android_kernel_samsung_msm8976/arch/tile/kernel/compat.c
Chris Metcalf 2c7387ef99 asm-generic/stat.h: support 64-bit file time_t for stat()
The existing asm-generic/stat.h specifies st_mtime, etc., as a 32-value,
and works well for 32-bit architectures (currently microblaze, score,
and 32-bit tile).  However, for 64-bit architectures it isn't sufficient
to return 32 bits of time_t; this isn't good insurance against the 2037
rollover.  (It also makes glibc support less convenient, since we can't
use glibc's handy STAT_IS_KERNEL_STAT mode.)

This change extends the two "timespec" fields for each of the three atime,
mtime, and ctime fields from "int" to "long".  As a result, on 32-bit
platforms nothing changes, and 64-bit platforms will now work as expected.

The only wrinkle is 32-bit userspace under 64-bit kernels taking advantage
of COMPAT mode.  For these, we leave the "struct stat64" definitions with
the "int" versions of the time_t and nsec fields, so that architectures
can implement compat_sys_stat64() and friends with sys_stat64(), etc.,
and get the expected 32-bit structure layout.  This requires a
field-by-field copy in the kernel, implemented by the code guarded
under __ARCH_WANT_STAT64.

This does mean that the shape of the "struct stat" and "struct stat64"
structures is different on a 64-bit kernel, but only one of the two
structures should ever be used by any given process: "struct stat"
is meant for 64-bit userspace only, and "struct stat64" for 32-bit
userspace only.  (On a 32-bit kernel the two structures continue to have
the same shape, since "long" is 32 bits.)

The alternative is keeping the two structures the same shape on 64-bit
kernels, which means a 64-bit time_t in "struct stat64" for 32-bit
processes.  This is a little unnatural since 32-bit userspace can't
do anything with 64 bits of time_t information, since time_t is just
"long", not "int64_t"; and in any case 32-bit userspace might expect
to be running under a 32-bit kernel, which can't provide the high 32
bits anyway.  In the case of a 32-bit kernel we'd then be extending the
kernel's 32-bit time_t to 64 bits, then truncating it back to 32 bits
again in userspace, for no particular reason.  And, as mentioned above,
if we have 64-bit time_t for 32-bit processes we can't easily use glibc's
STAT_IS_KERNEL_STAT, since glibc's stat structure requires an embedded
"struct timespec", which is a pair of "long" (32-bit) values in a 32-bit
userspace.  "Inventive" solutions are possible, but are pretty hacky.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
2010-11-01 15:31:29 -04:00

