[PATCH v7 2/2] sysv: linux: Pass 64-bit version of semctl syscall
Alistair Francis
alistair23@gmail.com
Tue May 5 18:22:05 GMT 2020
On Tue, May 5, 2020 at 10:29 AM Lukasz Majewski <lukma@denx.de> wrote:
>
> Hi Alistair,
>
> > The semctl_syscall() function passes a union semun to the kernel. The
> > union includes struct semid_ds as a member. On 32-bit architectures
> > the Linux kernel provides a *_high version of the 32-bit sem_otime and
> > sem_ctime values. These can be combined to get a 64-bit version of the
> > time.
> >
> > This patch adjusts the struct semid_ds to support the *_high versions
> > of sem_otime and sem_ctime. For 32-bit systems with a 64-bit time_t
> > this can be used to get a 64-bit time from the two 32-bit values.
> >
> > This change handles issues that would arrise with architectures that
> > might select __TIMESIZE at build time (and result in different size
> > semid_ds structs).
> >
> > As described by Adhemerval:
> > 1. If an ABI issues 'semctl (semid, semnum, IPC_STAT, ...)' with
> > IPC_STAT without _IPC_CMD_TIME_64, the provided semid_ds buffer
> > will be used directly on the syscall. This is the case for
> > 64-bit architectures and 32-bit architecture without
> > __TIMESIZE==32 support (RV32 for instance).
> >
> > 2. If an ABI issues 'semctl (semid, semnum, IPC_STAT, ...)' with
> > IPC_STAT with _IPC_CMD_TIME_64 then __TIMESIZE==64 is implied.
> > A temporary __semid_ds32 will be used to issue the syscall and
> > its contents will be copied to users semid_ds buffer (which is also
> > implied to be the __TIMESIZE==64).
>
> Shall I provide any extra configuration (i.e. any extra flags) to have
> support for 64 bit time for this syscall on machines with __WORDSIZE ==
> 32 && __TIMESIZE != 64 (i.e. ARM 32 bit)?
I don't think so. This should "just work" with __TIMESIZE == 64 for ARM.
I have a change for RV32 (ipctypes.h) to support RV32 as __TIMESIZE is
always 64.
>
> Please correct me if I'm wrong, but from the below code (at
> bits/ipctypes.h) it seems like #define __IPC_CMD_TIME64 0x0 is for the
> above case (ARM 32 bit).
It should be 0 by default and 0x100 for __TIMESIZE == 64.
Alistair
>
> > ---
> > bits/ipctypes.h | 10 ++
> > sysdeps/mips/bits/ipctypes.h | 10 ++
> > sysdeps/unix/sysv/linux/bits/ipc.h | 3 +-
> > sysdeps/unix/sysv/linux/bits/sem.h | 4 +-
> > sysdeps/unix/sysv/linux/ipc_priv.h | 4 +
> > sysdeps/unix/sysv/linux/semctl.c | 121
> > ++++++++++++++++---- sysdeps/unix/sysv/linux/x86/bits/ipctypes.h |
> > 13 +++ 7 files changed, 141 insertions(+), 24 deletions(-)
> >
> > diff --git a/bits/ipctypes.h b/bits/ipctypes.h
> > index a955cdda7f..1b94122c32 100644
> > --- a/bits/ipctypes.h
> > +++ b/bits/ipctypes.h
> > @@ -32,5 +32,15 @@ typedef unsigned short int __ipc_pid_t;
> > typedef int __ipc_pid_t;
> > # endif
> >
> > +#if __WORDSIZE == 64 \
> > + || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64)
> > +# define __IPC_CMD_TIME64 0x0
> > +#else
