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Re: [Qemu-devel] softMMU / MOV translation
From: |
Eddie C. Dost |
Subject: |
Re: [Qemu-devel] softMMU / MOV translation |
Date: |
Wed, 25 Jul 2007 15:41:35 +0200 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Hi Clemens,
if you enable "log asm_in,op,op_opt,asm_out" you will see the
intermediate code used during translation.
The opcodes are generated from the macros you already found in
softmmu_header.h by target-i386/ops_mem.h included from target-i386/op.c
Hope this helps,
Eddie
On Wed, Jul 25, 2007 at 02:04:47PM +0200, Clemens Kolbitsch wrote:
> hi!
> i tried asking this in the irc but got no answer, hope someone can help me
> here :-)
>
> i'm working on memory-protection for my mather's thesis and have to dig into
> qemu memory management... could someone help me here please? i have the
> following problem:
>
> i'm trying to understand the dynamic translation for the following mov-opcode
> (it's taken from the qemu log with "log asm_in,asm_out"):
>
> IN:
> 0xc011c9f2: mov 0x60(%esi),%edx
> the hex-code would be "0x8b 0x56 0x60"
> ...
>
> OUT:
> OUT: [size=455]
> 0x08d30fa0: mov 0x18(%ebp),%edi
> 0x08d30fa3: add $0x60,%edi
> 0x08d30fa9: mov %edi,%edx
> 0x08d30fab: mov %edi,%eax
> 0x08d30fad: shr $0x8,%edx
> 0x08d30fb0: and $0xfffff003,%eax
> 0x08d30fb5: and $0xff0,%edx
> 0x08d30fbb: lea 0x350(%edx,%ebp,1),%edx
> 0x08d30fc2: cmp (%edx),%eax
> 0x08d30fc4: mov %edi,%eax
> 0x08d30fc6: je 0x8d30fd4
> 0x08d30fc8: push $0x0
> 0x08d30fca: call 0x80ee06a // __ldl_mmu
> 0x08d30fcf: pop %edx
> 0x08d30fd0: mov %eax,%ebx
> 0x08d30fd2: jmp 0x8d30fd9
> 0x08d30fd4: add 0xc(%edx),%eax
> 0x08d30fd7: mov (%eax),%ebx // possibly the output of
> gen_op_ld_T0_A0
> [ot]+ s->mem_index]();
> 0x08d30fd9: mov %ebx,0x8(%ebp) // this is the output of
> gen_op_mov_reg_T0
> [ot][reg](); (translate.c:4005)
> ...
>
>
> therefore, i think the following code in translate.c should be executed:
>
> case 0x8b: /* mov Ev, Gv */
> if ((b & 1) == 0)
> ot = OT_BYTE;
> else
> ot = OT_WORD + dflag;
> modrm = ldub_code(s->pc++);
> reg = ((modrm >> 3) & 7) | rex_r;
>
> gen_ldst_modrm(s, modrm, ot, OR_TMP0, 0);
> gen_op_mov_reg_T0[ot][reg]();
> break;
>
>
> i debugged some time and found out that the last gen_op
>
> gen_op_mov_reg_T0[ot][reg]();
>
> only produces
>
> mov %ebx,0x8(%ebp).
>
> thus, the rest of the OUT-codes is produced by
>
> gen_ldst_modrm(s, modrm, ot, OR_TMP0, 0);
>
> however, i tried reading through the code but i could not find the function
> where
>
> 0x08d30fca: call 0x80ee06a // __ldl_mmu
>
> is inserted into the translation-buffer... i (think to) know why it must be
> inserted, but i just cannot figure out where it is put into the buffer.
>
> if someone could point that out, it would help me a LOT!
> thanks,
> Clemens
>
>
--
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