From a42e3c4de9642d5de524a0a48a7ce96872662dca Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Thu, 20 Jun 2019 00:08:37 +0900 Subject: tracing/probe: Add immediate string parameter support Add immediate string parameter (\"string") support to probe events. This allows you to specify an immediate (or dummy) parameter instead of fetching a string from memory. This feature looks odd, but imagine that you put a probe on a code to trace some string data. If the code is compiled into 2 instructions and 1 instruction has a string on memory but other has no string since it is optimized out. In that case, you can not fold those into one event, even if ftrace supported multiple probes on one event. With this feature, you can set a dummy string like foo=\"(optimized)":string instead of something like foo=+0(+0(%bp)):string. Link: http://lkml.kernel.org/r/156095691687.28024.13372712423865047991.stgit@devnote2 Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_uprobe.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel/trace/trace_uprobe.c') diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index 84925b5b6db5..cbf4da4bf367 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -248,6 +248,9 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest, case FETCH_OP_COMM: val = FETCH_TOKEN_COMM; break; + case FETCH_OP_DATA: + val = (unsigned long)code->data; + break; case FETCH_OP_FOFFS: val = translate_user_vaddr(code->immediate); break; -- cgit