From: Ian Rogers Date: Tue, 2 Jun 2026 15:25:16 +0000 (-0700) Subject: perf symbol: Lazily compute idle X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=044462f6f64d16e9f51a695719a3248e277c1d4e;p=thirdparty%2Fkernel%2Flinux.git perf symbol: Lazily compute idle Switch from an idle boolean to a helper symbol__is_idle function. In the function lazily compute whether a symbol is an idle function taking into consideration the kernel version and architecture of the machine. As symbols__insert no longer needs to know if a symbol is for the kernel, remove the argument. To protect against drop-filtering of legitimate setup, online, or hotplug management functions (such as intel_idle_init), x86 matches are strictly constrained to exact known run-loops (intel_idle, intel_idle_irq, mwait_idle, mwait_idle_with_hints). If the target environment OS release is unresolvable (such as on guest traces), default to treating psw_idle as idle to prevent false negatives and match legacy trace behavior safely. This change is inspired by mailing list discussion, particularly from Thomas Richter and Heiko Carstens : https://lore.kernel.org/lkml/20260219113850.354271-1-tmricht@linux.ibm.com/ Assisted-by: Gemini:gemini-3.1-pro-preview Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Alexander Gordeev Cc: Heiko Carstens Cc: Honglei Wang Cc: Jan Polensky Cc: Sumanth Korikkar Cc: Thomas Richter Cc: Vasily Gorbik Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index c5ed5e0519764..186e6d92ac3d7 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -1734,7 +1734,7 @@ dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss, arch__sym_update(f, &sym); - __symbols__insert(dso__symbols(curr_dso), f, dso__kernel(dso)); + __symbols__insert(dso__symbols(curr_dso), f); nr++; } dso__put(curr_dso); diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index ddd3106b03b16..0c46b24ee0986 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -50,7 +50,6 @@ static int dso__load_kernel_sym(struct dso *dso, struct map *map); static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map); -static bool symbol__compute_is_idle(const char *name); int vmlinux_path__nr_entries; char **vmlinux_path; @@ -379,7 +378,7 @@ void symbol__set_ifunc_alias(struct symbol *sym, bool ifunc_alias) static void symbol__set_idle(struct symbol *sym, bool idle) { - uint16_t old_flags = atomic_load(&sym->flags); + uint16_t old_flags = atomic_load_explicit(&sym->flags, memory_order_relaxed); uint16_t new_flags; uint16_t idle_val = idle ? SYMBOL_IDLE__IDLE : SYMBOL_IDLE__NOT_IDLE; @@ -401,8 +400,7 @@ void symbols__delete(struct rb_root_cached *symbols) } } -void __symbols__insert(struct rb_root_cached *symbols, - struct symbol *sym, bool kernel) +void __symbols__insert(struct rb_root_cached *symbols, struct symbol *sym) { struct rb_node **p = &symbols->rb_root.rb_node; struct rb_node *parent = NULL; @@ -410,17 +408,6 @@ void __symbols__insert(struct rb_root_cached *symbols, struct symbol *s; bool leftmost = true; - if (kernel) { - const char *name = sym->name; - /* - * ppc64 uses function descriptors and appends a '.' to the - * start of every instruction address. Remove it. - */ - if (name[0] == '.') - name++; - symbol__set_idle(sym, symbol__compute_is_idle(name)); - } - while (*p != NULL) { parent = *p; s = rb_entry(parent, struct symbol, rb_node); @@ -437,7 +424,7 @@ void __symbols__insert(struct rb_root_cached *symbols, void symbols__insert(struct rb_root_cached *symbols, struct symbol *sym) { - __symbols__insert(symbols, sym, false); + __symbols__insert(symbols, sym); } static struct symbol *symbols__find(struct rb_root_cached *symbols, u64 ip) @@ -598,7 +585,7 @@ void dso__reset_find_symbol_cache(struct dso *dso) void dso__insert_symbol(struct dso *dso, struct symbol *sym) { - __symbols__insert(dso__symbols(dso), sym, dso__kernel(dso)); + __symbols__insert(dso__symbols(dso), sym); /* update the symbol cache if necessary */ if (dso__last_find_result_addr(dso) >= sym->start && @@ -760,57 +747,120 @@ out: return err; } -bool symbol__is_idle(struct symbol *sym, - const struct dso *dso __maybe_unused, - struct perf_env *env __maybe_unused) -{ - uint16_t flags = atomic_load_explicit(&sym->flags, memory_order_relaxed); - uint16_t idle_val = (flags & SYMBOL_FLAG_IDLE_MASK) >> SYMBOL_FLAG_IDLE_SHIFT; - - return idle_val == SYMBOL_IDLE__IDLE; -} /* * These are symbols in the kernel image, so make sure that * sym is from a kernel DSO. */ -static bool symbol__compute_is_idle(const char *name) +static int sym_name_cmp(const void *a, const void *b) +{ + const char *name = a; + const char *const *sym = b; + + return strcmp(name, *sym); +} + +static