Commit 19c1a6f5 authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Ingo Molnar
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x86 gart: reimplement IOMMU_LEAK feature by using DMA_API_DEBUG 



IOMMU_LEAK, GART's own feature, dumps the used IOMMU entries when
IOMMU entries is full, which might be useful to find a bad driver that
eats IOMMU entries.

DMA_API_DEBUG provides the similar feature, debug_dma_dump_mappings,
and it's better than GART's IOMMU_LEAK feature. GART's IOMMU_LEAK
feature doesn't say who uses IOMMU entries so it's hard to find a bad
driver.

This patch reimplements the GART's IOMMU_LEAK feature by using
DMA_API_DEBUG.

Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <1239669799-23579-2-git-send-email-fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent e6a1a89d

arch/x86/Kconfig.debug

+1 −2
Original line number Diff line number Diff line
@@ -161,8 +161,7 @@ config IOMMU_DEBUG 


config IOMMU_LEAK

	bool "IOMMU leak tracing"

	depends on DEBUG_KERNEL

	depends on IOMMU_DEBUG

	depends on IOMMU_DEBUG && DMA_API_DEBUG

	---help---

	  Add a simple leak tracer to the IOMMU code. This is useful when you

	  are debugging a buggy device driver that leaks IOMMU mappings.

arch/x86/kernel/pci-gart_64.c

+8 −37
Original line number Diff line number Diff line
@@ -144,48 +144,21 @@ static void flush_gart(void) 
}



#ifdef CONFIG_IOMMU_LEAK



#define SET_LEAK(x)							\

	do {								\

		if (iommu_leak_tab)					\

			iommu_leak_tab[x] = __builtin_return_address(0);\

	} while (0)



#define CLEAR_LEAK(x)							\

	do {								\

		if (iommu_leak_tab)					\

			iommu_leak_tab[x] = NULL;			\

	} while (0)



/* Debugging aid for drivers that don't free their IOMMU tables */

static void **iommu_leak_tab;

static int leak_trace;

static int iommu_leak_pages = 20;



static void dump_leak(void)

{

	int i;

	static int dump;



	if (dump || !iommu_leak_tab)

	if (dump)

		return;

	dump = 1;

	show_stack(NULL, NULL);



	/* Very crude. dump some from the end of the table too */

	printk(KERN_DEBUG "Dumping %d pages from end of IOMMU:\n",

	       iommu_leak_pages);

	for (i = 0; i < iommu_leak_pages; i += 2) {

		printk(KERN_DEBUG "%lu: ", iommu_pages-i);

		printk_address((unsigned long) iommu_leak_tab[iommu_pages-i],

				0);

		printk(KERN_CONT "%c", (i+1)%2 == 0 ? '\n' : ' ');

	}

	printk(KERN_DEBUG "\n");

	show_stack(NULL, NULL);

	debug_dma_dump_mappings(NULL);

}

#else

# define SET_LEAK(x)

# define CLEAR_LEAK(x)

#endif



static void iommu_full(struct device *dev, size_t size, int dir)
@@ -248,7 +221,6 @@ static dma_addr_t dma_map_area(struct device *dev, dma_addr_t phys_mem, 


	for (i = 0; i < npages; i++) {

		iommu_gatt_base[iommu_page + i] = GPTE_ENCODE(phys_mem);

		SET_LEAK(iommu_page + i);

		phys_mem += PAGE_SIZE;

	}

	return iommu_bus_base + iommu_page*PAGE_SIZE + (phys_mem & ~PAGE_MASK);
@@ -294,7 +266,6 @@ static void gart_unmap_page(struct device *dev, dma_addr_t dma_addr, 
	npages = iommu_num_pages(dma_addr, size, PAGE_SIZE);

	for (i = 0; i < npages; i++) {

		iommu_gatt_base[iommu_page + i] = gart_unmapped_entry;

		CLEAR_LEAK(iommu_page + i);

	}

	free_iommu(iommu_page, npages);

}
@@ -377,7 +348,6 @@ static int __dma_map_cont(struct device *dev, struct scatterlist *start, 
		pages = iommu_num_pages(s->offset, s->length, PAGE_SIZE);

		while (pages--) {

			iommu_gatt_base[iommu_page] = GPTE_ENCODE(addr);

			SET_LEAK(iommu_page);

			addr += PAGE_SIZE;

			iommu_page++;

		}
@@ -801,11 +771,12 @@ void __init gart_iommu_init(void) 


#ifdef CONFIG_IOMMU_LEAK

	if (leak_trace) {

		iommu_leak_tab = (void *)__get_free_pages(GFP_KERNEL|__GFP_ZERO,

				  get_order(iommu_pages*sizeof(void *)));

		if (!iommu_leak_tab)

		int ret;



		ret = dma_debug_resize_entries(iommu_pages);

		if (ret)

			printk(KERN_DEBUG

			       "PCI-DMA: Cannot allocate leak trace area\n");

			       "PCI-DMA: Cannot trace all the entries\n");

	}

#endif

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