Subject: [PATCH v12.update2 02/15] PCI: Let pci_mmap_page_range() take resource address

From: Yinghai Lu <[email-masked]>
Date: Thu, 9 Jun 2016 15:25:52 -0700

In 8c05cd08a7 ("PCI: fix offset check for sysfs mmapped files"), try
to check exposed value with resource start/end in proc mmap path.

|        start = vma->vm_pgoff;
|        size = ((pci_resource_len(pdev, resno) - 1) >> PAGE_SHIFT) + 1;
|        pci_start = (mmap_api == PCI_MMAP_PROCFS) ?
|                        pci_resource_start(pdev, resno) >> PAGE_SHIFT : 0;
|        if (start >= pci_start && start < pci_start + size &&
|                        start + nr <= pci_start + size)

That breaks sparc that exposed value is BAR value, and need to be offseted
to resource address.

Original pci_mmap_page_range() is taking PCI BAR value aka usr_address.

Bjorn found out that it would be much simple to pass resource address
directly and avoid extra those __pci_mmap_make_offset.

In this patch:
1. in proc path: proc_bus_pci_mmap, try convert back to resource
   before calling pci_mmap_page_range
2. in sysfs path: pci_mmap_resource will just offset with resource start.
3. all pci_mmap_page_range will have vma->vm_pgoff with in resource
   range instead of BAR value.
4. remove __pci_mmap_make_offset, as the checking is done
   in pci_mmap_fits().

-v2: add pci_user_to_resource() and remove __pci_mmap_make_offset()
-v4: update after three patches with __pci_mmap_set_pgprot()

Signed-off-by: Yinghai Lu <[email-masked]>
Cc: [email-masked]
Cc: [email-masked]
Cc: [email-masked]
---
 arch/microblaze/pci/pci-common.c |  78 +++-----------------------
 arch/powerpc/kernel/pci-common.c |  78 +++-----------------------
 arch/sparc/kernel/pci.c          | 117 ---------------------------------------
 arch/xtensa/kernel/pci.c         |  75 ++++---------------------
 drivers/pci/pci-sysfs.c          |  33 ++++++++---
 drivers/pci/pci.h                |   2 +-
 drivers/pci/proc.c               |  60 +++++++++++++++++---
 7 files changed, 103 insertions(+), 340 deletions(-)

diff --git a/arch/microblaze/pci/pci-common.c b/arch/microblaze/pci/pci-common.c
index 1974567..881249f 100644
--- a/arch/microblaze/pci/pci-common.c
+++ b/arch/microblaze/pci/pci-common.c
@@ -156,69 +156,6 @@ void pcibios_set_master(struct pci_dev *dev)
  */
 
 /*
- * Adjust vm_pgoff of VMA such that it is the physical page offset
- * corresponding to the 32-bit pci bus offset for DEV requested by the user.
- *
- * Basically, the user finds the base address for his device which he wishes
- * to mmap.  They read the 32-bit value from the config space base register,
- * add whatever PAGE_SIZE multiple offset they wish, and feed this into the
- * offset parameter of mmap on /proc/bus/pci/XXX for that device.
- *
- * Returns negative error code on failure, zero on success.
- */
-static struct resource *__pci_mmap_make_offset(struct pci_dev *dev,
-					       resource_size_t *offset,
-					       enum pci_mmap_state mmap_state)
-{
-	struct pci_controller *hose = pci_bus_to_host(dev->bus);
-	unsigned long io_offset = 0;
-	int i, res_bit;
-
-	if (!hose)
-		return NULL;		/* should never happen */
-
-	/* If memory, add on the PCI bridge address offset */
-	if (mmap_state == pci_mmap_mem) {
-#if 0 /* See comment in pci_resource_to_user() for why this is disabled */
-		*offset += hose->pci_mem_offset;
-#endif
-		res_bit = IORESOURCE_MEM;
-	} else {
-		io_offset = (unsigned long)hose->io_base_virt - _IO_BASE;
-		*offset += io_offset;
-		res_bit = IORESOURCE_IO;
-	}
-
-	/*
-	 * Check that the offset requested corresponds to one of the
-	 * resources of the device.
-	 */
-	for (i = 0; i <= PCI_ROM_RESOURCE; i++) {
-		struct resource *rp = &dev->resource[i];
-		int flags = rp->flags;
-
-		/* treat ROM as memory (should be already) */
-		if (i == PCI_ROM_RESOURCE)
-			flags |= IORESOURCE_MEM;
-
-		/* Active and same type? */
-		if ((flags & res_bit) == 0)
-			continue;
-
-		/* In the range of this resource? */
-		if (*offset < (rp->start & PAGE_MASK) || *offset > rp->end)
-			continue;
-
-		/* found it! construct the final physical address */
-		if (mmap_state == pci_mmap_io)
-			*offset += hose->io_base_phys - io_offset;
-		return rp;
-	}
-
-	return NULL;
-}
-
-/*
  * This one is used by /dev/mem and fbdev who have no clue about the
  * PCI device, it tries to find the PCI device first and calls the
  * above routine
@@ -282,12 +219,15 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 {
 	resource_size_t offset =
 		((resource_size_t)vma->vm_pgoff) << PAGE_SHIFT;
-	struct resource *rp;
 	int ret;
 
