glibc/sysdeps/unix/sysv/linux/semctl.c
Adhemerval Zanella dba950e317 sysv: linux: Add 64-bit time_t variant for semctl
Different than others 64-bit time_t syscalls, the SysIPC interface
does not provide a new set of syscall for y2038 safeness.  Instead it
uses unused fields in semid_ds structure to return the high bits for
the timestamps.

To provide a y2038 safe interface a new symbol __semctl64 is added
and __semctl is change to call it instead (it adds some extra buffer
copying for the 32 bit time_t implementation).

Two new structures are added:

  1. kernel_semid64_ds: used internally only on 32-bit architectures
     to issue the syscall.  A handful of architectures (hppa, i386,
     mips, powerpc32, sparc32) require specific implementations due
     their kernel ABI.

  2. semid_ds64: this is only for __TIMESIZE != 64 to use along with
     the 64-bit semctl.  It is different than the kernel struct because
     the exported 64-bit time_t might require different alignment
     depending on the architecture ABI.

So the resulting implementation does:

  1. For 64-bit architectures it assumes semid_ds already contains
     64-bit time_t fields and will result in just the __semctl symbol
     using the __semctl64 code.  The semid_ds argument is passed as-is
     to the syscall.

  2. For 32-bit architectures with default 64-bit time_t (newer ABIs
     such riscv32 or arc), it will also result in only one exported
     symbol but with the required high/low handling.

     It might be possible to optimize it further to avoid the
     kernel_semid64_ds to semun transformation if the exported ABI
     for the architectures matches the expected kernel ABI, but the
     implementation is already complex enough and don't think this
     should be a hotspot in any case.

  3. Finally for 32-bit architecture with both 32-bit and 64-bit time_t
     support we follow the already set way to provide one symbol with
     64-bit time_t support and implement the 32-bit time_t support
     using the 64-bit one.

     The default 32-bit symbol will allocate and copy the semid_ds
     over multiple buffers, but this should be deprecated in favor
     of the __semctl64 anyway.

Checked on i686-linux-gnu and x86_64-linux-gnu.  I also did some sniff
tests on powerpc, powerpc64, mips, mips64, armhf, sparcv9, and
sparc64.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Vineet Gupta <vgupta@synopsys.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
2020-07-09 12:05:35 -03:00

