sub_822FE040 is a fully unrolled registration: 1023 slots filled with a default,
then 57 explicit writes, of which 48 are real handlers and nine are a shared
accept-and-discard stub. Return convention is nonzero = consumed, 0 = retry,
which is how the interpreter waits for a named unit to exist.
Opcode 995 is the ONLY handler touching the phase mirror [*(0x828F35F8)+236] --
the sole read and sole write in the table -- independently confirming why polling
that mirror saw nothing during phase 1. And no handler spawns or despawns a unit:
256 is the strongest deploy candidate but is unconfirmed because the message ids
are write-only in this image.
WITHDRAWN, verified wrong: I had recorded the writes to '+20' in sub_8226E7D8 /
sub_8226E930 as block initialisations by container constructors. At
0x8226E86C-0x8226E8E0 they do li r3,28 / bl 0x8230C160 then
lis r10,0xAB03 / ori r7,r10,0xE4BA / stw r7,4(r3): they build an INTERPRETER
COMMAND RECORD for opcode 996 and push it, i.e. AddSelector and RemoveSelector,
with a 32-entry cap. The stw to 20(r3) is the command record's +20, a different
object. Wrong twice: not constructors, and not that container.
Also flags that sub_8230C398 -- gated on *(0x82899CE0) == 16 at both call sites
-- looks like Stage 16's script compiled in C++, which 'debug defaults' does not
survive given the .ssb loader explicitly refuses mission 16.
The watchpoint plus Canary's source settle it. At the write, the guest context
(rsi, per x64_emitter.cc:881) holds 0x8226EAE0, inside sub_8226EAB8. That
function is a generic list-node insert: it reads the count at 8(r30), guards
against 0x3FFFFFFF overflow, does addi r11,r11,1 / stw r11,8(r30), then links the
node. It has 16 callers, so it is a shared container helper.
That explains why two static searches missed it. The trigger container at
phase+272 EMBEDS an inner list object at +12 -- which is why the push does
'addi r31, r30, 12' -- and the inner object keeps its count at its own +8. So
272 + 12 + 8 = 292 = the watched word, and the instruction is stw r11, 8(r30)
with r30 = phase+284. Searching for 'stw rN, 20(rM)' could never have found it.
Also resolves the earlier open item on +12: it is the embedded list object, not
a list head pointer, which is why it read 0x000A0009 instead of an address.
Method note kept: the static hunt assumed the field's offset in the OUTER object
would appear in the writing instruction. A watchpoint is indifferent to the
addressing form, which is why it was the right tool after two failed offset
searches.
From Canary's own source (x64_emitter.cc:881) GetContextReg() returns rsi, so at
any JIT instruction %rsi is the PPCContext* -- which is also why the faulting
instruction read 0x110(%rsi), a guest register load. That is the way past the
watchpoint's ceiling: the guest register file is available at the write, and a
0x82xxxxxx word picked out of it resolves against sylpheed.db to name the caller.
trigger_watch.sh now dumps x/128wx instead of a useless host backtrace.
The re-run then failed for an unrelated and unexplained reason: it reached
flight, the pilot bound, the guest was animating, and find_mission returned
NOTFOUND. Narrowed: the .ssb header is absent from guest memory (0 hits where
earlier runs hit immediately), ADN110 is absent too, but the manifest string
'Stage02.ssb' IS present at 0xBDA6C50B. So memory is readable and the manifest
is loaded while the script is not, in a mission that is flying.
No explanation offered. The cheap discriminator for next time is to poll for the
header from the moment flight starts and record when it appears, instead of
sampling once.
All 25 opcodes now have meanings. Ops 2/4/6/8 are integer compound assignment
(+= -= *= /=) and 3/5/7/9 the float versions; 10 and 11 are integer and float
compare writing three condition bits; 13-18 are je/jne/jl/jle/jg/jge; 21-24 are
push.i/push.f/pop.i/pop.f over deques at phase+44 and phase+64.
The shared-handler question is answered: the dispatcher leaves the opcode in r4
and the shared thunks never overwrite it, so those helpers take an extra opcode
argument and index a secondary table (0x82271448, 0x8227152C).
CORRECTION to my own tool and note: the branch/jump base is [phase+232], which
the phase initialiser sets to 0x24 + the phase's entry from the mission-level
stream -- 0xE4 / 0x14AA8 / 0x24B4C for Stage 02's three phases, not the file's
0x24. Measured on phase 1: base 0xE4 puts 525 of 525 branch targets on an
instruction boundary; base 0x24 manages 188. isl.py had been using 0x24 for
every phase, so its jump targets were wrong throughout. Fixed via
isl.phase_bases().
That also settles two things mission-script-ssb.md left open: offsets ARE
code-base-relative, and 0x1883's operand IS a code pointer -- the earlier worry
that some 'land on IEEE floats' was an artefact of adding the wrong base.
