80 lines
5.3 KiB
Python
80 lines
5.3 KiB
Python
#!/usr/bin/env python3
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"""Derive exact original Metal device ABI metadata without extracting executable code."""
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import hashlib
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import json
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from pathlib import Path
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import runpy
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import struct
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import subprocess
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ROOT=Path(__file__).resolve().parents[1]
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n=runpy.run_path(str(ROOT/'scripts/audit-target-metal-discovery.py'))
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read,pointer,symbol,require=n['read'],n['pointer'],n['symbol'],n['require']
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OUT=ROOT/'build/gpu-analysis';main=n['main'];region=n['region']
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source=OUT/'metal-device-layout.cpp';exe=OUT/'metal-device-layout'
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source.write_text('#include <cstddef>\n#include <cstdio>\n#include "dyld_cache_format.h"\nint main(){printf("%zu\\n",offsetof(dyld_cache_header,objcOptsOffset));}\n')
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subprocess.run(['xcrun','clang++','-I',ROOT/'refer/dyld/cache-builder',source,'-o',exe],check=True,timeout=30)
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require(subprocess.check_output([exe],text=True).strip()=='464','Compiler-derived ObjC optimization-header field')
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opt=region+struct.unpack_from('<Q',main,464)[0]
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require(struct.unpack('<I',read(opt,4))[0]==1,'Actual supported ObjC optimization header version')
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selector_base=region+struct.unpack('<Q',read(opt+48,8))[0]
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def string(address):
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out=bytearray()
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# Bound reads also at file-mapping boundaries instead of speculative 4K reads.
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for i in range(4096):
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b=read(address+i,1)
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if b==b'\0':return out.decode('utf-8')
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out+=b
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raise SystemExit('Unterminated original ObjC metadata string')
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def methods(address):
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if not address:return []
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if address&1:
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header=address&~1;stride,count=struct.unpack('<II',read(header,8))
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require(stride==8 and 0<count<=4096,f'Bounded cache category list-of-lists {header:x} stride={stride} count={count}')
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entry=header+count*8
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offset=struct.unpack('<q',read(entry,8))[0]>>16
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address=entry+offset # Pinned MachOAnalyzer: final list is the class list.
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flags,count=struct.unpack('<II',read(address,8));size=flags&0xfffc
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require(count<=4096 and size==(12 if flags&0x80000000 else 24),f'Bounded actual method list profile {address:x} flags={flags:x} count={count}')
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result=[]
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for i in range(count):
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entry=address+8+i*size
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if flags&0x80000000:
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nameoff,typeoff,impoff=struct.unpack('<Iii',read(entry,12))
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if flags&0x40000000:name=selector_base+nameoff
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else:name=pointer(entry+struct.unpack('<i',read(entry,4))[0])
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types=entry+4+typeoff;imp=entry+8+impoff
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else:name,types,imp=(pointer(entry+j) for j in (0,8,16))
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selector=string(name);encoding=string(types)
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require(selector and encoding and imp%4==0,'Original method selector/types/aligned implementation')
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result.append(dict(selector=selector,encoding=encoding,implementation=imp))
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require(len({x['selector'] for x in result})==len(result),'Unique original own method selectors')
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return sorted(result,key=lambda x:x['selector'])
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def cls(address):
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ro=pointer(address+32)&0x00007ffffffffff8
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flags,start,size=struct.unpack('<III',read(ro,12));name=string(pointer(ro+24))
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require(size>=start and size<=1024*1024 and name,'Bounded actual class instance layout')
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return dict(address=address,name=name,superclass=pointer(address+8),instance_start=start,instance_size=size,
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methods=methods(pointer(ro+32)))
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base=cls(symbol('_OBJC_CLASS_$__MTLDevice'));meta=cls(pointer(base['address']))
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require(base['name']=='_MTLDevice' and base['instance_size']==536 and len(base['methods'])==575,'Exact original base-device metadata')
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# Record actual ancestry; the bundle principal's name alone does not establish
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# which runtime device class will be published. Never inherit an AGX class.
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family=[];address=symbol('_OBJC_CLASS_$_AGXA10FamilyDevice')
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while address:
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require(len(family)<16 and address not in {x['address'] for x in family},'Bounded original class ancestry')
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item=cls(address);family.append(item);address=item['superclass']
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require(any(x['name']=='_MTLDevice' for x in family),'Actual Apple device ancestry reaches Metal base')
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principal=cls(symbol('_OBJC_CLASS_$_AGXPrincipalDevice'))
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require(cls(principal['superclass'])['name']=='NSObject','Original principal class has NSObject ancestry')
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functions={name:symbol(name) for name in ('_MTLCreateSystemDefaultDevice','_MTLRegisterDevices')}
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pins={str(p.relative_to(ROOT/'refer/dyld')):hashlib.sha256(p.read_bytes()).hexdigest() for p in
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(ROOT/'refer/dyld/common/ObjCVisitor.h',ROOT/'refer/dyld/common/ObjCVisitor.cpp',ROOT/'refer/dyld/common/DyldSharedCache.h',ROOT/'refer/dyld/common/DyldSharedCache.cpp',ROOT/'refer/dyld/common/MachOAnalyzer.cpp',ROOT/'refer/dyld/common/OptimizerObjC.h')}
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report=dict(cache_uuid=main[88:104].hex(),dyld_revision=subprocess.check_output(['git','-C',ROOT/'refer/dyld','rev-parse','HEAD'],text=True).strip(),
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layout_source_sha256=pins,selector_base=selector_base,device=base,metaclass=meta,
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principal_class={k:v for k,v in principal.items() if k!='methods'},
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apple_device_ancestry=[{k:v for k,v in x.items() if k!='methods'} for x in family],functions=functions,
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runtime_observed=False,native_adreno_device=False)
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(OUT/'metal-device-abi.json').write_text(json.dumps(report,indent=2)+'\n')
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print('PASS: original _MTLDevice has',len(base['methods']),'own methods,',len(meta['methods']),'class methods and',base['instance_size'],'instance bytes')
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print('Actual Apple family ancestry:', ' -> '.join(c['name'] for c in family))
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