Re: [PATCH v2 03/14] perf report: create real callchain entries for inlined frames

[Namhyung Kim <namhyung@kernel.org>]

Hi Milian,

Sorry for late reply, I was on vacation.


On Mon, Aug 21, 2017 at 5:57 AM, Milian Wolff <milian.wolff@kdab.com> wrote:
> On Mittwoch, 16. August 2017 09:53:13 CEST Namhyung Kim wrote:
>> Hi Milian,
>>
>> On Sun, Aug 06, 2017 at 11:24:35PM +0200, Milian Wolff wrote:
>> > The inlined frames use a fake symbol that is tracked in a special
>> > map inside the dso, which is always sorted by name. All other
>>
>> It seems the above is not true.  Fake symbols are maintained by
>> inline_node which in turn maintained by dso->inlines tree.
>
> OK, I'll rephrase this to make it more explicit. But what I call "map" is what
> you call "tree", no?

Right, but as we have "map" in perf code base, I think it's better to
use "tree".

>
> <snip>
>
>> > @@ -201,7 +202,8 @@ static inline void callchain_cursor_reset(struct
>> > callchain_cursor *cursor)>
>> >  int callchain_cursor_append(struct callchain_cursor *cursor, u64 ip,
>> >
>> >                         struct map *map, struct symbol *sym,
>> >                         bool branch, struct branch_flags *flags,
>> >
>> > -                       int nr_loop_iter, int samples, u64 branch_from);
>> > +                       int nr_loop_iter, int samples, u64 branch_from,
>> > +                       const char *srcline);
>> >
>> >  /* Close a cursor writing session. Initialize for the reader */
>> >  static inline void callchain_cursor_commit(struct callchain_cursor
>> >  *cursor)
>>
>> I think it'd be better splitting srcline change into a separate
>> commit.
>
> OK, I'll try to see how this goes. It would simply add the boiler plate code
> to pass the srcline around, and then set it from within the callchain code,
> right?

Yes.  It'd help reviewers to concentrate on the logic IMHO.