378 lines
9.5 KiB
C

/* Copyright (C) 1995-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, August 1995.
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
<https://www.gnu.org/licenses/>. */
#include <sys/sem.h>
#include <stdarg.h>
#include <ipc_priv.h>
#include <sysdep.h>
#include <shlib-compat.h>
#include <bits/types/struct_semid64_ds.h> /* For __semid64_ds. */
#include <linux/posix_types.h> /* For __kernel_mode_t. */
/* The struct used to issue the syscall. For architectures that assume
64-bit time as default (!__ASSUME_TIME64_SYSCALLS) the syscall will
split the resulting 64-bit sem_{o,c}time in two fields (sem_{o,c}time
and __sem_{o,c}time_high). */
union semun
{
int val; /* value for SETVAL */
struct semid_ds *buf; /* buffer for IPC_STAT & IPC_SET */
unsigned short int *array; /* array for GETALL & SETALL */
struct seminfo *__buf; /* buffer for IPC_INFO */
};
#if __IPC_TIME64 == 0
# define semun64 semun
typedef union semun semctl_arg_t;
#else
# include <struct_kernel_semid64_ds.h>
union ksemun64
{
int val;
struct kernel_semid64_ds *buf;
unsigned short int *array;
struct seminfo *__buf;
};
# if __TIMESIZE == 64
# define semun64 semun
# else
/* The struct used when __semctl64 is called. */
union semun64
{
int val;
struct __semid64_ds *buf;
unsigned short int *array;
struct seminfo *__buf;
};
# endif
static void
semid64_to_ksemid64 (const struct __semid64_ds *semid64,
struct kernel_semid64_ds *ksemid)
{
ksemid->sem_perm = semid64->sem_perm;
ksemid->sem_otime = semid64->sem_otime;
ksemid->sem_otime_high = semid64->sem_otime >> 32;
ksemid->sem_ctime = semid64->sem_ctime;
ksemid->sem_ctime_high = semid64->sem_ctime >> 32;
ksemid->sem_nsems = semid64->sem_nsems;
}
static void
ksemid64_to_semid64 (const struct kernel_semid64_ds *ksemid,
struct __semid64_ds *semid64)
{
semid64->sem_perm = ksemid->sem_perm;
semid64->sem_otime = ksemid->sem_otime
| ((__time64_t) ksemid->sem_otime_high << 32);
semid64->sem_ctime = ksemid->sem_ctime
| ((__time64_t) ksemid->sem_ctime_high << 32);
semid64->sem_nsems = ksemid->sem_nsems;
}
static union ksemun64
semun64_to_ksemun64 (int cmd, union semun64 semun64,
struct kernel_semid64_ds *buf)
{
union ksemun64 r = { 0 };
switch (cmd)
{
case SETVAL:
r.val = semun64.val;
break;
case GETALL:
case SETALL:
r.array = semun64.array;
break;
case SEM_STAT:
case IPC_STAT:
case IPC_SET:
r.buf = buf;
semid64_to_ksemid64 (semun64.buf, r.buf);
break;
case IPC_INFO:
case SEM_INFO:
r.__buf = semun64.__buf;
break;
}
return r;
}
typedef union ksemun64 semctl_arg_t;
#endif
static int
semctl_syscall (int semid, int semnum, int cmd, semctl_arg_t arg)
{
#ifdef __ASSUME_DIRECT_SYSVIPC_SYSCALLS
return INLINE_SYSCALL_CALL (semctl, semid, semnum, cmd | __IPC_64,
arg.array);
#else
return INLINE_SYSCALL_CALL (ipc, IPCOP_semctl, semid, semnum, cmd | __IPC_64,
SEMCTL_ARG_ADDRESS (arg));
#endif
}
/* POSIX states ipc_perm mode should have type of mode_t. */
_Static_assert (sizeof ((struct semid_ds){0}.sem_perm.mode)
== sizeof (mode_t),
"sizeof (msqid_ds.msg_perm.mode) != sizeof (mode_t)");
int
__semctl64 (int semid, int semnum, int cmd, ...)
{
union semun64 arg64 = { 0 };
va_list ap;
/* Get the argument only if required. */
switch (cmd)
{
case SETVAL: /* arg.val */
case GETALL: /* arg.array */
case SETALL:
case IPC_STAT: /* arg.buf */
case IPC_SET:
case SEM_STAT:
case IPC_INFO: /* arg.__buf */
case SEM_INFO:
va_start (ap, cmd);
arg64 = va_arg (ap, union semun64);
va_end (ap);
break;
}
#if __IPC_TIME64
struct kernel_semid64_ds ksemid;
union ksemun64 ksemun = semun64_to_ksemun64 (cmd, arg64, &ksemid);
# ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
if (cmd == IPC_SET)
ksemid.sem_perm.mode *= 0x10000U;
# endif
union ksemun64 arg = ksemun;
#else
union semun arg = arg64;
#endif
int ret = semctl_syscall (semid, semnum, cmd, arg);
if (ret < 0)
return ret;
switch (cmd)
{
case IPC_STAT:
case SEM_STAT:
case SEM_STAT_ANY:
#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
arg.buf->sem_perm.mode >>= 16;
#else
/* Old Linux kernel versions might not clear the mode padding. */
