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

[Peter Maydell]

On 6 December 2012 09:36, Andreas Färber <address@hidden> wrote:
> 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().

The check you want is
 (hw_local_breakpoint_enabled() && !hw_global_breakpoint_enabled())

if you're going to do it like that. [We don't want to take out the
bp if it was enabled globally as well as locally.]

-- PMM