173 lines
4.9 KiB
C

/*
* Copyright 2010 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program 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, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/
/* Adjust unistd.h to provide 32-bit numbers and functions. */
#define __SYSCALL_COMPAT
#include <linux/compat.h>
#include <linux/msg.h>
#include <linux/syscalls.h>
#include <linux/kdev_t.h>
#include <linux/fs.h>
#include <linux/fcntl.h>
#include <linux/smp_lock.h>
#include <linux/uaccess.h>
#include <linux/signal.h>
#include <asm/syscalls.h>
/*
* Syscalls that take 64-bit numbers traditionally take them in 32-bit
* "high" and "low" value parts on 32-bit architectures.
* In principle, one could imagine passing some register arguments as
* fully 64-bit on TILE-Gx in 32-bit mode, but it seems easier to
* adapt the usual convention.
*/
long compat_sys_truncate64(char __user *filename, u32 dummy, u32 low, u32 high)
{
return sys_truncate(filename, ((loff_t)high << 32) | low);
}
long compat_sys_ftruncate64(unsigned int fd, u32 dummy, u32 low, u32 high)
{
return sys_ftruncate(fd, ((loff_t)high << 32) | low);
}
long compat_sys_pread64(unsigned int fd, char __user *ubuf, size_t count,
u32 dummy, u32 low, u32 high)
{
return sys_pread64(fd, ubuf, count, ((loff_t)high << 32) | low);
}
long compat_sys_pwrite64(unsigned int fd, char __user *ubuf, size_t count,
u32 dummy, u32 low, u32 high)
{
return sys_pwrite64(fd, ubuf, count, ((loff_t)high << 32) | low);
}
long compat_sys_lookup_dcookie(u32 low, u32 high, char __user *buf, size_t len)
{
return sys_lookup_dcookie(((loff_t)high << 32) | low, buf, len);
}
long compat_sys_sync_file_range2(int fd, unsigned int flags,
u32 offset_lo, u32 offset_hi,
u32 nbytes_lo, u32 nbytes_hi)
{
return sys_sync_file_range(fd, ((loff_t)offset_hi << 32) | offset_lo,
((loff_t)nbytes_hi << 32) | nbytes_lo,
flags);
}
long compat_sys_fallocate(int fd, int mode,
u32 offset_lo, u32 offset_hi,
u32 len_lo, u32 len_hi)
{
return sys_fallocate(fd, mode, ((loff_t)offset_hi << 32) | offset_lo,
((loff_t)len_hi << 32) | len_lo);
}
long compat_sys_sched_rr_get_interval(compat_pid_t pid,
struct compat_timespec __user *interval)
{
struct timespec t;
int ret;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
ret = sys_sched_rr_get_interval(pid,
(struct timespec __force __user *)&t);
set_fs(old_fs);
if (put_compat_timespec(&t, interval))
return -EFAULT;
return ret;
}
/*
* The usual compat_sys_msgsnd() and _msgrcv() seem to be assuming
* some different calling convention than our normal 32-bit tile code.
*/
/* Already defined in ipc/compat.c, but we need it here. */
struct compat_msgbuf {
compat_long_t mtype;
char mtext[1];
};
long tile_compat_sys_msgsnd(int msqid,
struct compat_msgbuf __user *msgp,
size_t msgsz, int msgflg)
{
compat_long_t mtype;
if (get_user(mtype, &msgp->mtype))
return -EFAULT;
return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
}
long tile_compat_sys_msgrcv(int msqid,
struct compat_msgbuf __user *msgp,
size_t msgsz, long msgtyp, int msgflg)
{
long err, mtype;
err = do_msgrcv(msqid, &mtype, msgp->mtext, msgsz, msgtyp, msgflg);
if (err < 0)
goto out;
if (put_user(mtype, &msgp->mtype))
err = -EFAULT;
out:
return err;
}
/* Provide the compat syscall number to call mapping. */
#undef __SYSCALL
#define __SYSCALL(nr, call) [nr] = (compat_##call),
/* The generic versions of these don't work for Tile. */
#define compat_sys_msgrcv tile_compat_sys_msgrcv
#define compat_sys_msgsnd tile_compat_sys_msgsnd
/* See comments in sys.c */
#define compat_sys_fadvise64 sys32_fadvise64
#define compat_sys_fadvise64_64 sys32_fadvise64_64
#define compat_sys_readahead sys32_readahead
#define compat_sys_sync_file_range compat_sys_sync_file_range2
/* We leverage the "struct stat64" type for 32-bit time_t/nsec. */
#define compat_sys_stat64 sys_stat64
#define compat_sys_lstat64 sys_lstat64
#define compat_sys_fstat64 sys_fstat64
#define compat_sys_fstatat64 sys_fstatat64
/* The native sys_ptrace dynamically handles compat binaries. */
#define compat_sys_ptrace sys_ptrace
/* Call the trampolines to manage pt_regs where necessary. */
#define compat_sys_execve _compat_sys_execve
#define compat_sys_sigaltstack _compat_sys_sigaltstack
#define compat_sys_rt_sigreturn _compat_sys_rt_sigreturn
#define sys_clone _sys_clone
/*
* Note that we can't include <linux/unistd.h> here since the header
* guard will defeat us; <asm/unistd.h> checks for __SYSCALL as well.
*/
void *compat_sys_call_table[__NR_syscalls] = {
[0 ... __NR_syscalls-1] = sys_ni_syscall,
#include <asm/unistd.h>
};