if (sizeof ((struct semid_ds){0}.sem_perm.mode)
!= sizeof (__kernel_mode_t))
arg.buf->sem_perm.mode &= 0xFFFF;
#endif
#if __IPC_TIME64
ksemid64_to_semid64 (arg.buf, arg64.buf);
#endif
}
return ret;
}
#if __TIMESIZE != 64
libc_hidden_def (__semctl64)
/* The 64-bit time_t semid_ds version might have a different layout and
internal field alignment. */
static void
semid_to_semid64 (struct __semid64_ds *ds64, const struct semid_ds *ds)
{
ds64->sem_perm = ds->sem_perm;
ds64->sem_otime = ds->sem_otime
| ((__time64_t) ds->__sem_otime_high << 32);
ds64->sem_ctime = ds->sem_ctime
| ((__time64_t) ds->__sem_ctime_high << 32);
ds64->sem_nsems = ds->sem_nsems;
}
static void
semid64_to_semid (struct semid_ds *ds, const struct __semid64_ds *ds64)
{
ds->sem_perm = ds64->sem_perm;
ds->sem_otime = ds64->sem_otime;
ds->__sem_otime_high = 0;
ds->sem_ctime = ds64->sem_ctime;
ds->__sem_ctime_high = 0;
ds->sem_nsems = ds64->sem_nsems;
}
static union semun64
semun_to_semun64 (int cmd, union semun semun, struct __semid64_ds *semid64)
{
union semun64 r = { 0 };
switch (cmd)
{
case SETVAL:
r.val = semun.val;
break;
case GETALL:
case SETALL:
r.array = semun.array;
break;
case SEM_STAT:
case IPC_STAT:
case IPC_SET:
r.buf = semid64;
semid_to_semid64 (r.buf, semun.buf);
break;
case IPC_INFO:
case SEM_INFO:
r.__buf = semun.__buf;
break;
}
return r;
}
int
__semctl (int semid, int semnum, int cmd, ...)
{
union semun arg = { 0 };
va_list ap;
/* Get the argument only if required. */
switch (cmd)
{
case SETVAL: /* arg.val */
case GETALL: /* arg.array */
case SETALL:
case IPC_STAT: /* arg.buf */
case IPC_SET:
case SEM_STAT:
case IPC_INFO: /* arg.__buf */
case SEM_INFO:
va_start (ap, cmd);
arg = va_arg (ap, union semun);
va_end (ap);
break;
}
struct __semid64_ds semid64;
union semun64 arg64 = semun_to_semun64 (cmd, arg, &semid64);
int ret = __semctl64 (semid, semnum, cmd, arg64);
if (ret < 0)
return ret;
switch (cmd)
{
case IPC_STAT:
case SEM_STAT:
case SEM_STAT_ANY:
semid64_to_semid (arg.buf, arg64.buf);
}
return ret;
}
#endif
#ifndef DEFAULT_VERSION
# ifndef __ASSUME_SYSVIPC_BROKEN_MODE_T
# define DEFAULT_VERSION GLIBC_2_2
# else
# define DEFAULT_VERSION GLIBC_2_31
# endif
#endif
versioned_symbol (libc, __semctl, semctl, DEFAULT_VERSION);
#if defined __ASSUME_SYSVIPC_BROKEN_MODE_T \
&& SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_31)
int
attribute_compat_text_section
__semctl_mode16 (int semid, int semnum, int cmd, ...)
{
semctl_arg_t arg = { 0 };
va_list ap;
/* Get the argument only if required. */
switch (cmd)
{
case SETVAL: /* arg.val */
case GETALL: /* arg.array */
case SETALL:
case IPC_STAT: /* arg.buf */
case IPC_SET:
case SEM_STAT:
case IPC_INFO: /* arg.__buf */
case SEM_INFO:
va_start (ap, cmd);
arg = va_arg (ap, semctl_arg_t);
va_end (ap);
break;
}
return semctl_syscall (semid, semnum, cmd, arg);
}
compat_symbol (libc, __semctl_mode16, semctl, GLIBC_2_2);
#endif
#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_2)
/* Since semctl use a variadic argument for semid_ds there is not need to
define and tie the compatibility symbol to the old 'union semun'
definition. */
int
attribute_compat_text_section
__old_semctl (int semid, int semnum, int cmd, ...)
{
union semun arg = { 0 };
va_list ap;
/* Get the argument only if required. */
switch (cmd)
{
case SETVAL: /* arg.val */
case GETALL: /* arg.array */
case SETALL:
case IPC_STAT: /* arg.buf */
case IPC_SET:
case SEM_STAT:
case IPC_INFO: /* arg.__buf */
case SEM_INFO:
va_start (ap, cmd);
arg = va_arg (ap, union semun);
va_end (ap);
break;
}
#if defined __ASSUME_DIRECT_SYSVIPC_SYSCALLS \
&& !defined __ASSUME_SYSVIPC_DEFAULT_IPC_64
/* For architectures that have wire-up semctl but also have __IPC_64 to a
value different than default (0x0) it means the compat symbol used the
__NR_ipc syscall. */
return INLINE_SYSCALL_CALL (semctl, semid, semnum, cmd, arg.array);
# else
return INLINE_SYSCALL_CALL (ipc, IPCOP_semctl, semid, semnum, cmd,
SEMCTL_ARG_ADDRESS (arg));
# endif
}
compat_symbol (libc, __old_semctl, semctl, GLIBC_2_0);
#endif