* [PATCH] tracing: Have unsigned int function args displayed as hexadecimal
@ 2025-07-31 23:31 Steven Rostedt
2025-08-01 14:49 ` Yonghong Song
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Steven Rostedt @ 2025-07-31 23:31 UTC (permalink / raw)
To: LKML, Linux Trace Kernel
Cc: Masami Hiramatsu, Mathieu Desnoyers, bpf, Douglas Raillard
From: Steven Rostedt <rostedt@goodmis.org>
Most function arguments that are passed in as unsigned int or unsigned
long are better displayed as hexadecimal than normal integer. For example,
the functions:
static void __create_object(unsigned long ptr, size_t size,
int min_count, gfp_t gfp, unsigned int objflags);
static bool stack_access_ok(struct unwind_state *state, unsigned long _addr,
size_t len);
void __local_bh_disable_ip(unsigned long ip, unsigned int cnt);
Show up in the trace as:
__create_object(ptr=-131387050520576, size=4096, min_count=1, gfp=3264, objflags=0) <-kmem_cache_alloc_noprof
stack_access_ok(state=0xffffc9000233fc98, _addr=-60473102566256, len=8) <-unwind_next_frame
__local_bh_disable_ip(ip=-2127311112, cnt=256) <-handle_softirqs
Instead, by displaying unsigned as hexadecimal, they look more like this:
__create_object(ptr=0xffff8881028d2080, size=0x280, min_count=1, gfp=0x82820, objflags=0x0) <-kmem_cache_alloc_node_noprof
stack_access_ok(state=0xffffc90000003938, _addr=0xffffc90000003930, len=0x8) <-unwind_next_frame
__local_bh_disable_ip(ip=0xffffffff8133cef8, cnt=0x100) <-handle_softirqs
Which is much easier to understand as most unsigned longs are usually just
pointers. Even the "unsigned int cnt" in __local_bh_disable_ip() looks
better as hexadecimal as a lot of flags are passed as unsigned.
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
kernel/trace/trace_output.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 0b3db02030a7..b18393d66a7f 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -690,6 +690,12 @@ int trace_print_lat_context(struct trace_iterator *iter)
}
#ifdef CONFIG_FUNCTION_TRACE_ARGS
+
+static u32 btf_type_int(const struct btf_type *t)
+{
+ return *(u32 *)(t + 1);
+}
+
void print_function_args(struct trace_seq *s, unsigned long *args,
unsigned long func)
{
@@ -701,6 +707,8 @@ void print_function_args(struct trace_seq *s, unsigned long *args,
struct btf *btf;
s32 tid, nr = 0;
int a, p, x;
+ int int_data;
+ u16 encode;
trace_seq_printf(s, "(");
@@ -744,7 +752,14 @@ void print_function_args(struct trace_seq *s, unsigned long *args,
trace_seq_printf(s, "0x%lx", arg);
break;
case BTF_KIND_INT:
- trace_seq_printf(s, "%ld", arg);
+ /* Get the INT encodoing */
+ int_data = btf_type_int(t);
+ encode = BTF_INT_ENCODING(int_data);
+ /* Print unsigned ints as hex */
+ if (encode & BTF_INT_SIGNED)
+ trace_seq_printf(s, "%ld", arg);
+ else
+ trace_seq_printf(s, "0x%lx", arg);
break;
case BTF_KIND_ENUM:
trace_seq_printf(s, "%ld", arg);
--
2.47.2
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH] tracing: Have unsigned int function args displayed as hexadecimal
2025-07-31 23:31 [PATCH] tracing: Have unsigned int function args displayed as hexadecimal Steven Rostedt
