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27 March 2024, 02:37:15 UTC
Revision 733b8bc183f491e8263009edf8ef184fb44a6882 authored by Maciej W. Rozycki on 22 January 2016, 05:20:46 UTC, committed by Ralf Baechle on 24 January 2016, 00:35:46 UTC 
MIPS: math-emu: Make microMIPS branch delay slot emulation work
 
Complement commit 102cedc32a6e ("MIPS: microMIPS: Floating point
support.") which introduced microMIPS FPU emulation, but did not adjust
the encoding of the BREAK instruction used to terminate the branch delay
slot emulation frame.  Consequently the execution of any such frame is
indeterminate and, depending on CPU configuration, will result in random
code execution or an offending program being terminated with SIGILL.

This is because the regular MIPS BREAK instruction is encoded with the 0
major and the 0xd minor opcode, however in the microMIPS instruction set
this major/minor opcode pair denotes an encoding reserved for the DSP
ASE.  Instead the microMIPS BREAK instruction is encoded with the 0
major and the 0x7 minor opcode.

Use the correct BREAK encoding for microMIPS FPU emulation then.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12174/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
1 parent a87265c
History
Tip revision: 733b8bc183f491e8263009edf8ef184fb44a6882 authored by Maciej W. Rozycki on 22 January 2016, 05:20:46 UTC
MIPS: math-emu: Make microMIPS branch delay slot emulation work
Tip revision: 733b8bc
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