[16/18] linux: Only use 64-bit syscall if required for utimensat family

Message ID 20210617115104.1359598-17-adhemerval.zanella@linaro.org
State New
Headers show
Series
  • More y2038 fixes
Related show

Commit Message

Wilco Dijkstra via Libc-alpha June 17, 2021, 11:51 a.m.
For !__ASSUME_TIME64_SYSCALLS there is no need to issue a 64-bit syscall
if the provided timeout fits in a 32-bit one.  The 64-bit usage should
be rare since the timeout is a relative one.

The large timeout are already tests by io/tst-utimensat-skeleton.c.

Checked on i686-linux-gnu on a 4.15 kernel and on a 5.11 kernel
(with and without --enable-kernel=5.1) and on x86_64-linux-gnu.
---
 sysdeps/unix/sysv/linux/utimensat.c | 35 ++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 13 deletions(-)

-- 
2.30.2

Comments

Lukasz Majewski June 21, 2021, 7:45 a.m. | #1
On Thu, 17 Jun 2021 08:51:02 -0300
Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote:

> For !__ASSUME_TIME64_SYSCALLS there is no need to issue a 64-bit

> syscall if the provided timeout fits in a 32-bit one.  The 64-bit

> usage should be rare since the timeout is a relative one.

> 

> The large timeout are already tests by io/tst-utimensat-skeleton.c.

> 

> Checked on i686-linux-gnu on a 4.15 kernel and on a 5.11 kernel

> (with and without --enable-kernel=5.1) and on x86_64-linux-gnu.

> ---

>  sysdeps/unix/sysv/linux/utimensat.c | 35

> ++++++++++++++++++----------- 1 file changed, 22 insertions(+), 13

> deletions(-)

> 

> diff --git a/sysdeps/unix/sysv/linux/utimensat.c

> b/sysdeps/unix/sysv/linux/utimensat.c index 909a29762b..e79e4351d6

> 100644 --- a/sysdeps/unix/sysv/linux/utimensat.c

> +++ b/sysdeps/unix/sysv/linux/utimensat.c

> @@ -31,34 +31,43 @@ __utimensat64_helper (int fd, const char *file,

>  #ifndef __NR_utimensat_time64

>  # define __NR_utimensat_time64 __NR_utimensat

>  #endif

> -  int ret = INLINE_SYSCALL_CALL (utimensat_time64, fd, file,

> &tsp64[0], flags); -#ifndef __ASSUME_TIME64_SYSCALLS

> -  if (ret == 0 || errno != ENOSYS)

> -    return ret;

>  

> +#ifdef __ASSUME_TIME64_SYSCALLS

> +  return INLINE_SYSCALL_CALL (utimensat_time64, fd, file, &tsp64[0],

> flags); +#else

>    /* For UTIME_NOW and UTIME_OMIT the value of tv_sec field is

> ignored.  */ -# define TS_VALID(ns) \

> -  ((((ns).tv_nsec == UTIME_NOW || (ns).tv_nsec == UTIME_OMIT) \

> -   || in_time_t_range ((ns).tv_sec)))

> +# define TS_SPECIAL(ts) \

> +  ((ts).tv_nsec == UTIME_NOW || (ts).tv_nsec == UTIME_OMIT)

>  

> -  if (tsp64 != NULL

> -      && (!TS_VALID (tsp64[0]) || !TS_VALID (tsp64[1])))

> +  bool is32bit_t0 = tsp64 != NULL

> +		    ? TS_SPECIAL (tsp64[0])

> +		      || in_time_t_range (tsp64[0].tv_sec)

> +	            : true;

> +  bool is32bit_t1 = tsp64 != NULL

> +		    ? TS_SPECIAL (tsp64[1])

> +		      || in_time_t_range (tsp64[1].tv_sec)

> +	            : true;

> +

> +  if (!is32bit_t0 || !is32bit_t1)

>      {

> +      int r = INLINE_SYSCALL_CALL (utimensat_time64, fd, file,

> &tsp64[0],

> +				   flags);