@ 2025-08-01 14:49 ` Yonghong Song
2025-08-01 15:09 ` Steven Rostedt
2025-08-01 19:59 ` Martin KaFai Lau
2025-08-04 13:19 ` Masami Hiramatsu
2 siblings, 1 reply; 6+ messages in thread
From: Yonghong Song @ 2025-08-01 14:49 UTC (permalink / raw)
To: Steven Rostedt, LKML, Linux Trace Kernel
Cc: Masami Hiramatsu, Mathieu Desnoyers, bpf, Douglas Raillard
On 7/31/25 4:31 PM, Steven Rostedt wrote:
> From: Steven Rostedt <rostedt@goodmis.org>
>
> Most function arguments that are passed in as unsigned int or unsigned
> long are better displayed as hexadecimal than normal integer. For example,
> the functions:
>
> static void __create_object(unsigned long ptr, size_t size,
> int min_count, gfp_t gfp, unsigned int objflags);
>
> static bool stack_access_ok(struct unwind_state *state, unsigned long _addr,
> size_t len);
>
> void __local_bh_disable_ip(unsigned long ip, unsigned int cnt);
>
> Show up in the trace as:
>
> __create_object(ptr=-131387050520576, size=4096, min_count=1, gfp=3264, objflags=0) <-kmem_cache_alloc_noprof
> stack_access_ok(state=0xffffc9000233fc98, _addr=-60473102566256, len=8) <-unwind_next_frame
> __local_bh_disable_ip(ip=-2127311112, cnt=256) <-handle_softirqs
>
> Instead, by displaying unsigned as hexadecimal, they look more like this:
>
> __create_object(ptr=0xffff8881028d2080, size=0x280, min_count=1, gfp=0x82820, objflags=0x0) <-kmem_cache_alloc_node_noprof
> stack_access_ok(state=0xffffc90000003938, _addr=0xffffc90000003930, len=0x8) <-unwind_next_frame
> __local_bh_disable_ip(ip=0xffffffff8133cef8, cnt=0x100) <-handle_softirqs
>
> Which is much easier to understand as most unsigned longs are usually just
> pointers. Even the "unsigned int cnt" in __local_bh_disable_ip() looks
> better as hexadecimal as a lot of flags are passed as unsigned.
>
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
LGTM. But it seems some format issue. See below.
Acked-by: Yonghong Song <yonghong.song@linux.dev>
> ---
> kernel/trace/trace_output.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> index 0b3db02030a7..b18393d66a7f 100644
> --- a/kernel/trace/trace_output.c
> +++ b/kernel/trace/trace_output.c
> @@ -690,6 +690,12 @@ int trace_print_lat_context(struct trace_iterator *iter)
> }
>
> #ifdef CONFIG_FUNCTION_TRACE_ARGS
> +
> +static u32 btf_type_int(const struct btf_type *t)
> +{
> + return *(u32 *)(t + 1);
> +}
> +
> void print_function_args(struct trace_seq *s, unsigned long *args,
> unsigned long func)
> {
> @@ -701,6 +707,8 @@ void print_function_args(struct trace_seq *s, unsigned long *args,
> struct btf *btf;
> s32 tid, nr = 0;
> int a, p, x;
> + int int_data;
> + u16 encode;
>
> trace_seq_printf(s, "(");
>
> @@ -744,7 +752,14 @@ void print_function_args(struct trace_seq *s, unsigned long *args,
> trace_seq_printf(s, "0x%lx", arg);
> break;
> case BTF_KIND_INT:
> - trace_seq_printf(s, "%ld", arg);
> + /* Get the INT encodoing */
> + int_data = btf_type_int(t);
> + encode = BTF_INT_ENCODING(int_data);
See different identation between above 'int_data' and 'encode'. The same as below.
