diff --git a/tools/build/feature/test-libdw.c b/tools/build/feature/test-libdw.c index aabd63ca76b4..46f75cde5947 100644 --- a/tools/build/feature/test-libdw.c +++ b/tools/build/feature/test-libdw.c @@ -49,8 +49,16 @@ int test_elfutils(void) return 0; } +/* Needs elfutils 0.160: taking its address fails the probe, not the link. */ +int test_libdw_cu_getdwarf(void) +{ + void *sym = (void *)dwarf_cu_getdwarf; + + return sym == NULL; +} + int main(void) { return test_libdw() + test_libdw_unwind() + test_libdw_getlocations() + - test_libdw_getcfi() + test_elfutils(); + test_libdw_getcfi() + test_libdw_cu_getdwarf() + test_elfutils(); } diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config index dca62e155fb5..b288ae0191ac 100644 --- a/tools/perf/Makefile.config +++ b/tools/perf/Makefile.config @@ -477,7 +477,7 @@ else else ifneq ($(feature-libdw), 1) ifndef NO_LIBDW - $(warning No libdw.h found or old libdw.h found or elfutils is older than 0.157, disables dwarf support. Please install new elfutils-devel/libdw-dev) + $(warning No libdw.h found or old libdw.h found or elfutils is older than 0.160, disables dwarf support. Please install new elfutils-devel/libdw-dev) NO_LIBDW := 1 endif endif # Dwarf support diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c index 2c135ebb1551..54f8b5ec74a2 100644 --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -1677,6 +1677,15 @@ Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die, Dwarf_Addr addr, return result; } +/* + * Whether two DIEs live in the same debug file: dwarf_dieoffset() is + * relative to the file the DIE is in. + */ +bool die_same_file(Dwarf_Die *die_a, Dwarf_Die *die_b) +{ + return dwarf_cu_getdwarf(die_a->cu) == dwarf_cu_getdwarf(die_b->cu); +} + static int __die_collect_vars_cb(Dwarf_Die *die_mem, void *arg) { struct die_var_type **var_types = arg; @@ -1721,6 +1730,8 @@ static int __die_collect_vars_cb(Dwarf_Die *die_mem, void *arg) vt->is_reg_var_addr = true; vt->die_off = dwarf_dieoffset(&type_die); + vt->die_tag = dwarf_tag(&type_die); + vt->from_alt = !die_same_file(die_mem, &type_die); vt->addr = start; vt->end = end; vt->has_range = (end != 0 || start != 0); @@ -1740,7 +1751,8 @@ static int __die_collect_vars_cb(Dwarf_Die *die_mem, void *arg) * * Save all variables and parameters in the @sc_die and save them to @var_types. * The @var_types is a singly-linked list containing type and location info. - * Actual type can be retrieved using dwarf_offdie() with 'die_off' later. + * Actual type can be retrieved using die_get_type_die() with 'die_off', + * 'die_tag' and 'from_alt' later. * * Callers should free @var_types. */ @@ -1786,6 +1798,8 @@ static int __die_collect_global_vars_cb(Dwarf_Die *die_mem, void *arg) return DIE_FIND_CB_END; vt->die_off = dwarf_dieoffset(&type_die); + vt->die_tag = dwarf_tag(&type_die); + vt->from_alt = !die_same_file(die_mem, &type_die); vt->addr = ops->number; vt->end = 0; vt->has_range = false; @@ -1797,6 +1811,43 @@ static int __die_collect_global_vars_cb(Dwarf_Die *die_mem, void *arg) return DIE_FIND_CB_SIBLING; } +/** + * die_get_type_die - Get a type DIE saved by die_collect_vars() + * @dbg: the main debug info + * @die_off: offset of the type DIE, from dwarf_dieoffset() + * @die_tag: tag that DIE had when the offset was saved + * @from_alt: whether the type DIE is in the dwz alt file + * @die_mem: where to store the resulting DIE + * + * Resolve @die_off in the file it was recorded as belonging to, with no + * fallback; @die_tag is a sanity check. + */ +Dwarf_Die *die_get_type_die(Dwarf *dbg, u64 die_off, int die_tag, bool from_alt, + Dwarf_Die *die_mem) +{ + Dwarf *target = dbg; + Dwarf_Die die; + + if (from_alt) { + /* No fallback: an alt offset here parses whatever is at it. */ + target = dwarf_getalt(dbg); + if (target == NULL) { + pr_debug("DWARF: no alt (dwz) debug file to resolve the type DIE at offset 0x%lx in\n", + (unsigned long)die_off); + return NULL; + } + } + + if (dwarf_offdie(target, die_off, &die) && dwarf_tag(&die) == die_tag) { + *die_mem = die; + return die_mem; + } + + pr_debug("DWARF: no DIE with tag %d at offset 0x%lx in the %s debug file\n", + die_tag, (unsigned long)die_off, from_alt ? "alt" : "main"); + return NULL; +} + /** * die_collect_global_vars - Save all global variables * @cu_die: a CU DIE @@ -1804,7 +1855,8 @@ static int __die_collect_global_vars_cb(Dwarf_Die *die_mem, void *arg) * * Save all global variables in the @cu_die and save them to @var_types. * The @var_types is a singly-linked list containing type and location info. - * Actual type can be retrieved using dwarf_offdie() with 'die_off' later. + * Actual type can be retrieved using die_get_type_die() with 'die_off', + * 'die_tag' and 'from_alt' later. * * Callers should free @var_types. */ diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h index 9b662db71022..6f9145510adc 100644 --- a/tools/perf/util/dwarf-aux.h +++ b/tools/perf/util/dwarf-aux.h @@ -152,6 +152,8 @@ int die_get_scopes(Dwarf_Die *cu_die, Dwarf_Addr pc, Dwarf_Die **scopes); struct die_var_type { struct die_var_type *next; u64 die_off; + int die_tag; + bool from_alt; /* die_off is relative to the alt (dwz) file */ u64 addr; u64 end; /* end address of location range */ int reg; @@ -183,6 +185,17 @@ Dwarf_Die *die_find_variable_by_addr(Dwarf_Die *sc_die, Dwarf_Addr addr, /* Save all variables and parameters in this scope */ void die_collect_vars(Dwarf_Die *sc_die, struct die_var_type **var_types); +/* + * Get the type DIE saved by die_collect_vars()/die_collect_global_vars(): + * @from_alt says which file the offset must be resolved in, @die_tag is + * a sanity check. + */ +Dwarf_Die *die_get_type_die(Dwarf *dbg, u64 die_off, int die_tag, bool from_alt, + Dwarf_Die *die_mem); + +/* Whether two DIEs live in the same debug file */ +bool die_same_file(Dwarf_Die *die_a, Dwarf_Die *die_b); + /* Save all global variables in this CU */ void die_collect_global_vars(Dwarf_Die *cu_die, struct die_var_type **var_types);