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SubjectRe: [PATCH] compatibility syscall layer (lets try again)
Linus Torvalds wrote:
>
> On Wed, 4 Dec 2002, george anzinger wrote:
> >
> > Once it changes the system call (eax, right), could the new
> > call code then just get the parms from the restart_block.
>
> Agreed.
>
> > I think it would be best to keep this as generic as
> > possible, i.e. let the new call code fetch its own
> > paramerers from the restart_block.
>
> We could even have one _single_ a generic "restart" system call, and have
> the function pointer for that be in the restart block.
>
> > My question is who sets up these values? I think you are
> > saying it should be the system call. Is this right?
>
> Whatever system call that return -ERESTART_RESTARTBLOCK, yes.
>
> So it would never get set up at all in the fast path. Only in the error
> case path of a system call that wants to have restarting capabilities.
>
> Linus

Ok, here is a patch to do all this. This is against
2.5.50-bk4. (Bk5 did not get posted this evening.)

I think this covers all the bases. It builds boots and
runs. I haven't tested nano_sleep to see if it does the
right thing yet...

--
George Anzinger george@mvista.com
High-res-timers:
http://sourceforge.net/projects/high-res-timers/
Preemption patch:
http://www.kernel.org/pub/linux/kernel/people/rmldiff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.50-bk4-kb/arch/i386/kernel/entry.S linux/arch/i386/kernel/entry.S
--- linux-2.5.50-bk4-kb/arch/i386/kernel/entry.S Wed Dec 4 23:28:20 2002
+++ linux/arch/i386/kernel/entry.S Wed Dec 4 23:48:49 2002
@@ -769,6 +769,7 @@
.long sys_epoll_wait
.long sys_remap_file_pages
.long sys_set_tid_address
+ .long sys_restart_syscall


.rept NR_syscalls-(.-sys_call_table)/4
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.50-bk4-kb/arch/i386/kernel/signal.c linux/arch/i386/kernel/signal.c
--- linux-2.5.50-bk4-kb/arch/i386/kernel/signal.c Thu Oct 3 10:41:57 2002
+++ linux/arch/i386/kernel/signal.c Thu Dec 5 00:27:21 2002
@@ -507,6 +507,7 @@
/* If so, check system call restarting.. */
switch (regs->eax) {
case -ERESTARTNOHAND:
+ case -ERESTART_RESTARTBLOCK:
regs->eax = -EINTR;
break;

@@ -589,6 +590,10 @@
regs->eax == -ERESTARTSYS ||
regs->eax == -ERESTARTNOINTR) {
regs->eax = regs->orig_eax;
+ regs->eip -= 2;
+ }
+ if (regs->eax == -ERESTART_RESTARTBLOCK){
+ regs->eax = __NR_restart_syscall;
regs->eip -= 2;
}
}
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.50-bk4-kb/include/asm-i386/thread_info.h linux/include/asm-i386/thread_info.h
--- linux-2.5.50-bk4-kb/include/asm-i386/thread_info.h Mon Sep 9 10:35:03 2002
+++ linux/include/asm-i386/thread_info.h Thu Dec 5 01:07:23 2002
@@ -20,6 +20,12 @@
* - if the contents of this structure are changed, the assembly constants must also be changed
*/
#ifndef __ASSEMBLY__
+struct restart_block {
+ int (*fun)(void *);
+ long arg0;
+ long arg1;
+};
+
struct thread_info {
struct task_struct *task; /* main task structure */
struct exec_domain *exec_domain; /* execution domain */
@@ -31,6 +37,7 @@
0-0xBFFFFFFF for user-thead
0-0xFFFFFFFF for kernel-thread
*/
+ struct restart_block restart_block;

__u8 supervisor_stack[0];
};
@@ -44,6 +51,7 @@
#define TI_CPU 0x0000000C
#define TI_PRE_COUNT 0x00000010
#define TI_ADDR_LIMIT 0x00000014
+#define TI_RESTART_BLOCK 0x0000018

#endif

@@ -63,6 +71,9 @@
.cpu = 0, \
.preempt_count = 1, \
.addr_limit = KERNEL_DS, \
+ .restart_block = { \
+ .fun = 0, \
+ }, \
}

