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However, function pointer arguments are currently not recognised during BTF pretty-printing and default to hexadecimal output. Introduce btf_is_func_ptr() to inspect BTF type hierarchies (i.e., traversing pointers, typedefs, and type modifiers) to determine whether a parameter resolves to a function prototype (BTF_KIND_FUNC_PROTO). Generalise BTF type caching via syscall_arg_fmt__cache_btf_type() to handle structs, unions, enums, and function pointers alike. When a field is identified as a kernel function pointer, trace__btf_scnprintf() routes its value to syscall_arg__scnprintf_ksym(), enabling automatic zero-config symbolisation of kernel function pointers whenever BTF is available. Signed-off-by: Aaron Tomlin --- tools/perf/builtin-trace.c | 87 ++++++++++++++++----- tools/perf/tests/shell/trace_btf_general.sh | 2 +- 2 files changed, 68 insertions(+), 21 deletions(-) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index bb8f4fd9ba24..4182906449a9 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -122,6 +122,7 @@ struct syscall_arg_fmt { #ifdef HAVE_LIBBPF_SUPPORT const struct btf_type *type; int type_id; /* used in btf_dump */ + bool btf_type_cached; #endif }; @@ -979,21 +980,61 @@ static size_t syscall_arg__scnprintf_getrandom_flags(char *bf, size_t size, #define SCA_GETRANDOM_FLAGS syscall_arg__scnprintf_getrandom_flags #ifdef HAVE_LIBBPF_SUPPORT -static void syscall_arg_fmt__cache_btf_enum(struct syscall_arg_fmt *arg_fmt, struct btf *btf, char *type) +static bool btf_is_func_ptr(const struct btf *btf, const struct btf_type *type) { + while (type) { + if (btf_is_ptr(type) || btf_is_typedef(type) || btf_is_mod(type)) + type = btf__type_by_id(btf, type->type); + else + break; + } + return type && btf_is_func_proto(type); +} + +static void syscall_arg_fmt__cache_btf_type(struct syscall_arg_fmt *arg_fmt, + struct btf *btf, const char *type) +{ + char name[128]; + const char *pos; + size_t len = 0; int id; - type = strstr(type, "enum "); + arg_fmt->btf_type_cached = true; + if (type == NULL) return; - type += 5; // skip "enum " to get the enumeration name + /* Pointers to enums are memory addresses, not scalar enums */ + if (strstr(type, "enum ") && strchr(type, '*')) + return; + + if ((pos = strstr(type, "enum ")) != NULL) + pos += 5; + else if ((pos = strstr(type, "struct ")) != NULL) + pos += 7; + else if ((pos = strstr(type, "union ")) != NULL) + pos += 6; + else + pos = type; + + while (isspace(*pos)) + pos++; - id = btf__find_by_name(btf, type); + while ((isalnum(pos[len]) || pos[len] == '_') && len < sizeof(name) - 1) { + name[len] = pos[len]; + len++; + } + name[len] = '\0'; + + if (len == 0) + return; + + id = btf__find_by_name(btf, name); if (id < 0) return; arg_fmt->type = btf__type_by_id(btf, id); + arg_fmt->type_id = id; } static bool syscall_arg__strtoul_btf_enum(char *bf, size_t size, struct syscall_arg *arg, u64 *val) @@ -1027,10 +1068,8 @@ static bool syscall_arg__strtoul_btf_type(char *bf, size_t size, struct syscall_ if (btf == NULL) return false; - if (arg->fmt->type == NULL) { - // See if this is an enum - syscall_arg_fmt__cache_btf_enum(arg->fmt, btf, type); - } + if (!arg->fmt->btf_type_cached) + syscall_arg_fmt__cache_btf_type(arg->fmt, btf, type); // Now let's see if we have a BTF type resolved bt = arg->fmt->type; @@ -1038,19 +1077,22 @@ static bool syscall_arg__strtoul_btf_type(char *bf, size_t size, struct syscall_ return false; // If it is an enum: - if (btf_is_enum(arg->fmt->type)) + if (btf_is_enum(arg->fmt->type)) { + if (type && strchr(type, '*')) + return false; return syscall_arg__strtoul_btf_enum(bf, size, arg, val); + } return false; } -static size_t btf_enum_scnprintf(const struct btf_type *type, struct btf *btf, char *bf, size_t size, int val) +static size_t btf_enum_scnprintf(const struct btf_type *type, struct btf *btf, char *bf, size_t size, unsigned long val) { struct btf_enum *be = btf_enum(type); const unsigned int nr_entries = btf_vlen(type); for (unsigned int i = 0; i < nr_entries; ++i, ++be) { - if (be->val == val) { + if ((unsigned long)(__u32)be->val == val || (unsigned long)be->val == val) { return scnprintf(bf, size, "%s", btf__name_by_offset(btf, be->name_off)); } @@ -1108,33 +1150,37 @@ static size_t btf_struct_scnprintf(const struct btf_type *type, struct btf *btf, } static size_t trace__btf_scnprintf(struct trace *trace, struct syscall_arg *arg, char *bf, - size_t size, int val, char *type) + size_t size, unsigned long val, char *type) { struct syscall_arg_fmt *arg_fmt = arg->fmt; if (trace->btf == NULL) return 0; - if (arg_fmt->type == NULL) { - // Check if this is an enum and if we have the BTF type for it. - syscall_arg_fmt__cache_btf_enum(arg_fmt, trace->btf, type); - } + if (!arg_fmt->btf_type_cached) + syscall_arg_fmt__cache_btf_type(arg_fmt, trace->btf, type); // Did we manage to find a BTF type for the syscall/tracepoint argument? if (arg_fmt->type == NULL) return 0; - if (btf_is_enum(arg_fmt->type)) + if (btf_is_enum(arg_fmt->type)) { + if (type && strchr(type, '*')) + return 0; return btf_enum_scnprintf(arg_fmt->type, trace->btf, bf, size, val); - else if (btf_is_struct(arg_fmt->type) || btf_is_union(arg_fmt->type)) + } else if (btf_is_struct(arg_fmt->type) || btf_is_union(arg_fmt->type)) return btf_struct_scnprintf(arg_fmt->type, trace->btf, bf, size, arg); + else if (btf_is_func_ptr(trace->btf, arg_fmt->type)) { + arg->val = val; + return syscall_arg__scnprintf_ksym(bf, size, arg); + } return 0; } #else // HAVE_LIBBPF_SUPPORT static size_t trace__btf_scnprintf(struct trace *trace __maybe_unused, struct syscall_arg *arg __maybe_unused, - char *bf __maybe_unused, size_t size __maybe_unused, int val __maybe_unused, + char *bf __maybe_unused, size_t size __maybe_unused, unsigned long val __maybe_unused, char *type __maybe_unused) { return 0; @@ -2566,7 +2612,8 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size, default_scnprintf = sc->arg_fmt[arg.idx].scnprintf; - if (trace->force_btf || default_scnprintf == NULL || default_scnprintf == SCA_PTR) { + if (trace->force_btf || default_scnprintf == NULL || + default_scnprintf == SCA_PTR || default_scnprintf == SCA_KSYM) { btf_printed = trace__btf_scnprintf(trace, &arg, bf + printed, size - printed, val, field->type); if (btf_printed) { diff --git a/tools/perf/tests/shell/trace_btf_general.sh b/tools/perf/tests/shell/trace_btf_general.sh index 7a94a5743924..255468eff128 100755 --- a/tools/perf/tests/shell/trace_btf_general.sh +++ b/tools/perf/tests/shell/trace_btf_general.sh @@ -49,7 +49,7 @@ trace_test_buffer() { trace_test_struct_btf() { echo "Testing perf trace's struct augmentation" output="$(perf trace --sort-events -e clock_nanosleep --force-btf --max-events=1 -- sleep 1 2>&1)" - if ! echo "$output" | grep -q -E "^sleep/[0-9]+ clock_nanosleep\(0, 0, \{1,.*\}, 0x[0-9a-f]+\) += +[0-9]+$" + if ! echo "$output" | grep -q -E "sleep/[0-9]+ clock_nanosleep\(.*(struct __kernel_timespec|\{1,).*\) = [0-9]+" then printf "BTF struct augmentation test failed, output:\n$output\n" err=1 -- 2.55.0