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Unable to disassemble specific instruction in RISCV #2278

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trojanwarriors opened this issue Feb 21, 2024 · 6 comments
Open

Unable to disassemble specific instruction in RISCV #2278

trojanwarriors opened this issue Feb 21, 2024 · 6 comments
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outdated-module Issue due to an outdated arch module RISCV Arch
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@trojanwarriors
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trojanwarriors commented Feb 21, 2024

I tried to disassemble a specific instruction, and Capstone couldn't return with the correct output
The following Python code reproduces the error:

# test1.py
from capstone import *

md = Cs(CS_ARCH_RISCV, CS_MODE_RISCVC)

# 1001 0100 0010 0101 0011 0101 0000 0011
# (1001 0100 0010) (0101 0)(011) (0101 0)000 0011
# ld x10, -1726(x10)
# 0x94253503

CODE = b"\x03\x35\x25\x94"
print("First instruction: ")
for i in md.disasm(CODE, 0x00000690):
    print("0x%x:\t%s\t%s" %(i.address, i.mnemonic, i.op_str))

CODE = b"\x03\x25\x35\x94"
print("Second instruction: ")
for i in md.disasm(CODE, 0x00000690):
    print("0x%x:\t%s\t%s" %(i.address, i.mnemonic, i.op_str))

The output shows that only the second instruction could be disassembled:
2024-02-21_13-04

@trojanwarriors trojanwarriors changed the title Unable to decompile specific instruction Unable to decompile specific instruction in RISCV Feb 21, 2024
@trojanwarriors
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another instruction: 0x63cd3d03 -> ld x26, 1596(x26). It seems it is affecting LD instructions. The interesting part is that tools like ROPGadget can disassemble it correctly.

@trojanwarriors trojanwarriors changed the title Unable to decompile specific instruction in RISCV Unable to disassemble specific instruction in RISCV Feb 21, 2024
@Rot127
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Rot127 commented Feb 22, 2024

Unfortunately, the RISCV module is still not updated and is at the level of LLVM 7. This is likely why it isn't decoding it.
Checkout #2015 for any progress in this regard.

@Rot127 Rot127 added RISCV Arch outdated-module Issue due to an outdated arch module labels Mar 19, 2024
@Rot127 Rot127 added this to the v6 milestone Mar 19, 2024
@trojanwarriors
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I am sorry. I couldn't find a way to send a private message to you, Rot127, so I am sending it here. Can I work to fix this issue? I just saw a Kaban-like dashboard after clicking the link Capstone V6 Plan. How does the collaboration work?

@Rot127
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Rot127 commented Mar 21, 2024

Can you ping me in the Telegram channel of Capstone, please?

@Rot127
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Rot127 commented Mar 21, 2024

If you can't use Telegram I would write something properly out for RISCV, but it will take a day or two.

@Rot127
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Rot127 commented Mar 25, 2024

@trojanwarriors There is the idea to generate the RISCV module not from LLVM, but use SAIL. Because the definitions have way better quality.
So please ping us before starting to work on anything.

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Labels
outdated-module Issue due to an outdated arch module RISCV Arch
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