From: Arnaldo Carvalho de Melo Date: Mon, 8 Sep 2025 20:36:28 +0000 (-0300) Subject: perf symbols: Handle 'N' symbols in /proc/kallsyms X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=945f50036169714dd30b8cb37370059f2dc924e1;p=users%2Fjedix%2Flinux-maple.git perf symbols: Handle 'N' symbols in /proc/kallsyms I started seeing this in recent Fedora 42 kernels: # uname -a Linux number 6.16.3-200.fc42.x86_64 #1 SMP PREEMPT_DYNAMIC Sat Aug 23 17:02:17 UTC 2025 x86_64 GNU/Linux # # perf test vmlinux 1: vmlinux symtab matches kallsyms : FAILED! # Rust is enabled and these were the symbols causing the above failure, i.e. found in vmlinux but not in /proc/kallsyms: $ grep -w N /proc/kallsyms 0000000000000000 N __pfx__RNCINvNtNtNtCsbDUBuN8AbD4_4core4iter8adapters3map12map_try_foldjNtCs6vVzKs5jPr6_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_ 0000000000000000 N _RNCINvNtNtNtCsbDUBuN8AbD4_4core4iter8adapters3map12map_try_foldjNtCs6vVzKs5jPr6_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_ $ So accept those 'N' symbols as well. About them, from 'man nm': "N" The symbol is a debugging symbol. "n" The symbol is in a non-data, non-code, non-debug read-only section. Reviewed-by: Ian Rogers Cc: Adrian Hunter Cc: Miguel Ojeda Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Signed-off-by: Arnaldo Carvalho de Melo --- diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 3fed54de5401..3d04382687d1 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -107,9 +107,14 @@ static enum dso_binary_type binary_type_symtab[] = { static bool symbol_type__filter(char __symbol_type) { // Since 'U' == undefined and 'u' == unique global symbol, we can't use toupper there + // 'N' is for debugging symbols, 'n' is a non-data, non-code, non-debug read-only section. + // According to 'man nm'. + // 'N' first seen in: + // ffffffff9b35d130 N __pfx__RNCINvNtNtNtCsbDUBuN8AbD4_4core4iter8adapters3map12map_try_foldjNtCs6vVzKs5jPr6_12drm_panic_qr7VersionuINtNtNtBa_3ops12control_flow11ControlFlowB10_ENcB10_0NCINvNvNtNtNtB8_6traits8iterator8Iterator4find5checkB10_NCNvMB12_B10_13from_segments0E0E0B12_ + // a seemingly Rust mangled name char symbol_type = toupper(__symbol_type); return symbol_type == 'T' || symbol_type == 'W' || symbol_type == 'D' || symbol_type == 'B' || - __symbol_type == 'u' || __symbol_type == 'l'; + __symbol_type == 'u' || __symbol_type == 'l' || __symbol_type == 'N'; } static int prefix_underscores_count(const char *str)