Re: [PATCH] LinuxPPS (with new syscalls API)

Rodolfo Giometti
2007-06-27T10:13:35Z

On Tue, Jun 26, 2007 at 06:38:40PM +0100, David Woodhouse wrote:
>
> 64-bit kernels can run 32-bit userspace programs. But some structures
> come out _differently_ between 32-bit and 64-bit compilation, so the
> system call needs a special 'compat' handler instead of just running the
> normal 64-bit system call.
>
> The 'struct timespec' is one structure which is sometimes different for
> 32-bit vs. 64-bit, so any system call taking a 'struct timespec' must
> have a separate compat_sys_xxxx() to handle that. See something like
> compat_sys_clock_settime() in kernel/compat.c for an example (but don't
> use set_fs() like it does; just see how it handles the compat_timespec).

Did you mean something like this?

diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index befe292..3e401e5 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -26,6 +26,7 @@
#include <linux/init.h>
#include <linux/linkage.h>
#include <linux/sched.h>
+#include <linux/compat.h>
#include <linux/pps.h>
#include <asm/uaccess.h>

@@ -284,9 +285,15 @@ sys_time_pps_getcap_exit:
return ret;
}

+#ifdef CONFIG_COMPAT
asmlinkage long sys_time_pps_fetch(int source, const int tsformat,
- struct pps_info __user *info,
- const struct timespec __user *timeout)
+ struct pps_info __user *info,
+ const struct compat_timespec __user *timeout)
+#else
+asmlinkage long sys_time_pps_fetch(int source, const int tsformat,
+ struct pps_info __user *info,
+ const struct timespec __user *timeout)
+#endif
{
unsigned long ticks;
struct pps_info pi;
@@ -318,7 +325,11 @@ asmlinkage long sys_time_pps_fetch(int source, const int ts
/* Manage the timeout */
if (timeout) {
+#ifdef CONFIG_COMPAT
+ ret = get_compat_timespec(&to, timeout);
+#else
ret = copy_from_user(&to, timeout, sizeof(struct timespec));
+#endif
if (ret)
goto sys_time_pps_fetch_exit;
if (to.tv_sec != -1) {

Ciao,

Rodolfo