-	rp = __pci_mmap_make_offset(dev, &offset, mmap_state);
-	if (rp == NULL)
-		return -EINVAL;
+	if (mmap_state == pci_mmap_io) {
+		struct pci_controller *hose = pci_bus_to_host(dev->bus);
+
+		/* hose should never be NULL */
+		offset += hose->io_base_phys -
+			 ((unsigned long)hose->io_base_virt - _IO_BASE);
+	}
 
 	vma->vm_pgoff = offset >> PAGE_SHIFT;
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
@@ -464,9 +404,7 @@ void pci_resource_to_user(const struct pci_dev *dev, int bar,
 	 *
 	 * Hopefully, the sysfs insterface is immune to that gunk. Once X
 	 * has been fixed (and the fix spread enough), we can re-enable the
-	 * 2 lines below and pass down a BAR value to userland. In that case
-	 * we'll also have to re-enable the matching code in
-	 * __pci_mmap_make_offset().
+	 * 2 lines below and pass down a BAR value to userland.
 	 *
 	 * BenH.
 	 */
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 8c6beb0..900b753 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -293,69 +293,6 @@ static int pci_read_irq_line(struct pci_dev *pci_dev)
  */
 
 /*
- * Adjust vm_pgoff of VMA such that it is the physical page offset
- * corresponding to the 32-bit pci bus offset for DEV requested by the user.
- *
- * Basically, the user finds the base address for his device which he wishes
- * to mmap.  They read the 32-bit value from the config space base register,
- * add whatever PAGE_SIZE multiple offset they wish, and feed this into the
- * offset parameter of mmap on /proc/bus/pci/XXX for that device.
- *
- * Returns negative error code on failure, zero on success.
- */
-static struct resource *__pci_mmap_make_offset(struct pci_dev *dev,
-					       resource_size_t *offset,
-					       enum pci_mmap_state mmap_state)
-{
-	struct pci_controller *hose = pci_bus_to_host(dev->bus);
-	unsigned long io_offset = 0;
-	int i, res_bit;
-
-	if (hose == NULL)
-		return NULL;		/* should never happen */
-
-	/* If memory, add on the PCI bridge address offset */
-	if (mmap_state == pci_mmap_mem) {
-#if 0 /* See comment in pci_resource_to_user() for why this is disabled */
-		*offset += hose->pci_mem_offset;
-#endif
-		res_bit = IORESOURCE_MEM;
-	} else {
-		io_offset = (unsigned long)hose->io_base_virt - _IO_BASE;
-		*offset += io_offset;
-		res_bit = IORESOURCE_IO;
-	}
-
-	/*
-	 * Check that the offset requested corresponds to one of the
-	 * resources of the device.
-	 */
-	for (i = 0; i <= PCI_ROM_RESOURCE; i++) {
-		struct resource *rp = &dev->resource[i];
-		int flags = rp->flags;
-
-		/* treat ROM as memory (should be already) */
-		if (i == PCI_ROM_RESOURCE)
-			flags |= IORESOURCE_MEM;
-
-		/* Active and same type? */
-		if ((flags & res_bit) == 0)
-			continue;
-
-		/* In the range of this resource? */
-		if (*offset < (rp->start & PAGE_MASK) || *offset > rp->end)
-			continue;
-
-		/* found it! construct the final physical address */
-		if (mmap_state == pci_mmap_io)
-			*offset += hose->io_base_phys - io_offset;
-		return rp;
-	}
-
-	return NULL;
-}
-
-/*
  * This one is used by /dev/mem and fbdev who have no clue about the
  * PCI device, it tries to find the PCI device first and calls the
  * above routine
@@ -420,12 +357,15 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 {
 	resource_size_t offset =
 		((resource_size_t)vma->vm_pgoff) << PAGE_SHIFT;
-	struct resource *rp;
 	int ret;
 