> +      if (r == 0 || errno != ENOSYS)

> +	return r;

>        __set_errno (EOVERFLOW);

>        return -1;

>      }

>  

> -  struct timespec tsp32[2];

> +  struct timespec tsp32[2], *ptsp32 = NULL;

>    if (tsp64)

>      {

>        tsp32[0] = valid_timespec64_to_timespec (tsp64[0]);

>        tsp32[1] = valid_timespec64_to_timespec (tsp64[1]);

> +      ptsp32 = tsp32;

>      }

>  

> -  ret = INLINE_SYSCALL_CALL (utimensat, fd, file, tsp64 ? &tsp32[0]

> : NULL,

> -			     flags);

> +  return INLINE_SYSCALL_CALL (utimensat, fd, file, ptsp32, flags);

>  #endif

> -  return ret;

>  }

>  libc_hidden_def (__utimensat64_helper)

>  


Reviewed-by: Lukasz Majewski <lukma@denx.de>



Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de

Patch

diff --git a/sysdeps/unix/sysv/linux/utimensat.c b/sysdeps/unix/sysv/linux/utimensat.c
index 909a29762b..e79e4351d6 100644
--- a/sysdeps/unix/sysv/linux/utimensat.c
+++ b/sysdeps/unix/sysv/linux/utimensat.c
@@ -31,34 +31,43 @@  __utimensat64_helper (int fd, const char *file,
 #ifndef __NR_utimensat_time64
 # define __NR_utimensat_time64 __NR_utimensat
 #endif
-  int ret = INLINE_SYSCALL_CALL (utimensat_time64, fd, file, &tsp64[0], flags);
-#ifndef __ASSUME_TIME64_SYSCALLS
-  if (ret == 0 || errno != ENOSYS)
-    return ret;
 
+#ifdef __ASSUME_TIME64_SYSCALLS
+  return INLINE_SYSCALL_CALL (utimensat_time64, fd, file, &tsp64[0], flags);
+#else
   /* For UTIME_NOW and UTIME_OMIT the value of tv_sec field is ignored.  */
-# define TS_VALID(ns) \
-  ((((ns).tv_nsec == UTIME_NOW || (ns).tv_nsec == UTIME_OMIT) \
-   || in_time_t_range ((ns).tv_sec)))
+# define TS_SPECIAL(ts) \
+  ((ts).tv_nsec == UTIME_NOW || (ts).tv_nsec == UTIME_OMIT)
 
-  if (tsp64 != NULL
-      && (!TS_VALID (tsp64[0]) || !TS_VALID (tsp64[1])))
+  bool is32bit_t0 = tsp64 != NULL
+		    ? TS_SPECIAL (tsp64[0])
+		      || in_time_t_range (tsp64[0].tv_sec)
+	            : true;
+  bool is32bit_t1 = tsp64 != NULL
+		    ? TS_SPECIAL (tsp64[1])
+		      || in_time_t_range (tsp64[1].tv_sec)
+	            : true;
+
+  if (!is32bit_t0 || !is32bit_t1)
     {
+      int r = INLINE_SYSCALL_CALL (utimensat_time64, fd, file, &tsp64[0],
+				   flags);
+      if (r == 0 || errno != ENOSYS)
+	return r;
       __set_errno (EOVERFLOW);
       return -1;
     }
 
-  struct timespec tsp32[2];
+  struct timespec tsp32[2], *ptsp32 = NULL;
   if (tsp64)
     {
       tsp32[0] = valid_timespec64_to_timespec (tsp64[0]);
       tsp32[1] = valid_timespec64_to_timespec (tsp64[1]);
+      ptsp32 = tsp32;
     }
 
-  ret = INLINE_SYSCALL_CALL (utimensat, fd, file, tsp64 ? &tsp32[0] : NULL,
-			     flags);
+  return INLINE_SYSCALL_CALL (utimensat, fd, file, ptsp32, flags);
 #endif
-  return ret;
 }
 libc_hidden_def (__utimensat64_helper)