| Message ID | 20250225222653.550619678@goodmis.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ftrace: Add function arguments to function tracers | expand |
On Tue, 25 Feb 2025 17:26:02 -0500 Steven Rostedt <rostedt@goodmis.org> wrote: > From: Sven Schnelle <svens@linux.ibm.com> > > 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. > > It can only handle simply arguments and up to FTRACE_REGS_MAX_ARGS number > of arguments. When it hits a max, it will print ", ...": > > page_to_skb(vi=0xffff8d53842dc980, rq=0xffff8d53843a0800, page=0xfffffc2e04337c00, offset=6160, len=64, truesize=1536, ...) > > And if it hits an argument that is not recognized, it will print the raw > value and the type of argument it is: > > make_vfsuid(idmap=0xffffffff87f99db8, fs_userns=0xffffffff87e543c0, kuid=0x0 (STRUCT)) > __pti_set_user_pgtbl(pgdp=0xffff8d5384ab47f8, pgd=0x110e74067 (STRUCT)) > This looks good to me. Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Thank you, > Cc: Masami Hiramatsu <mhiramat@kernel.org> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Paul Walmsley <paul.walmsley@sifive.com> > Cc: Palmer Dabbelt <palmer@dabbelt.com> > Cc: Albert Ou <aou@eecs.berkeley.edu> > Cc: Guo Ren <guoren@kernel.org> > Cc: Donglin Peng <dolinux.peng@gmail.com> > Cc: Zheng Yejian <zhengyejian@huaweicloud.com> > Link: https://lore.kernel.org/20241223201541.898496620@goodmis.org > Co-developed-by: Steven Rostedt (Google) <rostedt@goodmis.org> > Signed-off-by: Sven Schnelle <svens@linux.ibm.com> > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > include/linux/ftrace_regs.h | 5 +++ > kernel/trace/Kconfig | 6 +++ > kernel/trace/trace_output.c | 85 +++++++++++++++++++++++++++++++++++++ > kernel/trace/trace_output.h | 9 ++++ > 4 files changed, 105 insertions(+) > > diff --git a/include/linux/ftrace_regs.h b/include/linux/ftrace_regs.h > index bbc1873ca6b8..15627ceea9bc 100644 > --- a/include/linux/ftrace_regs.h > +++ b/include/linux/ftrace_regs.h > @@ -35,4 +35,9 @@ struct ftrace_regs; > > #endif /* HAVE_ARCH_FTRACE_REGS */ > > +/* This can be overridden by the architectures */ > +#ifndef FTRACE_REGS_MAX_ARGS > +# define FTRACE_REGS_MAX_ARGS 6 > +#endif > + > #endif /* _LINUX_FTRACE_REGS_H */ > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig > index d570b8b9c0a9..60412c1012ef 100644 > --- a/kernel/trace/Kconfig > +++ b/kernel/trace/Kconfig > @@ -263,6 +263,12 @@ config FUNCTION_GRAPH_RETADDR > the function is called. This feature is off by default, and you can > enable it via the trace option funcgraph-retaddr. > > +config FUNCTION_TRACE_ARGS > + bool > + depends on HAVE_FUNCTION_ARG_ACCESS_API > + depends on DEBUG_INFO_BTF > + default y > + > config DYNAMIC_FTRACE > bool "enable/disable function tracing dynamically" > depends on FUNCTION_TRACER > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c > index 03d56f711ad1..4b721cd4f21d 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 > @@ -684,6 +687,88 @@ 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; > + > + /* TODO: Pass module name here too */ > + 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 > diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h > index dca40f1f1da4..2e305364f2a9 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, unsigned long *args, > + unsigned long func); > +#else > +static inline void print_function_args(struct trace_seq *s, unsigned long *args, > + unsigned long func) { > + trace_seq_puts(s, "()"); > +} > +#endif > #endif > > -- > 2.47.2 > >
diff --git a/include/linux/ftrace_regs.h b/include/linux/ftrace_regs.h index bbc1873ca6b8..15627ceea9bc 100644 --- a/include/linux/ftrace_regs.h +++ b/include/linux/ftrace_regs.h @@ -35,4 +35,9 @@ struct ftrace_regs; #endif /* HAVE_ARCH_FTRACE_REGS */ +/* This can be overridden by the architectures */ +#ifndef FTRACE_REGS_MAX_ARGS +# define FTRACE_REGS_MAX_ARGS 6 +#endif + #endif /* _LINUX_FTRACE_REGS_H */ diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index d570b8b9c0a9..60412c1012ef 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -263,6 +263,12 @@ config FUNCTION_GRAPH_RETADDR the function is called. This feature is off by default, and you can enable it via the trace option funcgraph-retaddr. +config FUNCTION_TRACE_ARGS + bool + depends on HAVE_FUNCTION_ARG_ACCESS_API + depends on DEBUG_INFO_BTF + default y + config DYNAMIC_FTRACE bool "enable/disable function tracing dynamically" depends on FUNCTION_TRACER diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c index 03d56f711ad1..4b721cd4f21d 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 @@ -684,6 +687,88 @@ 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; + + /* TODO: Pass module name here too */ + 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 diff --git a/kernel/trace/trace_output.h b/kernel/trace/trace_output.h index dca40f1f1da4..2e305364f2a9 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, unsigned long *args, + unsigned long func); +#else +static inline void print_function_args(struct trace_seq *s, unsigned long *args, + unsigned long func) { + trace_seq_puts(s, "()"); +} +#endif #endif