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convert remap_page_range() to remap_pfn_range() vs. 2.6.9-rc2-mm3

PATCH New William Lee Irwin III 1 participant 7 messages Sep 25, 2004

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Memory management Media (V4L/DVB) MM core Framebuffer layer +1 more subsystems
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William Lee Irwin III

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#0 lore raw

cover convert remap_page_range() to remap_pfn_range() vs. 2.6.9-rc2-mm3

This series resolves a physical address overflow issue in the remap_page_range() API by replacing it with remap_pfn_range(), which accepts its physical address argument as a pfn, hence allowing the use of a single-precision physical address argument without the risk of overflow at the API boundary. The above issue has hobbled support for various 32-bit architectures, including some embedded systems (ppc440 IIRC), caused persistent portability issues for sound drivers for legacy systems (sparc32; unfortunately this patch alone does not fully resolve those), and according to John Fusco's reports, made drivers for some PCI-X hardware infeasible to port to recent ia32 PAE enterprise systems. With this patch series applied, physical address overflows on 32-bit systems caused directly by remap_page_range() are gone forever, and ca. 100LOC of cut-and-waste driver code are swept out of existence alongside them.

vs. 2.6.9-rc2-mm3 and the scheduler header cleanups. The parts touching mm.h should apply with just offsets if those aren't applied beforehand. Successfully tested on x86-64.

-- wli

P.S.: The existing solution to the sparc32 issue was to pass a double
precision representation of the physical address as 2 single- precision arguments in an API (io_remap_page_range()) whose argument corresponding to those two was a single single- precision argument on most/all other architectures. The sparc32-specific issue requires more work beyond these patches to rectify. The most apparent consequence of the API skew is that drivers don't compile on sparc32 when they use io_remap_page_range() due to passing insufficient arguments, or vice-versa for drivers originally written for sparc32.

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#1 lore raw

PATCH 1/76 introduce remap_pfn_range()

This patch introduces remap_pfn_range(), destined to replace remap_page_range(). In the sequel, the callers of remap_page_range() will be converted one at a time.

By using a pfn to specify its physical address argument, remap_pfn_range() resolves a longstanding physical address overflow issue.

include/linux/mm.h +9 -2
Index: mm3-2.6.9-rc2/include/linux/mm.h
===================================================================
@@ -856,8 +856,15 @@
 extern struct page * vmalloc_to_page(void *addr);
 extern struct page * follow_page(struct mm_struct *mm, unsigned long address,
 		int write);
-extern int remap_page_range(struct vm_area_struct *vma, unsigned long from,
-		unsigned long to, unsigned long size, pgprot_t prot);
+int remap_pfn_range(struct vm_area_struct *, unsigned long,
+		unsigned long, unsigned long, pgprot_t);
+
+static inline
+int remap_page_range(struct vm_area_struct *vma, unsigned long uvaddr,
+			unsigned long paddr, unsigned long size, pgprot_t prot)
+{
+	return remap_pfn_range(vma, uvaddr, paddr >> PAGE_SHIFT, size, prot);
+}
 
 #ifdef CONFIG_PROC_FS
 void __vm_stat_account(struct mm_struct *, unsigned long, struct file *, long);
mm/memory.c +8 -11
Index: mm3-2.6.9-rc2/mm/memory.c
===================================================================
@@ -945,16 +945,14 @@
  * in null mappings (currently treated as "copy-on-access")
  */
 static inline void remap_pte_range(pte_t * pte, unsigned long address, unsigned long size,
-	unsigned long phys_addr, pgprot_t prot)
+	unsigned long pfn, pgprot_t prot)
 {
 	unsigned long end;
-	unsigned long pfn;
 
 	address &= ~PMD_MASK;
 	end = address + size;
 	if (end > PMD_SIZE)
 		end = PMD_SIZE;
-	pfn = phys_addr >> PAGE_SHIFT;
 	do {
 		BUG_ON(!pte_none(*pte));
 		if (!pfn_valid(pfn) || PageReserved(pfn_to_page(pfn)))

