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Commit 2e34bde1 authored by Joerg Roedel's avatar Joerg Roedel
Browse files

dma-debug: add checks for kernel text and rodata 



Impact: get notified if a device dma maps illegal areas

This patch adds a check to print a warning message when a device driver
tries to map a memory area from the kernel text segment or rodata.

Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
parent 6c132d1b

lib/dma-debug.c

+25 −1
Original line number Diff line number Diff line
@@ -29,6 +29,8 @@ 
#include <linux/list.h>

#include <linux/slab.h>



#include <asm/sections.h>



#define HASH_SIZE       1024ULL

#define HASH_FN_SHIFT   13

#define HASH_FN_MASK    (HASH_SIZE - 1)
@@ -549,6 +551,24 @@ static void check_for_stack(struct device *dev, void *addr) 
				"stack [addr=%p]\n", addr);

}



static inline bool overlap(void *addr, u64 size, void *start, void *end)

{

	void *addr2 = (char *)addr + size;



	return ((addr >= start && addr < end) ||

		(addr2 >= start && addr2 < end) ||

		((addr < start) && (addr2 >= end)));

}



static void check_for_illegal_area(struct device *dev, void *addr, u64 size)

{

	if (overlap(addr, size, _text, _etext) ||

	    overlap(addr, size, __start_rodata, __end_rodata))

		err_printk(dev, NULL, "DMA-API: device driver maps "

				"memory from kernel text or rodata "

				"[addr=%p] [size=%llu]\n", addr, size);

}



static void check_sync(struct device *dev, dma_addr_t addr,

		       u64 size, u64 offset, int direction, bool to_cpu)

{
@@ -645,8 +665,11 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset, 
	entry->direction = direction;



	if (map_single) {

		void *addr = ((char *)page_address(page)) + offset;



		entry->type = dma_debug_single;

		check_for_stack(dev, page_address(page) + offset);

		check_for_stack(dev, addr);

		check_for_illegal_area(dev, addr, size);

	}



	add_dma_entry(entry);
@@ -699,6 +722,7 @@ void debug_dma_map_sg(struct device *dev, struct scatterlist *sg, 
		entry->sg_mapped_ents = mapped_ents;



		check_for_stack(dev, sg_virt(s));

		check_for_illegal_area(dev, sg_virt(s), s->length);



		add_dma_entry(entry);

	}