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(x86) Emulated CPU is not translating virtual memory addresses #947

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StrikerX3 opened this Issue Feb 24, 2018 · 1 comment

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StrikerX3 commented Feb 24, 2018

The emulated CPU does not translate memory addresses after setting up paging correctly. The two tests related to paging (here) are skipped; they fail if enabled.

I also tried using uc_map_mem_ptr with a char[] already containing the PDEs, PTEs, code and data, then prepared the CPU registers, protected mode, MTRRs and PAT with uc_reg_write and tried to run only the last part of the code where it reads from the virtual address. This fails too. If I manually translate the address using the data existing on the memory and CR3 register at the end of emulation, I can fetch the correct value.

If the CPU tries to read, write or execute code that was not previously mapped with uc_mem_map or uc_mem_map_ptr, uc_emu_start returns one of UC_ERR_READ_UNMAPPED, UC_ERR_WRITE_UNMAPPED or UC_ERR_FETCH_UNMAPPED, depending on what happened. I believe #439 is related to this.

I built Unicorn from master with MSYS2 / MinGW32 and MinGW64 on Windows 10 and with the default C++ toolchain on Ubuntu 16.04.3.

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aut0 commented Nov 29, 2018

This happens in arm64 as well. Is this a bug or is virtual memory just unsupported? It looks like the code that checks for mapped memory just doesn't care if the address is virtual. Maybe adding a hook and just returning true if the address is virtual is enough?

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