@@ -966,7 +964,7 @@
 }
 
 static inline int remap_pmd_range(struct mm_struct *mm, pmd_t * pmd, unsigned long address, unsigned long size,
-	unsigned long phys_addr, pgprot_t prot)
+	unsigned long pfn, pgprot_t prot)
 {
 	unsigned long base, end;
 

@@ -975,12 +973,12 @@
 	end = address + size;
 	if (end > PGDIR_SIZE)
 		end = PGDIR_SIZE;
-	phys_addr -= address;
+	pfn -= address >> PAGE_SHIFT;
 	do {
 		pte_t * pte = pte_alloc_map(mm, pmd, base + address);
 		if (!pte)
 			return -ENOMEM;
-		remap_pte_range(pte, base + address, end - address, address + phys_addr, prot);
+		remap_pte_range(pte, base + address, end - address, pfn + (address >> PAGE_SHIFT), prot);
 		pte_unmap(pte);
 		address = (address + PMD_SIZE) & PMD_MASK;
 		pmd++;

@@ -989,7 +987,7 @@
 }
 
 /*  Note: this is only safe if the mm semaphore is held when called. */
-int remap_page_range(struct vm_area_struct *vma, unsigned long from, unsigned long phys_addr, unsigned long size, pgprot_t prot)
+int remap_pfn_range(struct vm_area_struct *vma, unsigned long from, unsigned long pfn, unsigned long size, pgprot_t prot)
 {
 	int error = 0;
 	pgd_t * dir;

@@ -997,7 +995,7 @@
 	unsigned long end = from + size;
 	struct mm_struct *mm = vma->vm_mm;
 
-	phys_addr -= from;
+	pfn -= from >> PAGE_SHIFT;
 	dir = pgd_offset(mm, from);
 	flush_cache_range(vma, beg, end);
 	if (from >= end)

@@ -1009,7 +1007,7 @@
 		error = -ENOMEM;
 		if (!pmd)
 			break;
-		error = remap_pmd_range(mm, pmd, from, end - from, phys_addr + from, prot);
+		error = remap_pmd_range(mm, pmd, from, end - from, pfn + (from >> PAGE_SHIFT), prot);
 		if (error)
 			break;
 		from = (from + PGDIR_SIZE) & PGDIR_MASK;

@@ -1022,8 +1020,7 @@
 	spin_unlock(&mm->page_table_lock);
 	return error;
 }
-
-EXPORT_SYMBOL(remap_page_range);
+EXPORT_SYMBOL(remap_pfn_range);
 
 /*
  * Do pte_mkwrite, but only if the vma says VM_WRITE.  We do this when
mm/nommu.c +1 -1
Index: mm3-2.6.9-rc2/mm/nommu.c
===================================================================
@@ -560,7 +560,7 @@
 	return NULL;
 }
 
-int remap_page_range(struct vm_area_struct *vma, unsigned long from,
+int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
 		unsigned long to, unsigned long size, pgprot_t prot)
 {
 	return -EPERM;
author
#2 lore raw

PATCH 2/76 convert atyfb.c to use remap_pfn_range()

Quoted 3 lines · William Lee Irwin III

This patch introduces remap_pfn_range(), destined to replace remap_page_range(). In the sequel, the callers of remap_page_range() will be converted one at a time.

Convert atyfb.c to use remap_pfn_range(). Here (as in numerous other cases) shifting the argument right by PAGE_SHIFT suffices.

drivers/video/aty/atyfb_base.c +2 -2
Index: mm3-2.6.9-rc2/drivers/video/aty/atyfb_base.c
===================================================================
@@ -1174,8 +1174,8 @@
 		    ~(par->mmap_map[i].prot_mask);
 		pgprot_val(vma->vm_page_prot) |= par->mmap_map[i].prot_flag;
 
-		if (remap_page_range(vma, vma->vm_start + page, map_offset,
-				     map_size, vma->vm_page_prot))
+		if (remap_pfn_range(vma, vma->vm_start + page,
+			map_offset >> PAGE_SHIFT, map_size, vma->vm_page_prot))
 			return -EAGAIN;
 
 		page += map_size;
author
#3 lore raw

PATCH 3/76 convert gbefb.c to use remap_pfn_range()

Quoted 2 lines · William Lee Irwin III

Convert atyfb.c to use remap_pfn_range(). Here (as in numerous other cases) shifting the argument right by PAGE_SHIFT suffices.

