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tracing/eprobes: Fix reading of string fields

Currently when an event probe (eprobe) hooks to a string field, it does not display it as a string, but instead as a number. This makes the field rather useless. Handle the different kinds of strings, dynamic, static, relational/dynamic etc. Now when a string field is used, the ":string" type can be used to display it: echo "e:sw sched/sched_switch comm=$next_comm:string" > dynamic_events Link: https://lkml.kernel.org/r/20220820134400.959640191@goodmis.org

Steven Rostedt (Google) committed 4 years ago

Commit f04dec91 parent 02333de1 file · +21 −0Browse files

Unified · Split

kernel/trace/trace_eprobe.c+21−0
@@ -311,6 +311,27 @@ static unsigned long get_event_field(struct fetch_insn *code, void *rec) · 310 unmodified lines
311 311
312 addr = rec + field->offset;312 addr = rec + field->offset;
313 313
314 if (is_string_field(field)) {
315 switch (field->filter_type) {
316 case FILTER_DYN_STRING:
317 val = (unsigned long)(rec + (*(unsigned int *)addr & 0xffff));
318 break;
319 case FILTER_RDYN_STRING:
320 val = (unsigned long)(addr + (*(unsigned int *)addr & 0xffff));
321 break;
322 case FILTER_STATIC_STRING:
323 val = (unsigned long)addr;
324 break;
325 case FILTER_PTR_STRING:
326 val = (unsigned long)(*(char *)addr);
327 break;
328 default:
329 WARN_ON_ONCE(1);
330 return 0;
331 }
332 return val;
333 }
334
314 switch (field->size) {335 switch (field->size) {
315 case 1:336 case 1:
316 if (field->is_signed)337 if (field->is_signed)

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