diff options
Diffstat (limited to 'results/classifier/semantic-bugs-usermode/test/1820686')
| -rw-r--r-- | results/classifier/semantic-bugs-usermode/test/1820686 | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/results/classifier/semantic-bugs-usermode/test/1820686 b/results/classifier/semantic-bugs-usermode/test/1820686 new file mode 100644 index 000000000..f7fd19f6d --- /dev/null +++ b/results/classifier/semantic-bugs-usermode/test/1820686 @@ -0,0 +1,25 @@ +instruction: 0.949 +device: 0.824 +network: 0.809 +other: 0.742 +socket: 0.724 +semantic: 0.691 +vnc: 0.683 +mistranslation: 0.678 +graphic: 0.598 +boot: 0.498 +KVM: 0.321 +assembly: 0.305 + +risc-v: 'c.unimp' instruction decoded as 'c.addi4spn fp, 0' + +QEMU 3.1 incorrectly decodes the "c.unimp" instruction (opcode 0x0000) as an "addi4spn fp, 0" when either of the two following bytes are non-zero. This is because the ctx->opcode value used when decoding the instruction is actually filled with a 32-bit load (to handle normal uncompressed instructions) but when a compressed instruction is found only the low 16 bits are valid. Other reserved/illegal bit patterns with the addi4spn opcode are also incorrectly decoded. + +I believe that the switch to decodetree on master happened to fix this issue, but hopefully it is helpful to have this recorded somewhere. I've included a simple one line patch if anyone wants to backport this. + + + +Thanks. If you spin a full patch (ie, "git commit -s" and then "git show") I can drop it on riscv-qemu-3.1, our backports branch. Otherwise hopefully we got the bug via the decodetree conversion. + +Since this bug isn't present in the decodetree version of the riscv decoder, we might as well just close this as fix-released; we won't be doing more point-releases of QEMU versions as old as 3.1. + |