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ftrace: Add test to make sure compiled time sorts work

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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: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware)
2021-12-06 15:18:58 -05:00
committed by Steven Rostedt
parent 72b3942a17
commit 8147dc78e6
2 changed files with 37 additions and 0 deletions
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14
kernel/trace/Kconfig
View File

@@ -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

23
kernel/trace/ftrace.c
View File

@@ -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);