Messages in this thread Patch in this message | | | Date | Mon, 6 Dec 2021 15:18:58 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH v6 1/2] scripts: ftrace - move the sort-processing in ftrace_init |
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On Thu, 2 Dec 2021 12:58:00 -0500 Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 2 Dec 2021 10:16:05 +0800 > Yinan Liu <yinan@linux.alibaba.com> wrote: > > > When the kernel starts, the initialization of ftrace takes > > up a portion of the time (approximately 6~8ms) to sort mcount > > addresses. We can save this time by moving mcount-sorting to > > compile time. > > > > Signed-off-by: Yinan Liu <yinan@linux.alibaba.com> > > Reported-by: kernel test robot <lkp@intel.com> > > After applying this, I get a failure on the kprobe self tests at boot up: > > Testing ftrace filter: OK > trace_kprobe: Testing kprobe tracing: > trace_kprobe: Could not probe notrace function kprobe_trace_selftest_target > ------------[ cut here ]------------ > WARNING: CPU: 2 PID: 1 at kernel/trace/trace_kprobe.c:1973 kprobe_trace_self_tests_init+0x5c/0x497 > Modules linked in:
And I added the below patch, and it shows that the section is not properly sorted. Something went wrong with your sorting.
I plan on keeping this check, at least as a compile option, to make sure that the output is sorted, otherwise things will silently fail if they are not.
This patch produced:
[ 1.315419] ftrace: allocating 43510 entries in 170 pages [ 1.320638] ------------[ cut here ]------------ [ 1.325227] [3] x86_pnpbios_disabled+0x0/0x1c at 8a51c707 is not sorted with __traceiter_initcall_level+0x0/0x60 at 87000660
I'm dropping the patches until this is "sorted out" :-)
-- Steve
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 9ca63df6553a..b112d00ba534 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6388,6 +6388,19 @@ static int ftrace_cmp_ips(const void *a, const void *b) return 0; } +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 %x is not sorted with %pS at %x\n", i, + (void *)start[i - 1], start[i - 1], + (void *)start[i], start[i])) + break; + } +} + static int ftrace_process_locs(struct module *mod, unsigned long *start, unsigned long *end) @@ -6414,6 +6427,8 @@ 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);
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