliance on <mach/vm_param.h> and on EXEC_PAGESIZE being defined.
> Currently, Mach headers still define *something* named PAGE_SIZE
> unconditionally, causing __mach_init () to pick it up and use it instead
> of querying the page size dynamically. We should make sure this does not
> happen (i.e. <mach/vm_param.h> should not define PAGE_SIZE on AArch64),
> this is just something I haven't figured out a nice way to fix yet.
>
> Sergey
>
> P.S. I have not forgotten about my other unmerged patch series! (Most
> importantly, O_IGNORE_CTTY everywhere and the fcntl fortification.) I
> hope to find some time to hack on them, hopefully some time soon.
>
> Sergey Bugaev (23):
>   hurd: Add some missing includes
>   hurd: Declare _hurd_intr_rpc_msg* with protected visibility
>   Allow glibc to be compiled without EXEC_PAGESIZE
>   mach: Drop some unnecessary vm_param.h includes
>   hurd: Disable Prefer_MAP_32BIT_EXEC on non-x86_64 for now
>   mach: Drop SNARF_ARGS macro
>   hurd: Pass the data pointer to _hurd_stack_setup explicitly
>   hurd: Drop x86-specific assembly from init-first.c
>   hurd: Make init-first.c no longer x86-specific
>   hurd: Only init early static TLS if it's used to store stack or
>     pointer guards
>   hurd: Initializy _dl_pagesize early in static builds
>   aarch64: Make cpu-features definitions not Linux-specific
>   aarch64: Add dl-procinfo
>   aarch64: Allow building without kernel support for BTI
>   mach: Add a basic AArch64 port
>   hurd: Add a basic AArch64 port
>   hurd: Implement TLS on AArch64
>   hurd: Implement longjmp for AArch64
>   Add FPE_FLTIDO
>   hurd: Add an AArch64 signal implementation
>   htl: Implement some support for TLS_DTV_AT_TP
>   htl: Add an AArch64 implementation
>   hurd: Add expected aarch64-gnu abistlists
>
>  bits/siginfo-consts.h                         |    4 +-
>  elf/dl-support.c                              |    6 +-
>  elf/rtld.c                                    |    2 +
>  htl/pt-create.c                               |    2 +
>  hurd/hurdsig.c                                |    8 +-
>  libio/libioP.h                                |    2 +-
>  mach/Makefile                                 |    1 +
>  mach/lowlevellock.h                           |    1 +
>  mach/setup-thread.c                           |    1 -
>  .../sysv/linux => }/aarch64/cpu-features.h    |    0
>  sysdeps/aarch64/dl-bti.c                      |   10 +
>  sysdeps/aarch64/dl-procinfo.c                 |   59 +
>  sysdeps/aarch64/dl-procinfo.h                 |   38 +
>  sysdeps/aarch64/htl/Makefile                  |   20 +
>  sysdeps/aarch64/htl/bits/pthreadtypes-arch.h  |   36 +
>  sysdeps/aarch64/htl/machine-sp.h              |   29 +
>  sysdeps/aarch64/htl/pt-machdep.h              |   28 +
>  sysdeps/aarch64/htl/tcb-offsets.sym           |    5 +
>  .../sysv/linux => }/aarch64/libc-start.c      |    0
>  sysdeps/htl/dl-thread_gscope_wait.c           |   16 +-
>  sysdeps/hurd/include/hurd.h                   |    1 +
>  sysdeps/hurd/include/hurd/signal.h            |    1 +
>  sysdeps/mach/aarch64/bits/mach/param.h        |   24 +
>  sysdeps/mach/aarch64/cpu-features.c           |  109 +
>  sysdeps/mach/aarch64/sys/ucontext.h           |   73 +
>  sysdeps/mach/aarch64/sysdep.h                 |   45 +
>  sysdeps/mach/aarch64/thread_state.h           |   44 +
>  sysdeps/mach/configure                        |    1 +
>  sysdeps/mach/configure.ac                     |    1 +
>  sysdeps/mach/hurd/aarch64/Implies             |    3 +
>  sysdeps/mach/hurd/aarch64/Makefile            |   24 +
>  sysdeps/mach/hurd/aarch64/____longjmp_chk.S   |  173 ++
>  sysdeps/mach/hurd/aarch64/__longjmp.S         |  150 ++
>  sysdeps/mach/hurd/aarch64/bits/sigcontext.h   |   96 +
>  .../mach/hurd/aarch64/dl-tls-initialized.c    |   19 +
>  sysdeps/mach/hurd/aarch64/exc2signal.c        |  119 +
>  sysdeps/mach/hurd/aarch64/htl/pt-machdep.c    |   55 +
>  sysdeps/mach/hurd/aarch64/htl/pt-setup.c      |   80 +
>  sysdeps/mach/hurd/aarch64/intr-msg.h          |  123 +
>  sysdeps/mach/hurd/aarch64/ld.abilist          |   18 +
>  .../mach/hurd/aarch64/libBrokenLocale.abilist |    1 +
>  sysdeps/mach/hurd/aarch64/libanl.abilist      |    4 +
>  sysdeps/mach/hurd/aarch64/libc.abilist        | 2123 +++++++++++++++++
