[Xenomai-core] [PATCH] provide rtdm_mmap_to_user / rtdm_munmap

[Jan Kiszka <jan.kiszka@domain.hid>]

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Hi all,

this is a first attempt to add the requested mmap functionality to the
RTDM driver API. Anyone interested in this feature is invited to test my
patch (Rodrigo... ;) ). Comments on the implementation are welcome as well.

Philippe, I need xnarch_remap_page_range for this and added a #define
XENO_HEAP_MODULE hack to rtdm/drvlib.c therefore. What would you suggest
as a cleaner approach? Make this function available unconditionally or
introduce something like XENO_RTDM_MODULE? Moreover, isn't this
implementation also interesting for nucleus/heap.c?

Jan

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Index: include/rtdm/rtdm_driver.h
===================================================================
--- include/rtdm/rtdm_driver.h	(Revision 551)
+++ include/rtdm/rtdm_driver.h	(Arbeitskopie)
@@ -995,6 +995,10 @@
     xnfree(ptr);
 }
 
+int rtdm_mmap_to_user(rtdm_user_info_t *user_info, void *src_addr, size_t len,
+                      int prot, void **pptr);
+int rtdm_munmap(rtdm_user_info_t *user_info, void *ptr, size_t len);
+
 static inline int rtdm_read_user_ok(rtdm_user_info_t *user_info,
                                     const void __user *ptr, size_t size)
 {
Index: ksrc/skins/rtdm/drvlib.c
===================================================================
--- ksrc/skins/rtdm/drvlib.c	(Revision 551)
+++ ksrc/skins/rtdm/drvlib.c	(Arbeitskopie)
@@ -31,7 +31,9 @@
 
 
 #include <linux/delay.h>
+#include <linux/mman.h>
 
+#define XENO_HEAP_MODULE
 #include <rtdm/rtdm_driver.h>
 
 
@@ -1286,7 +1288,7 @@
  * Rescheduling: never.
  */
 int rtdm_irq_disable(rtdm_irq_t *irq_handle);
-/** @} */
+/** @} Interrupt Management Services */
 
 
 /*!
@@ -1358,16 +1360,127 @@
  * environments.
  */
 void rtdm_nrtsig_pend(rtdm_nrtsig_t *nrt_sig);
-/** @} */
+/** @} Non-Real-Time Signalling Services */
 
+#endif /* DOXYGEN_CPP */
 
+
 /*!
  * @ingroup driverapi
  * @defgroup util Utility Services
  * @{
  */
 
+static int rtdm_mmap_buffer(struct file *filp, struct vm_area_struct *vma)
+{
+    return xnarch_remap_page_range(vma, vma->vm_start,
+                                   virt_to_phys(filp->private_data),
+                                   vma->vm_end - vma->vm_start, PAGE_SHARED);
+}
+
+static struct file_operations rtdm_mmap_fops = {
+    .mmap = rtdm_mmap_buffer,
+};
+
 /**
+ * Map a kernel memory range into the address space of the user.
+ *
+ * @param[in] user_info User information pointer as passed to the invoked
+ * device operation handler
+ * @param[in] src_addr Kernel address to be mapped
+ * @param[in] len Length of the memory range
+ * @param[in] prot Protection flags for the user's memory range, typically
+ * either PROT_READ or PROT_READ|PROT_WRITE
+ * @param[in,out] pptr Address of a pointer containing the desired user
+ * address or NULL on entry and the finally assigned address on return
+ *
+ * @return 0 on success, otherwise:
+ *
+ * - -EXXX is returned if .
+ *
+ * @note An RTDM driver is expected to invoke rtdm_munmap on every mapped
+ * memory range either when the user requests it explicitly or when the
+ * related device is closed.
+ *
+ * Environments:
+ *
+ * This service can be called from:
+ *
+ * - Kernel module initialization/cleanup code
+ * - User-space task (non-RT)
+ *
+ * Rescheduling: possible.
+ */
+int rtdm_mmap_to_user(rtdm_user_info_t *user_info, void *src_addr, size_t len,
+                      int prot, void **pptr)
+{
+    struct file             *filp;
+    struct file_operations  *old_fops;
+    void                    *old_priv_data;
+    void                    *user_ptr;
+
+    filp = filp_open("/dev/zero", O_RDWR, 0);
+    if (IS_ERR(filp))
+        return PTR_ERR(filp);
+
+    old_fops = filp->f_op;
+    filp->f_op = &rtdm_mmap_fops;
+
+    old_priv_data = filp->private_data;
+    filp->private_data = src_addr;
+
+    down_write(&user_info->mm->mmap_sem);
+    user_ptr = (void *)do_mmap(filp, (unsigned long)*pptr, len, prot,
+                               MAP_SHARED, 0);
+    up_write(&user_info->mm->mmap_sem);
+
+    filp->f_op = old_fops;
+    filp->private_data = old_priv_data;
+
+    filp_close(filp, user_info->files);
+
+    if (IS_ERR(user_ptr))
+        return PTR_ERR(user_ptr);
+
+    *pptr = user_ptr;
+    return 0;
+}
+
+/**
+ * Unmap a user memory range.
+ *
+ * @param[in] user_info User information pointer as passed to
+ * rtdm_mmap_to_user() when requesting to map the memory range
+ * @param[in] ptr User address or the memory range
+ * @param[in] len Length of the memory range
+ *
+ * @return 0 on success, otherwise:
+ *
+ * - -EXXX is returned if .
+ *
+ * Environments:
+ *
+ * This service can be called from:
+ *
+ * - Kernel module initialization/cleanup code
+ * - User-space task (non-RT)
+ *
+ * Rescheduling: possible.
+ */
+int rtdm_munmap(rtdm_user_info_t *user_info, void *ptr, size_t len)
+{
+    int err;
+
+    down_write(&user_info->mm->mmap_sem);
+    err = do_munmap(user_info->mm, (unsigned long)ptr, len);
+    up_write(&user_info->mm->mmap_sem);
+
+    return err;
+}
+
+#ifdef DOXYGEN_CPP /* Only used for doxygen doc generation */
+
+/**
  * Real-time safe message printing on kernel console
  *
  * @param[in] format Format string (conforming standard @c printf())
@@ -1583,6 +1696,6 @@
  */
 int rtdm_in_rt_context(void);
 
-/** @} */
+#endif /* DOXYGEN_CPP */
 
-#endif /* DOXYGEN_CPP */
+/** @} Utility Services */

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