Commit a8258ffe authored by Mostafa Saleh's avatar Mostafa Saleh Committed by Joerg Roedel
Browse files

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: default avatarSamiullah Khawaja <skhawaja@google.com>
Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: default avatarMostafa Saleh <smostafa@google.com>
Reviewed-by: default avatarPranjal Shrivastava <praan@google.com>
Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
parent 7e845937

drivers/iommu/iommu-debug-pagealloc.c

+23 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/iommu-debug-pagealloc.h

+14 −0
Original line number Diff line number Diff line
@@ -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 */

include/linux/mm.h

+5 −0
Original line number Diff line number Diff line
@@ -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);

}