perf symbols: Fix kallsyms perf test on ppc64le

ppc64le functions have a Global Entry Point (GEP) and a Local Entry
Point (LEP). While placing a probe, we always prefer the LEP since it
catches function calls through both the GEP and the LEP. In order to do
this, we fixup the function entry points during elf symbol table lookup
to point to the LEPs. This works, but breaks 'perf test kallsyms' since
the symbols loaded from the symbol table (pointing to the LEP) do not
match the symbols in kallsyms.

To fix this, we do not adjust all the symbols during symbol table load.
Instead, we note down st_other in a newly introduced arch-specific
member of perf symbol structure, and later use this to adjust the probe
trace point.

Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Cc: Mark Wielaard <mjw@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/6be7c2b17e370100c2f79dd444509df7929bdd3e.1460451721.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/arch/powerpc/util/sym-handling.c b/tools/perf/arch/powerpc/util/sym-handling.c
index 6974ba0fa0655744dd42b55513157d82484329bb..c6d0f91731a14732333af62d0a40a3ea43fb4c99 100644 (file)
--- a/tools/perf/arch/powerpc/util/sym-handling.c
+++ b/tools/perf/arch/powerpc/util/sym-handling.c
@@ -19,12 +19,6 @@ bool elf__needs_adjust_symbols(GElf_Ehdr ehdr)
               ehdr.e_type == ET_DYN;
 }
 
-#if defined(_CALL_ELF) && _CALL_ELF == 2
-void arch__elf_sym_adjust(GElf_Sym *sym)
-{
-       sym->st_value += PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
-}
-#endif
 #endif
 
 #if !defined(_CALL_ELF) || _CALL_ELF != 2
@@ -65,11 +59,21 @@ bool arch__prefers_symtab(void)
        return true;
 }
 
+#ifdef HAVE_LIBELF_SUPPORT
+void arch__sym_update(struct symbol *s, GElf_Sym *sym)
+{
+       s->arch_sym = sym->st_other;
+}
+#endif
+
 #define PPC64LE_LEP_OFFSET     8
 
 void arch__fix_tev_from_maps(struct perf_probe_event *pev,
-                            struct probe_trace_event *tev, struct map *map)
+                            struct probe_trace_event *tev, struct map *map,
+                            struct symbol *sym)
 {
+       int lep_offset;
+
        /*
         * When probing at a function entry point, we normally always want the
         * LEP since that catches calls to the function through both the GEP and
@@ -82,10 +86,18 @@ void arch__fix_tev_from_maps(struct perf_probe_event *pev,
         *
         * In addition, we shouldn't specify an offset for kretprobes.
         */
-       if (pev->point.offset || pev->point.retprobe || !map)
+       if (pev->point.offset || pev->point.retprobe || !map || !sym)
                return;
 
+       lep_offset = PPC64_LOCAL_ENTRY_OFFSET(sym->arch_sym);
+
        if (map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS)
                tev->point.offset += PPC64LE_LEP_OFFSET;
+       else if (lep_offset) {
+               if (pev->uprobes)
+                       tev->point.address += lep_offset;
+               else
+                       tev->point.offset += lep_offset;
+       }
 }
 #endif

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 85d82f4dc5e9e1e3c9fb6c4a5e060b25031d5b5f..c82c625395ab955185fe609a3deb7f8a2a10351b 100644 (file)
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -2477,7 +2477,8 @@ static int find_probe_functions(struct map *map, char *name,
 
 void __weak arch__fix_tev_from_maps(struct perf_probe_event *pev __maybe_unused,
                                struct probe_trace_event *tev __maybe_unused,
-                               struct map *map __maybe_unused) { }
+                               struct map *map __maybe_unused,
+                               struct symbol *sym __maybe_unused) { }
 
 /*
  * Find probe function addresses from map.
@@ -2614,7 +2615,7 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
                                        strdup_or_goto(pev->args[i].type,
                                                        nomem_out);
                }
-               arch__fix_tev_from_maps(pev, tev, map);
+               arch__fix_tev_from_maps(pev, tev, map, sym);
        }
        if (ret == skipped) {
                ret = -ENOENT;

diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index e2209623f981b9dc4e1aec3e1fb9948fe529d229..5a27eb4fad05a29e518ac7b9ecad4a25fb8f4dd6 100644 (file)
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -154,7 +154,8 @@ int show_available_vars(struct perf_probe_event *pevs, int npevs,
 int show_available_funcs(const char *module, struct strfilter *filter, bool user);
 bool arch__prefers_symtab(void);
 void arch__fix_tev_from_maps(struct perf_probe_event *pev,
-                            struct probe_trace_event *tev, struct map *map);
+                            struct probe_trace_event *tev, struct map *map,
+                            struct symbol *sym);
 
 /* If there is no space to write, returns -E2BIG. */
 int e_snprintf(char *str, size_t size, const char *format, ...)

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 3f9d6798bd18358945c86e260afd135417d88163..87a297dd89016e13a829d4a7397c74e0892eae30 100644 (file)
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -770,7 +770,8 @@ static bool want_demangle(bool is_kernel_sym)
        return is_kernel_sym ? symbol_conf.demangle_kernel : symbol_conf.demangle;
 }
 
-void __weak arch__elf_sym_adjust(GElf_Sym *sym __maybe_unused) { }
+void __weak arch__sym_update(struct symbol *s __maybe_unused,
+               GElf_Sym *sym __maybe_unused) { }
 
 int dso__load_sym(struct dso *dso, struct map *map,
                  struct symsrc *syms_ss, struct symsrc *runtime_ss,
@@ -947,8 +948,6 @@ int dso__load_sym(struct dso *dso, struct map *map,
                    (sym.st_value & 1))
                        --sym.st_value;
 
-               arch__elf_sym_adjust(&sym);
-
                if (dso->kernel || kmodule) {
                        char dso_name[PATH_MAX];
 
@@ -1082,6 +1081,8 @@ new_symbol:
                if (!f)
                        goto out_elf_end;
 
+               arch__sym_update(f, &sym);
+
                if (filter && filter(curr_map, f))
                        symbol__delete(f);
                else {

diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index c8e43979ed5c481204182fba128d7ccbc9415d28..07211c2f8456b409982532632726cb524c150ac1 100644 (file)
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -55,6 +55,7 @@ struct symbol {
        u16             namelen;
        u8              binding;
        bool            ignore;
+       u8              arch_sym;
        char            name[0];
 };
 
@@ -323,7 +324,7 @@ int setup_intlist(struct intlist **list, const char *list_str,
 
 #ifdef HAVE_LIBELF_SUPPORT
 bool elf__needs_adjust_symbols(GElf_Ehdr ehdr);
-void arch__elf_sym_adjust(GElf_Sym *sym);
+void arch__sym_update(struct symbol *s, GElf_Sym *sym);
 #endif
 
 #define SYMBOL_A 0