Initial efforts to transform utcb handling.

tasks/libl4/include/l4lib/arch-arm/utcb.h

@@ -15,23 +15,20 @@
  * needed for all ipcs. Those mrs are defined the kernel message.h
  */
 
-/* Compact utcb for now! :-) */
+/*
+ * This is a per-task private structure where message registers are
+ * pushed for ipc. Its *not* TLS, but can be part of TLS when it is
+ * supported.
+ */
 struct utcb {
 	u32 mr[MR_TOTAL];
 	u32 tid;		/* Thread id */
-
+}; __attribute__((__packed__));
-	/*
+extern struct utcb utcb;
-	 * For passing ipc data larger than mrs,
-	 * that is, if the callee is allowed to map it
-	 */
-	char buf[];
-};
-extern struct utcb *utcb;
 
 static inline struct utcb *l4_get_utcb()
 {
-	return utcb;
+	return &utcb;
-	// (struct utcb **)USER_UTCB_REF;
 }
 
 /* Functions to read/write utcb registers */

tasks/libl4/include/l4lib/ipcdefs.h

@@ -19,10 +19,10 @@
 /* For ping ponging */
 #define L4_IPC_TAG_WAIT			3
 
-/* To negotiate a shared memory mapping */
+/* To obtain utcb address */
-#define L4_IPC_TAG_SHM			4
+#define L4_IPC_TAG_UTCB			4
 
-/* To negotiate a grant mapping */
+/* XXX: unused */
 #define L4_IPC_TAG_GRANT		5
 
 /* Posix system call tags */

tasks/libl4/src/init.c

@@ -5,8 +5,11 @@
  */
 #include <l4lib/kip.h>
 #include <l4lib/arch/syslib.h>
+#include <l4lib/arch/utcb.h>
+#include <l4lib/ipcdefs.h>
 #include <l4/macros.h>
 #include INC_GLUE(memlayout.h)
+#include <stdio.h>
 
 __l4_ipc_t __l4_ipc = 0;
 __l4_map_t __l4_map = 0;
@@ -23,9 +26,47 @@ __l4_kmem_reclaim_t __l4_kmem_reclaim = 0;
 
 struct kip *kip;
 
-/* UTCB address of this task. */
+/*
-struct utcb *utcb;
+ * Private UTCB of this task. Used only for pushing/reading ipc
-#include <stdio.h>
+ * message registers.
+ */
+struct utcb utcb;
+
+/*
+ * Shared utcb page for this task. Used for passing data among ipc
+ * parties when message registers are not big enough. Every thread
+ * has right to own one, and it has an address unique to every
+ * thread. It must be explicitly mapped by both parties of the ipc
+ * in order to be useful.
+ */
+void *utcb_page;
+
+
+/*
+ * Obtains a unique address for the task's shared utcb page. Note this
+ * does *not* map the utcb, just returns the address. This address
+ * is used as an shm key to map it via shmget()/shmat() later on.
+ */
+static void *l4_utcb_page(void)
+{
+	void *addr;
+	int err;
+
+	/* Call pager with utcb address request. Check ipc error. */
+	if ((err = l4_sendrecv(PAGER_TID, PAGER_TID, L4_IPC_TAG_UTCB)) < 0) {
+		printf("%s: L4 IPC Error: %d.\n", __FUNCTION__, err);
+		return PTR_ERR(err);
+	}
+
+	/* Check if syscall itself was successful */
+	if (IS_ERR(addr = (void *)l4_get_retval())) {
+		printf("%s: Request UTCB Address Error: %d.\n",
+		       __FUNCTION__, (int)addr);
+		return addr;
+	}
+
+	return addr;
+}
 
 void __l4_init(void)
 {
@@ -47,10 +88,9 @@ void __l4_init(void)
 
 	/* Initialise utcb only if we're not the pager */
 	if (self_tid() != PAGER_TID) {
-		/* FIXME: C library should give the environ pointer for this */
+		utcb_page = l4_utcb_page();
-		utcb = *(struct utcb **)(USER_AREA_END - PAGE_SIZE);
+		printf("UTCB Read from mm0 as: 0x%x\n",
-		printf("UTCB Read from userspace as: 0x%x\n",
+		(unsigned long)utcb_page);
-		(unsigned long)utcb);
 	}
 }
 

tasks/libposix/read.c

@@ -20,7 +20,7 @@ static inline int l4_readdir(int fd, void *buf, size_t count)
 	write_mr(L4SYS_ARG1, (unsigned long)buf);
 	write_mr(L4SYS_ARG2, count);
 
-	/* Call pager with shmget() request. Check ipc error. */
+	/* Call pager with readdir() request. Check ipc error. */
 	if ((cnt = l4_sendrecv(VFS_TID, VFS_TID, L4_IPC_TAG_READDIR)) < 0) {
 		printf("%s: L4 IPC Error: %d.\n", __FUNCTION__, cnt);
 		return cnt;
@@ -42,8 +42,8 @@ static inline int l4_read(int fd, void *buf, size_t count)
 	write_mr(L4SYS_ARG1, (unsigned long)buf);
 	write_mr(L4SYS_ARG2, count);
 
-	/* Call pager with shmget() request. Check ipc error. */
+	/* Call pager with read() request. Check ipc error. */
-	if ((cnt = l4_sendrecv(VFS_TID, VFS_TID, L4_IPC_TAG_READ)) < 0) {
+	if ((cnt = l4_sendrecv(PAGER_TID, PAGER_TID, L4_IPC_TAG_READ)) < 0) {
 		printf("%s: L4 IPC Error: %d.\n", __FUNCTION__, cnt);
 		return cnt;
 	}