Cleanup: Move all source files to src/

[lttng-modules.git] / src / lib / ringbuffer / ring_buffer_mmap.c

diff --git a/src/lib/ringbuffer/ring_buffer_mmap.c b/src/lib/ringbuffer/ring_buffer_mmap.c
new file mode 100644 (file)
index 0000000..34174a5
--- /dev/null
+++ b/src/lib/ringbuffer/ring_buffer_mmap.c
@@ -0,0 +1,139 @@
+/* SPDX-License-Identifier: GPL-2.0-only
+ *
+ * ring_buffer_mmap.c
+ *
+ * Copyright (C) 2002-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp
+ * Copyright (C) 1999-2005 - Karim Yaghmour <karim@opersys.com>
+ * Copyright (C) 2008-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Re-using code from kernel/relay.c, hence the GPL-2.0-only license for this
+ * file.
+ */
+
+#include <linux/module.h>
+#include <linux/mm.h>
+
+#include <ringbuffer/backend.h>
+#include <ringbuffer/frontend.h>
+#include <ringbuffer/vfs.h>
+
+/*
+ * fault() vm_op implementation for ring buffer file mapping.
+ */
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,1,0))
+static vm_fault_t lib_ring_buffer_fault_compat(struct vm_area_struct *vma, struct vm_fault *vmf)
+#else
+static int lib_ring_buffer_fault_compat(struct vm_area_struct *vma, struct vm_fault *vmf)
+#endif
+{
+       struct lib_ring_buffer *buf = vma->vm_private_data;
+       struct channel *chan = buf->backend.chan;
+       const struct lib_ring_buffer_config *config = &chan->backend.config;
+       pgoff_t pgoff = vmf->pgoff;
+       unsigned long *pfnp;
+       void **virt;
+       unsigned long offset, sb_bindex;
+
+       /*
+        * Verify that faults are only done on the range of pages owned by the
+        * reader.
+        */
+       offset = pgoff << PAGE_SHIFT;
+       sb_bindex = subbuffer_id_get_index(config, buf->backend.buf_rsb.id);
+       if (!(offset >= buf->backend.array[sb_bindex]->mmap_offset
+             && offset < buf->backend.array[sb_bindex]->mmap_offset +
+                         buf->backend.chan->backend.subbuf_size))
+               return VM_FAULT_SIGBUS;
+       /*
+        * ring_buffer_read_get_pfn() gets the page frame number for the
+        * current reader's pages.
+        */
+       pfnp = lib_ring_buffer_read_get_pfn(&buf->backend, offset, &virt);
+       if (!*pfnp)
+               return VM_FAULT_SIGBUS;
+       get_page(pfn_to_page(*pfnp));
+       vmf->page = pfn_to_page(*pfnp);
+
+       return 0;
+}
+
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,1,0))
+static vm_fault_t lib_ring_buffer_fault(struct vm_fault *vmf)
+{
+       struct vm_area_struct *vma = vmf->vma;
+       return lib_ring_buffer_fault_compat(vma, vmf);
+}
+#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0))
+static int lib_ring_buffer_fault(struct vm_fault *vmf)
+{
+       struct vm_area_struct *vma = vmf->vma;
+       return lib_ring_buffer_fault_compat(vma, vmf);
+}
+#else /* #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) */
+static int lib_ring_buffer_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+       return lib_ring_buffer_fault_compat(vma, vmf);
+}
+#endif /* #else #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,11,0)) */
+
+/*
+ * vm_ops for ring buffer file mappings.
+ */
+static const struct vm_operations_struct lib_ring_buffer_mmap_ops = {
+       .fault = lib_ring_buffer_fault,
+};
+
+/**
+ *     lib_ring_buffer_mmap_buf: - mmap channel buffer to process address space
+ *     @buf: ring buffer to map
+ *     @vma: vm_area_struct describing memory to be mapped
+ *
+ *     Returns 0 if ok, negative on error
+ *
+ *     Caller should already have grabbed mmap_sem.
+ */
+static int lib_ring_buffer_mmap_buf(struct lib_ring_buffer *buf,
+                                   struct vm_area_struct *vma)
+{
+       unsigned long length = vma->vm_end - vma->vm_start;
+       struct channel *chan = buf->backend.chan;
+       const struct lib_ring_buffer_config *config = &chan->backend.config;
+       unsigned long mmap_buf_len;
+
+       if (config->output != RING_BUFFER_MMAP)
+               return -EINVAL;
+
+       mmap_buf_len = chan->backend.buf_size;
+       if (chan->backend.extra_reader_sb)
+               mmap_buf_len += chan->backend.subbuf_size;
+
+       if (length != mmap_buf_len)
+               return -EINVAL;
+
+       vma->vm_ops = &lib_ring_buffer_mmap_ops;
+       vma->vm_flags |= VM_DONTEXPAND;
+       vma->vm_private_data = buf;
+
+       return 0;
+}
+
+int lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma,
+               struct lib_ring_buffer *buf)
+{
+       return lib_ring_buffer_mmap_buf(buf, vma);
+}
+EXPORT_SYMBOL_GPL(lib_ring_buffer_mmap);
+
+/**
+ *     vfs_lib_ring_buffer_mmap - mmap file op
+ *     @filp: the file
+ *     @vma: the vma describing what to map
+ *
+ *     Calls upon lib_ring_buffer_mmap_buf() to map the file into user space.
+ */
+int vfs_lib_ring_buffer_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+       struct lib_ring_buffer *buf = filp->private_data;
+       return lib_ring_buffer_mmap(filp, vma, buf);
+}
+EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_mmap);