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

From: Bjorn Helgaas <[email-masked]>
Date: Thu, 16 Jun 2016 21:15:55 -0500

On Thu, Jun 09, 2016 at 03:25:52PM -0700, Yinghai Lu wrote:
> 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.

I'm not quite sure what you're saying here.  Are you saying that sparc
is currently broken, and this patch fixes it?  If so, what exactly is
broken?  Can you give a small example of an mmap that is currently
broken?

> 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().

This is a pretty big patch.  It would help a lot to split it up.

> -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;

If you can, please split the validation removal into a separate patch,
so we can easily review and make sure the equivalent validation is
being done in pci_mmap_fits() (or wherever it is).

> -
> -		/* found it! construct the final physical address */
> -		if (mmap_state == pci_mmap_io)
> -			*offset += hose->io_base_phys - io_offset;
> -		return rp;

Then __pci_mmap_make_offset() will basically only do this I/O address
computation, and you'll have a simple patch that just inlines that
into pci_mmap_page_range().

> -	}
> -
> -	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.

I think the comment about "re-enabling the 2 lines below" is pointless
because doing that would break applications, which I don't think we'll
do.

I propose the microblaze, powerpc, and sparc patches below, which
remove simplify pci_resource_to_user() and clean up this comment.

>  	 */
> 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);

Ditto the microblaze comment -- if you can split this patch up, it
will be obvious that this is just inlining what's left of
__pci_mmap_make_offset() here.

> +	}
>  
>  	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;

And here (same comment as microblaze and powerpc).

> +	}
> +
> +	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;

It seems reasonable to require that the mmap start and end be
page-aligned.  It seems like we ought to do the same for the sysfs and
the procfs paths.

Since we haven't enforced this in the past, there is the potential for
breaking user programs, isn't there?

The alignment enforcement should be in a patch by itself, so bisection
would tell us something useful.

> +
>  	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

commit 3dbd970b6d9a96ab471b4b86650a0200a47d375d
Author: Bjorn Helgaas <[email-masked]>
Date:   Thu May 5 11:39:04 2016 -0500

    microblaze/PCI: Implement pci_resource_to_user() with pcibios_resource_to_bus()
    
    "User" addresses are shown in /sys/devices/pci.../.../resource and
    /proc/bus/pci/devices and used as mmap offsets for /proc/bus/pci/BB/DD.F
    files.  For I/O port resources on microblaze, these are PCI bus addresses,
    i.e., raw BAR values.
    
    Previously pci_resource_to_user() computed the user address by subtracting
    "hose->io_base_virt - _IO_BASE" from the resource start:
    
      pci_resource_to_user()
        if (IO)
          offset = (unsigned long)hose->io_base_virt - _IO_BASE;
        *start = rsrc->start - offset;
    
    We've already told the PCI core about that "hose->io_base_virt - _IO_BASE"
    offset:
    
      pcibios_setup_phb_resources()
        res = &hose->io_resource;
        pci_add_resource_offset(resources, res, hose->io_base_virt - _IO_BASE);
    
    so pcibios_resource_to_bus() knows how to do that translation.
    
    No functional change intended.
    
    Signed-off-by: Bjorn Helgaas <[email-masked]>

diff --git a/arch/microblaze/pci/pci-common.c b/arch/microblaze/pci/pci-common.c
index 1974567..e0dd64e 100644
--- a/arch/microblaze/pci/pci-common.c
+++ b/arch/microblaze/pci/pci-common.c
@@ -444,39 +444,24 @@ void pci_resource_to_user(const struct pci_dev *dev, int bar,
 			  const struct resource *rsrc,
 			  resource_size_t *start, resource_size_t *end)
 {
-	struct pci_controller *hose = pci_bus_to_host(dev->bus);
-	resource_size_t offset = 0;
+	struct pci_bus_region region;
 
-	if (hose == NULL)
+	if (rsrc->flags & IORESOURCE_IO) {
+		pcibios_resource_to_bus(dev, &region, rsrc);
+		*start = region.start;
+		*end = region.end;
 		return;
+	}
 
-	if (rsrc->flags & IORESOURCE_IO)
-		offset = (unsigned long)hose->io_base_virt - _IO_BASE;
-
-	/* We pass a fully fixed up address to userland for MMIO instead of
-	 * a BAR value because X is lame and expects to be able to use that
-	 * to pass to /dev/mem !
+	/* We pass a CPU physical address to userland for MMIO instead of a
+	 * BAR value because X is lame and expects to be able to use that
+	 * to pass to /dev/mem!
 	 *
-	 * That means that we'll have potentially 64 bits values where some
-	 * userland apps only expect 32 (like X itself since it thinks only
-	 * Sparc has 64 bits MMIO) but if we don't do that, we break it on
-	 * 32 bits CHRPs :-(
-	 *
-	 * 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().
-	 *
-	 * BenH.
+	 * That means we may have 64-bit values where some apps only expect
+	 * 32 (like X itself since it thinks only Sparc has 64-bit MMIO).
 	 */
-#if 0
-	else if (rsrc->flags & IORESOURCE_MEM)
-		offset = hose->pci_mem_offset;
-#endif
-
-	*start = rsrc->start - offset;
-	*end = rsrc->end - offset;
+	*start = rsrc->start;
+	*end = rsrc->end;
 }
 
 /**

commit 8549d796d788da46236d22be8da283819d5b5a12
Author: Bjorn Helgaas <[email-masked]>
Date:   Thu Jun 16 17:47:22 2016 -0500

    powerpc/pci: Implement pci_resource_to_user() with pcibios_resource_to_bus()
    
    "User" addresses are shown in /sys/devices/pci.../.../resource and
    /proc/bus/pci/devices and used as mmap offsets for /proc/bus/pci/BB/DD.F
    files.  For I/O port resources on powerpc, these are PCI bus addresses,
    i.e., raw BAR values.
    
