Re: [Qemu-devel] qemu log function to print out the registers of the guest

[Max Filippov]

On Fri, Aug 17, 2012 at 9:38 AM, Steven <address@hidden> wrote:
> Hi, Max,
> I appreciate your help and got some results using your patch. But I
> still have two questions as blow.
>
>>> I see that with the following patch
>>>
>>> diff --git a/softmmu_template.h b/softmmu_template.h
>>> index b8bd700..2d02133 100644
>>> --- a/softmmu_template.h
>>> +++ b/softmmu_template.h
>>> @@ -114,6 +114,7 @@ glue(glue(glue(HELPER_PREFIX, ld), SUFFIX),
>>> MMUSUFFIX)(ENV_PARAM
>>>      target_phys_addr_t ioaddr;
>>>      uintptr_t retaddr;
>>>
>>> +    fprintf(stderr, "%s: %08x\n", __func__, addr);
>>>      /* test if there is match for unaligned or IO access */
>>>      /* XXX: could done more in memory macro in a non portable way */
>>>      index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
>>>
>>> I get some memory accesses logged, but not all. That's due to fast
>>> path in tcg_out_qemu_ld
>>> in case there's TLB hit. I guess you can play with tcg_out_qemu_ld and
>>> make it produce a call
>>> to a helper function, like qemu_ld_helpers, that will print addresses
>>> for all memory access
>>> attempts.
>>
>> Easier solution would be to disable fast path and always go through
>> softmmu helpers, like this (specific for x86 host):
>>
>> diff --git a/softmmu_template.h b/softmmu_template.h
>> index b8bd700..2d02133 100644
>> --- a/softmmu_template.h
>> +++ b/softmmu_template.h
>> @@ -114,6 +114,7 @@ glue(glue(glue(HELPER_PREFIX, ld), SUFFIX),
>> MMUSUFFIX)(ENV_PARAM
>>      target_phys_addr_t ioaddr;
>>      uintptr_t retaddr;
>>
>> +    fprintf(stderr, "%s: %08x\n", __func__, addr);
>>      /* test if there is match for unaligned or IO access */
>>      /* XXX: could done more in memory macro in a non portable way */
>>      index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
>> diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c
>> index da17bba..ec68c19 100644
>> --- a/tcg/i386/tcg-target.c
>> +++ b/tcg/i386/tcg-target.c
>> @@ -1062,7 +1062,7 @@ static inline void tcg_out_tlb_load(TCGContext
>> *s, int addrlo_idx,
>>      tcg_out_mov(s, type, r0, addrlo);
>>
>>      /* jne label1 */
>> -    tcg_out8(s, OPC_JCC_short + JCC_JNE);
>> +    tcg_out8(s, OPC_JMP_short);
>>      label_ptr[0] = s->code_ptr;
>>      s->code_ptr++;
>>
>
> IN:
> 0x00000000c13e3a33:  mov    0x8(%ebp),%ebx (guest code in the tb)
> __ldl_mmu: c13a9fdc
>
> So 0xc13a9fdc is the guest virtual memory address of 0x8(%ebp). Is this 
> correct?

Right.

> IN:
> 0x00000000c13e3a36:  mov    %eax,-0x10(%ebp)
> However, for this instruction, no ldl_mmu is logged.
> Does that mean the patch you provided does not cover this case?

Yes, this is not 'ld', it is 'st'; to see it too I guess you need this:

diff --git a/softmmu_template.h b/softmmu_template.h
index b8bd700..b2ae078 100644
--- a/softmmu_template.h
+++ b/softmmu_template.h
@@ -114,6 +114,7 @@ glue(glue(glue(HELPER_PREFIX, ld), SUFFIX),
MMUSUFFIX)(ENV_PARAM
     target_phys_addr_t ioaddr;
     uintptr_t retaddr;

+    fprintf(stderr, "%s: %08x\n", __func__, addr);
     /* test if there is match for unaligned or IO access */
     /* XXX: could done more in memory macro in a non portable way */
     index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
@@ -263,6 +264,7 @@ void glue(glue(glue(HELPER_PREFIX, st), SUFFIX),
MMUSUFFIX)(ENV_PARAM
     uintptr_t retaddr;
     int index;

+    fprintf(stderr, "%s: %08x\n", __func__, addr);
     index = (addr >> TARGET_PAGE_BITS) & (CPU_TLB_SIZE - 1);
  redo:
     tlb_addr = env->tlb_table[mmu_idx][index].addr_write;


-- 
Thanks.
-- Max