Thanks,
Namhyung


>
>> > diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
>> > index b9e087fb8247..72e6e390fd26 100644
>> > --- a/tools/perf/util/dso.c
>> > +++ b/tools/perf/util/dso.c
>> > @@ -9,6 +9,7 @@
>> >
>> >  #include "compress.h"
>> >  #include "path.h"
>> >  #include "symbol.h"
>> >
>> > +#include "srcline.h"
>> >
>> >  #include "dso.h"
>> >  #include "machine.h"
>> >  #include "auxtrace.h"
>> >
>> > @@ -1233,6 +1234,7 @@ void dso__delete(struct dso *dso)
>> >
>> >                    dso->long_name);
>> >
>> >     for (i = 0; i < MAP__NR_TYPES; ++i)
>> >
>> >             symbols__delete(&dso->symbols[i]);
>> >
>> > +   inlines__tree_delete(&dso->inlined_nodes);
>>
>> Hmm.. inline_node is released after symbol but it seems to have a
>> problem.  Please see below.
>>
>> >     if (dso->short_name_allocated) {
>> >
>> >             zfree((char **)&dso->short_name);
>> >
>> > diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
>> > index f886141678eb..7d1e2b3c1f10 100644
>> > --- a/tools/perf/util/dso.h
>> > +++ b/tools/perf/util/dso.h
>> > @@ -141,6 +141,7 @@ struct dso {
>> >
>> >     struct rb_root   *root;         /* root of rbtree that rb_node is in
> */
>> >     struct rb_root   symbols[MAP__NR_TYPES];
>> >     struct rb_root   symbol_names[MAP__NR_TYPES];
>> >
>> > +   struct rb_root   inlined_nodes;
>> >
>> >     struct {
>> >
>> >             u64             addr;
>> >             struct symbol   *symbol;
>>
>> [SNIP]
>>
>> > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
>> > index d4df353051af..a7f8499c8756 100644
>> > --- a/tools/perf/util/machine.c
>> > +++ b/tools/perf/util/machine.c
>> > diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
>> > index ebc88a74e67b..a1fdf035d1dd 100644
>> > --- a/tools/perf/util/srcline.c
>> > +++ b/tools/perf/util/srcline.c
>> > @@ -33,28 +33,17 @@ static const char *dso__name(struct dso *dso)
>> >
>> >     return dso_name;
>> >
>> >  }
>> >
>> > -static int inline_list__append(char *filename, char *funcname, int
>> > line_nr, -                         struct inline_node *node, struct dso *dso)
>> > +static int inline_list__append(struct symbol *symbol, char *srcline,
>> > +                          struct inline_node *node)
>> >
>> >  {
>> >
>> >     struct inline_list *ilist;
>> >
>> > -   char *demangled;
>> >
>> >     ilist = zalloc(sizeof(*ilist));
>> >     if (ilist == NULL)
>> >
>> >             return -1;
>> >
>> > -   ilist->filename = filename;
>> > -   ilist->line_nr = line_nr;
>> > -
>> > -   if (dso != NULL) {
>> > -           demangled = dso__demangle_sym(dso, 0, funcname);
>> > -           if (demangled == NULL) {
>> > -                   ilist->funcname = funcname;
>> > -           } else {
>> > -                   ilist->funcname = demangled;
>> > -                   free(funcname);
>> > -           }
>> > -   }
>> > +   ilist->symbol = symbol;
>> > +   ilist->srcline = srcline;
>> >
>> >     if (callchain_param.order == ORDER_CALLEE)
>> >
>> >             list_add_tail(&ilist->list, &node->val);
>> >
>> > @@ -64,6 +53,30 @@ static int inline_list__append(char *filename, char
>> > *funcname, int line_nr,>
>> >     return 0;
>> >
>> >  }
>> >
>> > +// basename version that takes a const input string
>> > +static const char *gnu_basename(const char *path)
>> > +{
>> > +   const char *base = strrchr(path, '/');
>> > +
>> > +   return base ? base + 1 : path;
>> > +}
>> > +
>> > +static char *srcline_from_fileline(const char *file, unsigned int line)
>> > +{
>> > +   char *srcline;
>> > +
>> > +   if (!file)
>> > +           return NULL;
>> > +
>> > +   if (!srcline_full_filename)
>> > +           file = gnu_basename(file);
>> > +
>> > +   if (asprintf(&srcline, "%s:%u", file, line) < 0)
>> > +           return NULL;
>> > +
>> > +   return srcline;
>> > +}
>> > +
>> >
>> >  #ifdef HAVE_LIBBFD_SUPPORT
>> >
>> >  /*
>> >
>> > @@ -203,19 +216,55 @@ static void addr2line_cleanup(struct a2l_data *a2l)
>> >
>> >  #define MAX_INLINE_NEST 1024
>> >
>> > +static struct symbol *new_inline_sym(struct dso *dso,
>> > +                                struct symbol *base_sym,
>> > +                                const char *funcname)
>> > +{
>> > +   struct symbol *inline_sym;
>> > +   char *demangled = NULL;
>> > +
>> > +   if (dso) {
>> > +           demangled = dso__demangle_sym(dso, 0, funcname);
>> > +           if (demangled)
>> > +                   funcname = demangled;
>> > +   }
>> > +
>> > +   if (strcmp(funcname, base_sym->name) == 0) {
>> > +           // reuse the real, existing symbol
>> > +           inline_sym = base_sym;
>>
>> So inline_node could refer the existing symbol.
>
> Yes, that does indeed seem to be an issue. I wonder why I'm not seeing any
> crashes or valgrind/ASAN reports though. I'll have to dig into this.
>
>> > +   } else {
>> > +           // create a fake symbol for the inline frame
>> > +           inline_sym = symbol__new(base_sym ? base_sym->start : 0,
>> > +                                    base_sym ? base_sym->end : 0,
>> > +                                    base_sym ? base_sym->binding : 0,
>> > +                                    funcname);
>> > +           if (inline_sym)
>> > +                   inline_sym->inlined = 1;
>> > +   }
>> > +
>> > +   free(demangled);
>> > +
>> > +   return inline_sym;
>> > +}
>> > +
>> >
>> >  static int inline_list__append_dso_a2l(struct dso *dso,
>> >
>> > -                                  struct inline_node *node)
>> > +                                  struct inline_node *node,
>> > +                                  struct symbol *sym)
>> >
>> >  {
>> >
>> >     struct a2l_data *a2l = dso->a2l;
>> >
>> > -   char *funcname = a2l->funcname ? strdup(a2l->funcname) : NULL;
>> > -   char *filename = a2l->filename ? strdup(a2l->filename) : NULL;
>> > +   struct symbol *inline_sym = new_inline_sym(dso, sym, a2l->funcname);
>> > +   char *srcline = NULL;
>> > +
>> > +   if (a2l->filename)
>> > +           srcline = srcline_from_fileline(a2l->filename, a2l->line);
>> >
>> > -   return inline_list__append(filename, funcname, a2l->line, node, dso);
>> > +   return inline_list__append(inline_sym, srcline, node);
>> >
>> >  }
>>
>> [SNIP]
>>
>> > @@ -511,10 +563,63 @@ void inline_node__delete(struct inline_node *node)
>> >
>> >     list_for_each_entry_safe(ilist, tmp, &node->val, list) {
>> >
>> >             list_del_init(&ilist->list);
>> >
>> > -           zfree(&ilist->filename);
>> > -           zfree(&ilist->funcname);
>> > +           zfree(&ilist->srcline);
>> > +           // only the inlined symbols are owned by the list
>> > +           if (ilist->symbol && ilist->symbol->inlined)
>> > +                   symbol__delete(ilist->symbol);
>>
>> Existing symbols are released at this moment.
>
> Thanks for the review, I'll try to look into these issues once I have more
> time again.
>
> Cheers
>
> --
> Milian Wolff | milian.wolff@kdab.com | Senior Software Engineer
> KDAB (Deutschland) GmbH&Co KG, a KDAB Group company
> Tel: +49-30-521325470
> KDAB - The Qt Experts



-- 
Thanks,
Namhyung