> > +# if __TIMESIZE == 64
> > +# define __IPC_CMD_TIME64 0x100 /* Same as __IPC_64. */
> > +# else
> > +# define __IPC_CMD_TIME64 0x0
> > +# endif
> > +#endif
> >
> > #endif /* bits/ipctypes.h */
> > diff --git a/sysdeps/mips/bits/ipctypes.h
> > b/sysdeps/mips/bits/ipctypes.h index 518f579b36..9a7218bf7d 100644
> > --- a/sysdeps/mips/bits/ipctypes.h
> > +++ b/sysdeps/mips/bits/ipctypes.h
> > @@ -27,5 +27,15 @@
> >
> > typedef __SLONG32_TYPE __ipc_pid_t;
> >
> > +#if __WORDSIZE == 64 \
> > + || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64)
> > +# define __IPC_CMD_TIME64 0x0
> > +#else
> > +# if __TIMESIZE == 64
> > +# define __IPC_CMD_TIME64 0x100 /* Same as __IPC_64. */
> > +# else
> > +# define __IPC_CMD_TIME64 0x0
> > +# endif
> > +#endif
> >
> > #endif /* bits/ipctypes.h */
> > diff --git a/sysdeps/unix/sysv/linux/bits/ipc.h
> > b/sysdeps/unix/sysv/linux/bits/ipc.h index 085dd628ac..2519322d16
> > 100644 --- a/sysdeps/unix/sysv/linux/bits/ipc.h
> > +++ b/sysdeps/unix/sysv/linux/bits/ipc.h
> > @@ -20,6 +20,7 @@
> > #endif
> >
> > #include <bits/types.h>
> > +#include <bits/ipctypes.h>
> >
> > /* Mode bits for `msgget', `semget', and `shmget'. */
> > #define IPC_CREAT 01000 /* Create key if key
> > does not exist. */ @@ -29,7 +30,7 @@
> > /* Control commands for `msgctl', `semctl', and `shmctl'. */
> > #define IPC_RMID 0 /* Remove identifier. */
> > #define IPC_SET 1 /* Set `ipc_perm'
> > options. */ -#define IPC_STAT 2 /* Get
> > `ipc_perm' options. */ +#define IPC_STAT (2 |
> > __IPC_CMD_TIME64) /* Get `ipc_perm' options. */
> > #ifdef __USE_GNU # define IPC_INFO 3 /* See
> > ipcs. */ #endif
> > diff --git a/sysdeps/unix/sysv/linux/bits/sem.h
> > b/sysdeps/unix/sysv/linux/bits/sem.h index ba1169fdb3..8d0b88f5e0
> > 100644 --- a/sysdeps/unix/sysv/linux/bits/sem.h
> > +++ b/sysdeps/unix/sysv/linux/bits/sem.h
> > @@ -54,9 +54,9 @@
> > #ifdef __USE_MISC
> >
> > /* ipcs ctl cmds */
> > -# define SEM_STAT 18
> > +# define SEM_STAT (18 | __IPC_CMD_TIME64)
> > # define SEM_INFO 19
> > -# define SEM_STAT_ANY 20
> > +# define SEM_STAT_ANY (20 | __IPC_CMD_TIME64)
> >
> > struct seminfo
> > {
> > diff --git a/sysdeps/unix/sysv/linux/ipc_priv.h
> > b/sysdeps/unix/sysv/linux/ipc_priv.h index 15a6e683a4..a1a7cacd17
> > 100644 --- a/sysdeps/unix/sysv/linux/ipc_priv.h
> > +++ b/sysdeps/unix/sysv/linux/ipc_priv.h
> > @@ -43,6 +43,10 @@ struct __old_ipc_perm
> > unsigned short int __seq; /* Sequence number. */
> > };
> >
> > +#define __IPC_TIME64 \
> > + (__WORDSIZE == 32 && __TIMESIZE == 64 \
> > + && (!defined __SYSCALL_WORDSIZE || __SYSCALL_WORDSIZE == 32))
> > +
> > #define SEMCTL_ARG_ADDRESS(__arg) &__arg.array
> >
> > #define MSGRCV_ARGS(__msgp, __msgtyp) \
> > diff --git a/sysdeps/unix/sysv/linux/semctl.c
> > b/sysdeps/unix/sysv/linux/semctl.c index 30571af49f..99ad686194 100644
> > --- a/sysdeps/unix/sysv/linux/semctl.c
> > +++ b/sysdeps/unix/sysv/linux/semctl.c
> > @@ -22,12 +22,16 @@
> > #include <sysdep.h>
