Re: [PATCH] ftrace: sample: avoid open-coded 64-bit division
From: Mark Rutland <mark.rutland@arm.com>
Date: 2023-01-30 13:07:46
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On Mon, Jan 30, 2023 at 02:02:37PM +0100, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@arndb.de> Calculating the average period requires a 64-bit division that leads to a link failure on 32-bit architectures: x86_64-linux-ld: samples/ftrace/ftrace-ops.o: in function `ftrace_ops_sample_init': ftrace-ops.c:(.init.text+0x23b): undefined reference to `__udivdi3'
Whoops; sorry about that.
Use the div_u64() helper to do this instead. Since this is an init function that
is not called frequently, the runtime overhead is going to be acceptable.
Fixes: b56c68f705ca ("ftrace: Add sample with custom ops")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>Acked-by: Mark Rutland <mark.rutland@arm.com> Mark.
quoted hunk ↗ jump to hunk
--- samples/ftrace/ftrace-ops.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/samples/ftrace/ftrace-ops.c b/samples/ftrace/ftrace-ops.c index 24deb51c7261..0c8da87ff5c3 100644 --- a/samples/ftrace/ftrace-ops.c +++ b/samples/ftrace/ftrace-ops.c@@ -223,7 +223,7 @@ static int __init ftrace_ops_sample_init(void) pr_info("Attempted %u calls to %ps in %lluns (%lluns / call)\n", nr_function_calls, tracee_relevant, - period, period / nr_function_calls); + period, div_u64(period, nr_function_calls)); if (persist) return 0;-- 2.39.0