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SubjectRe: [PATCH v4] tools lib traceevent: str addresses in heterogeneous arch environments
Hi Steve,

On 21/09/15 16:02, Steven Rostedt wrote:
> On Mon, 21 Sep 2015 15:26:23 +0100
> Kapileshwar Singh <kapileshwar.singh@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 ignored
>>
>> 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 *)
>>
>> Heterogeneous architectures cases below can arise and should be handled:
>>
>> * Traces recorded using 32-bit addresses processed on a 64-bit machine
>> * Traces recorded using 64-bit addresses processed on a 32-bit machine
>>
>> Cc: Steven Rostedt <rostedt@goodmis.org>
>> Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
>> Cc: Namhyung Kim <namhyung@kernel.org>
>> Cc: Javi Merino <javi.merino@arm.com>
>> Cc: David Ahern <dsahern@gmail.com>
>> Cc: Jiri Olsa <jolsa@kernel.org>
>> Reported-by: Juri Lelli <juri.lelli@arm.com>
>> Signed-off-by: Kapileshwar Singh <kapileshwar.singh@arm.com>
>> ---
>> tools/lib/traceevent/event-parse.c | 24 +++++++++++++++++++++---
>> 1 file changed, 21 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
>> index cc25f059ab3d..e622d2efeccf 100644
>> --- a/tools/lib/traceevent/event-parse.c
>> +++ b/tools/lib/traceevent/event-parse.c
>> @@ -3721,7 +3721,7 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
>> struct format_field *field;
>> struct printk_map *printk;
>> long long val, fval;
>> - unsigned long addr;
>> + unsigned long long addr;
>> char *str;
>> unsigned char *hex;
>> int print;
>> @@ -3754,13 +3754,31 @@ 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);
>> +
>> + /* Handle heterogeneous recording and processing
>> + * architectures
>> + *
>> + * CASE I:
>> + * Traces recorded on 32-bit devices (32-bit
>> + * addressing) and processed on 64-bit devices:
>> + * In this case, the higher 32-bits of the address
>> + * need to be ignored.
>
> I just re-read this, and realized that it's not quite accurate. It
> should say something like "In this case, only 32 bits should be read.",
> as the above describes more of Namhyung's version which was incorrect.

Will correct the comment and send an updated patch.

Regards,
KP
>
> -- Steve
>
>
>> + *
>> + * CASE II:
>> + * Traces recorded on 64 bit devices and processed
>> + * on 32-bit devices. In this case 64 bits must be
>> + * read.
>> + */
>> + addr = (pevent->long_size == 8) ?
>> + *(unsigned long long *)(data + field->offset) :
>> + (unsigned long long)*(unsigned int *)(data + field->offset);
>> +
>> /* Check if it matches a print format */
>> printk = find_printk(pevent, addr);
>> if (printk)
>> trace_seq_puts(s, printk->printk);
>> else
>> - trace_seq_printf(s, "%lx", addr);
>> + trace_seq_printf(s, "%llx", addr);
>> break;
>> }
>> str = malloc(len + 1);
>



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