On Mon, 23 Dec 2024 15:13:48 -0500 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > +#ifdef CONFIG_FUNCTION_TRACE_ARGS > +void print_function_args(struct trace_seq *s, unsigned long *args, > + unsigned long func) > +{ > + const struct btf_param *param; > + const struct btf_type *t; > + const char *param_name; > + char name[KSYM_NAME_LEN]; > + unsigned long arg; > + struct btf *btf; > + s32 tid, nr = 0; > + int i; > + > + trace_seq_printf(s, "("); > + > + if (!args) > + goto out; > + if (lookup_symbol_name(func, name)) > + goto out; > + > + btf = bpf_get_btf_vmlinux(); > + if (IS_ERR_OR_NULL(btf)) > + goto out; > + > + t = btf_find_func_proto(name, &btf); > + if (IS_ERR_OR_NULL(t)) > + goto out; > + > + param = btf_get_func_param(t, &nr); > + if (!param) > + goto out_put; > + > + for (i = 0; i < nr; i++) { > + /* This only prints what the arch allows (6 args by default) */ > + if (i == FTRACE_REGS_MAX_ARGS) { > + trace_seq_puts(s, "..."); > + break; > + } > + > + arg = args[i]; > + > + param_name = btf_name_by_offset(btf, param[i].name_off); > + if (param_name) > + trace_seq_printf(s, "%s=", param_name); > + t = btf_type_skip_modifiers(btf, param[i].type, &tid); > + > + switch (t ? BTF_INFO_KIND(t->info) : BTF_KIND_UNKN) { > + case BTF_KIND_UNKN: > + trace_seq_putc(s, '?'); > + /* Still print unknown type values */ > + fallthrough; > + case BTF_KIND_PTR: > + trace_seq_printf(s, "0x%lx", arg); > + break; > + case BTF_KIND_INT: > + trace_seq_printf(s, "%ld", arg); > + break; > + case BTF_KIND_ENUM: > + trace_seq_printf(s, "%ld", arg); > + break; > + default: > + /* This does not handle complex arguments */ > + trace_seq_printf(s, "0x%lx (%s)", arg, btf_type_str(t)); This will need to take into account the size of the type. STRUCTs show up, and most of the time they are simply the size of the architecture's word. But I hit this: timespec64_add_safe(lhs=0x6c2 (STRUCT), rhs=0x39c4153f (STRUCT)) Where it definitely isn't correct, as we have: struct timespec64 { time64_t tv_sec; /* seconds */ long tv_nsec; /* nanoseconds */ }; struct timespec64 timespec64_add_safe(const struct timespec64 lhs, const struct timespec64 rhs) > + break; > + } > + if (i < nr - 1) > + trace_seq_printf(s, ", "); > + } > +out_put: > + btf_put(btf); > +out: > + trace_seq_printf(s, ")"); > +} > +#endif > + I updated to this (separating the args array from the BTF parameters): @@ -684,6 +683,91 @@ int trace_print_lat_context(struct trace_iterator *iter) return !trace_seq_has_overflowed(s); } +#ifdef CONFIG_FUNCTION_TRACE_ARGS +void print_function_args(struct trace_seq *s, unsigned long *args, + unsigned long func) +{ + const struct btf_param *param; + const struct btf_type *t; + const char *param_name; + char name[KSYM_NAME_LEN]; + unsigned long arg; + struct btf *btf; + s32 tid, nr = 0; + int a, p, x; + + trace_seq_printf(s, "("); + + if (!args) + goto out; + if (lookup_symbol_name(func, name)) + goto out; + + btf = bpf_get_btf_vmlinux(); + if (IS_ERR_OR_NULL(btf)) + goto out; + + t = btf_find_func_proto(name, &btf); + if (IS_ERR_OR_NULL(t)) + goto out; + + param = btf_get_func_param(t, &nr); + if (!param) + goto out_put; + + for (a = 0, p = 0; p < nr; a++, p++) { + if (p) + trace_seq_puts(s, ", "); + + /* This only prints what the arch allows (6 args by default) */ + if (a == FTRACE_REGS_MAX_ARGS) { + trace_seq_puts(s, "..."); + break; + } + + arg = args[a]; + + param_name = btf_name_by_offset(btf, param[p].name_off); + if (param_name) + trace_seq_printf(s, "%s=", param_name); + t = btf_type_skip_modifiers(btf, param[p].type, &tid); + + switch (t ? BTF_INFO_KIND(t->info) : BTF_KIND_UNKN) { + case BTF_KIND_UNKN: + trace_seq_putc(s, '?'); + /* Still print unknown type values */ + fallthrough; + case BTF_KIND_PTR: + trace_seq_printf(s, "0x%lx", arg); + break; + case BTF_KIND_INT: + trace_seq_printf(s, "%ld", arg); + break; + case BTF_KIND_ENUM: + trace_seq_printf(s, "%ld", arg); + break; + default: + /* This does not handle complex arguments */ + trace_seq_printf(s, "(%s)[0x%lx", btf_type_str(t), arg); + for (x = sizeof(long); x < t->size; x += sizeof(long)) { + trace_seq_putc(s, ':'); + if (++a == FTRACE_REGS_MAX_ARGS) { + trace_seq_puts(s, "...]"); + goto out_put; + } + trace_seq_printf(s, "0x%lx", args[a]); + } + trace_seq_putc(s, ']'); + break; + } + } +out_put: + btf_put(btf); +out: + trace_seq_printf(s, ")"); +} +#endif + /** * ftrace_find_event - find a registered event * @type: the type of event to look for And now I get this as output: less-912 [006] ...1. 240.085082: timespec64_add_safe(lhs=(STRUCT)[0xef:0x10c8f152], rhs=(STRUCT)[0x4:0x0]) <-__se_sys_poll less-914 [006] ...1. 241.241416: timespec64_add_safe(lhs=(STRUCT)[0xf0:0x1a1af859], rhs=(STRUCT)[0x4:0x0]) <-__se_sys_poll less-916 [006] ...1. 242.653586: timespec64_add_safe(lhs=(STRUCT)[0xf1:0x32ac56c9], rhs=(STRUCT)[0x4:0x0]) <-__se_sys_poll wpa_supplicant-488 [004] ...1. 246.771910: timespec64_add_safe(lhs=(STRUCT)[0xf5:0x39ba39d3], rhs=(STRUCT)[0x9:0x3b9ac618]) <-__se_sys_pselect6 wpa_supplicant-488 [004] ...1. 256.783841: timespec64_add_safe(lhs=(STRUCT)[0xff:0x3a714d62], rhs=(STRUCT)[0xa:0x0]) <-__se_sys_pselect6 NetworkManager-485 [006] ...1. 257.008653: timespec64_add_safe(lhs=(STRUCT)[0x100:0xc3ce7d5], rhs=(STRUCT)[0x0:0x16358818]) <-__se_sys_ppoll NetworkManager-485 [006] ...1. 257.008676: timespec64_add_safe(lhs=(STRUCT)[0x100:0xc3d477e], rhs=(STRUCT)[0x0:0x16352288]) <-__se_sys_ppoll NetworkManager-485 [006] ...1. 257.383973: timespec64_add_safe(lhs=(STRUCT)[0x100:0x229be0b6], rhs=(STRUCT)[0x11:0x11c46e70]) <-__se_sys_ppoll Which looks much more reasonable. -- Steve