resource: allow MMIO exclusivity for device drivers

Device drivers that use pci_request_regions() (and similar APIs) have a
reasonable expectation that they are the only ones accessing their device.
As part of the e1000e hunt, we were afraid that some userland (X or some
bootsplash stuff) was mapping the MMIO region that the driver thought it
had exclusively via /dev/mem or via various sysfs resource mappings.

This patch adds the option for device drivers to cause their reserved
regions to the "banned from /dev/mem use" list, so now both kernel memory
and device-exclusive MMIO regions are banned.
NOTE: This is only active when CONFIG_STRICT_DEVMEM is set.

In addition to the config option, a kernel parameter iomem=relaxed is
provided for the cases where developers want to diagnose, in the field,
drivers issues from userspace.

Reviewed-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

2 files changed, 11 insertions, 3 deletions

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 041e95aac2bf..f6bb2ca8e3ba 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -49,6 +49,7 @@ struct resource_list {
 #define IORESOURCE_SIZEALIGN    0x00020000      /* size indicates alignment */
 #define IORESOURCE_STARTALIGN   0x00040000      /* start field is alignment */
 
+#define IORESOURCE_EXCLUSIVE    0x08000000      /* Userland may not map this resource */
 #define IORESOURCE_DISABLED     0x10000000
 #define IORESOURCE_UNSET        0x20000000
 #define IORESOURCE_AUTO         0x40000000
@@ -133,13 +134,16 @@ static inline unsigned long resource_type(struct resource *res)
 }
 
 /* Convenience shorthand with allocation */
-#define request_region(start,n,name)    __request_region(&ioport_resource, (start), (n), (name))
-#define request_mem_region(start,n,name) __request_region(&iomem_resource, (start), (n), (name))
+#define request_region(start,n,name)    __request_region(&ioport_resource, (start), (n), (name), 0)
+#define __request_mem_region(start,n,name, excl) __request_region(&iomem_resource, (start), (n), (name), excl)
+#define request_mem_region(start,n,name) __request_region(&iomem_resource, (start), (n), (name), 0)
+#define request_mem_region_exclusive(start,n,name) \
+        __request_region(&iomem_resource, (start), (n), (name), IORESOURCE_EXCLUSIVE)
 #define rename_region(region, newname) do { (region)->name = (newname); } while (0)
 
 extern struct resource * __request_region(struct resource *,
                                         resource_size_t start,
-                                        resource_size_t n, const char *name);
+                                        resource_size_t n, const char *name, int relaxed);
 
 /* Compatibility cruft */
 #define release_region(start,n) __release_region(&ioport_resource, (start), (n))
@@ -175,6 +179,7 @@ extern struct resource * __devm_request_region(struct device *dev,
 extern void __devm_release_region(struct device *dev, struct resource *parent,
                                   resource_size_t start, resource_size_t n);
 extern int iomem_map_sanity_check(resource_size_t addr, unsigned long size);
+extern int iomem_is_exclusive(u64 addr);
 
 #endif /* __ASSEMBLY__ */
 #endif  /* _LINUX_IOPORT_H */
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 59a3dc2059d3..bfcb39ca8879 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -686,10 +686,13 @@ void pci_fixup_irqs(u8 (*)(struct pci_dev *, u8 *),
                     int (*)(struct pci_dev *, u8, u8));
 #define HAVE_PCI_REQ_REGIONS    2
 int __must_check pci_request_regions(struct pci_dev *, const char *);
+int __must_check pci_request_regions_exclusive(struct pci_dev *, const char *);
 void pci_release_regions(struct pci_dev *);
 int __must_check pci_request_region(struct pci_dev *, int, const char *);
+int __must_check pci_request_region_exclusive(struct pci_dev *, int, const char *);
 void pci_release_region(struct pci_dev *, int);
 int pci_request_selected_regions(struct pci_dev *, int, const char *);
+int pci_request_selected_regions_exclusive(struct pci_dev *, int, const char *);
 void pci_release_selected_regions(struct pci_dev *, int);
 
 /* drivers/pci/bus.c */