[PATCH v2 1/2] perf bench futex: Use a 64-bit time_t
Arnaldo Carvalho de Melo
acme at kernel.org
Tue Oct 19 09:56:32 PDT 2021
Em Fri, Oct 15, 2021 at 10:56:33AM +1000, Alistair Francis escreveu:
> From: Alistair Francis <alistair.francis at wdc.com>
>
> Convert tools/perf to only use a 64-bit time_t. On 64-bit architectures
> this isn't a functional change. On 32-bit architectures we now only
> perform 64-bit time_t syscalls (__NR_futex_time64) and use a struct
> timespec64.
>
> This won't work on kernels before 5.1, but as perf is tied to the kernel
> that's ok.
No, perf is not tied to the kernel, one can use a new perf tool on any
previous kernel, and an old perf tool should work on new kernels as
well.
- Arnaldo
> This allows us to build perf for 32-bit architectures with 64-bit time_t
> like RISC-V 32-bit.
>
> Signed-off-by: Alistair Francis <alistair.francis at wdc.com>
> ---
> tools/perf/bench/futex.h | 26 ++++++++++++++++++++------
> 1 file changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/bench/futex.h b/tools/perf/bench/futex.h
> index b3853aac3021c..b9665d43d2988 100644
> --- a/tools/perf/bench/futex.h
> +++ b/tools/perf/bench/futex.h
> @@ -12,6 +12,7 @@
> #include <sys/syscall.h>
> #include <sys/types.h>
> #include <linux/futex.h>
> +#include <linux/time_types.h>
>
> struct bench_futex_parameters {
> bool silent;
> @@ -27,12 +28,14 @@ struct bench_futex_parameters {
> unsigned int nrequeue;
> };
>
> +#define timespec64 __kernel_timespec
> +
> /**
> * futex() - SYS_futex syscall wrapper
> * @uaddr: address of first futex
> * @op: futex op code
> * @val: typically expected value of uaddr, but varies by op
> - * @timeout: typically an absolute struct timespec (except where noted
> + * @timeout: typically an absolute struct timespec64 (except where noted
> * otherwise). Overloaded by some ops
> * @uaddr2: address of second futex for some ops
> * @val3: varies by op
> @@ -47,15 +50,26 @@ struct bench_futex_parameters {
> * These argument descriptions are the defaults for all
> * like-named arguments in the following wrappers except where noted below.
> */
> -#define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \
> - syscall(SYS_futex, uaddr, op | opflags, val, timeout, uaddr2, val3)
> +/**
> + * We only support 64-bit time_t for the timeout.
> + * On 64-bit architectures we can use __NR_futex
> + * On 32-bit architectures we use __NR_futex_time64. This only works on kernel
> + * versions 5.1+.
> + */
> +#if __BITS_PER_LONG == 64
> +# define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \
> + syscall(__NR_futex, uaddr, op | opflags, val, timeout, uaddr2, val3)
> +#else
> +# define futex(uaddr, op, val, timeout, uaddr2, val3, opflags) \
> + syscall(__NR_futex_time64, uaddr, op | opflags, val, timeout, uaddr2, val3)
> +#endif
>
> /**
> * futex_wait() - block on uaddr with optional timeout
> * @timeout: relative timeout
> */
> static inline int
> -futex_wait(u_int32_t *uaddr, u_int32_t val, struct timespec *timeout, int opflags)
> +futex_wait(u_int32_t *uaddr, u_int32_t val, struct timespec64 *timeout, int opflags)
> {
> return futex(uaddr, FUTEX_WAIT, val, timeout, NULL, 0, opflags);
> }
> @@ -74,7 +88,7 @@ futex_wake(u_int32_t *uaddr, int nr_wake, int opflags)
> * futex_lock_pi() - block on uaddr as a PI mutex
> */
> static inline int
> -futex_lock_pi(u_int32_t *uaddr, struct timespec *timeout, int opflags)
> +futex_lock_pi(u_int32_t *uaddr, struct timespec64 *timeout, int opflags)
> {
> return futex(uaddr, FUTEX_LOCK_PI, 0, timeout, NULL, 0, opflags);
> }
> @@ -111,7 +125,7 @@ futex_cmp_requeue(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2, int nr_wak
> */
> static inline int
> futex_wait_requeue_pi(u_int32_t *uaddr, u_int32_t val, u_int32_t *uaddr2,
> - struct timespec *timeout, int opflags)
> + struct timespec64 *timeout, int opflags)
> {
> return futex(uaddr, FUTEX_WAIT_REQUEUE_PI, val, timeout, uaddr2, 0,
> opflags);
> --
> 2.31.1
--
- Arnaldo
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