-	rp = __pci_mmap_make_offset(dev, &offset, mmap_state);
-	if (rp == NULL)
-		return -EINVAL;
+	if (mmap_state == pci_mmap_io) {
+		struct pci_controller *hose = pci_bus_to_host(dev->bus);
+
+		/* hose should never be NULL */
+		offset += hose->io_base_phys -
+			  ((unsigned long)hose->io_base_virt - _IO_BASE);
+	}
 
 	vma->vm_pgoff = offset >> PAGE_SHIFT;
 	if (write_combine)
@@ -601,9 +541,7 @@ void pci_resource_to_user(const struct pci_dev *dev, int bar,
 	 *
 	 * Hopefully, the sysfs insterface is immune to that gunk. Once X
 	 * has been fixed (and the fix spread enough), we can re-enable the
-	 * 2 lines below and pass down a BAR value to userland. In that case
-	 * we'll also have to re-enable the matching code in
-	 * __pci_mmap_make_offset().
+	 * 2 lines below and pass down a BAR value to userland.
 	 *
 	 * BenH.
 	 */
diff --git a/arch/sparc/kernel/pci.c b/arch/sparc/kernel/pci.c
index c2b202d..4357c07 100644
--- a/arch/sparc/kernel/pci.c
+++ b/arch/sparc/kernel/pci.c
@@ -732,119 +732,6 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
 
