Re: [Qemu-devel] [PATCH 3/3] target-i386:slightly refactor dr7 related function

[Andreas Färber]

Am 06.12.2012 10:27, schrieb li guang:
> 在 2012-12-06四的 09:23 +0000，Peter Maydell写道：
>> On 6 December 2012 09:16, li guang <address@hidden> wrote:
>>> 在 2012-12-06四的 08:54 +0000，Peter Maydell写道：
>>>> On 6 December 2012 03:03, liguang <address@hidden> wrote:
>>>>> Signed-off-by: liguang <address@hidden>
>>>>> --- a/target-i386/seg_helper.c
>>>>> +++ b/target-i386/seg_helper.c
>>>>> @@ -465,9 +465,9 @@ static void switch_tss(CPUX86State *env, int 
>>>>> tss_selector,
>>>>>
>>>>>  #ifndef CONFIG_USER_ONLY
>>>>>      /* reset local breakpoints */
>>>>> -    if (env->dr[7] & 0x55) {
>>>>> -        for (i = 0; i < 4; i++) {
>>>>> -            if (hw_breakpoint_enabled(env->dr[7], i) == 0x1) {
>>>>> +    if (env->dr[7] & DR7_LOCAL_BP_MASK) {
>>>>> +        for (i = 0; i < DR7_MAX_BP; i++) {
>>>>> +            if (hw_breakpoint_enabled(env->dr[7], i)) {
>>>>>                  hw_breakpoint_remove(env, i);
>>>>>              }
>>>>>          }
>>>>
>>>> This is still wrong.
>>>
>>> do you mean the use of 'hw_breakpoint_enabled'? or others?
>>> maybe a mistake, I change it to 'hw_local_breakpoint_enabled'.
>>> if it is I'll re-send a corrected patch.
>>
>> I mean that in the comments on the previous version of this
>> patchseet we explained that this check is specifically checking
>> for whether the breakpoint is enabled locally, and that your
>> change to just returning bool broke this. And in this version
>> of the patch there is still exactly the same problem.
> 
> why broke?
> this function just ask if breakpoint 'i' was enable,
> so we answer enabled or not? 2 simple cases, any problem?

The code comment specifically says "reset local breakpoints". IIUC you
are also resetting global breakpoints, which you shouldn't.

Personally I'd be fine with a hw_local_breakpoint_enabled().

Regards,
Andreas

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