Conver the SGI GBE framebuffer driver to use remap_pfn_range().

drivers/video/gbefb.c +2 -2
Index: mm3-2.6.9-rc2/drivers/video/gbefb.c
===================================================================
@@ -1018,8 +1018,8 @@
 		else
 			phys_size = TILE_SIZE - offset;
 
-		if (remap_page_range
-		    (vma, addr, phys_addr, phys_size, vma->vm_page_prot))
+		if (remap_pfn_range(vma, addr, phys_addr >> PAGE_SHIFT,
+						phys_size, vma->vm_page_prot))
 			return -EAGAIN;
 
 		offset = 0;
author
#4 lore raw

PATCH 4/76 convert sgivwfb.c to use remap_pfn_range()

Quoted 1 line · William Lee Irwin III

Conver the SGI GBE framebuffer driver to use remap_pfn_range().

Convert the SGI DBE framebuffer driver to use remap_pfn_range().

drivers/video/sgivwfb.c +2 -2
Index: mm3-2.6.9-rc2/drivers/video/sgivwfb.c
===================================================================
@@ -719,8 +719,8 @@
 	pgprot_val(vma->vm_page_prot) =
 	    pgprot_val(vma->vm_page_prot) | _PAGE_PCD;
 	vma->vm_flags |= VM_IO;
-	if (remap_page_range
-	    (vma, vma->vm_start, offset, size, vma->vm_page_prot))
+	if (remap_pfn_range(vma, vma->vm_start, offset >> PAGE_SHIFT,
+						size, vma->vm_page_prot))
 		return -EAGAIN;
 	vma->vm_file = file;
 	printk(KERN_DEBUG "sgivwfb: mmap framebuffer P(%lx)->V(%lx)\n",
author
#5 lore raw

PATCH 5/76 convert igafb.c to use remap_pfn_range()

Quoted 1 line · William Lee Irwin III

Convert the SGI DBE framebuffer driver to use remap_pfn_range().

Convert the IGA 1682 framebuffer driver to use remap_pfn_range().

drivers/video/igafb.c +2 -2
Index: mm3-2.6.9-rc2/drivers/video/igafb.c
===================================================================
@@ -262,8 +262,8 @@
 		pgprot_val(vma->vm_page_prot) &= ~(par->mmap_map[i].prot_mask);
 		pgprot_val(vma->vm_page_prot) |= par->mmap_map[i].prot_flag;
 
-		if (remap_page_range(vma, vma->vm_start + page, map_offset,
-				     map_size, vma->vm_page_prot))
+		if (remap_pfn_range(vma, vma->vm_start + page,
+			map_offset >> PAGE_SHIFT, map_size, vma->vm_page_prot))
 			return -EAGAIN;
 
 		page += map_size;
author
#6 lore raw

PATCH 6/76 convert zr36120.c to use remap_pfn_range()

Quoted 1 line · William Lee Irwin III

Convert the IGA 1682 framebuffer driver to use remap_pfn_range().

Conver the Zoran 36120/36125 framegrabber driver to use remap_pfn_range().

drivers/media/video/zr36120.c +2 -2
Index: mm3-2.6.9-rc2/drivers/media/video/zr36120.c
===================================================================
@@ -1474,8 +1474,8 @@
 	/* start mapping the whole shabang to user memory */
 	pos = (unsigned long)ztv->fbuffer;
 	while (size>0) {
-		unsigned long page = virt_to_phys((void*)pos);
-		if (remap_page_range(vma, start, page, PAGE_SIZE, PAGE_SHARED))
+		unsigned long pfn = virt_to_phys((void*)pos) >> PAGE_SHIFT;
+		if (remap_pfn_range(vma, start, pfn, PAGE_SIZE, PAGE_SHARED))
 			return -EAGAIN;
 		start += PAGE_SIZE;
 		pos += PAGE_SIZE;