iommu: debug-pagealloc: Check mapped/unmapped kernel memory

Now, as the page_ext holds count of IOMMU mappings, we can use it to
assert that any page allocated/freed is indeed not in the IOMMU.

The sanitizer doesn’t protect against mapping/unmapping during this
period. However, that’s less harmful as the page is not used by the
kernel.

Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mostafa Saleh <smostafa@google.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

diff --git a/drivers/iommu/iommu-debug-pagealloc.c b/drivers/iommu/iommu-debug-pagealloc.c
index 9eb49e1230eebb37676023e33386f2c42709dd59..c080a38f45a44915ae67a22b1f74aeef14f0756d 100644 (file)
--- a/drivers/iommu/iommu-debug-pagealloc.c
+++ b/drivers/iommu/iommu-debug-pagealloc.c
@@ -9,6 +9,7 @@
 #include <linux/iommu-debug-pagealloc.h>
 #include <linux/kernel.h>
 #include <linux/page_ext.h>
+#include <linux/page_owner.h>
 
 #include "iommu-priv.h"
 
@@ -73,6 +74,28 @@ static size_t iommu_debug_page_size(struct iommu_domain *domain)
        return 1UL << __ffs(domain->pgsize_bitmap);
 }
 
+static bool iommu_debug_page_count(const struct page *page)
+{
+       unsigned int ref;
+       struct page_ext *page_ext = page_ext_get(page);
+       struct iommu_debug_metadata *d = get_iommu_data(page_ext);
+
+       ref = atomic_read(&d->ref);
+       page_ext_put(page_ext);
+       return ref != 0;
+}
+
+void __iommu_debug_check_unmapped(const struct page *page, int numpages)
+{
+       while (numpages--) {
+               if (WARN_ON(iommu_debug_page_count(page))) {
+                       pr_warn("iommu: Detected page leak!\n");
+                       dump_page_owner(page);
+               }
+               page++;
+       }
+}
+
 void __iommu_debug_map(struct iommu_domain *domain, phys_addr_t phys, size_t size)
 {
        size_t off, end;

diff --git a/include/linux/iommu-debug-pagealloc.h b/include/linux/iommu-debug-pagealloc.h
index a439d6815ca1dfef807b7b7437bf34bbaec0a38f..46c3c1f701501448a044482a9dbda80f9836a14d 100644 (file)
--- a/include/linux/iommu-debug-pagealloc.h
+++ b/include/linux/iommu-debug-pagealloc.h
@@ -13,6 +13,20 @@ DECLARE_STATIC_KEY_FALSE(iommu_debug_initialized);
 
 extern struct page_ext_operations page_iommu_debug_ops;
 
+void __iommu_debug_check_unmapped(const struct page *page, int numpages);
+
+static inline void iommu_debug_check_unmapped(const struct page *page, int numpages)
+{
+       if (static_branch_unlikely(&iommu_debug_initialized))
+               __iommu_debug_check_unmapped(page, numpages);
+}
+
+#else
+static inline void iommu_debug_check_unmapped(const struct page *page,
+                                             int numpages)
+{
+}
+
 #endif /* CONFIG_IOMMU_DEBUG_PAGEALLOC */
 
 #endif /* __LINUX_IOMMU_DEBUG_PAGEALLOC_H */

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 6f959d8ca4b42a973d4f61daf81616d1b4a308da..32205d2a24b274851fdeaece7d9bd4ee80cf601b 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -36,6 +36,7 @@
 #include <linux/rcuwait.h>
 #include <linux/bitmap.h>
 #include <linux/bitops.h>
+#include <linux/iommu-debug-pagealloc.h>
 
 struct mempolicy;
 struct anon_vma;
@@ -4133,12 +4134,16 @@ extern void __kernel_map_pages(struct page *page, int numpages, int enable);
 #ifdef CONFIG_DEBUG_PAGEALLOC
 static inline void debug_pagealloc_map_pages(struct page *page, int numpages)
 {
+       iommu_debug_check_unmapped(page, numpages);
+
        if (debug_pagealloc_enabled_static())
                __kernel_map_pages(page, numpages, 1);
 }
 
 static inline void debug_pagealloc_unmap_pages(struct page *page, int numpages)
 {
+       iommu_debug_check_unmapped(page, numpages);
+
        if (debug_pagealloc_enabled_static())
                __kernel_map_pages(page, numpages, 0);
 }