bool match_x86_idle_routine(const char *name, const char *base) { - const char * const idle_symbols[] = { + if (strstarts(name, base)) { + size_t len = strlen(base); + + if (name[len] == '\0' || name[len] == '.') + return true; + } + return false; +} + +bool symbol__is_idle(struct symbol *sym, const struct dso *dso, struct perf_env *env) +{ + static const char * const idle_symbols[] = { "acpi_idle_do_entry", "acpi_processor_ffh_cstate_enter", "arch_cpu_idle", "cpu_idle", "cpu_startup_entry", - "idle_cpu", - "intel_idle", - "intel_idle_ibrs", "default_idle", - "native_safe_halt", "enter_idle", "exit_idle", - "mwait_idle", - "mwait_idle_with_hints", - "mwait_idle_with_hints.constprop.0", + "idle_cpu", + "native_safe_halt", "poll_idle", - "ppc64_runlatch_off", "pseries_dedicated_idle_sleep", - "psw_idle", - "psw_idle_exit", - NULL }; - int i; - static struct strlist *idle_symbols_list; + const char *name = sym->name; + uint16_t e_machine; - if (idle_symbols_list) - return strlist__has_entry(idle_symbols_list, name); + { + uint16_t flags = atomic_load_explicit(&sym->flags, memory_order_relaxed); + uint16_t idle_val = (flags & SYMBOL_FLAG_IDLE_MASK) >> SYMBOL_FLAG_IDLE_SHIFT; - idle_symbols_list = strlist__new(NULL, NULL); + if (idle_val != SYMBOL_IDLE__UNKNOWN) + return idle_val == SYMBOL_IDLE__IDLE; + } - for (i = 0; idle_symbols[i]; i++) - strlist__add(idle_symbols_list, idle_symbols[i]); + if (!dso || dso__kernel(dso) == DSO_SPACE__USER) { + symbol__set_idle(sym, /*idle=*/false); + return false; + } + + /* + * ppc64 uses function descriptors and appends a '.' to the + * start of every instruction address. Remove it. + */ + if (name[0] == '.') + name++; + + if (bsearch(name, idle_symbols, ARRAY_SIZE(idle_symbols), + sizeof(idle_symbols[0]), sym_name_cmp)) { + symbol__set_idle(sym, /*idle=*/true); + return true; + } + + e_machine = (env && env->arch) ? perf_env__e_machine(env, NULL) : EM_NONE; + if (e_machine == EM_NONE && dso) + e_machine = dso__e_machine((struct dso *)dso, NULL, NULL); + if (e_machine == EM_NONE && env) + e_machine = perf_env__e_machine(env, NULL); + + if (e_machine == EM_386 || e_machine == EM_X86_64) { + if (match_x86_idle_routine(name, "intel_idle") || + match_x86_idle_routine(name, "intel_idle_irq") || + match_x86_idle_routine(name, "intel_idle_ibrs") || + match_x86_idle_routine(name, "mwait_idle") || + match_x86_idle_routine(name, "mwait_idle_with_hints")) { + symbol__set_idle(sym, /*idle=*/true); + return true; + } + } + + if (e_machine == EM_PPC64 && !strcmp(name, "ppc64_runlatch_off")) { + symbol__set_idle(sym, /*idle=*/true); + return true; + } + + if (e_machine == EM_S390 && strstarts(name, "psw_idle")) { + int major = 0, minor = 0; + const char *release = env ? perf_env__os_release(env) : NULL; - return strlist__has_entry(idle_symbols_list, name); + /* + * If we can't determine the release (e.g. unpopulated guest traces), + * default to idle. + */ + if (!release) { + symbol__set_idle(sym, /*idle=*/true); + return true; + } + + /* Before v6.10, s390 used psw_idle. */ + if (sscanf(release, "%d.%d", &major, &minor) == 2 && + (major < 6 || (major == 6 && minor < 10))) { + symbol__set_idle(sym, /*idle=*/true); + return true; + } + } + + symbol__set_idle(sym, /*idle=*/false); + return false; } static int map__process_kallsym_symbol(void *arg, const char *name, @@ -839,7 +889,7 @@ static int map__process_kallsym_symbol(void *arg, const char *name, * We will pass the symbols to the filter later, in * map__split_kallsyms, when we have split the maps per module */ - __symbols__insert(root, sym, !strchr(name, '[')); + __symbols__insert(root, sym); return 0; } diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h index 16a27074a474f..a715253357037 100644 --- a/tools/perf/util/symbol.h +++ b/tools/perf/util/symbol.h @@ -76,7 +76,6 @@ enum symbol_idle_kind { #define SYMBOL_FLAG_INLINED (1 << 11) #define SYMBOL_FLAG_ANNOTATE2 (1 << 12) #define SYMBOL_FLAG_IFUNC_ALIAS (1 << 13) - /** * A symtab entry. When allocated this may be preceded by an annotation (see * symbol__annotation) and/or a browser_index (see symbol__browser_index). @@ -257,8 +256,7 @@ int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss); char *dso__demangle_sym(struct dso *dso, int kmodule, const char *elf_name); -void __symbols__insert(struct rb_root_cached *symbols, struct symbol *sym, - bool kernel); +void __symbols__insert(struct rb_root_cached *symbols, struct symbol *sym); void symbols__insert(struct rb_root_cached *symbols, struct symbol *sym); void symbols__fixup_duplicate(struct rb_root_cached *symbols); void symbols__fixup_end(struct rb_root_cached *symbols, bool is_kallsyms);