>  .../hurd/aarch64/libc_malloc_debug.abilist    |   26 +
>  sysdeps/mach/hurd/aarch64/libdl.abilist       |    0
>  sysdeps/mach/hurd/aarch64/libm.abilist        | 1030 ++++++++
>  sysdeps/mach/hurd/aarch64/libmvec.abilist     |   75 +
>  sysdeps/mach/hurd/aarch64/libpthread.abilist  |  165 ++
>  sysdeps/mach/hurd/aarch64/libresolv.abilist   |   55 +
>  sysdeps/mach/hurd/aarch64/librt.abilist       |   33 +
>  sysdeps/mach/hurd/aarch64/longjmp-ts.c        |   50 +
>  sysdeps/mach/hurd/aarch64/shlib-versions      |    2 +
>  sysdeps/mach/hurd/aarch64/signal-defines.sym  |   10 +
>  sysdeps/mach/hurd/aarch64/static-start.S      |   52 +
>  sysdeps/mach/hurd/aarch64/tls.h               |  206 ++
>  sysdeps/mach/hurd/aarch64/trampoline.c        |  327 +++
>  sysdeps/mach/hurd/aarch64/vm_param.h          |   24 +
>  sysdeps/mach/hurd/dl-sysdep.c                 |    3 +-
>  sysdeps/mach/hurd/htl/pt-sysdep.c             |    9 +
>  sysdeps/mach/hurd/i386/static-start.S         |    3 +
>  sysdeps/mach/hurd/{x86 => }/init-first.c      |   45 +-
>  sysdeps/mach/hurd/mig-reply.c                 |    1 +
>  sysdeps/mach/hurd/mmap.c                      |    2 +-
>  sysdeps/mach/hurd/x86_64/static-start.S       |    1 +
>  sysdeps/mach/sysdep.h                         |    7 -
>  sysdeps/mach/x86/sysdep.h                     |   14 -
>  66 files changed, 5639 insertions(+), 56 deletions(-)
>  rename sysdeps/{unix/sysv/linux => }/aarch64/cpu-features.h (100%)
>  create mode 100644 sysdeps/aarch64/dl-procinfo.c
>  create mode 100644 sysdeps/aarch64/dl-procinfo.h
>  create mode 100644 sysdeps/aarch64/htl/Makefile
>  create mode 100644 sysdeps/aarch64/htl/bits/pthreadtypes-arch.h
>  create mode 100644 sysdeps/aarch64/htl/machine-sp.h
>  create mode 100644 sysdeps/aarch64/htl/pt-machdep.h
>  create mode 100644 sysdeps/aarch64/htl/tcb-offsets.sym
>  rename sysdeps/{unix/sysv/linux => }/aarch64/libc-start.c (100%)
>  create mode 100644 sysdeps/mach/aarch64/bits/mach/param.h
>  create mode 100644 sysdeps/mach/aarch64/cpu-features.c
>  create mode 100644 sysdeps/mach/aarch64/sys/ucontext.h
>  create mode 100644 sysdeps/mach/aarch64/sysdep.h
>  create mode 100644 sysdeps/mach/aarch64/thread_state.h
>  create mode 100644 sysdeps/mach/hurd/aarch64/Implies
>  create mode 100644 sysdeps/mach/hurd/aarch64/Makefile
>  create mode 100644 sysdeps/mach/hurd/aarch64/____longjmp_chk.S
>  create mode 100644 sysdeps/mach/hurd/aarch64/__longjmp.S
>  create mode 100644 sysdeps/mach/hurd/aarch64/bits/sigcontext.h
>  create mode 100644 sysdeps/mach/hurd/aarch64/dl-tls-initialized.c
>  create mode 100644 sysdeps/mach/hurd/aarch64/exc2signal.c
>  create mode 100644 sysdeps/mach/hurd/aarch64/htl/pt-machdep.c
>  create mode 100644 sysdeps/mach/hurd/aarch64/htl/pt-setup.c
>  create mode 100644 sysdeps/mach/hurd/aarch64/intr-msg.h
>  create mode 100644 sysdeps/mach/hurd/aarch64/ld.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/libBrokenLocale.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/libanl.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/libc.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/libc_malloc_debug.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/libdl.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/libm.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/libmvec.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/libpthread.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/libresolv.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/librt.abilist
>  create mode 100644 sysdeps/mach/hurd/aarch64/longjmp-ts.c
>  create mode 100644 sysdeps/mach/hurd/aarch64/shlib-versions
>  create mode 100644 sysdeps/mach/hurd/aarch64/signal-defines.sym
>  create mode 100644 sysdeps/mach/hurd/aarch64/static-start.S
>  create mode 100644 sysdeps/mach/hurd/aarch64/tls.h
>  create mode 100644 sysdeps/mach/hurd/aarch64/trampoline.c
>  create mode 100644 sysdeps/mach/hurd/aarch64/vm_param.h
>  rename sysdeps/mach/hurd/{x86 => }/init-first.c (87%)
>
>

I think hurd maintainers can approve and check in all hurd specific
changes now even if they won't build.   The generic changes should
be looked at more closely so that they have no impacts on any
future Linux changes and future Linux changes won't be blocked
because of hurd.

-- 
H.J.