tile: add virt_to_kpte() API and clean up and document behavior

We use virt_to_pte(NULL, va) a lot, which isn't very obvious. I added virt_to_kpte(va) as a more obvious wrapper function, that also validates the va as being a kernel adddress. And, I fixed the semantics of virt_to_pte() so that we handle the pud and pmd the same way, and we now document the fact that we handle the final pte level differently. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

tile: add virt_to_kpte() API and clean up and document behavior
We use virt_to_pte(NULL, va) a lot, which isn't very obvious. I added virt_to_kpte(va) as a more obvious wrapper function, that also validates the va as being a kernel adddress. And, I fixed the semantics of virt_to_pte() so that we handle the pud and pmd the same way, and we now document the fact that we handle the final pte level differently. Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Chris Metcalf
1 parent 49cf78ef7b
Showing 6 changed files with 30 additions and 11 deletions Side-by-side Diff
arch/tile/include/asm/mmu_context.h
arch/tile/include/asm/page.h
arch/tile/kernel/setup.c
arch/tile/mm/homecache.c
arch/tile/mm/init.c
arch/tile/mm/pgtable.c
@@ -45,7 +45,7 @@
  
 static inline void install_page_table(pgd_t *pgdir, int asid)
 {
-	pte_t *ptep = virt_to_pte(NULL, (unsigned long)pgdir);
+	pte_t *ptep = virt_to_kpte((unsigned long)pgdir);
 	__install_page_table(pgdir, asid, *ptep);
 }
  
@@ -328,6 +328,7 @@
  
 struct mm_struct;
 extern pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr);
+extern pte_t *virt_to_kpte(unsigned long kaddr);
  
 #endif /* !__ASSEMBLY__ */
  
@@ -1600,7 +1600,7 @@
  
 			/* Update the vmalloc mapping and page home. */
 			unsigned long addr = (unsigned long)ptr + i;
-			pte_t *ptep = virt_to_pte(NULL, addr);
+			pte_t *ptep = virt_to_kpte(addr);
 			pte_t pte = *ptep;
 			BUG_ON(pfn != pte_pfn(pte));
 			pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_TILE_L3);
  
@@ -1609,12 +1609,12 @@
  
 			/* Update the lowmem mapping for consistency. */
 			lowmem_va = (unsigned long)pfn_to_kaddr(pfn);
-			ptep = virt_to_pte(NULL, lowmem_va);
+			ptep = virt_to_kpte(lowmem_va);
 			if (pte_huge(*ptep)) {
 				printk(KERN_DEBUG "early shatter of huge page"
 				       " at %#lx\n", lowmem_va);
 				shatter_pmd((pmd_t *)ptep);
-				ptep = virt_to_pte(NULL, lowmem_va);
+				ptep = virt_to_kpte(lowmem_va);
 				BUG_ON(pte_huge(*ptep));
 			}
 			BUG_ON(pfn != pte_pfn(*ptep));
@@ -200,7 +200,7 @@
 #else
 	va = __fix_to_virt(FIX_HOMECACHE_BEGIN + smp_processor_id());
 #endif
-	ptep = virt_to_pte(NULL, (unsigned long)va);
+	ptep = virt_to_kpte(va);
 	pte = pfn_pte(page_to_pfn(page), PAGE_KERNEL);
 	__set_pte(ptep, pte_set_home(pte, home));
 	homecache_finv_page_va((void *)va, home);
@@ -385,7 +385,7 @@
 		return initial_page_home();
 	} else {
 		unsigned long kva = (unsigned long)page_address(page);
-		return pte_to_home(*virt_to_pte(NULL, kva));
+		return pte_to_home(*virt_to_kpte(kva));
 	}
 }
 EXPORT_SYMBOL(page_home);
@@ -404,7 +404,7 @@
 		     NULL, 0);
  
