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radareorg / radare2

UNIX-like reverse engineering framework and command-line toolset
https://www.radare.org/
GNU Lesser General Public License v3.0
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disassembly for mips mtc/mfc: incorrect coprocessor registry #19528

Open cavedon opened 2 years ago

cavedon commented 2 years ago

Environment

Radare 5.5.4 (or today's master, 0c6d40c) on Ubuntu focal 64 bit

Description

The disassembly in mfc/mtc instructions allows to read and write coprocessor registers. For example

00608340 mtc0 v1, $12

Writes v1 to the coprocessor 0 register 12. The disassembly when using -e mips.gnu is correct, as shown above. When using -e mips, the disassembly references the GPR number 12 (i.e. t4):

00608340  mtc0 v1, t4, 0

Test

Correct:

% rasm2 -a mips -D 00608340
0x00000000   4                 00608340  mtc0 v1, t4, 0

Incorrect:

% rasm2 -a mips.gnu -D 00608340
0x00000000   4                 00608340  mtc0 v1, $12
cavedon commented 2 years ago

Actually this is a duplicate of #17372. The bug is actually in the capstone project https://github.com/capstone-engine/capstone/issues/1673. It may be worthwhile keeping the bug open in radare2 as well until the upstream bug is resolved, as it manifests as bug in radare2 as well.

radare commented 2 years ago

Thanks

On 23 Dec 2021, at 18:37, Ludovico Cavedon @.***> wrote:

 Actually this is a duplicate of #17372. The bug is actually in the capstone project capstone-engine/capstone#1673. It may be worthwhile keeping the bug open in radare2 as well until the upstream bug is resolved, as it manifests as bug in radare2 as well.

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