 /* Platform support for /proc/bus/pci/X/Y mmap()s. */
 
-/* If the user uses a host-bridge as the PCI device, he may use
- * this to perform a raw mmap() of the I/O or MEM space behind
- * that controller.
- *
- * This can be useful for execution of x86 PCI bios initialization code
- * on a PCI card, like the xfree86 int10 stuff does.
- */
-static int __pci_mmap_make_offset_bus(struct pci_dev *pdev, struct vm_area_struct *vma,
-				      enum pci_mmap_state mmap_state)
-{
-	struct pci_pbm_info *pbm = pdev->dev.archdata.host_controller;
-	unsigned long space_size, user_offset, user_size;
-
-	if (mmap_state == pci_mmap_io) {
-		space_size = resource_size(&pbm->io_space);
-	} else {
-		space_size = resource_size(&pbm->mem_space);
-	}
-
-	/* Make sure the request is in range. */
-	user_offset = vma->vm_pgoff << PAGE_SHIFT;
-	user_size = vma->vm_end - vma->vm_start;
-
-	if (user_offset >= space_size ||
-	    (user_offset + user_size) > space_size)
-		return -EINVAL;
-
-	if (mmap_state == pci_mmap_io) {
-		vma->vm_pgoff = (pbm->io_space.start +
-				 user_offset) >> PAGE_SHIFT;
-	} else {
-		vma->vm_pgoff = (pbm->mem_space.start +
-				 user_offset) >> PAGE_SHIFT;
-	}
-
-	return 0;
-}
-
-/* Adjust vm_pgoff of VMA such that it is the physical page offset
- * corresponding to the 32-bit pci bus offset for DEV requested by the user.
- *
- * Basically, the user finds the base address for his device which he wishes
- * to mmap.  They read the 32-bit value from the config space base register,
- * add whatever PAGE_SIZE multiple offset they wish, and feed this into the
- * offset parameter of mmap on /proc/bus/pci/XXX for that device.
- *
- * Returns negative error code on failure, zero on success.
- */
-static int __pci_mmap_make_offset(struct pci_dev *pdev,
-				  struct vm_area_struct *vma,
-				  enum pci_mmap_state mmap_state)
-{
-	unsigned long user_paddr, user_size;
-	int i, err;
-
-	/* First compute the physical address in vma->vm_pgoff,
-	 * making sure the user offset is within range in the
-	 * appropriate PCI space.
-	 */
-	err = __pci_mmap_make_offset_bus(pdev, vma, mmap_state);
-	if (err)
-		return err;
-
-	/* If this is a mapping on a host bridge, any address
-	 * is OK.
-	 */
-	if ((pdev->class >> 8) == PCI_CLASS_BRIDGE_HOST)
-		return err;
-
-	/* Otherwise make sure it's in the range for one of the
-	 * device's resources.
-	 */
-	user_paddr = vma->vm_pgoff << PAGE_SHIFT;
-	user_size = vma->vm_end - vma->vm_start;
-
-	for (i = 0; i <= PCI_ROM_RESOURCE; i++) {
-		struct resource *rp = &pdev->resource[i];
-		resource_size_t aligned_end;
-
-		/* Active? */
-		if (!rp->flags)
-			continue;
-
-		/* Same type? */
-		if (i == PCI_ROM_RESOURCE) {
-			if (mmap_state != pci_mmap_mem)
-				continue;
-		} else {
-			if ((mmap_state == pci_mmap_io &&
-			     (rp->flags & IORESOURCE_IO) == 0) ||
-			    (mmap_state == pci_mmap_mem &&
-			     (rp->flags & IORESOURCE_MEM) == 0))
-				continue;
-		}
-
-		/* Align the resource end to the next page address.
-		 * PAGE_SIZE intentionally added instead of (PAGE_SIZE - 1),
-		 * because actually we need the address of the next byte
-		 * after rp->end.
-		 */
-		aligned_end = (rp->end + PAGE_SIZE) & PAGE_MASK;
-
-		if ((rp->start <= user_paddr) &&
-		    (user_paddr + user_size) <= aligned_end)
-			break;
-	}
-
-	if (i > PCI_ROM_RESOURCE)
-		return -EINVAL;
-
-	return 0;
-}
-
 /* Set vm_page_prot of VMA, as appropriate for this architecture, for a pci
  * device mapping.
  */
@@ -868,10 +755,6 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 {
 	int ret;
 
-	ret = __pci_mmap_make_offset(dev, vma, mmap_state);
-	if (ret < 0)
-		return ret;
-
 	__pci_mmap_set_pgprot(dev, vma, mmap_state);
 
 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
diff --git a/arch/xtensa/kernel/pci.c b/arch/xtensa/kernel/pci.c
index b848cc3..97ad3dd 100644
--- a/arch/xtensa/kernel/pci.c
+++ b/arch/xtensa/kernel/pci.c
@@ -272,68 +272,6 @@ pci_controller_num(struct pci_dev *dev)
  */
 
