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perf trace: Format fields with hex specifiers in print_fmt as hexadecimal

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Currently, when a probe event is added using perf probe --add with a
hexadecimal type cast (e.g., var:x64 and var:x32), the kernel traceprobe
subsystem sets the field type to "u64" in the event's format file, yet
generates a print format specifier of "var=0x%Lx" or "0x%x".

By default, perf trace uses its internal beautifiers which only inspect
field->type and field->flags. Because traceprobe events declare
primitive integer field types ("u64") without a C pointer asterisk
(i.e., "*"), perf trace defaults to printing the field's value as a
decimal unsigned long ("%ld"), ignoring the hexadecimal intent.

Introduce field_has_hex_fmt() to inspect the tracepoint's print_fmt
format string. If a field's print format assignment uses hexadecimal
specifiers (i.e., "=0x", "=%#", or "=%p"), assign SCA_PTR formatting so
perf trace displays the value in hexadecimal by default without
requiring --libtraceevent. For example:

    ❯ sudo ./perf probe --add 'enqueue_task_fair rq=rq:x64 p=p:x64 flags=flags:x32'
    Added new event:
      probe:enqueue_task_fair (on enqueue_task_fair with rq=rq:x64 p=p:x64 flags=flags:x32)

    You can now use it in all perf tools, such as:

            perf record -e probe:enqueue_task_fair -aR sleep 1

    ❯ sudo ./perf trace --show-cpu --event probe:enqueue_task_fair --max-event 3
         0.000 [000] :0/0 probe:enqueue_task_fair(rq: 0xffff8ac632233180, p: 0xffff8ac2c1240000, flags: 0x100009)
         0.006 [004] :0/0 probe:enqueue_task_fair(rq: 0xffff8ac632433180, p: 0xffff8ac624cf8000, flags: 0x9)
         0.069 [001] :0/0 probe:enqueue_task_fair(rq: 0xffff8ac6322b3180, p: 0xffff8ac4c4212c40, flags: 0x9)

Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Aaron Tomlin 2026-08-03 08:48:45 -04:00 committed by Namhyung Kim
parent 00ab8057cc
commit 9dd7c82d46
1 changed files with 45 additions and 1 deletions
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46
tools/perf/builtin-trace.c
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@ -2099,6 +2099,49 @@ static bool is_internal_field(struct tep_format_field *field)
return !strcmp(field->type, "__data_loc char[]");
}
static bool field_has_hex_fmt(struct tep_format_field *field, int len)
{
const char *fmt, *pos, *end = NULL;
if (!field || !field->event || !field->event->print_fmt.format)
return false;
fmt = field->event->print_fmt.format;
/* NB: Limit scanning strictly to the quoted printf format string */
if (*fmt == '"') {
const char *p = ++fmt;
while (*p) {
if (*p == '\\' && p[1] != '\0') {
/* NB: Skip escaped character */
p += 2;
} else if (*p == '"') {
end = p;
break;
} else {
p++;
}
}
} else {
end = strchr(fmt, ',');
}
for (pos = strstr(fmt, field->name); pos && (!end || pos < end);
pos = strstr(pos + 1, field->name)) {
if (pos == fmt || !(isalnum(pos[-1]) || pos[-1] == '_')) {
const char *after = pos + len;
if (*after == '=' && (strstarts(after + 1, "0x") ||
strstarts(after + 1, "%#") ||
strstarts(after + 1, "%p")))
return true;
}
}
return false;
}
static struct tep_format_field *
syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field *field,
bool *use_btf)
@ -2126,7 +2169,8 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field
((len >= 4 && strcmp(field->name + len - 4, "name") == 0) ||
strstr(field->name, "path") != NULL)) {
arg->scnprintf = SCA_FILENAME;
} else if ((field->flags & TEP_FIELD_IS_POINTER) || strstr(field->name, "addr"))
} else if ((field->flags & TEP_FIELD_IS_POINTER) || strstr(field->name, "addr") ||
field_has_hex_fmt(field, len))
arg->scnprintf = SCA_PTR;
else if (strcmp(field->type, "pid_t") == 0)
arg->scnprintf = SCA_PID;