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sysv: linux: Add 64-bit time_t variant for semctl

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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>
This commit is contained in:
Adhemerval Zanella
2020-06-29 13:35:50 -03:00
parent ffb17e7ba3
commit dba950e317
17 changed files with 378 additions and 78 deletions
Download Patch File Download Diff File Expand all files Collapse all files

274
sysdeps/unix/sysv/linux/semctl.c
View File

@ -21,10 +21,13 @@
#include <ipc_priv.h>
#include <sysdep.h>
#include <shlib-compat.h>
#include <errno.h>
#include <linux/posix_types.h> /* For __kernel_mode_t. */
#include <bits/types/struct_semid64_ds.h> /* For __semid64_ds. */
#include <linux/posix_types.h> /* For __kernel_mode_t. */
/* Define a `union semun' suitable for Linux here. */
/* 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 */
@ -33,16 +36,90 @@ union semun
struct seminfo *__buf; /* buffer for IPC_INFO */
};
#ifndef DEFAULT_VERSION
# ifndef __ASSUME_SYSVIPC_BROKEN_MODE_T
# define DEFAULT_VERSION GLIBC_2_2
#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
# define DEFAULT_VERSION GLIBC_2_31
/* 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, union semun arg)
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,
@ -53,15 +130,132 @@ semctl_syscall (int semid, int semnum, int cmd, union semun arg)
#endif
}
int
__new_semctl (int semid, int semnum, int cmd, ...)
{
/* 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)");
/* 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. */
@ -81,39 +275,33 @@ __new_semctl (int semid, int semnum, int cmd, ...)
break;
}
#ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
struct semid_ds tmpds;
if (cmd == IPC_SET)
{
tmpds = *arg.buf;
tmpds.sem_perm.mode *= 0x10000U;
arg.buf = &tmpds;
}
#endif
struct __semid64_ds semid64;
union semun64 arg64 = semun_to_semun64 (cmd, arg, &semid64);
int ret = semctl_syscall (semid, semnum, cmd, arg);
int ret = __semctl64 (semid, semnum, cmd, arg64);
if (ret < 0)
return ret;
if (ret >= 0)
switch (cmd)
{
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
}
case IPC_STAT:
case SEM_STAT:
case SEM_STAT_ANY:
semid64_to_semid (arg.buf, arg64.buf);
}
return ret;
}
versioned_symbol (libc, __new_semctl, semctl, DEFAULT_VERSION);
#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)
@ -121,7 +309,7 @@ int
attribute_compat_text_section
__semctl_mode16 (int semid, int semnum, int cmd, ...)
{
union semun arg = { 0 };
semctl_arg_t arg = { 0 };
va_list ap;
/* Get the argument only if required. */
@ -136,7 +324,7 @@ __semctl_mode16 (int semid, int semnum, int cmd, ...)
case IPC_INFO: /* arg.__buf */
case SEM_INFO:
va_start (ap, cmd);
arg = va_arg (ap, union semun);
arg = va_arg (ap, semctl_arg_t);
va_end (ap);
break;
}