From 867bddcf7be374221a04b7ae89f93a5f5d703ee6 Mon Sep 17 00:00:00 2001
From: "Suren A. Chilingaryan" <csa@suren.me>
Date: Wed, 2 Mar 2016 06:41:30 +0100
Subject: Resolve user-space addresses to physical addresses in the driver

---
 driver/Makefile |  2 +-
 driver/rdma.c   | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 driver/rdma.h   |  9 +++++++++
 3 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 driver/rdma.c
 create mode 100644 driver/rdma.h

diff --git a/driver/Makefile b/driver/Makefile
index a783c3f..0a860bf 100644
--- a/driver/Makefile
+++ b/driver/Makefile
@@ -1,7 +1,7 @@
 CONFIG_MODULE_SIG=n
 
 obj-m := pciDriver.o
-pciDriver-objs := base.o int.o umem.o kmem.o sysfs.o ioctl.o compat.o
+pciDriver-objs := base.o int.o umem.o kmem.o sysfs.o ioctl.o compat.o rdma.o
 
 KERNELDIR ?= /lib/modules/$(shell uname -r)/build
 INSTALLDIR ?= /lib/modules/$(shell uname -r)/kernel/extra
diff --git a/driver/rdma.c b/driver/rdma.c
new file mode 100644
index 0000000..22a4a5e
--- /dev/null
+++ b/driver/rdma.c
@@ -0,0 +1,53 @@
+#include <linux/version.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/pci.h>
+#include <linux/wait.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/hugetlb.h>
+
+#include "rdma.h"
+
+static unsigned long pcidriver_follow_pte(struct mm_struct *mm, unsigned long address)
+{
+    pgd_t *pgd;
+    pud_t *pud;
+    pmd_t *pmd;
+    pte_t *pte;
+
+    spinlock_t *ptl; 
+    unsigned long pfn = 0;
+
+
+    pgd = pgd_offset(mm, address);
+    if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 
+	return 0;
+        
+    pud = pud_offset(pgd, address);
+    if (pud_none(*pud) || unlikely(pud_bad(*pud)))     
+	return 0;
+
+    pmd = pmd_offset(pud, address);
+    if (pmd_none(*pmd)) 
+	return 0;
+
+    pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+    if (!pte_none(*pte))
+	pfn = (pte_pfn(*pte) << PAGE_SHIFT);
+    pte_unmap_unlock(pte, ptl); 
+
+    return pfn;
+}
+
+unsigned long pcidriver_resolve_bar(unsigned long address) {
+    unsigned long pfn;
+
+    address = (address >> PAGE_SHIFT) << PAGE_SHIFT;
+    pfn = pcidriver_follow_pte(current->mm, address);
+
+    return pfn;
+}
+
+EXPORT_SYMBOL(pcidriver_resolve_bar);
diff --git a/driver/rdma.h b/driver/rdma.h
new file mode 100644
index 0000000..4aeda78
--- /dev/null
+++ b/driver/rdma.h
@@ -0,0 +1,9 @@
+#ifndef _PCIDRIVER_RDMA_H
+#define _PCIDRIVER_RDMA_H
+
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+
+extern unsigned long pcidriver_resolve_bar(unsigned long address);
+
+#endif /* _PCIDRIVER_RDMA_H */
-- 
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