Hi Jiping,
(CC: +linux-arm-kernel)
On 31/07/2019 11:57, Steven Rostedt wrote:
> On Wed, 31 Jul 2019 17:04:37 +0800
> Jiping Ma <jiping....@windriver.com> wrote:
> Note, the subject is not properly written, as it is missing the
> subsystem. In this case, it should start with "tracing: "
>
>
>> The PC of one the frame is matched to the next frame function, rather
>> than the function of his frame.
>
> The above change log doesn't make sense. I have no idea what the actual
> problem is here. Why is this different for arm64 and no one else? Seems
> the bug is with the stack logic code in arm64 not here.
Please copy the mailing list for the arm64 arch code too.
Is this thing a recent change? arm64's stacktrace code gained some better
protection for
loops at -rc2.
Thanks,
James
>> diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
>> index 5d16f73898db..ed80b95abf06 100644
>> --- a/kernel/trace/trace_stack.c
>> +++ b/kernel/trace/trace_stack.c
>> @@ -40,16 +40,28 @@ static void print_max_stack(void)
>>
>> pr_emerg(" Depth Size Location (%d entries)\n"
>> " ----- ---- --------\n",
>> +#ifdef CONFIG_ARM64
>
> We do not allow arch specific defines in generic code. Otherwise this
> would blow up and become unmaintainable. Not to mention it makes the
> code ugly and hard to follow.
>
> Please explain the problem better. I'm sure there's much better ways to
> solve this than this patch.
>
> Thanks,
>
> -- Steve
>
>
>
>> + stack_trace_nr_entries - 1);
>> +#else
>> stack_trace_nr_entries);
>> -
>> +#endif
>> +#ifdef CONFIG_ARM64
>> + for (i = 1; i < stack_trace_nr_entries; i++) {
>> +#else
>> for (i = 0; i < stack_trace_nr_entries; i++) {
>> +#endif
>> if (i + 1 == stack_trace_nr_entries)
>> size = stack_trace_index[i];
>> else
>> size = stack_trace_index[i] - stack_trace_index[i+1];
>>
>> +#ifdef CONFIG_ARM64
>> + pr_emerg("%3ld) %8d %5d %pS\n", i-1, stack_trace_index[i],
>> + size, (void *)stack_dump_trace[i-1]);
>> +#else
>> pr_emerg("%3ld) %8d %5d %pS\n", i, stack_trace_index[i],
>> size, (void *)stack_dump_trace[i]);
>> +#endif
>> }
>> }
>>
>> @@ -324,8 +336,11 @@ static int t_show(struct seq_file *m, void *v)
>> seq_printf(m, " Depth Size Location"
>> " (%d entries)\n"
>> " ----- ---- --------\n",
>> +#ifdef CONFIG_ARM64
>> + stack_trace_nr_entries - 1);
>> +#else
>> stack_trace_nr_entries);
>> -
>> +#endif
>> if (!stack_tracer_enabled && !stack_trace_max_size)
>> print_disabled(m);
>>
>> @@ -334,6 +349,10 @@ static int t_show(struct seq_file *m, void *v)
>>
>> i = *(long *)v;
>>
>> +#ifdef CONFIG_ARM64
>> + if (i == 0)
>> + return 0;
>> +#endif
>> if (i >= stack_trace_nr_entries)
>> return 0;
>>
>> @@ -342,9 +361,14 @@ static int t_show(struct seq_file *m, void *v)
>> else
>> size = stack_trace_index[i] - stack_trace_index[i+1];
>>
>> +#ifdef CONFIG_ARM64
>> + seq_printf(m, "%3ld) %8d %5d ", i-1, stack_trace_index[i], size);
>> + trace_lookup_stack(m, i-1);
>> +#else
>> seq_printf(m, "%3ld) %8d %5d ", i, stack_trace_index[i], size);
>>
>> trace_lookup_stack(m, i);
>> +#endif
>>
>> return 0;
>> }
>
