Hi Steve,
Thanks for looking into this!
On 17/09/15 14:11, Steven Rostedt wrote:
> On Thu, 17 Sep 2015 12:14:36 +0100
> Kapileshwar Singh <kapileshwar.si...@arm.com> wrote:
>
>> When a trace recorded on a 32-bit device is processed with a 64-bit
>> binary, the higher 32-bits of the address need to be masked.
>>
>> The lack of this results in the output of the 64-bit pointer
>> value to the trace as the 32-bit address lookup fails in find_printk.
>>
>> Before:
>> burn-1778 [003] 548.600305: bputs: 0xc0046db2s: 2cec5c058d98c
>>
>> After:
>> burn-1778 [003] 548.600305: bputs: 0xc0046db2s: RT throttling
>> activated
>>
>> The problem occurs in PRINT_FEILD when the field is recognized as a pointer
>> to a string (of the type const char *)
>
> Actually, there's two bugs here. You only fixed one of them.
>
>>
>> Cc: Steven Rostedt <rost...@goodmis.org>
>> Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
>> Cc: Namhyung Kim <namhy...@kernel.org>
>> Cc: Javi Merino <javi.mer...@arm.com>
>> Cc: David Ahern <dsah...@gmail.com>
>> Cc: Jiri Olsa <jo...@kernel.org>
>> Reported-by: Juri-Lelli <juri.le...@arm.com>
>> Signed-off-by: Kapileshwar Singh <kapileshwar.si...@arm.com>
>> ---
>> tools/lib/traceevent/event-parse.c | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> diff --git a/tools/lib/traceevent/event-parse.c
>> b/tools/lib/traceevent/event-parse.c
>> index 4d885934b919..39163ea4a048 100644
>> --- a/tools/lib/traceevent/event-parse.c
>> +++ b/tools/lib/traceevent/event-parse.c
>> @@ -3829,6 +3829,17 @@ static void print_str_arg(struct trace_seq *s, void
>> *data, int size,
>> if (!(field->flags & FIELD_IS_ARRAY) &&
>> field->size == pevent->long_size) {
>> addr = *(unsigned long *)(data + field->offset);
>
> addr is of type unsigned long. That means if we read a 64 bit record on
> a 32 bit machine (which is supported), this will be truncated.
>
> Perhaps we need to make addr into a unsigned long long, and then add:
>
> addr = (pevent->long_size == 8) ?
> *(unsigned long long *)(data + field->offset) :
> (unsigned long long )*(unsigned int *)(data + field->offset);
I agree, we need to handle both cases:
* Traces recorded using 32-bit addresses processed on a 64-bit machine
* Traces recorded using 64-bit addresses processed on a 32-bit machine
The change you suggested fixes both these cases.
Will send a v2 of the patch with the changes.
Regards,
KP
>
>
>
> -- Steve
>
>
>> +
>> + /* In case the long_size is 4. The higher 32bits
>> + * need to be masked for a successful lookup in
>> + * in the printk table. As the pointers are 32-bit
>> + * long. This could happen if a trace recorded on
>> + * 32-bit platform is processed using a 64-bit
>> + * binary
>> + */
>> + if (pevent->long_size == 4)
>> + addr = addr & 0xffffffff;
>> +
>> /* Check if it matches a print format */
>> printk = find_printk(pevent, addr);
>> if (printk)
>
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