Add a function to decode argument types with the help of BTF. Will be used to display arguments in the function and function graph tracer.
Signed-off-by: Sven Schnelle <[email protected]> --- kernel/trace/trace_output.c | 68 +++++++++++++++++++++++++++++++++++++ kernel/trace/trace_output.h | 9 +++++ 2 files changed, 77 insertions(+) diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index d8b302d01083..70405c4cceb6 100644 --- a/kernel/trace/trace_output.c +++ b/kernel/trace/trace_output.c @@ -12,8 +12,11 @@ #include <linux/sched/clock.h> #include <linux/sched/mm.h> #include <linux/idr.h> +#include <linux/btf.h> +#include <linux/bpf.h> #include "trace_output.h" +#include "trace_btf.h" /* must be a power of 2 */ #define EVENT_HASHSIZE 128 @@ -669,6 +672,71 @@ 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, struct ftrace_regs *fregs, + 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 (!ftrace_regs_has_args(fregs)) + 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++) { + arg = ftrace_regs_get_argument(fregs, 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); + if (!t) + continue; + switch (BTF_INFO_KIND(t->info)) { + 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: + trace_seq_printf(s, "0x%lx (%d)", arg, BTF_INFO_KIND(param[i].type)); + break; + } + if (i < nr - 1) + trace_seq_printf(s, ", "); + } +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 diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h index dca40f1f1da4..a21d8ce606f7 100644 --- a/kernel/trace/trace_output.h +++ b/kernel/trace/trace_output.h @@ -41,5 +41,14 @@ extern struct rw_semaphore trace_event_sem; #define SEQ_PUT_HEX_FIELD(s, x) \ trace_seq_putmem_hex(s, &(x), sizeof(x)) +#ifdef CONFIG_FUNCTION_TRACE_ARGS +void print_function_args(struct trace_seq *s, struct ftrace_regs *fregs, + unsigned long func); +#else +static inline void print_function_args(struct trace_seq *s, struct ftrace_regs *fregs, + unsigned long func) { + trace_seq_puts(s, "()"); +} +#endif #endif -- 2.43.0
