Re: [RFC v6 05/23] linux: Use 32-bit time_t for rusage

[Lukasz Majewski <lukma at denx dot de>]

Hi Alistair,

> The Linux kernel expects rusage to use a 32-bit time_t, even on archs
> with a 64-bit time_t (like RV32). To address this let's convert
> rusage to/from 32-bit and 64-bit to ensure the kernel always gets
> a 32-bit time_t.
> 
> This means that all 32-bit architectures with a 64-bit time_t will be
> able to use this generic implementation.
> 
> This code is bsaed on similar code in alpha, but adjusted to pass the
	       ^^^^^ - based?

> 32-bit time_t to the kernel.
> 
> We can't directly call __wait4 as it expects a structrusage but we
						 ^^^^^^^^^^^^ - struct
						 rusage

> have to pass in and use a struct rusage32. The same appies to
> __getrusage. ---
>  .../linux/generic/wordsize-32/getrusage.c     | 39 +++++++++
>  .../linux/generic/wordsize-32/tv32-compat.h   | 47 +++++++++++
>  .../sysv/linux/generic/wordsize-32/wait4.c    | 79
> +++++++++++++++++++ 3 files changed, 165 insertions(+)
>  create mode 100644
> sysdeps/unix/sysv/linux/generic/wordsize-32/getrusage.c create mode
> 100644 sysdeps/unix/sysv/linux/generic/wordsize-32/wait4.c
> 
> diff --git a/sysdeps/unix/sysv/linux/generic/wordsize-32/getrusage.c
> b/sysdeps/unix/sysv/linux/generic/wordsize-32/getrusage.c new file
> mode 100644 index 0000000000..2ada94a954
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/generic/wordsize-32/getrusage.c
> @@ -0,0 +1,39 @@
> +/* utimes -- change file timestamps.  Linux/RV32/tv32 version.
      
Please update the in-comment header.

> +   Copyright (C) 2020 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be
> useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sys/time.h>
> +#include <sys/resource.h>
> +#include <sysdep.h>
> +#include <tv32-compat.h>
> +
> +int
> +__getrusage (int who, struct rusage *usage)
> +{
> +#if __TIMESIZE == 64
> +  struct rusage32 usage32;
> +  if (INLINE_SYSCALL_CALL (getrusage, who, &usage32) == -1)
> +    return -1;
> +
> +  rusage32_to_rusage64 (&usage32, usage);
> +  return 0;
> +#else
> +  return INLINE_SYSCALL_CALL (getrusage, who, usage);
> +#endif
> +}

This is the same issue as pointed out with __setitimer support.

Following the conversion convention (as in e.g. clock_settime.c) would
allow Y2038 safe 32 bit ports benefit from this patch.

> +
> +strong_alias (__getrusage, getrusage)
> diff --git
> a/sysdeps/unix/sysv/linux/generic/wordsize-32/tv32-compat.h
> b/sysdeps/unix/sysv/linux/generic/wordsize-32/tv32-compat.h index
> aa960a6632..8a4bd15002 100644 ---
> a/sysdeps/unix/sysv/linux/generic/wordsize-32/tv32-compat.h +++
> b/sysdeps/unix/sysv/linux/generic/wordsize-32/tv32-compat.h @@ -24,6
> +24,7 @@ #include <bits/types.h> #include <bits/types/time_t.h>
>  #include <bits/types/struct_timeval.h>
> +#include <bits/types/struct_rusage.h>
>  
>  /* Structures containing 'struct timeval' with 32-bit time_t.  */
>  struct itimerval32
> @@ -32,4 +33,50 @@ struct itimerval32
>    struct __timeval_long it_value;
>  };
>  
> +struct rusage32

struct __rusage32 ?

> +{
> +  struct __timeval_long ru_utime;	/* user time used */
> +  struct __timeval_long ru_stime;	/* system time used */
	
	    As pointed out in the other comment - maybe struct
	    __timeval32 would be more appropriate?

