Continue work on dynamic imports
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Aiden Isik
parent
5a9951f6be
commit
a69cfac73e
1 changed files with 108 additions and 9 deletions
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@ -15,6 +15,8 @@
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# Kernel function ordinal constants
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.set KERN_ORDINAL_VDDISPLAYFATALERROR, 0x1B2
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.set KERN_ORDINAL_XEXGETMODULEHANDLE, 0x195
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.set KERN_ORDINAL_XEXGETPROCEDUREADDRESS, 0x197
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# PE MZ magic ('M' 'Z')
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.set PE_MZ_MAGIC, 0x4D5A
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@ -43,8 +45,10 @@
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# Constants used for dynamic linking
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.set ELF_SECT_TYPE_DYNAMIC, 0x6
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.set ELF_DYN_TAG_HASH, 0x4
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.set ELF_DYN_TAG_STRTAB, 0x5
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.set ELF_DYN_TAG_SYMTAB, 0x6
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.set ELF_DYN_SHN_UNDEF, 0x0
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.global _start
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@ -498,11 +502,40 @@ verifyElf:
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blr
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# Resolves a single dynamic symbol import
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# IN: r3 == address of symbol entry
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# IN: r4 == address of string table
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# IN: LR == address to return to
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resolveImportEntryElf:
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mflr r12
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subi r1, r1, 0x8
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std r12, 0(r1)
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bl saveNonVolatileRegisters
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# Save symbol entry and string table addresses to nonvolatile registers
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mr r14, r3
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mr r15, r4
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# Make sure the symbol format is ordinal (_fcxelo_).
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# We don't support named symbols here, no need to, dlopen/LoadLibrary exist.
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# We only do this here because it's required to get the standard library up and working.
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bl restoreNonVolatileRegisters
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ld r12, 0(r1)
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addi r1, r1, 0x8
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mtlr r12
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blr
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# Resolves any dynamic imports within the embedded ELF file
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# IN: r3 == address in memory of the ELF
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# IN: LR == address to return to
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resolveImportsElf:
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mflr r12
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subi r1, r1, 0x8
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std r12, 0(r1)
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bl saveNonVolatileRegisters
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# Save the address of the ELF to r14
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@ -575,36 +608,102 @@ elfFindDynamicImportTablesLoop:
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cmpli cr0, r4, ELF_DYN_TAG_SYMTAB
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beq elfDynamicImportsFoundSymTab
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cmpli cr0, r4, ELF_DYN_TAG_HASH
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beq elfDynamicImportsFoundHash
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b elfFindDynamicImportTablesNext
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elfDynamicImportsFoundStrTab:
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lwz r17, 0x4(r3)
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# If we previously found the symbol table, we've got them both
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# If we previously found the symbol table & hash section, we've got them both
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cmpli cr0, r18, 0
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bne elfFoundDynamicImportTables
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b elfFindDynamicImportTablesNext
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beq elfFindDynamicImportTablesNext
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cmpli cr0, r19, 0
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beq elfFindDynamicImportTablesNext
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b elfFoundDynamicImportTables
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elfDynamicImportsFoundSymTab:
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lwz r18, 0x4(r3)
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# If we previously found the string table, we've got them both
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# If we previously found the string table & hash section, we've got them both
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cmpli cr0, r17, 0
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bne elfFoundDynamicImportTables
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b elfFindDynamicImportTablesNext
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beq elfFindDynamicImportTablesNext
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cmpli cr0, r19, 0
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beq elfFindDynamicImportTablesNext
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b elfFoundDynamicImportTables
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elfDynamicImportsFoundHash:
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lwz r19, 0x4(r3)
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# If we previously found the string table & symbol table, we've got them both
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cmpli cr0, r17, 0
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beq elfFindDynamicImportTablesNext
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cmpli cr0, r18, 0
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beq elfFindDynamicImportTablesNext
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b elfFoundDynamicImportTables
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elfFindDynamicImportTablesNext:
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bdnz elfFindDynamicImportTablesLoop
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# If we get here, we couldn't find both tables. Return.
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# If we get here, we couldn't find both tables. Return.
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b resolveImportsElfReturn
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elfFoundDynamicImportTables:
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# Address of STRTAB is now in r17, SYMTAB in r18
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# Make sure we got the hash section. If we didn't, we can't get the section count. Error out.
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cmpli cr0, r19, 0
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bne elfFoundDynamicImportTablesNoError
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b error
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elfFoundDynamicImportTablesNoError:
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# Virtual address of STRTAB is now in r17, SYMTAB in r18, DT_HASH in r19
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# Add base address to get absolute addresses
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add r17, r17, r14
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add r18, r18, r14
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add r19, r19, r14
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# Get the number of symbols in SYMTAB from DT_HASH and put it in r20
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lwz r20, 0x4(r19)
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# Iterate backwards through STRTAB, resolving any dynamic imports we find.
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# If we can't find any, abort. The program will likely crash otherwise.
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mtctr r20
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elfResolveDynamicImportSymbolsLoop:
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# Get current index into symbol table
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mfctr r3
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subi r3, r3, 1
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# If it's zero, we're done
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cmpli r3, 0
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beq resolveImportsElfReturn
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# Transform symbol table index into address
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mulli r3, r3, 0x18
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add r3, r3, r18
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# Check whether the current symbol is an import
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lhz r4, 0xE(r3)
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cmpli cr0, r4, ELF_DYN_SHN_UNDEF
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bne elfResolveDynamicImportSymbolsNext
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# If it is an import, resolve it
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mr r4, r17
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bl resolveImportEntryElf
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elfResolveDynamicImportSymbolsNext:
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bdnz elfResolveDynamicImportSymbolsLoop
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resolveImportsElfReturn:
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bl restoreNonVolatileRegisters
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ld r12, 0(r1)
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addi r1, r1, 0x8
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mtlr r12
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blr
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