Changeset fbcdeb8 in mainline for kernel/generic/src/ipc/sysipc.c

Timestamp:

2011-12-19T17:30:39Z (14 years ago)

Author:

Martin Decky <martin@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

58f6229

Parents:

24cf31f1

Message:

Remove the two-phase way of creating virtual memory areas (first asking for a mappable address and then mapping it) which was prone to race conditions when two or more calls to as_get_mappable_page() and as_area_create() were interleaved. This for example caused the e1k driver to randomly fail.

The memory area related syscalls and IPC calls have all been altered to accept a special value (void *) -1, representing a demand to atomically search for a mappable address space "hole" and map to it.

Individual changes:

• IPC_M_SHARE_OUT: the destination address space area is supplied by the kernel, the callee only specifies the lower bound

(the address is returned to the callee via a pointer in an IPC reply argument)

• IPC_M_SHARE_IN: the destination address space ares is supplied by the kernel, the callee only specifies the lower bound

(the address is returned to the caller as usual via an IPC argument)

• SYS_AS_GET_UNMAPPED_AREA was removed
• dummy implementations of SYS_PHYSMEM_UNMAP and SYS_IOSPACE_DISABLE were added for the sake of symmetry (they do nothing yet)
• SYS_PHYSMEM_MAP and SYS_DMAMEM_MAP were altered to accept (void *) -1 as address space area base and a lower bound
• kernel as_area_create() and as_area_share() were altered to accept (void *) -1 as address space area base and a lower bound
• uspace libraries and programs were altered to reflect the new API

File:

• kernel/generic/src/ipc/sysipc.c (modified) (2 diffs)

kernel/generic/src/ipc/sysipc.c

@@ -271 +271 @@
                         irq_spinlock_unlock(&answer->sender->lock, true);
                         
+                        uintptr_t dst_base = (uintptr_t) -1;
                         int rc = as_area_share(as, IPC_GET_ARG1(*olddata),
-                            IPC_GET_ARG2(*olddata), AS,
-                            IPC_GET_ARG1(answer->data), IPC_GET_ARG3(*olddata));
+                            IPC_GET_ARG2(*olddata), AS, IPC_GET_ARG3(*olddata),
+                            &dst_base, IPC_GET_ARG1(answer->data));
+                        
+                        if (rc == EOK)
+                                rc = copy_to_uspace((void *) IPC_GET_ARG2(answer->data),
+                                    &dst_base, sizeof(dst_base));
+                        
                         IPC_SET_RETVAL(answer->data, rc);
                         return rc;
@@ -283 +289 @@
                         irq_spinlock_unlock(&answer->sender->lock, true);
                         
+                        uintptr_t dst_base = (uintptr_t) -1;
                         int rc = as_area_share(AS, IPC_GET_ARG1(answer->data),
-                            IPC_GET_ARG2(*olddata), as, IPC_GET_ARG1(*olddata),
-                            IPC_GET_ARG2(answer->data));
+                            IPC_GET_ARG1(*olddata), as, IPC_GET_ARG2(answer->data),
+                            &dst_base, IPC_GET_ARG3(answer->data));
+                        IPC_SET_ARG4(answer->data, dst_base);
                         IPC_SET_RETVAL(answer->data, rc);
                 }