	This is the same convention as we already have with struct
	__timespec64 and __itimerspec64

> +  long ru_maxrss;		/* maximum resident set size */
> +  long ru_ixrss;		/* integral shared memory size */
> +  long ru_idrss;		/* integral unshared data size */
> +  long ru_isrss;		/* integral unshared stack size */
> +  long ru_minflt;		/* page reclaims */
> +  long ru_majflt;		/* page faults */
> +  long ru_nswap;		/* swaps */
> +  long ru_inblock;		/* block input operations */
> +  long ru_oublock;		/* block output operations */
> +  long ru_msgsnd;		/* messages sent */
> +  long ru_msgrcv;		/* messages received */
> +  long ru_nsignals;		/* signals received */
> +  long ru_nvcsw;		/* voluntary context switches */
> +  long ru_nivcsw;		/* involuntary " */
> +};
> +
> +static inline void
> +rusage32_to_rusage64 (const struct rusage32 *restrict r32,
> +                      struct rusage *restrict r64)
> +{
> +  /* Make sure the entire output structure is cleared, including
> +     padding and reserved fields.  */
> +  memset (r64, 0, sizeof *r64);
> +
> +  r64->ru_utime    = valid_timeval_long_to_timeval64 (r32->ru_utime);
> +  r64->ru_stime    = valid_timeval_long_to_timeval64 (r32->ru_stime);
> +  r64->ru_maxrss   = r32->ru_maxrss;
> +  r64->ru_ixrss    = r32->ru_ixrss;
> +  r64->ru_idrss    = r32->ru_idrss;
> +  r64->ru_isrss    = r32->ru_isrss;
> +  r64->ru_minflt   = r32->ru_minflt;
> +  r64->ru_majflt   = r32->ru_majflt;
> +  r64->ru_nswap    = r32->ru_nswap;
> +  r64->ru_inblock  = r32->ru_inblock;
> +  r64->ru_oublock  = r32->ru_oublock;
> +  r64->ru_msgsnd   = r32->ru_msgsnd;
> +  r64->ru_msgrcv   = r32->ru_msgrcv;
> +  r64->ru_nsignals = r32->ru_nsignals;
> +  r64->ru_nvcsw    = r32->ru_nvcsw;
> +  r64->ru_nivcsw   = r32->ru_nivcsw;
> +}
> +
>  #endif /* tv32-compat.h */
> diff --git a/sysdeps/unix/sysv/linux/generic/wordsize-32/wait4.c
> b/sysdeps/unix/sysv/linux/generic/wordsize-32/wait4.c new file mode
> 100644 index 0000000000..a4a81a0587
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/generic/wordsize-32/wait4.c
> @@ -0,0 +1,79 @@
> +/* wait4 -- wait for process to change state.  Linux/RV32/tv32
> version.
> +   Copyright (C) 2020 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be
> useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <http://www.gnu.org/licenses/>.  */
> +
> +#include <sys/wait.h>
> +#include <sys/resource.h>
> +#include <sysdep-cancel.h>
> +#include <tv32-compat.h>
> +
> +pid_t
> +__wait4 (pid_t pid, int *stat_loc, int options, struct rusage *usage)
> +{
> +  struct rusage32 usage32;
> +  idtype_t idtype = P_PID;
> +
> +  if (pid < -1)
> +    {
> +      idtype = P_PGID;
> +      pid *= -1;
> +    }
> +  else if (pid == -1)
> +    idtype = P_ALL;
> +  else if (pid == 0)
> +    idtype = P_PGID;
> +
> +  options |= WEXITED;
> +
> +  siginfo_t infop;
> +  if (SYSCALL_CANCEL (waitid, idtype, pid, &infop, options,
> &usage32) < 0)
> +    return -1;
> +
> +  if (stat_loc)
> +    {
> +      switch (infop.si_code)
> +        {
> +        case CLD_EXITED:
> +          *stat_loc = W_EXITCODE (infop.si_status, 0);
> +          break;
> +        case CLD_DUMPED:
> +          *stat_loc = WCOREFLAG | infop.si_status;
> +    break;
> +        case CLD_KILLED:
> +          *stat_loc = infop.si_status;
> +          break;
> +        case CLD_TRAPPED:
> +        case CLD_STOPPED:
> +          *stat_loc = W_STOPCODE (infop.si_status);
> +          break;
> +        case CLD_CONTINUED:
> +          *stat_loc = __W_CONTINUED;
> +          break;
> +  default:
> +    *stat_loc = 0;
> +    break;
> +        }
> +    }
> +
> +  if (usage != NULL)
> +    rusage32_to_rusage64 (&usage32, usage);
> +
> +  return infop.si_pid;
> +}
> +
> +libc_hidden_def (__wait4);
> +weak_alias (__wait4, wait4)

This wait4 implementation (as it doesn't use #define __TIMESIZE == 64)
could be used by all 32 bit ports. Am I right?


Best regards,

Lukasz Majewski

--

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