Messages in this thread | | | Date | Tue, 15 Dec 2009 03:12:03 +0100 | From | Frederic Weisbecker <> | Subject | Re: [tip:perf/urgent] perf symbols: Allow lookups by symbol name too |
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On Sat, Dec 12, 2009 at 07:22:03AM +0000, tip-bot for Arnaldo Carvalho de Melo wrote: > Commit-ID: 79406cd789f745ac6aa9d597895f904a98a14007 > Gitweb: http://git.kernel.org/tip/79406cd789f745ac6aa9d597895f904a98a14007 > Author: Arnaldo Carvalho de Melo <acme@redhat.com> > AuthorDate: Fri, 11 Dec 2009 18:50:22 -0200 > Committer: Ingo Molnar <mingo@elte.hu> > CommitDate: Sat, 12 Dec 2009 07:42:11 +0100 > > perf symbols: Allow lookups by symbol name too > > Configurable via symbol_conf.sort_by_name, so that the cost of an > extra rb_node on all 'struct symbol' instances is not paid by tools > that only want to decode addresses. > > How to use it: > > symbol_conf.sort_by_name = true; > symbol_init(&symbol_conf); > > struct map *map = map_groups__find_by_name(kmaps, MAP__VARIABLE, "[kernel.kallsyms]"); > > if (map == NULL) { > pr_err("couldn't find map!\n"); > kernel_maps__fprintf(stdout); > } else { > struct symbol *sym = map__find_symbol_by_name(map, sym_filter, NULL); > if (sym == NULL) > pr_err("couldn't find symbol %s!\n", sym_filter); > else > pr_info("symbol %s: %#Lx-%#Lx \n", sym_filter, sym->start, sym->end); > } > > Looking over the vmlinux/kallsyms is common enough that I'll add a > variable to the upcoming struct perf_session to avoid the need to > use map_groups__find_by_name to get the main vmlinux/kallsyms map. > > The above example looks on the 'variable' symtab, but it is just > like that for the functions one. > > Also the sort operation is done when we first use > map__find_symbol_by_name, in a lazy way.
It would be nice to also have a kernel symbol resolution helper independant of any session.
The problem is that I need to resolve a kernel variable symbol very early, when we parse record options. We don't have any session at this time so I can't retrieve the kmaps.
I'm not sure what's the proper way to handle that.
Thanks.
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