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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2014-11-21 13:25:16 +0300
committerSteven Rostedt <rostedt@goodmis.org>2014-11-21 22:42:10 +0300
commitf8b8be8a310a55856fd2c369dade08088d85df3b (patch)
tree4c427a2981e4b66392b5bf9d7f8988479040150c /Documentation
parenta017784f1b236cbc42ce83b4345a667c21113481 (diff)
downloadlinux-f8b8be8a310a55856fd2c369dade08088d85df3b.tar.xz
ftrace, kprobes: Support IPMODIFY flag to find IP modify conflict
Introduce FTRACE_OPS_FL_IPMODIFY to avoid conflict among ftrace users who may modify regs->ip to change the execution path. If two or more users modify the regs->ip on the same function entry, one of them will be broken. So they must add IPMODIFY flag and make sure that ftrace_set_filter_ip() succeeds. Note that ftrace doesn't allow ftrace_ops which has IPMODIFY flag to have notrace hash, and the ftrace_ops must have a filter hash (so that the ftrace_ops can hook only specific entries), because it strongly depends on the address and must be allowed for only few selected functions. Link: http://lkml.kernel.org/r/20141121102516.11844.27829.stgit@localhost.localdomain Cc: Jiri Kosina <jkosina@suse.cz> Cc: Seth Jennings <sjenning@redhat.com> Cc: Petr Mladek <pmladek@suse.cz> Cc: Vojtech Pavlik <vojtech@suse.cz> Cc: Miroslav Benes <mbenes@suse.cz> Cc: Ingo Molnar <mingo@kernel.org> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> [ fixed up some of the comments ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/trace/ftrace.txt5
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 4da42616939f..f10f5f5d260d 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -234,6 +234,11 @@ of ftrace. Here is a list of some of the key files:
will be displayed on the same line as the function that
is returning registers.
+ If the callback registered to be traced by a function with
+ the "ip modify" attribute (thus the regs->ip can be changed),
+ an 'I' will be displayed on the same line as the function that
+ can be overridden.
+
function_profile_enabled:
When set it will enable all functions with either the function