On 2017/12/1 19:47, David Laight wrote:
>> of noise in the log and cause confusion.
>>
>> This patch will close the detection of unaligned access when
>> the system support unaligned access.
>>
>> Signed-off-by: Ding Tianhong <[email protected]>
>> ---
>> lib/ubsan.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/ubsan.c b/lib/ubsan.c
>> index fb0409d..278b4c3 100644
>> --- a/lib/ubsan.c
>> +++ b/lib/ubsan.c
>> @@ -321,7 +321,8 @@ void __ubsan_handle_type_mismatch(struct
>> type_mismatch_data *data,
>>
>> if (!ptr)
>> handle_null_ptr_deref(data);
>> - else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
>> + else if (data->alignment && !IS_ALIGNED(ptr, data->alignment) &&
>> + !IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
>> handle_missaligned_access(data, ptr);
>> else
>> handle_object_size_mismatch(data, ptr);
>
> Won't that report an object size error instead of actually
> doing the required access?
>
Yes，I miss it.
> Surely it shouldn't get into this function at all?
>
> I guess 'alignment' is set to 4 or 8.
> If it were set to 3 or 7 (or 0) then the tests on the pointer
> would be much simpler - maybe at a slight extra cost in setup.
>
Looks like we need to fix it in the handle_missaligned_access:
diff --git a/lib/ubsan.c b/lib/ubsan.c
index 278b4c3..040f8b2 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -289,6 +289,9 @@ static void handle_missaligned_access(struct
type_mismatch_data *data,
if (suppress_report(&data->location))
return;
+ if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
+ return;
+
ubsan_prologue(&data->location, &flags);
pr_err("%s misaligned address %p for type %s\n",
Thanks
Ding
> David
>
