Re: [PATCH] linux-user: Update TASK_UNMAPPED_BASE for aarch64

[Laurent Vivier]

Le 14/03/2020 à 18:01, Aleksandar Markovic a écrit :
> On Sat, Mar 14, 2020 at 11:45 AM Laurent Vivier <address@hidden> wrote:
>>
>> Le 14/03/2020 à 04:06, Aleksandar Markovic a écrit :
>>> On Fri, Mar 13, 2020 at 1:28 AM Lirong Yuan <address@hidden> wrote:
>>>>
>>>> This change updates TASK_UNMAPPED_BASE (the base address for guest 
>>>> programs) for aarch64. It is needed to allow qemu to work with Thread 
>>>> Sanitizer (TSan), which has specific boundary definitions for memory 
>>>> mappings on different platforms:
>>>> https://github.com/llvm/llvm-project/blob/master/compiler-rt/lib/tsan/rtl/tsan_platform.h
>>>>
>>>> Signed-off-by: Lirong Yuan <address@hidden>
>>>> ---
>>>>  linux-user/mmap.c | 4 ++++
>>>>  1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
>>>> index 8685f02e7e..e378033797 100644
>>>> --- a/linux-user/mmap.c
>>>> +++ b/linux-user/mmap.c
>>>> @@ -184,7 +184,11 @@ static int mmap_frag(abi_ulong real_start,
>>>>  }
>>>>
>>>>  #if HOST_LONG_BITS == 64 && TARGET_ABI_BITS == 64
>>>> +#ifdef TARGET_AARCH64
>>>> +# define TASK_UNMAPPED_BASE  0x5500000000
>>>
>>> Hi, Lirong,
>>>
>>> Can you point from which line of the file you linked to did you
>>> arrive to the value 0x5500000000?
>>>
>>> Second question: What about other targets?
>>
>> Personally, I prefer to not change the value for other targets if it is
>> not required by someone that had some problems with the current value.
>>
>> It needs to be changed carefully and to be well tested after change.
>>
> 
> Sure, but again, from where " 0x5500000000" comes from?

The URL is in the comment, but more precisely I guess:

 
https://github.com/llvm/llvm-project/blob/master/compiler-rt/lib/tsan/rtl/tsan_platform.h#L164

Thanks,
Laurent