 /*
- * Adjust vm_pgoff of VMA such that it is the physical page offset
- * corresponding to the 32-bit pci bus offset for DEV requested by the user.
- *
- * Basically, the user finds the base address for his device which he wishes
- * to mmap.  They read the 32-bit value from the config space base register,
- * add whatever PAGE_SIZE multiple offset they wish, and feed this into the
- * offset parameter of mmap on /proc/bus/pci/XXX for that device.
- *
- * Returns negative error code on failure, zero on success.
- */
-static __inline__ int
-__pci_mmap_make_offset(struct pci_dev *dev, struct vm_area_struct *vma,
-		       enum pci_mmap_state mmap_state)
-{
-	struct pci_controller *pci_ctrl = (struct pci_controller*) dev->sysdata;
-	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
-	unsigned long io_offset = 0;
-	int i, res_bit;
-
-	if (pci_ctrl == 0)
-		return -EINVAL;		/* should never happen */
-
-	/* If memory, add on the PCI bridge address offset */
-	if (mmap_state == pci_mmap_mem) {
-		res_bit = IORESOURCE_MEM;
-	} else {
-		io_offset = (unsigned long)pci_ctrl->io_space.base;
-		offset += io_offset;
-		res_bit = IORESOURCE_IO;
-	}
-
-	/*
-	 * Check that the offset requested corresponds to one of the
-	 * resources of the device.
-	 */
-	for (i = 0; i <= PCI_ROM_RESOURCE; i++) {
-		struct resource *rp = &dev->resource[i];
-		int flags = rp->flags;
-
-		/* treat ROM as memory (should be already) */
-		if (i == PCI_ROM_RESOURCE)
-			flags |= IORESOURCE_MEM;
-
-		/* Active and same type? */
-		if ((flags & res_bit) == 0)
-			continue;
-
-		/* In the range of this resource? */
-		if (offset < (rp->start & PAGE_MASK) || offset > rp->end)
-			continue;
-
-		/* found it! construct the final physical address */
-		if (mmap_state == pci_mmap_io)
-			offset += pci_ctrl->io_space.start - io_offset;
-		vma->vm_pgoff = offset >> PAGE_SHIFT;
-		return 0;
-	}
-
-	return -EINVAL;
-}
-
-/*
  * Set vm_page_prot of VMA, as appropriate for this architecture, for a pci
  * device mapping.
  */
@@ -366,11 +304,18 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
 			enum pci_mmap_state mmap_state,
 			int write_combine)
 {
+	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
 	int ret;
 
-	ret = __pci_mmap_make_offset(dev, vma, mmap_state);
-	if (ret < 0)
-		return ret;
+	if (mmap_state == pci_mmap_io) {
+		struct pci_controller *pci_ctrl =
+					 (struct pci_controller *)dev->sysdata;
+
+		/* pci_ctrl should never be NULL */
+		offset += pci_ctrl->io_space.start - pci_ctrl->io_space.base;
+	}
+
+	vma->vm_pgoff = offset >> PAGE_SHIFT;
 
 	__pci_mmap_set_pgprot(dev, vma, mmap_state, write_combine);
 
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index d319a9c..138dfc2 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -967,12 +967,23 @@ void pci_remove_legacy_files(struct pci_bus *b)
 #ifdef HAVE_PCI_MMAP
 
 int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vma,
+		  enum pci_mmap_state mmap_type,
 		  enum pci_mmap_api mmap_api)
 {
 	unsigned long nr, start, size, pci_start;
+	int flags;
 
 	if (pci_resource_len(pdev, resno) == 0)
 		return 0;
+
+	if (mmap_type == pci_mmap_mem)
+		flags = IORESOURCE_MEM;
+	else
+		flags = IORESOURCE_IO;
+
+	if (!(pci_resource_flags(pdev, resno) & flags))
+		return 0;
+
 	nr = vma_pages(vma);
 	start = vma->vm_pgoff;
 	size = ((pci_resource_len(pdev, resno) - 1) >> PAGE_SHIFT) + 1;
@@ -999,7 +1010,6 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
 	struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
 	struct resource *res = attr->private;
 	enum pci_mmap_state mmap_type;
-	resource_size_t start, end;
 	int i;
 
 	for (i = 0; i < PCI_ROM_RESOURCE; i++)
@@ -1008,10 +1018,21 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
 	if (i >= PCI_ROM_RESOURCE)
 		return -ENODEV;
 
+	/*
+	 * resource start have to be PAGE_SIZE aligned, as we pass
+	 * back virt address include round down of resource_start,
+	 * that caller can not figure out directly.
+	 * when it is not aligned, that mean it is io port, should go
+	 * pci_read_resource_io()/pci_write_resource_io() path.
+	 */
+	if (res->start & ~PAGE_MASK)
+		return -EINVAL;
+
 	if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(res->start))
 		return -EINVAL;
 
-	if (!pci_mmap_fits(pdev, i, vma, PCI_MMAP_SYSFS)) {
+	mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;
+	if (!pci_mmap_fits(pdev, i, vma, mmap_type, PCI_MMAP_SYSFS)) {
 		WARN(1, "process \"%s\" tried to map 0x%08lx bytes at page 0x%08lx on %s BAR %d (start 0x%16Lx, size 0x%16Lx)\n",
 			current->comm, vma->vm_end-vma->vm_start, vma->vm_pgoff,
 			pci_name(pdev), i,
@@ -1020,13 +1041,7 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
 		return -EINVAL;
 	}
 
