NSO: Difference between revisions
No edit summary |
No edit summary |
||
| Line 97: | Line 97: | ||
| | | | ||
| Compressed sections | | Compressed sections | ||
|} | |||
Most data in Switch binaries are standard ELF structures, however some are custom. | |||
For example, the MOD header is essentially a replacement for a PT_DYNAMIC program header. | |||
=== MOD === | |||
All offsets are signed 32bit values relative to the magic field. | |||
The 32bits at image base + 4 must point to the magic field. | |||
The MOD structure is designed such that it can be placed at image base and point to itself. | |||
The 2 fields preceding the magic field get copied around with the structure, even if it is relocated to somewhere besides the image base. | |||
{| class="wikitable" border="1" | |||
|- | |||
! Offset | |||
! Size | |||
! Description | |||
|- | |||
| 0x00 | |||
| 4 | |||
| zero padding | |||
|- | |||
| 0x04 | |||
| 4 | |||
| offset to magic. Always 8 (so it works when MOD is at image_base + 0). | |||
|- | |||
| 0x08 | |||
| 4 | |||
| magic "MOD0" | |||
|- | |||
| 0x0C | |||
| 4 | |||
| .dynamic offset | |||
|- | |||
| 0x10 | |||
| 4 | |||
| .bss start offset | |||
|- | |||
| 0x14 | |||
| 4 | |||
| .bss end offset | |||
|- | |||
| 0x18 | |||
| 4 | |||
| .eh_frame start offset | |||
|- | |||
| 0x1C | |||
| 4 | |||
| .eh_frame end offset | |||
|- | |||
| 0x20 | |||
| 4 | |||
| offset to runtime-generated module object. typically equal to .bss base. | |||
|} | |} | ||