> + /* Print unsigned ints as hex */
> + if (encode & BTF_INT_SIGNED)
> + trace_seq_printf(s, "%ld", arg);
> + else
> + trace_seq_printf(s, "0x%lx", arg);
> break;
> case BTF_KIND_ENUM:
> trace_seq_printf(s, "%ld", arg);
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] tracing: Have unsigned int function args displayed as hexadecimal
2025-08-01 14:49 ` Yonghong Song
@ 2025-08-01 15:09 ` Steven Rostedt
0 siblings, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2025-08-01 15:09 UTC (permalink / raw)
To: Yonghong Song
Cc: LKML, Linux Trace Kernel, Masami Hiramatsu, Mathieu Desnoyers,
bpf, Douglas Raillard
On Fri, 1 Aug 2025 07:49:53 -0700
Yonghong Song <yonghong.song@linux.dev> wrote:
> > @@ -744,7 +752,14 @@ void print_function_args(struct trace_seq *s, unsigned long *args,
> > trace_seq_printf(s, "0x%lx", arg);
> > break;
> > case BTF_KIND_INT:
> > - trace_seq_printf(s, "%ld", arg);
> > + /* Get the INT encodoing */
> > + int_data = btf_type_int(t);
> > + encode = BTF_INT_ENCODING(int_data);
>
> See different identation between above 'int_data' and 'encode'. The same as below.
Bah, I think I cut and pasted into emacs and it used spaces instead of tabs.
-- Steve
>
> > + /* Print unsigned ints as hex */
> > + if (encode & BTF_INT_SIGNED)
> > + trace_seq_printf(s, "%ld", arg);
> > + else
> > + trace_seq_printf(s, "0x%lx", arg);
> > break;
> > case BTF_KIND_ENUM:
> > trace_seq_printf(s, "%ld", arg);
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] tracing: Have unsigned int function args displayed as hexadecimal
2025-07-31 23:31 [PATCH] tracing: Have unsigned int function args displayed as hexadecimal Steven Rostedt
2025-08-01 14:49 ` Yonghong Song
@ 2025-08-01 19:59 ` Martin KaFai Lau
2025-08-01 20:05 ` Steven Rostedt
2025-08-04 13:19 ` Masami Hiramatsu
2 siblings, 1 reply; 6+ messages in thread
From: Martin KaFai Lau @ 2025-08-01 19:59 UTC (permalink / raw)
To: Steven Rostedt
Cc: Masami Hiramatsu, Mathieu Desnoyers, bpf, Douglas Raillard, LKML,
Linux Trace Kernel
On 7/31/25 4:31 PM, Steven Rostedt wrote:
> + int_data = btf_type_int(t);
> + encode = BTF_INT_ENCODING(int_data);
There is a btf_int_encoding(t) helper in btf.h, so only "encode =
btf_int_encoding(t);" will be simpler.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] tracing: Have unsigned int function args displayed as hexadecimal
2025-08-01 19:59 ` Martin KaFai Lau
@ 2025-08-01 20:05 ` Steven Rostedt
0 siblings, 0 replies; 6+ messages in thread
From: Steven Rostedt @ 2025-08-01 20:05 UTC (permalink / raw)
To: Martin KaFai Lau
Cc: Masami Hiramatsu, Mathieu Desnoyers, bpf, Douglas Raillard, LKML,
Linux Trace Kernel
On Fri, 1 Aug 2025 12:59:05 -0700
Martin KaFai Lau <martin.lau@linux.dev> wrote:
> On 7/31/25 4:31 PM, Steven Rostedt wrote:
> > + int_data = btf_type_int(t);
> > + encode = BTF_INT_ENCODING(int_data);
>
> There is a btf_int_encoding(t) helper in btf.h, so only "encode =
> btf_int_encoding(t);" will be simpler.
Thanks, I didn't see that. I was looking at the code in btf.c which had
this open coded.
