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x86_64 imm-call relinking needs it's own private PLT/GOT to handle calls to further than 2GB away in either direction #23

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elfmaster opened this issue Mar 7, 2024 · 1 comment

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elfmaster commented Mar 7, 2024

The patch image is loaded further than 2gb away in memory and thus we cannot re-link call instructions with an offset that fits in 4 bytes

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elfmaster commented Apr 30, 2024

This same problem applies to relinking load/stores of global variables with mov instructions who's destination register is only 32bits.

8b 2d f0 ad 00 00: mov 0xadf0(%rip), %ebp

The instruction above only has 3 bytes for encoding the offset, and we need 4 bytes to reach the patch target (The global variable).

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