Re: [PATCH v11 04/60] sparc/PCI: Use correct offset for bus address to resource

From: Yinghai Lu
Date: Wed May 04 2016 - 01:52:39 EST

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On Tue, May 3, 2016 at 10:08 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> On Tue, May 3, 2016 at 6:25 PM, Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>> I did not propose changing any user-visible ABI. To recap what I did
>> propose:
>
> I want to avoid introduce one strange pci_user_to_resource.
>
>>
>> - The sysfs path uses offsets between 0 and BAR size on all arches.
>> It uses pci_resource_to_user() today, but I think it should not.
>>
>> - The procfs path uses offsets of resource values (CPU physical
>> addresses) on most architectures, but uses something else, e.g.,
>> BAR values, on others. pci_resource_to_user() does this
>> translation. The procfs path does not use pci_resource_to_user()
>> today, but I think it should.
>
> current powerpc pci_resource_to_user is strange:
> it will return resource start for io mem.
> but will return BAR (?) start for io port.
>
> sparc pci_resource_to_user does return BAR value for iomem.
>
>>
>> - This implies that pci_mmap_page_range() should deal with resource
>> values (CPU physical addresses), and proc_bus_pci_mmap() should do
>> any necessary arch-specific translation from BAR values to
>> resource values.
>
> so will need one different version pci_user_to_resource.
> and can not use pcibios_bus_to_resource directly, and will be another mess.

looks like we can avoid that pci_user_to_resource() via trying out.

Please check it:

Subject: [RFC PATCH] PCI: Let pci_mmap_page_range() take resource addr

Some arch where cpu address (resource value) is not same as pci bus address
(BAR value in pci BAR registers), include sparc, powerpc, microblaze.

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 would break sparc that exposed value is still BAR value.

According to Bjorn, we could just pass resource addr instead of BAR.

In the 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 all have vma->vm_pgoff with in resource range
instead of BAR value.

Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>

---
arch/microblaze/pci/pci-common.c | 14 ++++----------
arch/powerpc/kernel/pci-common.c | 14 ++++----------
arch/sparc/kernel/pci.c | 27 +++++++++------------------
arch/xtensa/kernel/pci.c | 11 ++++-------
drivers/pci/pci-sysfs.c | 8 +-------
drivers/pci/proc.c | 13 +++++++++++++
6 files changed, 35 insertions(+), 52 deletions(-)

Index: linux-2.6/arch/microblaze/pci/pci-common.c
===================================================================
--- linux-2.6.orig/arch/microblaze/pci/pci-common.c
+++ linux-2.6/arch/microblaze/pci/pci-common.c
@@ -169,23 +169,16 @@ static struct resource *__pci_mmap_make_
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
+ if (mmap_state == pci_mmap_mem)
res_bit = IORESOURCE_MEM;
- } else {
- io_offset = (unsigned long)hose->io_base_virt - _IO_BASE;
- *offset += io_offset;
+ else
res_bit = IORESOURCE_IO;
- }

/*
* Check that the offset requested corresponds to one of the
@@ -209,7 +202,8 @@ static struct resource *__pci_mmap_make_

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

Index: linux-2.6/arch/powerpc/kernel/pci-common.c
===================================================================
--- linux-2.6.orig/arch/powerpc/kernel/pci-common.c
+++ linux-2.6/arch/powerpc/kernel/pci-common.c
@@ -308,23 +308,16 @@ static struct resource *__pci_mmap_make_
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
+ if (mmap_state == pci_mmap_mem)
res_bit = IORESOURCE_MEM;
- } else {
- io_offset = (unsigned long)hose->io_base_virt - _IO_BASE;
- *offset += io_offset;
+ else
res_bit = IORESOURCE_IO;
- }

/*
* Check that the offset requested corresponds to one of the
@@ -348,7 +341,8 @@ static struct resource *__pci_mmap_make_

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

Index: linux-2.6/arch/sparc/kernel/pci.c
===================================================================
--- linux-2.6.orig/arch/sparc/kernel/pci.c
+++ linux-2.6/arch/sparc/kernel/pci.c
@@ -743,30 +743,21 @@ static int __pci_mmap_make_offset_bus(st
enum pci_mmap_state mmap_state)
{
struct pci_pbm_info *pbm = pdev->dev.archdata.host_controller;
- unsigned long space_size, user_offset, user_size;
+ unsigned long start, end;
+ struct resource *res;

