tracing: Show real address for trace event arguments

[ Upstream commit efbbdaa22bb78761bff8dfdde027ad04bedd47ce ]

To help debugging kernel, show real address for trace event arguments
in tracefs/trace{,pipe} instead of hashed pointer value.

Since ftrace human-readable format uses vsprintf(), all %p are
translated to hash values instead of pointer address.

However, when debugging the kernel, raw address value gives a
hint when comparing with the memory mapping in the kernel.
(Those are sometimes used with crash log, which is not hashed too)
So converting %p with %px when calling trace_seq_printf().

Moreover, this is not improving the security because the tracefs
can be used only by root user and the raw address values are readable
from tracefs/percpu/cpu*/trace_pipe_raw file.

Link: https://lkml.kernel.org/r/160277370703.29307.5134475491761971203.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Stable-dep-of: d5a821896360 ("tracing: Fix memory leak of iter->temp when reading trace_pipe")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Masami Hiramatsu
2020-10-15 23:55:07 +09:00
committed by Greg Kroah-Hartman
parent 8996b13051
commit 840ce9cfc8
5 changed files with 88 additions and 3 deletions

View File

@@ -364,7 +364,7 @@ trace_raw_output_##call(struct trace_iterator *iter, int flags, \
if (ret != TRACE_TYPE_HANDLED) \
return ret; \
\
trace_seq_printf(s, print); \
trace_event_printf(iter, print); \
\
return trace_handle_return(s); \
} \