[PATCH v2] tracing: Have unsigned int function args displayed as hexadecimal

[Steven Rostedt]

From: Steven Rostedt <rost...@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.

Acked-by: Yonghong Song <yonghong.s...@linux.dev>
Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
---
Changes since v1: 
https://lore.kernel.org/20250731193126.2eeb2...@gandalf.local.home

- Fixed whitespace issues (Yonghong Song)

 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..fe54003de860 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