minix/lib/libsys/sys_vircopy.c

#include "syslib.h"

int sys_vircopy(src_proc, src_vir, 
	dst_proc, dst_vir, bytes, flags)
endpoint_t src_proc;		/* source process */
vir_bytes src_vir;		/* source virtual address */
endpoint_t dst_proc;		/* destination process */
vir_bytes dst_vir;		/* destination virtual address */
phys_bytes bytes;		/* how many bytes */
int flags;			/* copy flags */
{
/* Transfer a block of data.  The source and destination can each either be a
 * process number or SELF (to indicate own process number).
 */

  message copy_mess;

  if (bytes == 0L) return(OK);
  memset(&copy_mess, 0, sizeof(copy_mess));
  copy_mess.m_lsys_krn_sys_copy.src_endpt = src_proc;
  copy_mess.m_lsys_krn_sys_copy.src_addr = src_vir;
  copy_mess.m_lsys_krn_sys_copy.dst_endpt = dst_proc;
  copy_mess.m_lsys_krn_sys_copy.dst_addr = dst_vir;
  copy_mess.m_lsys_krn_sys_copy.nr_bytes = bytes;
  copy_mess.m_lsys_krn_sys_copy.flags = flags;

  return(_kernel_call(SYS_VIRCOPY, &copy_mess));
}
Initial revision 2005-04-21 16:53:53 +02:00			`#include "syslib.h"`