> > #include <shlib-compat.h>
> > #include <errno.h>
> > +#include <struct__semid_ds32.h>
> > #include <linux/posix_types.h> /* For __kernel_mode_t. */
> >
> > /* Define a `union semun' suitable for Linux here. */
> > union semun
> > {
> > int val; /* value for SETVAL */
> > +#if __IPC_TIME64
> > + struct __semid_ds32 *buf32;
> > +#endif
> > 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 */
> > @@ -44,13 +48,54 @@ union semun
> > static int
> > semctl_syscall (int semid, int semnum, int cmd, union semun arg)
> > {
> > + int ret;
> > +#if __IPC_TIME64
> > + /* A temporary buffer is used to avoid both an issue where the
> > export
> > + semid_ds might not follow the kernel's expected layout (due
> > + to {o,c}time{_high} alignment in 64-bit time case) and the
> > issue where
> > + some kernel versions might not clear the high bits when
> > returning
> > + then {o,c}time{_high} information. */
> > + struct __semid_ds32 tmp;
> > + struct semid_ds *orig;
> > + bool restore = false;
> > + if (cmd == IPC_STAT || cmd == SEM_STAT || cmd == SEM_STAT_ANY)
> > + {
> > + tmp = (struct __semid_ds32) {
> > + .sem_perm = arg.buf->sem_perm,
> > + .sem_otime = arg.buf->sem_otime,
> > + .sem_otime_high = arg.buf->sem_otime >> 32,
> > + .sem_ctime = arg.buf->sem_ctime,
> > + .sem_ctime_high = arg.buf->sem_ctime >> 32,
> > + .sem_nsems = arg.buf->sem_nsems,
> > + };
> > + orig = arg.buf;
> > + arg.buf = (struct semid_ds*) &tmp;
> > + restore = true;
> > + }
> > +#endif
> > +
> > #ifdef __ASSUME_DIRECT_SYSVIPC_SYSCALLS
> > - return INLINE_SYSCALL_CALL (semctl, semid, semnum, cmd | __IPC_64,
> > - arg.array);
> > + ret = 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));
> > + ret = INLINE_SYSCALL_CALL (ipc, IPCOP_semctl, semid, semnum, cmd |
> > __IPC_64,
> > + SEMCTL_ARG_ADDRESS (arg));
> > #endif
> > +
> > +#if __IPC_TIME64
> > + if (ret >= 0 && restore)
> > + {
> > + arg.buf = orig;
> > + arg.buf->sem_perm = tmp.sem_perm;
> > + arg.buf->sem_otime = tmp.sem_otime
> > + | ((__time64_t) tmp.sem_otime_high << 32);
> > + arg.buf->sem_ctime = tmp.sem_ctime
> > + | ((__time64_t) tmp.sem_ctime_high << 32);
> > + arg.buf->sem_nsems = tmp.sem_nsems;
> > + }
> > +#endif
> > +
> > + return ret;
> > }
> >
> > int
> > @@ -64,15 +109,15 @@ __new_semctl (int semid, int semnum, int cmd,
> > ...) union semun arg = { 0 };
> > va_list ap;
> >
> > - /* Get the argument only if required. */
> > - switch (cmd)
> > + /* Get the argument only if required. Ignore the
> > __IPC_CMD_TIME64. */
> > + switch (cmd & ~__IPC_CMD_TIME64)
> > {
> > case SETVAL: /* arg.val */
> > case GETALL: /* arg.array */
> > case SETALL:
> > - case IPC_STAT: /* arg.buf */
> > + case IPC_STAT & ~__IPC_CMD_TIME64: /* arg.buf */
> > case IPC_SET:
> > - case SEM_STAT:
> > + case SEM_STAT & ~__IPC_CMD_TIME64:
> > case IPC_INFO: /* arg.__buf */
> > case SEM_INFO:
> > va_start (ap, cmd);
> > @@ -81,6 +126,20 @@ __new_semctl (int semid, int semnum, int cmd, ...)
