Commit 773c1670 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware)
Browse files

ftrace: Add recording of functions that caused recursion 

This adds CONFIG_FTRACE_RECORD_RECURSION that will record to a file
"recursed_functions" all the functions that caused recursion while a
callback to the function tracer was running.

Link: https://lkml.kernel.org/r/20201106023548.102375687@goodmis.org



Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Guo Ren <guoren@kernel.org>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Anton Vorontsov <anton@enomsg.org>
Cc: Colin Cross <ccross@android.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-csky@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: live-patching@vger.kernel.org
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent a25d036d

Documentation/trace/ftrace-uses.rst

+4 −2
Original line number Diff line number Diff line
@@ -118,7 +118,7 @@ can help in this regard. If you start your code with: 


	int bit;



	bit = ftrace_test_recursion_trylock();

	bit = ftrace_test_recursion_trylock(ip, parent_ip);

	if (bit < 0)

		return;
@@ -130,7 +130,9 @@ The code in between will be safe to use, even if it ends up calling a 
function that the callback is tracing. Note, on success,

ftrace_test_recursion_trylock() will disable preemption, and the

ftrace_test_recursion_unlock() will enable it again (if it was previously

enabled).

enabled). The instruction pointer (ip) and its parent (parent_ip) is passed to

ftrace_test_recursion_trylock() to record where the recursion happened

(if CONFIG_FTRACE_RECORD_RECURSION is set).



Alternatively, if the FTRACE_OPS_FL_RECURSION flag is set on the ftrace_ops

(as explained below), then a helper trampoline will be used to test

arch/csky/kernel/probes/ftrace.c

+1 −1
Original line number Diff line number Diff line
@@ -18,7 +18,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
	struct kprobe *p;

	struct kprobe_ctlblk *kcb;



	bit = ftrace_test_recursion_trylock();

	bit = ftrace_test_recursion_trylock(ip, parent_ip);

	if (bit < 0)

		return;

arch/parisc/kernel/ftrace.c

+1 −1
Original line number Diff line number Diff line
@@ -210,7 +210,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
	struct kprobe *p;

	int bit;



	bit = ftrace_test_recursion_trylock();

	bit = ftrace_test_recursion_trylock(ip, parent_ip);

	if (bit < 0)

		return;

arch/powerpc/kernel/kprobes-ftrace.c

+1 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned long parent_nip, 
	struct kprobe_ctlblk *kcb;

	int bit;



	bit = ftrace_test_recursion_trylock();

	bit = ftrace_test_recursion_trylock(nip, parent_nip);

	if (bit < 0)

		return;

arch/s390/kernel/ftrace.c

+1 −1
Original line number Diff line number Diff line
@@ -204,7 +204,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, 
	struct kprobe *p;

	int bit;



	bit = ftrace_test_recursion_trylock();

	bit = ftrace_test_recursion_trylock(ip, parent_ip);

	if (bit < 0)

		return;

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