-- Steve
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] tracing: Have unsigned int function args displayed as hexadecimal
2025-07-31 23:31 [PATCH] tracing: Have unsigned int function args displayed as hexadecimal Steven Rostedt
2025-08-01 14:49 ` Yonghong Song
2025-08-01 19:59 ` Martin KaFai Lau
@ 2025-08-04 13:19 ` Masami Hiramatsu
2 siblings, 0 replies; 6+ messages in thread
From: Masami Hiramatsu @ 2025-08-04 13:19 UTC (permalink / raw)
To: Steven Rostedt
Cc: LKML, Linux Trace Kernel, Masami Hiramatsu, Mathieu Desnoyers,
bpf, Douglas Raillard
On Thu, 31 Jul 2025 19:31:26 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> From: Steven Rostedt <rostedt@goodmis.org>
>
> Most function arguments that are passed in as unsigned int or unsigned
> long are better displayed as hexadecimal than normal integer. For example,
> the functions:
>
> static void __create_object(unsigned long ptr, size_t size,
> int min_count, gfp_t gfp, unsigned int objflags);
>
> static bool stack_access_ok(struct unwind_state *state, unsigned long _addr,
> size_t len);
>
> void __local_bh_disable_ip(unsigned long ip, unsigned int cnt);
>
> Show up in the trace as:
>
> __create_object(ptr=-131387050520576, size=4096, min_count=1, gfp=3264, objflags=0) <-kmem_cache_alloc_noprof
> stack_access_ok(state=0xffffc9000233fc98, _addr=-60473102566256, len=8) <-unwind_next_frame
> __local_bh_disable_ip(ip=-2127311112, cnt=256) <-handle_softirqs
>
> Instead, by displaying unsigned as hexadecimal, they look more like this:
>
> __create_object(ptr=0xffff8881028d2080, size=0x280, min_count=1, gfp=0x82820, objflags=0x0) <-kmem_cache_alloc_node_noprof
> stack_access_ok(state=0xffffc90000003938, _addr=0xffffc90000003930, len=0x8) <-unwind_next_frame
> __local_bh_disable_ip(ip=0xffffffff8133cef8, cnt=0x100) <-handle_softirqs
>
> Which is much easier to understand as most unsigned longs are usually just
> pointers. Even the "unsigned int cnt" in __local_bh_disable_ip() looks
> better as hexadecimal as a lot of flags are passed as unsigned.
>
Looks good to me. Maybe this format is better for programers :)
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Thanks,
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---
> kernel/trace/trace_output.c | 17 ++++++++++++++++-
> 1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> index 0b3db02030a7..b18393d66a7f 100644
> --- a/kernel/trace/trace_output.c
> +++ b/kernel/trace/trace_output.c
> @@ -690,6 +690,12 @@ int trace_print_lat_context(struct trace_iterator *iter)
> }
>
> #ifdef CONFIG_FUNCTION_TRACE_ARGS
> +
> +static u32 btf_type_int(const struct btf_type *t)
> +{
> + return *(u32 *)(t + 1);
> +}
> +
> void print_function_args(struct trace_seq *s, unsigned long *args,
> unsigned long func)
> {
> @@ -701,6 +707,8 @@ void print_function_args(struct trace_seq *s, unsigned long *args,
> struct btf *btf;
> s32 tid, nr = 0;
> int a, p, x;
> + int int_data;
> + u16 encode;
>
> trace_seq_printf(s, "(");
>
> @@ -744,7 +752,14 @@ void print_function_args(struct trace_seq *s, unsigned long *args,
> trace_seq_printf(s, "0x%lx", arg);
> break;
> case BTF_KIND_INT:
> - trace_seq_printf(s, "%ld", arg);
> + /* Get the INT encodoing */
> + int_data = btf_type_int(t);
> + encode = BTF_INT_ENCODING(int_data);
> + /* Print unsigned ints as hex */
> + if (encode & BTF_INT_SIGNED)
> + trace_seq_printf(s, "%ld", arg);
> + else
> + trace_seq_printf(s, "0x%lx", arg);
> break;
> case BTF_KIND_ENUM:
> trace_seq_printf(s, "%ld", arg);
> --
> 2.47.2
>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2025-08-04 13:20 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-07-31 23:31 [PATCH] tracing: Have unsigned int function args displayed as hexadecimal Steven Rostedt
2025-08-01 14:49 ` Yonghong Song
2025-08-01 15:09 ` Steven Rostedt
2025-08-01 19:59 ` Martin KaFai Lau
2025-08-01 20:05 ` Steven Rostedt
2025-08-04 13:19 ` Masami Hiramatsu
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).