Add x86_64-via-Apple-Rosetta translator support

[jserv]

This enables elfuse to load and run statically-linked x86_64-linux ELF binaries by hosting Apple's Rosetta Linux translator inside the guest. The translator lives in the primary buffer at a low GPA but is exposed at its statically-linked virtual address (0x800000000000) via a non-identity page-table mapping. This works around the macOS HVF 36-bit Stage-2 IPA cap on M1 while preserving the translator's link-time addresses, and broadens application coverage to pre-compiled x86_64 Linux software without paying box64's per-instruction translation tax.

Bootstrap path:

• src/core/rosetta.{c,h} loads the Rosetta ELF, places its image and the TTBR1 kbuf inside the primary buffer, and builds a binfmt_misc argv [ROSETTA_PATH, binary, original argv[1..]].
• src/core/guest.{c,h} gains guest_install_kbuf_user_alias to mirror the kbuf at KBUF_USER_VA under TTBR0 (for the translator's tagged pointer extraction that strips bits 63:48), and guest_install_va_pages to write 4 KiB L3 PTEs directly with the correct backing GPA.
• src/runtime/forkipc.c + fork-state.h bump IPC to v10 to propagate rosetta_guest_base, rosetta_va_base, rosetta_size, kbuf_gpa, ttbr1, and TTBR1_EL1 across fork.

Runtime gates:

• src/syscall/io.c traps the VZ ioctl trio (CHECK 0x80456125, CAPS 0x80806123, ACTIVATE 0x6124) and synthesises the responses the translator expects. The gate keys on g->is_rosetta plus an F_GETPATH match against the rosetta translator path so the trio triggers when rosetta opens /proc/self/exe.
• src/runtime/procemu.c redirects /proc/self/exe (open and readlink) to the rosetta path when active, matching the binfmt_misc convention that exposes the interpreter as the running image.
• src/core/rosetta.c implements the rosettad SCM_RIGHTS bridge. Socket interception in src/syscall/net.c forwards translation requests to a host-side handler thread that hashes the input binary, looks up a SHA-256-keyed AOT cache, and returns the translated artifact fd via SCM_RIGHTS.

High-VA mmap:

• src/syscall/mem.c adds sys_mmap_fixed_high_va for MAP_FIXED requests above guest_size. Each iteration detects freshness of the enclosing 2 MiB block before guest_map_va_range so split-inherited L3 entries in fresh blocks get zeroed (no gap-page perm inheritance) while pre-existing blocks are untouched (preserving earlier mmaps in the same block). guest_install_va_pages then installs L3 PTEs for the requested range with the correct backing GPA.
• Fail-path rollback narrowed to [addr, addr+length) so neighbor mappings survive a partial failure.

CLI surface:

• src/main.c adds --no-rosetta and ELFUSE_NO_ROSETTA=1 to opt out (default-on with ELF-header auto-detect).
• --gdb is refused for x86_64 guests; the current GDB stub serves the aarch64 view rosetta produces, not the original x86_64 state.
• A 'rosettad translate' subcommand rewrites argv to invoke the translator directly for AOT cache priming.

execve fidelity:

• src/syscall/exec.c clears proc_rosetta_active, resets HVF TCR_EL1 to TCR_EL1_VALUE, and clears TTBR1_EL1 on every image transition so a rosetta-to-aarch64 execve sees the right MMU state.

Known limits:

• Mid-process aarch64-to-x86_64 execve still rejects -LINUX_ENOEXEC; the re-bootstrap path is not yet wired (initial-load only).
• Dynamic x86_64 binaries fail at interpreter mmap with 'failed to mmap segment: 12'; static binaries work.
• ROSETTA_CAPS_BINARY_PATH_LEN is 42 bytes; longer paths truncate before rosettad lookup. Test scripts stage /tmp/elfuse-*/ symlink farms to stay inside the cap.

---

Summary by cubic

Add x86_64‑via‑Apple‑Rosetta support to run statically linked x86_64 Linux ELFs on macOS through elfuse. Includes high‑VA mapping, TTBR1 kbuf, runtime gates, CLI controls, resilient slab sizing, and a long‑path fd fallback; supports rosetta‑to‑rosetta execve.

• New Features

  • Load Rosetta at low GPA and expose it at 0x800000000000 via a non‑identity mapping; enable TTBR1 kbuf plus a TTBR0 user alias (new TCR_EL1_VALUE_KBUF).
  • High‑VA mmap above guest_size with safe 4 KiB L3 installs and narrow rollback; fixes split‑block aliasing.
  • Gate Rosetta’s VZ ioctl trio; redirect /proc/self/exe; add a rosettad SCM_RIGHTS bridge with SHA‑256 AOT cache and socket shims; add fuse_materialize_fd.
  • CLI: default‑on Rosetta with ELF auto‑detect; --no-rosetta and ELFUSE_NO_ROSETTA=1 to opt out; refuse --gdb for x86_64; add rosettad translate.
  • Mid‑process execve: support rosetta‑to‑rosetta re‑entry; keep correct TTBR0/TCR/TTBR1 state.
  • Resilient slab sizing: decouple VM IPA width from slab size and bisect on hv_vm_map failure (1 TiB → 256 GiB → 64 GiB); keep vm_ipa=48 for Rosetta; fork path inherits placement and kbuf (validator accepts ipa_bits up to 48).
  • Tests/tooling: new x86_64 static, Alpine, CLI, and failure‑mode suites plus a bench harness; CI‑safe busybox wget; futex canonical user‑VA check; improved per‑thread CPU clock IDs.