    Previously pci_resource_to_user() computed the user address by subtracting
    "hose->io_base_virt - _IO_BASE" from the resource start:
    
      pci_resource_to_user()
        if (IO)
          offset = (unsigned long)hose->io_base_virt - _IO_BASE;
        *start = rsrc->start - offset;
    
    We've already told the PCI core about that "hose->io_base_virt - _IO_BASE"
    offset:
    
      pcibios_setup_phb_resources()
        res = &hose->io_resource;
        offset = pcibios_io_space_offset();
        /* i.e., "offset = hose->io_base_virt - _IO_BASE" */
        pci_add_resource_offset(resources, res, offset);
    
    so pcibios_resource_to_bus() knows how to do that translation.
    
    No functional change intended.
    
    Signed-off-by: Bjorn Helgaas <[email-masked]>

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 8c6beb0..16d9e14 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -581,39 +581,24 @@ void pci_resource_to_user(const struct pci_dev *dev, int bar,
 			  const struct resource *rsrc,
 			  resource_size_t *start, resource_size_t *end)
 {
-	struct pci_controller *hose = pci_bus_to_host(dev->bus);
-	resource_size_t offset = 0;
+	struct pci_bus_region region;
 
-	if (hose == NULL)
+	if (rsrc->flags & IORESOURCE_IO) {
+		pcibios_resource_to_bus(dev, &region, rsrc);
+		*start = region.start;
+		*end = region.end;
 		return;
+	}
 
-	if (rsrc->flags & IORESOURCE_IO)
-		offset = (unsigned long)hose->io_base_virt - _IO_BASE;
-
-	/* We pass a fully fixed up address to userland for MMIO instead of
-	 * a BAR value because X is lame and expects to be able to use that
-	 * to pass to /dev/mem !
-	 *
-	 * That means that we'll have potentially 64 bits values where some
-	 * userland apps only expect 32 (like X itself since it thinks only
-	 * Sparc has 64 bits MMIO) but if we don't do that, we break it on
-	 * 32 bits CHRPs :-(
-	 *
-	 * 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().
+	/* We pass a CPU physical address to userland for MMIO instead of a
+	 * BAR value because X is lame and expects to be able to use that
+	 * to pass to /dev/mem!
 	 *
-	 * BenH.
+	 * That means we may have 64-bit values where some apps only expect
+	 * 32 (like X itself since it thinks only Sparc has 64-bit MMIO).
 	 */
-#if 0
-	else if (rsrc->flags & IORESOURCE_MEM)
-		offset = hose->pci_mem_offset;
-#endif
-
-	*start = rsrc->start - offset;
-	*end = rsrc->end - offset;
+	*start = rsrc->start;
+	*end = rsrc->end;
 }
 
 /**

commit 2ad70d5e96f3945656cfca8c005384f2a858a8c5
Author: Bjorn Helgaas <[email-masked]>
Date:   Thu May 5 10:56:58 2016 -0500

    sparc/PCI: Implement pci_resource_to_user() with pcibios_resource_to_bus()
    
    "User" addresses are shown in /sys/devices/pci.../.../resource and
    /proc/bus/pci/devices and used as mmap offsets for /proc/bus/pci/BB/DD.F
    files.  On sparc, these are PCI bus addresses, i.e., raw BAR values.
    
    Previously pci_resource_to_user() computed the user address by
    subtracting either pbm->io_space.start or pbm->mem_space.start from the
    resource start.
    
    We've already told the PCI core about those offsets here:
    
      pci_scan_one_pbm()
        pci_add_resource_offset(&resources, &pbm->io_space, pbm->io_space.start);
        pci_add_resource_offset(&resources, &pbm->mem_space, pbm->mem_space.start);
        pci_add_resource_offset(&resources, &pbm->mem64_space, pbm->mem_space.start);
    
    so pcibios_resource_to_bus() knows how to do that translation.
    
    No functional change intended.
    
    Signed-off-by: Bjorn Helgaas <[email-masked]>

diff --git a/arch/sparc/kernel/pci.c b/arch/sparc/kernel/pci.c
index c2b202d..a4f158b 100644
--- a/arch/sparc/kernel/pci.c
+++ b/arch/sparc/kernel/pci.c
@@ -986,16 +986,18 @@ void pci_resource_to_user(const struct pci_dev *pdev, int bar,
 			  const struct resource *rp, resource_size_t *start,
 			  resource_size_t *end)
 {
-	struct pci_pbm_info *pbm = pdev->dev.archdata.host_controller;
-	unsigned long offset;
-
-	if (rp->flags & IORESOURCE_IO)
-		offset = pbm->io_space.start;
-	else
-		offset = pbm->mem_space.start;
+	struct pci_bus_region region;
 
-	*start = rp->start - offset;
-	*end = rp->end - offset;
+	/*
+	 * "User" addresses are shown in /sys/devices/pci.../.../resource
+	 * and /proc/bus/pci/devices and used as mmap offsets for
+	 * /proc/bus/pci/BB/DD.F files (see proc_bus_pci_mmap()).
+	 *
+	 * On sparc, these are PCI bus addresses, i.e., raw BAR values.
+	 */
+	pcibios_resource_to_bus(pdev->bus, &region, rp);
+	*start = region.start;
+	*end = region.end;
 }
 
 void pcibios_set_master(struct pci_dev *dev)