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perf symbols: Demangle symbols for synthesized @plt entries. 

The symbols in the synthesized @plt entries where not demangled before,
i.e. we could end up with entries such as:

    $ perf report
    Samples: 7K of event 'cycles:ppp', Event count (approx.): 6223833141
    Children      Self  Command          Shared Object           Symbol
    -   93.63%    28.89%  lab_mandelbrot   lab_mandelbrot        [.] main
        - 73.81% main
            - 33.57% hypot
              27.76% __hypot_finite
              15.97% __muldc3
               2.90% __muldc3@plt
               2.40% _ZNK6QImage6heightEv@plt
             + 2.14% QColor::rgb
               1.94% _ZNK6QImage5widthEv@plt
               1.92% cabs@plt

This patch remedies this issue by also applying demangling to the
synthesized symbols. The output for the above is now:

    $ perf report
    Samples: 7K of event 'cycles:ppp', Event count (approx.): 6223833141
    Children      Self  Command          Shared Object           Symbol
    -   93.63%    28.89%  lab_mandelbrot   lab_mandelbrot        [.] main
        - 73.81% main
            - 33.57% hypot
              27.76% __hypot_finite
              15.97% __muldc3
               2.90% __muldc3@plt
               2.40% QImage::height() const@plt
             + 2.14% QColor::rgb
               1.94% QImage::width() const@plt
               1.92% cabs@plt

Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
LPU-Reference: 20160830114102.30863-1-milian.wolff@kdab.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Milian Wolff 2016-08-30 13:41:02 +02:00 committed by Arnaldo Carvalho de Melo
parent fd2275984d
commit 2a8d41b465
1 changed files with 52 additions and 29 deletions
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81
tools/perf/util/symbol-elf.c
View File

@ -206,6 +206,37 @@ Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
return NULL;
}
static bool want_demangle(bool is_kernel_sym)
{
return is_kernel_sym ? symbol_conf.demangle_kernel : symbol_conf.demangle;
}
static char *demangle_sym(struct dso *dso, int kmodule, const char *elf_name)
{
int demangle_flags = verbose ? (DMGL_PARAMS | DMGL_ANSI) : DMGL_NO_OPTS;
char *demangled = NULL;
/*
* We need to figure out if the object was created from C++ sources
* DWARF DW_compile_unit has this, but we don't always have access
* to it...
*/
if (!want_demangle(dso->kernel || kmodule))
return demangled;
demangled = bfd_demangle(NULL, elf_name, demangle_flags);
if (demangled == NULL)
demangled = java_demangle_sym(elf_name, JAVA_DEMANGLE_NORET);
else if (rust_is_mangled(demangled))
/*
* Input to Rust demangling is the BFD-demangled
* name which it Rust-demangles in place.
*/
rust_demangle_sym(demangled);
return demangled;
}
#define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \
for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \
idx < nr_entries; \
@ -301,11 +332,19 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss, struct map *
elf_section__for_each_rela(reldata, pos, pos_mem, idx,
nr_rel_entries) {
const char *elf_name = NULL;
char *demangled = NULL;
symidx = GELF_R_SYM(pos->r_info);
plt_offset += shdr_plt.sh_entsize;
gelf_getsym(syms, symidx, &sym);
elf_name = elf_sym__name(&sym, symstrs);
demangled = demangle_sym(dso, 0, elf_name);
if (demangled != NULL)
elf_name = demangled;
snprintf(sympltname, sizeof(sympltname),
"%s@plt", elf_sym__name(&sym, symstrs));
"%s@plt", elf_name);
free(demangled);
f = symbol__new(plt_offset, shdr_plt.sh_entsize,
STB_GLOBAL, sympltname);
@ -323,11 +362,19 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss, struct map *
GElf_Rel pos_mem, *pos;
elf_section__for_each_rel(reldata, pos, pos_mem, idx,
nr_rel_entries) {
const char *elf_name = NULL;
char *demangled = NULL;
symidx = GELF_R_SYM(pos->r_info);
plt_offset += shdr_plt.sh_entsize;
gelf_getsym(syms, symidx, &sym);
elf_name = elf_sym__name(&sym, symstrs);
demangled = demangle_sym(dso, 0, elf_name);
if (demangled != NULL)
elf_name = demangled;
snprintf(sympltname, sizeof(sympltname),
"%s@plt", elf_sym__name(&sym, symstrs));
"%s@plt", elf_name);
free(demangled);
f = symbol__new(plt_offset, shdr_plt.sh_entsize,
STB_GLOBAL, sympltname);
@ -775,11 +822,6 @@ static u64 ref_reloc(struct kmap *kmap)
return 0;
}
static bool want_demangle(bool is_kernel_sym)
{
return is_kernel_sym ? symbol_conf.demangle_kernel : symbol_conf.demangle;
}
void __weak arch__sym_update(struct symbol *s __maybe_unused,
GElf_Sym *sym __maybe_unused) { }
@ -1070,29 +1112,10 @@ int dso__load_sym(struct dso *dso, struct map *map,
sym.st_value -= shdr.sh_addr - shdr.sh_offset;
}
new_symbol:
/*
* We need to figure out if the object was created from C++ sources
* DWARF DW_compile_unit has this, but we don't always have access
* to it...
*/
if (want_demangle(dso->kernel || kmodule)) {
int demangle_flags = DMGL_NO_OPTS;
if (verbose)
demangle_flags = DMGL_PARAMS | DMGL_ANSI;
demangled = demangle_sym(dso, kmodule, elf_name);
if (demangled != NULL)
elf_name = demangled;
demangled = bfd_demangle(NULL, elf_name, demangle_flags);
if (demangled == NULL)
demangled = java_demangle_sym(elf_name, JAVA_DEMANGLE_NORET);
else if (rust_is_mangled(demangled))
/*
* Input to Rust demangling is the BFD-demangled
* name which it Rust-demangles in place.
*/
rust_demangle_sym(demangled);
if (demangled != NULL)
elf_name = demangled;
}
f = symbol__new(sym.st_value, sym.st_size,
GELF_ST_BIND(sym.st_info), elf_name);
free(demangled);