• Migration

  • Requires Apple Rosetta for Linux; preflight shows an install hint if missing.
  • Supported: static x86_64 ELFs (initial load and rosetta‑to‑rosetta execve). Not supported: dynamic x86_64, mid‑process aarch64→x86_64 execve, --gdb on x86_64.
  • Long binary paths are handled via a pre‑opened fd 3 (/proc/self/fd/3) fallback to bypass Rosetta’s 42‑byte caps field; short paths still work. Use --no-rosetta or ELFUSE_NO_ROSETTA=1 to disable.

^{Written for commit c12dd42. Summary will update on new commits. Review in cubic}

[jserv]

@devarajabc : Help validate on Apple M2 and M5 based machines
@Max042004 : Help validate on Apple M4 based machines

Steps:

make distclean
make test-rosetta-all

[devarajabc]

Still the same on the Mac M5:

FAIL rosetta-default: stderr did not contain requires the Rosetta Linux translator\|translate produced empty/missing output\|Translation failed, invalid path or invalid executable\|VMAllocationTracker\|Rosetta is only intended to run on Apple Silicon
22:16:23 ERROR src/core/guest.c:382: guest: hv_vm_map failed: -85377021
22:16:23 ERROR src/core/bootstrap.c:293: failed to initialize guest
make: *** [test-rosetta-cli] Error 1
devaraja@Chi-Kuans-MacBook-Air-3 elfuse % git log
commit c437f8e8af19c2eab9eaae92327caf5cda0a7804 (HEAD -> rosetta, origin/rosetta)

[jserv]

Still the same:

Always describe the hardware configurations properly.
See if commit 6beb553 helps.

[devarajabc]

All tests passed on the Mac M5.

devaraja@Chi-Kuans-MacBook-Air-3 elfuse % make test-rosetta-all
  GEN     build/dispatch.h
PASS rosetta-disabled-flag
PASS rosetta-disabled-env
PASS rosetta-gdb
PASS rosetta-default
   PASS: no-rosetta-flag (rc=1)
   PASS: no-rosetta-env (rc=1)
   PASS: gdb-x86_64 (rc=1)
   PASS: dynamic-x86_64-segment-mmap (rc=133)
   PASS: mid-process-execve-x86_64 (rc=126)

Results: 5 passed, 0 failed, 0 skipped (of 5)
elfuse:    /Users/devaraja/Work/elfuse/build/elfuse
fixtures:  /tmp/elfuse-r/bin -> /Users/devaraja/Work/elfuse/externals/test-fixtures/x86_64-musl/staticbin/bin
rosetta:   /Library/Apple/usr/libexec/oah/RosettaLinux/rosetta

   PASS: echo
   PASS: true
   PASS: false
   PASS: printenv
   PASS: expr-zero
   PASS: expr-mul
   PASS: basename
   PASS: dirname
   PASS: stat-self
   PASS: factor
   PASS: seq
   PASS: sha256sum
   PASS: md5sum
   PASS: uname-m
   PASS: date-utc
   PASS: id-u
   PASS: nproc
   PASS: env-execve-rejects (rc=126)

Results: 18 passed, 0 failed, 0 skipped (of 18)
elfuse:    /Users/devaraja/Work/elfuse/build/elfuse
fixtures:  /tmp/elfuse-ra/bin -> /Users/devaraja/Work/elfuse/externals/test-fixtures/x86_64-musl/staticbin/bin
rosetta:   /Library/Apple/usr/libexec/oah/RosettaLinux/rosetta

   PASS: cat-fruits-first-line
   PASS: wc-l-fruits
   PASS: wc-l-lines
   PASS: wc-c-lines
   PASS: ls-data
   PASS: stat-data
   PASS: find-by-name
   PASS: du-sk-data
   PASS: sha256-fruits
   PASS: sha256-lines-matches-host
   PASS: sha512-lines
   PASS: md5-fruits
   PASS: cksum-fruits
   PASS: sort-first
   PASS: sort-reverse-first
   PASS: pipe-sort-wc
   PASS: pipe-tr-uppercase
   PASS: pipe-cat-grep
   PASS: pipe-sed-subst
   PASS: pipe-awk-field
   PASS: head-n3
   PASS: tail-n3
   PASS: pipe-sort-uniq
   PASS: pipe-cut-field
   PASS: pipe-rev
   PASS: tac-reverse-first-line
   PASS: seq-1-5
   PASS: seq-step
   PASS: factor-prime
   PASS: factor-composite
   PASS: diff-identical
   PASS: diff-differs (rc=1)
   PASS: pipe-base64-decode

Results: 33 passed, 0 failed, 0 skipped (of 33)

[Max042004]

All test pass on M4