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SubjectRe: [PATCH v2 3/4] perf augmented_raw_syscalls: Support arm64 raw syscalls
On Thu, Jun 13, 2019 at 03:15:14PM -0300, Arnaldo Carvalho de Melo wrote:

[...]

> > > > diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> > > > index 1a2a605cf068..eb70a4b71755 100644
> > > > --- a/tools/perf/builtin-trace.c
> > > > +++ b/tools/perf/builtin-trace.c
> > > > @@ -1529,6 +1529,7 @@ static int trace__read_syscall_info(struct trace *trace, int id)
> > > > static int trace__validate_ev_qualifier(struct trace *trace)
> > > > {
> > > > int err = 0, i;
> > > > + bool printed_invalid_prefix = false;
> > > > size_t nr_allocated;
> > > > struct str_node *pos;
> > > >
> > > > @@ -1555,14 +1556,15 @@ static int trace__validate_ev_qualifier(struct trace *trace)
> > > > if (id >= 0)
> > > > goto matches;
> > > >
> > > > - if (err == 0) {
> > > > - fputs("Error:\tInvalid syscall ", trace->output);
> > > > - err = -EINVAL;
> > > > + if (!printed_invalid_prefix) {
> > > > + pr_debug("Skipping unknown syscalls: ");
> > > > + printed_invalid_prefix = true;
> > > > } else {
> > > > - fputs(", ", trace->output);
> > > > + pr_debug(", ");
> > > > }
> > > >
> > > > - fputs(sc, trace->output);
> > > > + pr_debug("%s", sc);
> > > > + continue;
> > >
> > > Here adds 'continue' so that we want to let ev_qualifier_ids.entries
> > > to only store valid system call ids. But this is not sufficient,
> > > because we have initialized ev_qualifier_ids.nr at the beginning of
> > > the function:
> > >
> > > trace->ev_qualifier_ids.nr = strlist__nr_entries(trace->ev_qualifier);
> > > This sentence will set ids number to the string table's length; but
> > > actually some strings are not really supported; this leads to some
> > > items in trace->ev_qualifier_ids.entries[] will be not initialized
> > > properly.
> > >
> > > If we want to get neat entries and entry number, I suggest at the
> > > beginning of the function we use variable 'nr_allocated' to store
> > > string table length and use it to allocate entries:
> > >
> > > nr_allocated = strlist__nr_entries(trace->ev_qualifier);
> > > trace->ev_qualifier_ids.entries = malloc(nr_allocated *
> > > sizeof(trace->ev_qualifier_ids.entries[0]));
> > >
> > > If we find any matched string, then increment the nr field under
> > > 'matches' tag:
> > >
> > > matches:
> > > trace->ev_qualifier_ids.nr++;
> > > trace->ev_qualifier_ids.entries[i++] = id;
> > >
> > > This can ensure the entries[0..nr-1] has valid id and we can use
> > > ev_qualifier_ids.nr to maintain the valid system call numbers.
> >
> > yeah, you're right, I'll address these issues in a followup patch,
> > tomorrow.
>
> This is equivalent and I think the smallest patch, I'll add one on top
> doing what you suggested about nr_allocated getting the
> strlist__nr_entries() and also will rename i to nr_used to contrast with
> nr_allocated, and then at the end set ev_qualifier_ids.nr to nr_used.

Thanks for this patch, I tested below changes and 'perf trace' works
well. You could add my test tag:

Tested-by: Leo Yan <leo.yan@linaro.org>

> - Arnaldo
>
> diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> index eb70a4b71755..bd1f00e7a2eb 100644
> --- a/tools/perf/builtin-trace.c
> +++ b/tools/perf/builtin-trace.c
> @@ -1528,9 +1528,9 @@ static int trace__read_syscall_info(struct trace *trace, int id)
>
> static int trace__validate_ev_qualifier(struct trace *trace)
> {
> - int err = 0, i;
> + int err = 0;
> bool printed_invalid_prefix = false;
> - size_t nr_allocated;
> + size_t nr_allocated, i;
> struct str_node *pos;
>
> trace->ev_qualifier_ids.nr = strlist__nr_entries(trace->ev_qualifier);
> @@ -1575,7 +1575,7 @@ static int trace__validate_ev_qualifier(struct trace *trace)
> id = syscalltbl__strglobmatch_next(trace->sctbl, sc, &match_next);
> if (id < 0)
> break;
> - if (nr_allocated == trace->ev_qualifier_ids.nr) {
> + if (nr_allocated == i) {
> void *entries;
>
> nr_allocated += 8;
> @@ -1588,11 +1588,11 @@ static int trace__validate_ev_qualifier(struct trace *trace)
> }
> trace->ev_qualifier_ids.entries = entries;
> }
> - trace->ev_qualifier_ids.nr++;
> trace->ev_qualifier_ids.entries[i++] = id;
> }
> }
>
> + trace->ev_qualifier_ids.nr = i;
> out:
> if (printed_invalid_prefix)
> pr_debug("\n");

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