drop from segments physcopy/vircopy invocations . sys_vircopy always uses D for both src and dst . sys_physcopy uses PHYS_SEG if and only if corresponding endpoint is NONE, so we can derive the mode (PHYS_SEG or D) from the endpoint arg in the kernel, dropping the seg args . fields in msg still filled in for backwards compatability, using same NONE-logic in the library 2012-06-16 19:29:37 +02:00			`int sys_vircopy(src_proc, src_vir,`
make vfs & filesystems use failable copying Change the kernel to add features to vircopy and safecopies so that transparent copy fixing won't happen to avoid deadlocks, and such copies fail with EFAULT. Transparently making copying work from filesystems (as normally done by the kernel & VM when copying fails because of missing/readonly memory) is problematic as it can happen that, for file-mapped ranges, that that same filesystem that is blocked on the copy request is needed to satisfy the memory range, leading to deadlock. Dito for VFS itself, if done with a blocking call. This change makes the copying done from a filesystem fail in such cases with EFAULT by VFS adding the CPF_TRY flag to the grants. If a FS call fails with EFAULT, VFS will then request the range to be made available to VM after the FS is unblocked, allowing it to be used to satisfy the range if need be in another VFS thread. Similarly, for datacopies that VFS itself does, it uses the failable vircopy variant and callers use a wrapper that talk to VM if necessary to get the copy to work. . kernel: add CPF_TRY flag to safecopies . kernel: only request writable ranges to VM for the target buffer when copying fails . do copying in VFS TRY-first . some fixes in VM to build SANITYCHECK mode . add regression test for the cases where - a FS system call needs memory mapped in a process that the FS itself must map. - such a range covers more than one file-mapped region. . add 'try' mode to vircopy, physcopy . add flags field to copy kernel call messages . if CP_FLAG_TRY is set, do not transparently try to fix memory ranges . for use by VFS when accessing user buffers to avoid deadlock . remove some obsolete backwards compatability assignments . VFS: let thread scheduling work for VM requests too Allows VFS to make calls to VM while suspending and resuming the currently running thread. Does currently not work for the main thread. . VM: add fix memory range call for use by VFS Change-Id: I295794269cea51a3163519a9cfe5901301d90b32 2014-01-16 14:22:13 +01:00			`dst_proc, dst_vir, bytes, flags)`
endpoint_t in syslib - headers use the endpoint_t in syslib.h and the implmentation was using int instead. Both uses endpoint_t now - every variable named like proc, proc_nr or proc_nr_e of type endpoint_t has name proc_ep now - endpoint_t defined as u32_t not int 2009-09-22 23:42:02 +02:00			`endpoint_t src_proc; /* source process */`
Initial revision 2005-04-21 16:53:53 +02:00			`vir_bytes src_vir; /* source virtual address */`
endpoint_t in syslib - headers use the endpoint_t in syslib.h and the implmentation was using int instead. Both uses endpoint_t now - every variable named like proc, proc_nr or proc_nr_e of type endpoint_t has name proc_ep now - endpoint_t defined as u32_t not int 2009-09-22 23:42:02 +02:00			`endpoint_t dst_proc; /* destination process */`
Initial revision 2005-04-21 16:53:53 +02:00			`vir_bytes dst_vir; /* destination virtual address */`
			`phys_bytes bytes; /* how many bytes */`
make vfs & filesystems use failable copying Change the kernel to add features to vircopy and safecopies so that transparent copy fixing won't happen to avoid deadlocks, and such copies fail with EFAULT. Transparently making copying work from filesystems (as normally done by the kernel & VM when copying fails because of missing/readonly memory) is problematic as it can happen that, for file-mapped ranges, that that same filesystem that is blocked on the copy request is needed to satisfy the memory range, leading to deadlock. Dito for VFS itself, if done with a blocking call. This change makes the copying done from a filesystem fail in such cases with EFAULT by VFS adding the CPF_TRY flag to the grants. If a FS call fails with EFAULT, VFS will then request the range to be made available to VM after the FS is unblocked, allowing it to be used to satisfy the range if need be in another VFS thread. Similarly, for datacopies that VFS itself does, it uses the failable vircopy variant and callers use a wrapper that talk to VM if necessary to get the copy to work. . kernel: add CPF_TRY flag to safecopies . kernel: only request writable ranges to VM for the target buffer when copying fails . do copying in VFS TRY-first . some fixes in VM to build SANITYCHECK mode . add regression test for the cases where - a FS system call needs memory mapped in a process that the FS itself must map. - such a range covers more than one file-mapped region. . add 'try' mode to vircopy, physcopy . add flags field to copy kernel call messages . if CP_FLAG_TRY is set, do not transparently try to fix memory ranges . for use by VFS when accessing user buffers to avoid deadlock . remove some obsolete backwards compatability assignments . VFS: let thread scheduling work for VM requests too Allows VFS to make calls to VM while suspending and resuming the currently running thread. Does currently not work for the main thread. . VM: add fix memory range call for use by VFS Change-Id: I295794269cea51a3163519a9cfe5901301d90b32 2014-01-16 14:22:13 +01:00			`int flags; /* copy flags */`
Initial revision 2005-04-21 16:53:53 +02:00			`{`
			`/* Transfer a block of data. The source and destination can each either be a`
make vfs & filesystems use failable copying Change the kernel to add features to vircopy and safecopies so that transparent copy fixing won't happen to avoid deadlocks, and such copies fail with EFAULT. Transparently making copying work from filesystems (as normally done by the kernel & VM when copying fails because of missing/readonly memory) is problematic as it can happen that, for file-mapped ranges, that that same filesystem that is blocked on the copy request is needed to satisfy the memory range, leading to deadlock. Dito for VFS itself, if done with a blocking call. This change makes the copying done from a filesystem fail in such cases with EFAULT by VFS adding the CPF_TRY flag to the grants. If a FS call fails with EFAULT, VFS will then request the range to be made available to VM after the FS is unblocked, allowing it to be used to satisfy the range if need be in another VFS thread. Similarly, for datacopies that VFS itself does, it uses the failable vircopy variant and callers use a wrapper that talk to VM if necessary to get the copy to work. . kernel: add CPF_TRY flag to safecopies . kernel: only request writable ranges to VM for the target buffer when copying fails . do copying in VFS TRY-first . some fixes in VM to build SANITYCHECK mode . add regression test for the cases where - a FS system call needs memory mapped in a process that the FS itself must map. - such a range covers more than one file-mapped region. . add 'try' mode to vircopy, physcopy . add flags field to copy kernel call messages . if CP_FLAG_TRY is set, do not transparently try to fix memory ranges . for use by VFS when accessing user buffers to avoid deadlock . remove some obsolete backwards compatability assignments . VFS: let thread scheduling work for VM requests too Allows VFS to make calls to VM while suspending and resuming the currently running thread. Does currently not work for the main thread. . VM: add fix memory range call for use by VFS Change-Id: I295794269cea51a3163519a9cfe5901301d90b32 2014-01-16 14:22:13 +01:00			`* process number or SELF (to indicate own process number).`
Initial revision 2005-04-21 16:53:53 +02:00			`*/`