#define init_thread_info (init_thread_union.thread_info)
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.50-bk4-kb/include/asm-i386/unistd.h linux/include/asm-i386/unistd.h
--- linux-2.5.50-bk4-kb/include/asm-i386/unistd.h Wed Nov 27 15:49:22 2002
+++ linux/include/asm-i386/unistd.h Wed Dec 4 23:48:46 2002
@@ -263,7 +263,7 @@
#define __NR_sys_epoll_wait 256
#define __NR_remap_file_pages 257
#define __NR_set_tid_address 258
-
+#define __NR_restart_syscall 259

/* user-visible error numbers are in the range -1 - -124: see <asm-i386/errno.h> */

diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.50-bk4-kb/include/linux/errno.h linux/include/linux/errno.h
--- linux-2.5.50-bk4-kb/include/linux/errno.h Mon Sep 9 10:35:15 2002
+++ linux/include/linux/errno.h Wed Dec 4 23:53:21 2002
@@ -10,6 +10,7 @@
#define ERESTARTNOINTR 513
#define ERESTARTNOHAND 514 /* restart if no handler.. */
#define ENOIOCTLCMD 515 /* No ioctl command */
+#define ERESTART_RESTARTBLOCK 516 /* restart by calling sys_restart_syscall */

/* Defined for the NFSv3 protocol */
#define EBADHANDLE 521 /* Illegal NFS file handle */
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.50-bk4-kb/kernel/signal.c linux/kernel/signal.c
--- linux-2.5.50-bk4-kb/kernel/signal.c Wed Dec 4 23:27:02 2002
+++ linux/kernel/signal.c Thu Dec 5 01:18:20 2002
@@ -1351,6 +1351,15 @@
* System call entry points.
*/

+asmlinkage long
+sys_restart_syscall( void *parm)
+{
+ if ( ! current_thread_info()->restart_block.fun){
+ return current_thread_info()->restart_block.fun(&parm);
+ }
+ return -ENOSYS;
+}
+
/*
* We don't need to get the kernel lock - this is all local to this
* particular thread.. (and that's good, because this is _heavily_
diff -urP -I \$Id:.*Exp \$ -X /usr/src/patch.exclude linux-2.5.50-bk4-kb/kernel/timer.c linux/kernel/timer.c
--- linux-2.5.50-bk4-kb/kernel/timer.c Wed Dec 4 23:27:02 2002
+++ linux/kernel/timer.c Thu Dec 5 01:16:03 2002
@@ -1020,19 +1020,39 @@
return current->pid;
}

+struct nano_sleep_call {
+ struct timespec *rqtp;
+ struct timespec *rmtp;
+};
+
+asmlinkage long sys_nanosleep_restart( struct nano_sleep_call * parms);
+
asmlinkage long sys_nanosleep(struct timespec *rqtp, struct timespec *rmtp)
{
struct timespec t;
unsigned long expire;
+ struct restart_block *restart_block;

- if(copy_from_user(&t, rqtp, sizeof(struct timespec)))
- return -EFAULT;
-
- if (t.tv_nsec >= 1000000000L || t.tv_nsec < 0 || t.tv_sec < 0)
- return -EINVAL;
+ if (rqtp) {
+ if(copy_from_user(&t, rqtp, sizeof(struct timespec)))
+ return -EFAULT;

- expire = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec);
+ if (t.tv_nsec >= 1000000000L || t.tv_nsec < 0 || t.tv_sec < 0)
+ return -EINVAL;
+ expire = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec);

+ }else{
+ restart_block = &current_thread_info()->restart_block;
+ if( restart_block->fun !=
+ (int (*)(void *))sys_nanosleep_restart ||
+ ! restart_block->arg0){
+ return -EFAULT;
+ }
+ restart_block->fun = NULL;
+ expire = restart_block->arg0 - jiffies;
+ if (expire < 0)
+ return 0;
+ }
current->state = TASK_INTERRUPTIBLE;
expire = schedule_timeout(expire);

@@ -1042,10 +1062,19 @@
if (copy_to_user(rmtp, &t, sizeof(struct timespec)))
return -EFAULT;
}
- return -EINTR;
+ restart_block = &current_thread_info()->restart_block;
+ restart_block->fun = (int (*)(void *))sys_nanosleep_restart;
+ restart_block->arg0 = jiffies + expire;
+ return -ERESTART_RESTARTBLOCK;
}
return 0;
}
+
+asmlinkage long sys_nanosleep_restart( struct nano_sleep_call * parms)
+{
+ return sys_nanosleep(NULL, parms->rmtp);
+}
+

/*
* sys_sysinfo - fill in sysinfo struct
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