> > break;
> > }
> >
> > +#ifdef __IPC_TIME64
> > + struct __semid_ds32 tmp32;
> > + struct semid_ds *orig64;
> > + bool restore = false;
> > +
> > + if (cmd & __IPC_CMD_TIME64)
> > + {
> > + tmp32 = (struct __semid_ds32) { 0 };
> > + orig64 = (struct semid_ds *) arg.buf;
> > + arg.buf = (struct semid_ds *) &tmp32;
> > + restore = true;
> > + }
> > +#endif
> > +
> > #ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
> > struct semid_ds tmpds;
> > if (cmd == IPC_SET)
> > @@ -91,26 +150,46 @@ __new_semctl (int semid, int semnum, int cmd,
> > ...) }
> > #endif
> >
> > - int ret = semctl_syscall (semid, semnum, cmd, arg);
> > + int ret = semctl_syscall (semid, semnum, cmd & ~__IPC_CMD_TIME64,
> > arg);
> > + if (ret < 0)
> > + return ret;
> >
> > - if (ret >= 0)
> > + switch (cmd & ~__IPC_CMD_TIME64)
> > {
> > - switch (cmd)
> > - {
> > - case IPC_STAT:
> > - case SEM_STAT:
> > - case SEM_STAT_ANY:
> > + case IPC_STAT:
> > + case SEM_STAT:
> > + case SEM_STAT_ANY:
> > #ifdef __ASSUME_SYSVIPC_BROKEN_MODE_T
> > - arg.buf->sem_perm.mode >>= 16;
> > +# if __IPC_TIME64
> > + arg.buf32->sem_perm.mode >>= 16;
> > +# else
> > + arg.buf->sem_perm.mode >>= 16;
> > +# endif
> > #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;
> > + /* Old Linux kernel versions might not clear the mode padding.
> > */
> > + if (sizeof ((struct semid_ds){0}.sem_perm.mode)
> > + != sizeof (__kernel_mode_t))
> > +# if __IPC_TIME64
> > + arg.buf32->sem_perm.mode &= 0xFFFF;
> > +# else
> > + arg.buf->sem_perm.mode &= 0xFFFF;
> > +# endif
> > #endif
> > - }
> > }
> >
> > +#ifdef __IPC_TIME64
> > + if (restore)
> > + {
> > + orig64->sem_perm = tmp32.sem_perm;
> > + orig64->sem_otime = tmp32.sem_otime
> > + | ((__time64_t) tmp32.sem_otime_high <<
> > 32);
> > + orig64->sem_ctime = tmp32.sem_ctime
> > + | ((__time64_t) tmp32.sem_ctime_high <<
> > 32);
> > + orig64->sem_nsems = tmp32.sem_nsems;
> > + arg.buf = (struct semid_ds *) orig64;
> > + }
> > +#endif
> > +
> > return ret;
> > }
> > versioned_symbol (libc, __new_semctl, semctl, DEFAULT_VERSION);
> > diff --git a/sysdeps/unix/sysv/linux/x86/bits/ipctypes.h
> > b/sysdeps/unix/sysv/linux/x86/bits/ipctypes.h index
> > 12e4cd7682..aa56da6cd5 100644 ---
> > a/sysdeps/unix/sysv/linux/x86/bits/ipctypes.h +++
> > b/sysdeps/unix/sysv/linux/x86/bits/ipctypes.h @@ -23,6 +23,8 @@
> > #ifndef _BITS_IPCTYPES_H
> > #define _BITS_IPCTYPES_H 1
> >
> > +#include <bits/types.h>
> > +
> > /* Used in `struct shmid_ds'. */
> > # ifdef __x86_64__
> > typedef int __ipc_pid_t;
> > @@ -30,4 +32,15 @@ typedef int __ipc_pid_t;
> > typedef unsigned short int __ipc_pid_t;
> > # endif
> >
> > +#if __WORDSIZE == 64 \
> > + || (defined __SYSCALL_WORDSIZE && __SYSCALL_WORDSIZE == 64)
> > +# define __IPC_CMD_TIME64 0x0
> > +#else
> > +# if __TIMESIZE == 64
> > +# define __IPC_CMD_TIME64 0x100 /* Same as __IPC_64. */
> > +# else
> > +# define __IPC_CMD_TIME64 0x0
> > +# endif
> > +#endif
> > +
> > #endif /* bits/ipctypes.h */
>
>
>
>
> 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
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