-	/* pci_mmap_page_range() expects the same kind of entry as coming
-	 * from /proc/bus/pci/ which is a "user visible" value. If this is
-	 * different from the resource itself, arch will do necessary fixup.
-	 */
-	pci_resource_to_user(pdev, i, res, &start, &end);
-	vma->vm_pgoff += start >> PAGE_SHIFT;
-	mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;
+	vma->vm_pgoff += res->start >> PAGE_SHIFT;
 	return pci_mmap_page_range(pdev, vma, mmap_type, write_combine);
 }
 
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index a814bbb..10bd163 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -30,7 +30,7 @@ enum pci_mmap_api {
 	PCI_MMAP_PROCFS	/* mmap on /proc/bus/pci/<BDF> */
 };
 int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vmai,
-		  enum pci_mmap_api mmap_api);
+		  enum pci_mmap_state mmap_type,enum pci_mmap_api mmap_api);
 #endif
 int pci_probe_reset_function(struct pci_dev *dev);
 
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index 2408abe..fadab8a 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -227,24 +227,68 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd,
 }
 
 #ifdef HAVE_PCI_MMAP
+
+static int pci_user_to_resource(struct pci_dev *dev, resource_size_t *offset,
+				int flags)
+{
+	int i;
+
+	for (i = 0; i < PCI_ROM_RESOURCE; i++) {
+		resource_size_t start, end;
+		struct resource *res = &dev->resource[i];
+
+		if (!(res->flags & flags))
+			continue;
+
+		if (pci_resource_len(dev, i) == 0)
+			continue;
+
+		/*
+		 * here *offset is PAGE_SIZE aligned from caller.
+		 * need align start/end for io port resource that is
+		 * usually not PAGE_SIZE aligned.
+		 * that means we let it go if they falls in same page.
+		 */
+		pci_resource_to_user(dev, i, res, &start, &end);
+		if ((start & PAGE_MASK) <= *offset &&
+		     *offset <= (end & PAGE_MASK)) {
+			*offset = res->start + (*offset - start);
+			return i;
+		}
+	}
+
+	return -ENODEV;
+}
+
 static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma)
 {
 	struct pci_dev *dev = PDE_DATA(file_inode(file));
 	struct pci_filp_private *fpriv = file->private_data;
-	int i, ret, write_combine;
+	resource_size_t offset;
+	int i, ret, flags, write_combine;
 
 	if (!capable(CAP_SYS_RAWIO))
 		return -EPERM;
 
-	/* Make sure the caller is mapping a real resource for this device */
-	for (i = 0; i < PCI_ROM_RESOURCE; i++) {
-		if (pci_mmap_fits(dev, i, vma,  PCI_MMAP_PROCFS))
-			break;
-	}
-
-	if (i >= PCI_ROM_RESOURCE)
+	offset = vma->vm_pgoff << PAGE_SHIFT;
+	if (fpriv->mmap_state == pci_mmap_mem)
+		flags = IORESOURCE_MEM;
+	else
+		flags = IORESOURCE_IO;
+	i = pci_user_to_resource(dev, &offset, flags);
+	if (i < 0)
 		return -ENODEV;
 
+	vma->vm_pgoff = offset >> PAGE_SHIFT;
+	if (!pci_mmap_fits(dev, i, vma, fpriv->mmap_state, PCI_MMAP_PROCFS)) {
+		WARN(1, "process \"%s\" tried to map 0x%08lx bytes at page 0x%08lx on %s BAR %d (start 0x%16Lx, size 0x%16Lx)\n",
+			current->comm, vma->vm_end-vma->vm_start, vma->vm_pgoff,
+			pci_name(dev), i,
+			(u64)pci_resource_start(dev, i),
+			(u64)pci_resource_len(dev, i));
+		return -EINVAL;
+	}
+
 	if (fpriv->mmap_state == pci_mmap_mem)
 		write_combine = fpriv->write_combine;
 	else
-- 
2.8.3