Commit Graph

2 Commits

Author SHA1 Message Date
Yossi Yadgar 7c473fa398 test(libkernel): keep JIT shared memory descriptors in step across dup2 2026-10-12 21:59:19 +02:00
screamm 7d3dd554da feat(libkernel): implement the JIT shared memory calls
The three JIT shared memory exports (avvJ3J0H0EY, MR221Mwo0Pc,
YKT49TOLQWs) are absent imports of three homebrew titles that cannot
finish loading without them. Predicted next stops (registry order):

- VLC PPSA85300 after getdtablesize (idx 354):
  "FAIL: unresolved ELF import YKT49TOLQWs from libkernel.prx"
  (Map idx 452, Create idx 462)
- XPSemu PPSA97358 after tcsendbreak (idx 214):
  "FAIL: unresolved ELF import avvJ3J0H0EY from libkernel.prx"
  (Create idx 398, Map idx 399)
- RetroArch PPSA99169:
  "FAIL: unresolved ELF import avvJ3J0H0EY from libkernel.prx"
  (Create 476, Alias 477, Map 478)

XPSemu and VLC (ps5/compat/mmap.c, __wrap_mmap) create an object for
every anonymous PROT_EXEC mapping (QEMU's TCG buffer) and map it with
the same protection, falling back to flexible memory on any non-zero
return. RetroArch's eboot runs a probe: Create("ps5-platform-probe",
0x10000, 7, &fd), Alias(fd, 3, &alias), Map(fd, 5, &address), then logs
"jit create=0x%08x alias=0x%08x map=0x%08x".

Signatures from Orbital cc408367 tools/ida/db_types.json (name, len,
maxProt, fdOut; fd, maxProt, fdOut; fd, prot, startOut), matching
ps4sdk 4df9d001 include/sce/kernel.h, ps5-jar-loader 8034177e
LibKernel.java and the three titles' call sites. SharpProspero 5dfdb4b0
declares the alias as returning the descriptor; the RetroArch call site
passes an out pointer.

The object is a host anonymous file (memfd on Linux, a delete-on-close
temporary file mapped as a PAGE_EXECUTE_READWRITE section on Windows),
the alias a duplicate descriptor, and each map maps the whole object
through the direct memory placement path, so a write through one view
is visible through the others. Bad lengths and protection bits are
EINVAL, protection past the descriptor's maximum is EACCES (FreeBSD 11
vm_map_protect), unknown descriptors are EBADF; close, dup and dup2
keep the descriptor table in step. Unverified details are recorded in
TechnicalDebt.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
2026-10-12 21:59:19 +02:00