summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--kernel/resource.c29
-rw-r--r--mm/Kconfig7
2 files changed, 26 insertions, 10 deletions
diff --git a/kernel/resource.c b/kernel/resource.c
index 2999f57da38c..5ad3eba619ba 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1719,26 +1719,23 @@ static int strict_iomem_checks;
#endif
/*
- * check if an address is reserved in the iomem resource tree
- * returns true if reserved, false if not reserved.
+ * Check if an address is exclusive to the kernel and must not be mapped to
+ * user space, for example, via /dev/mem.
+ *
+ * Returns true if exclusive to the kernel, otherwise returns false.
*/
bool iomem_is_exclusive(u64 addr)
{
+ const unsigned int exclusive_system_ram = IORESOURCE_SYSTEM_RAM |
+ IORESOURCE_EXCLUSIVE;
bool skip_children = false, err = false;
int size = PAGE_SIZE;
struct resource *p;
- if (!strict_iomem_checks)
- return false;
-
addr = addr & PAGE_MASK;
read_lock(&resource_lock);
for_each_resource(&iomem_resource, p, skip_children) {
- /*
- * We can probably skip the resources without
- * IORESOURCE_IO attribute?
- */
if (p->start >= addr + size)
break;
if (p->end < addr) {
@@ -1748,11 +1745,23 @@ bool iomem_is_exclusive(u64 addr)
skip_children = false;
/*
+ * IORESOURCE_SYSTEM_RAM resources are exclusive if
+ * IORESOURCE_EXCLUSIVE is set, even if they
+ * are not busy and even if "iomem=relaxed" is set. The
+ * responsible driver dynamically adds/removes system RAM within
+ * such an area and uncontrolled access is dangerous.
+ */
+ if ((p->flags & exclusive_system_ram) == exclusive_system_ram) {
+ err = true;
+ break;
+ }
+
+ /*
* A resource is exclusive if IORESOURCE_EXCLUSIVE is set
* or CONFIG_IO_STRICT_DEVMEM is enabled and the
* resource is busy.
*/
- if ((p->flags & IORESOURCE_BUSY) == 0)
+ if (!strict_iomem_checks || !(p->flags & IORESOURCE_BUSY))
continue;
if (IS_ENABLED(CONFIG_IO_STRICT_DEVMEM)
|| p->flags & IORESOURCE_EXCLUSIVE) {
diff --git a/mm/Kconfig b/mm/Kconfig
index ae1f151c2924..068ce591a13a 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -109,6 +109,13 @@ config NUMA_KEEP_MEMINFO
config MEMORY_ISOLATION
bool
+# IORESOURCE_SYSTEM_RAM regions in the kernel resource tree that are marked
+# IORESOURCE_EXCLUSIVE cannot be mapped to user space, for example, via
+# /dev/mem.
+config EXCLUSIVE_SYSTEM_RAM
+ def_bool y
+ depends on !DEVMEM || STRICT_DEVMEM
+
#
# Only be set on architectures that have completely implemented memory hotplug
# feature. If you are not sure, don't touch it.