- if (mmap_state == pci_mmap_io) {
- space_size = resource_size(&pbm->io_space);
- } else {
- space_size = resource_size(&pbm->mem_space);
- }
+ if (mmap_state == pci_mmap_io)
+ res = &pbm->io_space;
+ else
+ res = &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;
+ start = vma->vm_pgoff << PAGE_SHIFT;
+ end = vma->vm_end - vma->vm_start + start - 1;

- if (user_offset >= space_size ||
- (user_offset + user_size) > space_size)
+ if (!((res->start <= start) && (res->end >= end)))
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;
}

Index: linux-2.6/arch/xtensa/kernel/pci.c
===================================================================
--- linux-2.6.orig/arch/xtensa/kernel/pci.c
+++ linux-2.6/arch/xtensa/kernel/pci.c
@@ -288,20 +288,16 @@ __pci_mmap_make_offset(struct pci_dev *d
{
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) {
+ if (mmap_state == pci_mmap_mem)
res_bit = IORESOURCE_MEM;
- } else {
- io_offset = (unsigned long)pci_ctrl->io_space.base;
- offset += io_offset;
+ else
res_bit = IORESOURCE_IO;
- }

/*
* Check that the offset requested corresponds to one of the
@@ -325,7 +321,8 @@ __pci_mmap_make_offset(struct pci_dev *d

/* found it! construct the final physical address */
if (mmap_state == pci_mmap_io)
- offset += pci_ctrl->io_space.start - io_offset;
+ offset += pci_ctrl->io_space.start -
+ pci_ctrl->io_space.base;
vma->vm_pgoff = offset >> PAGE_SHIFT;
return 0;
}
Index: linux-2.6/drivers/pci/pci-sysfs.c
===================================================================
--- linux-2.6.orig/drivers/pci/pci-sysfs.c
+++ linux-2.6/drivers/pci/pci-sysfs.c
@@ -999,7 +999,6 @@ static int pci_mmap_resource(struct kobj
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++)
@@ -1020,12 +1019,7 @@ static int pci_mmap_resource(struct kobj
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;
+ vma->vm_pgoff += res->start >> PAGE_SHIFT;
mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;
return pci_mmap_page_range(pdev, vma, mmap_type, write_combine);
}
Index: linux-2.6/drivers/pci/proc.c
===================================================================
--- linux-2.6.orig/drivers/pci/proc.c
+++ linux-2.6/drivers/pci/proc.c
@@ -231,13 +231,26 @@ static int proc_bus_pci_mmap(struct file
{
struct pci_dev *dev = PDE_DATA(file_inode(file));
struct pci_filp_private *fpriv = file->private_data;
+ resource_size_t start, end, offset;
+ struct resource *res;
int i, ret;

if (!capable(CAP_SYS_RAWIO))
return -EPERM;

+ offset = vma->vm_pgoff << PAGE_SHIFT;
+
/* Make sure the caller is mapping a real resource for this device */
for (i = 0; i < PCI_ROM_RESOURCE; i++) {
+ res = &dev->resource[i];
+ if (!res->flags)
+ continue;
+
+ pci_resource_to_user(dev, i, res, &start, &end);
+ if (!(offset >= start && offset <= end))
+ continue;
+
+ vma->vm_pgoff = (res->start + (offset - start)) >> PAGE_SHIFT;
if (pci_mmap_fits(dev, i, vma, PCI_MMAP_PROCFS))
break;
}

Next message: Greg KH: "Re: [PATCH] staging: dgnc: Fix a NULL pointer dereference"
Previous message: Stephen Rothwell: "linux-next: build warning after merge of the lightnvm tree"
In reply to: Yinghai Lu: "Re: [PATCH v11 04/60] sparc/PCI: Use correct offset for bus address to resource"
Next in thread: Bjorn Helgaas: "Re: [PATCH v11 04/60] sparc/PCI: Use correct offset for bus address to resource"
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