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>
diff --git a/kernel/compat.c b/kernel/compat.c
index d52e2ec..42d5654 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -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 @@
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 @@
if (tloc) {
if (put_user(i,tloc))
- i = -EFAULT;
+ return -EFAULT;
}
+ force_successful_syscall_return();
return i;
}