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);
-- 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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