REL (File Format): Difference between revisions
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→Relocation Table
>Aruki (→Header) |
>Aruki |
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== Format == | == Format == | ||
=== Header === | === Header === | ||
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| u32 | | u32 | ||
| 1 | | 1 | ||
| '''Name Offset''' | | '''Module Name Offset''' | ||
| Offset to the module name. Can be 0, in which case this module doesn't contain a name string. | | Offset to the module name. Can be 0, in which case this module doesn't contain a name string. | ||
| {{check}} | | {{check}} | ||
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| u32 | | u32 | ||
| 1 | | 1 | ||
| '''Name Size''' | | '''Module Name Size''' | ||
| Size of the module name string. | | Size of the module name string. | ||
| {{check}} | | {{check}} | ||
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| 1 | | 1 | ||
| '''BSS Size''' | | '''BSS Size''' | ||
| Size of the BSS section, which is allocated at runtime (not included in the file) | | Size of the BSS section, which is allocated at runtime (not included in the file). | ||
| {{check}} | | {{check}} | ||
| {{check}} | | {{check}} | ||
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| 1 | | 1 | ||
| '''Prolog Function Offset''' | | '''Prolog Function Offset''' | ||
| Section-relative offset of the prolog function. 0 if this module doesn't contain a prolog function. | | Section-relative offset of the prolog function. 0 if this module doesn't contain a prolog function. This is converted into a function pointer at runtime by OSLink. | ||
| {{check}} | | {{check}} | ||
| {{check}} | | {{check}} | ||
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| 1 | | 1 | ||
| '''Epilog Function Offset''' | | '''Epilog Function Offset''' | ||
| Section-relative offset of the epilog function. 0 if this module doesn't contain an epilog function. | | Section-relative offset of the epilog function. 0 if this module doesn't contain an epilog function. This is converted into a function pointer at runtime by OSLink. | ||
| {{check}} | | {{check}} | ||
| {{check}} | | {{check}} | ||
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| 1 | | 1 | ||
| '''Unresolved Function Offset''' | | '''Unresolved Function Offset''' | ||
| Section-relative offset of the unresolved function. 0 if this module doesn't contain an unresolved function. | | Section-relative offset of the unresolved function. 0 if this module doesn't contain an unresolved function. This is converted into a function pointer at runtime by OSLink. | ||
| {{check}} | | {{check}} | ||
| {{check}} | | {{check}} | ||
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| '''Offset''' | | '''Offset''' | ||
| | | Absolute offset of the section. The 0x1 bit is toggled to indicate whether this section contains executable code. AND out that bit to get the correct offset. | ||
|- | |- | ||
| 0x4 | | 0x4 | ||
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=== Relocation Table === | === Relocation Table === | ||
This data is pointed to by the ''Relocation Table Offset'' value in the header. Since modules have space allocated at runtime and | This data is pointed to by the ''Relocation Table Offset'' value in the header. Since modules have space allocated at runtime and therefore do not have a fixed memory address, the relocations table is needed to ensure all data and function addresses in the REL are correct; this includes both symbols within the REL itself, which don't have a fixed address until the REL is linked in, and symbols within the DOL, which need corrections due to the usage of relative offsets in branch instructions. The relocation table describes the location of every instruction that needs to be patched, and how to patch it. | ||
There are multiple distinct groups of relocations, with each one being pointed to by an entry in the [[#Import Table|import table]]. To read the relocations for a given module, you need to iterate over all relocation entries until you hit an R_DOLPHIN_END directive. Each relocation is 0x8 bytes. | There are multiple distinct groups of relocations, with each one being pointed to by an entry in the [[#Import Table|import table]]. To read the relocations for a given module, you need to iterate over all relocation entries until you hit an R_DOLPHIN_END directive. Each relocation is 0x8 bytes. | ||
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| 1 | | 1 | ||
| '''Section Index''' | | '''Section Index''' | ||
| The section index of the symbol being patched to. | | The section index of the symbol being patched to. This is only used for module patches. | ||
|- | |- | ||
| 0x4 | | 0x4 | ||
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| 9 | | 9 | ||
| R_PPC_ADDR14_BRNTAKEN | | R_PPC_ADDR14_BRNTAKEN | ||
| Write the 14-bit address of the symbol. Leave the existing value of the bottom two bits intact. '''Note:''' Needs a proper check on | | Write the 14-bit address of the symbol. Leave the existing value of the bottom two bits intact. '''Note:''' Needs a proper check on differences between this and ADDR14 | ||
| {{nocheck}} | | {{nocheck}} | ||
|- | |- | ||