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[Qemu-devel] Re: i386 emulation bug: mov reg, [addr]
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From: |
Paolo Bonzini |
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Subject: |
[Qemu-devel] Re: i386 emulation bug: mov reg, [addr] |
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Date: |
Wed, 16 Dec 2009 00:37:37 +0100 |
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User-agent: |
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On 12/15/2009 10:26 PM, Jamie Lokier wrote:
But that said, I'm not sure if this line from earlier breaks the test:
index = ((code>> 3)& 7) | REX_X(s);
When is REX_X(s) not zero, and does it break the index != 4 test?
When %r12 (4+8=12) is used as an index. That's a valid statement, so
it's okay to test index != 4 (when REX_X(s) is not zero it is always
eight, and you'd get index == 12):
0: 8b 04 65 11 22 33 44 mov 0x44332211(,%riz,2),%eax
7: 42 8b 04 65 11 22 33 44 mov 0x44332211(,%r12,2),%eax
(BTW %eiz/%riz are not accepted by my GAS, only produced by the
disassembler).
Paolo