Allow times and time system calls to return small negative values

At the moment, the times() system call will appear to fail for a period
shortly after boot, while the value it want to return is between -4095 and
-1.  The same thing will also happen for the time() system call on 32-bit
platforms some time in 2106 or so.

On some platforms, such as x86, this is unavoidable because of the system
call ABI, but other platforms such as powerpc have a separate error
indication from the return value, so system calls can in fact return small
negative values without indicating an error.  On those platforms,
force_successful_syscall_return() provides a way to indicate that the
system call return value should not be treated as an error even if it is
in the range which would normally be taken as a negative error number.

This adds a force_successful_syscall_return() call to the time() and
times() system calls plus their 32-bit compat versions, so that they don't
erroneously indicate an error on those platforms whose system call ABI has
a separate error indication.  This will not affect anything on other
platforms.

Joakim Tjernlund added the fix for time() and the compat versions of
time() and times(), after I did the fix for times().

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Paul Mackerras 2009-01-06 14:41:02 -08:00 committed by Linus Torvalds
parent af9379c712
commit e3d5a27d58
3 changed files with 9 additions and 2 deletions

View File

@ -24,6 +24,7 @@
#include <linux/migrate.h>
#include <linux/posix-timers.h>
#include <linux/times.h>
#include <linux/ptrace.h>
#include <asm/uaccess.h>
@ -229,6 +230,7 @@ asmlinkage long compat_sys_times(struct compat_tms __user *tbuf)
if (copy_to_user(tbuf, &tmp, sizeof(tmp)))
return -EFAULT;
}
force_successful_syscall_return();
return compat_jiffies_to_clock_t(jiffies);
}
@ -894,8 +896,9 @@ asmlinkage long compat_sys_time(compat_time_t __user * tloc)
if (tloc) {
if (put_user(i,tloc))
i = -EFAULT;
return -EFAULT;
}
force_successful_syscall_return();
return i;
}

View File

@ -33,6 +33,7 @@
#include <linux/task_io_accounting_ops.h>
#include <linux/seccomp.h>
#include <linux/cpu.h>
#include <linux/ptrace.h>
#include <linux/compat.h>
#include <linux/syscalls.h>
@ -927,6 +928,7 @@ asmlinkage long sys_times(struct tms __user * tbuf)
if (copy_to_user(tbuf, &tmp, sizeof(struct tms)))
return -EFAULT;
}
force_successful_syscall_return();
return (long) jiffies_64_to_clock_t(get_jiffies_64());
}

View File

@ -37,6 +37,7 @@
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/math64.h>
#include <linux/ptrace.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
@ -65,8 +66,9 @@ asmlinkage long sys_time(time_t __user * tloc)
if (tloc) {
if (put_user(i,tloc))
i = -EFAULT;
return -EFAULT;
}
force_successful_syscall_return();
return i;
}