Commit 8147dc78 authored by Steven Rostedt (VMware)'s avatar Steven Rostedt (VMware) Committed by Steven Rostedt
Browse files

ftrace: Add test to make sure compiled time sorts work 

Now that ftrace function pointers are sorted at compile time, add a test
that makes sure they are sorted at run time. This test is only run if it is
configured in.

Link: https://lkml.kernel.org/r/20211206151858.4d21a24d@gandalf.local.home



Cc: Yinan Liu <yinan@linux.alibaba.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 72b3942a

kernel/trace/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -915,6 +915,20 @@ config EVENT_TRACE_TEST_SYSCALLS 
	 TBD - enable a way to actually call the syscalls as we test their

	       events



config FTRACE_SORT_STARTUP_TEST

       bool "Verify compile time sorting of ftrace functions"

       depends on DYNAMIC_FTRACE

       depends on BUILDTIME_TABLE_SORT

       help

	 Sorting of the mcount_loc sections that is used to find the

	 where the ftrace knows where to patch functions for tracing

	 and other callbacks is done at compile time. But if the sort

	 is not done correctly, it will cause non-deterministic failures.

	 When this is set, the sorted sections will be verified that they

	 are in deed sorted and will warn if they are not.



	 If unsure, say N



config RING_BUFFER_STARTUP_TEST

       bool "Ring buffer startup self test"

       depends on RING_BUFFER

kernel/trace/ftrace.c

+23 −0
Original line number Diff line number Diff line
@@ -6388,6 +6388,27 @@ static int ftrace_cmp_ips(const void *a, const void *b) 
	return 0;

}



#ifdef CONFIG_FTRACE_SORT_STARTUP_TEST

static void test_is_sorted(unsigned long *start, unsigned long count)

{

	int i;



	for (i = 1; i < count; i++) {

		if (WARN(start[i - 1] > start[i],

			 "[%d] %pS at %lx is not sorted with %pS at %lx\n", i,

			 (void *)start[i - 1], start[i - 1],

			 (void *)start[i], start[i]))

			break;

	}

	if (i == count)

		pr_info("ftrace section at %px sorted properly\n", start);

}

#else

static void test_is_sorted(unsigned long *start, unsigned long count)

{

}

#endif



static int ftrace_process_locs(struct module *mod,

			       unsigned long *start,

			       unsigned long *end)
@@ -6414,6 +6435,8 @@ static int ftrace_process_locs(struct module *mod, 
	if (!IS_ENABLED(CONFIG_BUILDTIME_TABLE_SORT) || mod) {

		sort(start, count, sizeof(*start),

		     ftrace_cmp_ips, NULL);

	} else {

		test_is_sorted(start, count);

	}



	start_pg = ftrace_allocate_pages(count);