			`message copy_mess;`

			`if (bytes == 0L) return(OK);`
make vfs & filesystems use failable copying Change the kernel to add features to vircopy and safecopies so that transparent copy fixing won't happen to avoid deadlocks, and such copies fail with EFAULT. Transparently making copying work from filesystems (as normally done by the kernel & VM when copying fails because of missing/readonly memory) is problematic as it can happen that, for file-mapped ranges, that that same filesystem that is blocked on the copy request is needed to satisfy the memory range, leading to deadlock. Dito for VFS itself, if done with a blocking call. This change makes the copying done from a filesystem fail in such cases with EFAULT by VFS adding the CPF_TRY flag to the grants. If a FS call fails with EFAULT, VFS will then request the range to be made available to VM after the FS is unblocked, allowing it to be used to satisfy the range if need be in another VFS thread. Similarly, for datacopies that VFS itself does, it uses the failable vircopy variant and callers use a wrapper that talk to VM if necessary to get the copy to work. . kernel: add CPF_TRY flag to safecopies . kernel: only request writable ranges to VM for the target buffer when copying fails . do copying in VFS TRY-first . some fixes in VM to build SANITYCHECK mode . add regression test for the cases where - a FS system call needs memory mapped in a process that the FS itself must map. - such a range covers more than one file-mapped region. . add 'try' mode to vircopy, physcopy . add flags field to copy kernel call messages . if CP_FLAG_TRY is set, do not transparently try to fix memory ranges . for use by VFS when accessing user buffers to avoid deadlock . remove some obsolete backwards compatability assignments . VFS: let thread scheduling work for VM requests too Allows VFS to make calls to VM while suspending and resuming the currently running thread. Does currently not work for the main thread. . VM: add fix memory range call for use by VFS Change-Id: I295794269cea51a3163519a9cfe5901301d90b32 2014-01-16 14:22:13 +01:00			`memset(&copy_mess, 0, sizeof(copy_mess));`
Message type for SYS_{VIR,PHYS}COPY Change-Id: I15d1acf9992d1b799f5687adffb186875fcd0c84 2014-05-21 17:21:26 +02:00			`copy_mess.m_lsys_krn_sys_copy.src_endpt = src_proc;`
			`copy_mess.m_lsys_krn_sys_copy.src_addr = src_vir;`
			`copy_mess.m_lsys_krn_sys_copy.dst_endpt = dst_proc;`
			`copy_mess.m_lsys_krn_sys_copy.dst_addr = dst_vir;`
			`copy_mess.m_lsys_krn_sys_copy.nr_bytes = bytes;`
			`copy_mess.m_lsys_krn_sys_copy.flags = flags;`
drop from segments physcopy/vircopy invocations . sys_vircopy always uses D for both src and dst . sys_physcopy uses PHYS_SEG if and only if corresponding endpoint is NONE, so we can derive the mode (PHYS_SEG or D) from the endpoint arg in the kernel, dropping the seg args . fields in msg still filled in for backwards compatability, using same NONE-logic in the library 2012-06-16 19:29:37 +02:00
Removal of the system task * Userspace change to use the new kernel calls - _taskcall(SYSTASK...) changed to _kernel_call(...) - int 32 reused for the kernel calls - _do_kernel_call() to make the trap to kernel - kernel_call() to make the actuall kernel call from C using _do_kernel_call() - unlike ipc call the kernel call always succeeds as kernel is always available, however, kernel may return an error * Kernel side implementation of kernel calls - the SYSTEm task does not run, only the proc table entry is preserved - every data_copy(SYSTEM is no data_copy(KERNEL - "locking" is an empty operation now as everything runs in kernel - sys_task() is replaced by kernel_call() which copies the message into kernel, dispatches the call to its handler and finishes by either copying the results back to userspace (if need be) or by suspending the process because of VM - suspended processes are later made runnable once the memory issue is resolved, picked up by the scheduler and only at this time the call is resumed (in fact restarted) which does not need to copy the message from userspace as the message is already saved in the process structure. - no ned for the vmrestart queue, the scheduler will restart the system calls - no special case in do_vmctl(), all requests remove the RTS_VMREQUEST flag 2010-02-09 16:20:09 +01:00			`return(_kernel_call(SYS_VIRCOPY, &copy_mess));`
Initial revision 2005-04-21 16:53:53 +02:00			`}`