 	for (i = 0; i < pages; ++i, kva += PAGE_SIZE) {
-		pte_t *ptep = virt_to_pte(NULL, kva);
+		pte_t *ptep = virt_to_kpte(kva);
 		pte_t pteval = *ptep;
 		BUG_ON(!pte_present(pteval) || pte_huge(pteval));
 		__set_pte(ptep, pte_set_home(pteval, home));
@@ -951,7 +951,7 @@
 	BUG_ON((addr & (PAGE_SIZE-1)) != 0);
 	for (; addr <= (unsigned long)__w1data_end - 1; addr += PAGE_SIZE) {
 		unsigned long pfn = kaddr_to_pfn((void *)addr);
-		pte_t *ptep = virt_to_pte(NULL, addr);
+		pte_t *ptep = virt_to_kpte(addr);
 		BUG_ON(pte_huge(*ptep));   /* not relevant for kdata_huge */
 		set_pte_at(&init_mm, addr, ptep, pfn_pte(pfn, PAGE_KERNEL_RO));
 	}
@@ -997,7 +997,7 @@
 		 */
 		int pfn = kaddr_to_pfn((void *)addr);
 		struct page *page = pfn_to_page(pfn);
-		pte_t *ptep = virt_to_pte(NULL, addr);
+		pte_t *ptep = virt_to_kpte(addr);
 		if (!initfree) {
 			/*
 			 * If debugging page accesses then do not free
@@ -325,6 +325,17 @@
  
 #endif
  
+/*
+ * Return a pointer to the PTE that corresponds to the given
+ * address in the given page table.  A NULL page table just uses
+ * the standard kernel page table; the preferred API in this case
+ * is virt_to_kpte().
+ *
+ * The returned pointer can point to a huge page in other levels
+ * of the page table than the bottom, if the huge page is present
+ * in the page table.  For bottom-level PTEs, the returned pointer
+ * can point to a PTE that is either present or not.
+ */
 pte_t *virt_to_pte(struct mm_struct* mm, unsigned long addr)
 {
 	pgd_t *pgd;
  
  
@@ -341,13 +352,20 @@
 	if (pud_huge_page(*pud))
 		return (pte_t *)pud;
 	pmd = pmd_offset(pud, addr);
-	if (pmd_huge_page(*pmd))
-		return (pte_t *)pmd;
 	if (!pmd_present(*pmd))
 		return NULL;
+	if (pmd_huge_page(*pmd))
+		return (pte_t *)pmd;
 	return pte_offset_kernel(pmd, addr);
 }
 EXPORT_SYMBOL(virt_to_pte);
+
+pte_t *virt_to_kpte(unsigned long kaddr)
+{
+	BUG_ON(kaddr < PAGE_OFFSET);
+	return virt_to_pte(NULL, kaddr);
+}
+EXPORT_SYMBOL(virt_to_kpte);
  
 pgprot_t set_remote_cache_cpu(pgprot_t prot, int cpu)
 {
...	...	@@ -45,7 +45,7 @@
45	45
46	46	static inline void install_page_table(pgd_t *pgdir, int asid)
47	47	{
48		- pte_t *ptep = virt_to_pte(NULL, (unsigned long)pgdir);
	48	+ pte_t *ptep = virt_to_kpte((unsigned long)pgdir);
49	49	__install_page_table(pgdir, asid, *ptep);
50	50	}
51	51
...	...	@@ -328,6 +328,7 @@
328	328
329	329	struct mm_struct;
330	330	extern pte_t virt_to_pte(struct mm_struct mm, unsigned long addr);
	331	+extern pte_t *virt_to_kpte(unsigned long kaddr);
331	332
332	333	#endif /* !__ASSEMBLY__ */
333	334
...	...	@@ -1600,7 +1600,7 @@
1600	1600
1601	1601	/* Update the vmalloc mapping and page home. */
1602	1602	unsigned long addr = (unsigned long)ptr + i;
1603		- pte_t *ptep = virt_to_pte(NULL, addr);
	1603	+ pte_t *ptep = virt_to_kpte(addr);
1604	1604	pte_t pte = *ptep;
1605	1605	BUG_ON(pfn != pte_pfn(pte));
1606	1606	pte = hv_pte_set_mode(pte, HV_PTE_MODE_CACHE_TILE_L3);
1607	1607
...	...	@@ -1609,12 +1609,12 @@
1609	1609
1610	1610	/* Update the lowmem mapping for consistency. */
1611	1611	lowmem_va = (unsigned long)pfn_to_kaddr(pfn);
1612		- ptep = virt_to_pte(NULL, lowmem_va);
	1612	+ ptep = virt_to_kpte(lowmem_va);
1613	1613	if (pte_huge(*ptep)) {
1614	1614	printk(KERN_DEBUG "early shatter of huge page"
1615	1615	" at %#lx\n", lowmem_va);
1616	1616	shatter_pmd((pmd_t *)ptep);
1617		- ptep = virt_to_pte(NULL, lowmem_va);
	1617	+ ptep = virt_to_kpte(lowmem_va);
1618	1618	BUG_ON(pte_huge(*ptep));
1619	1619	}
1620	1620	BUG_ON(pfn != pte_pfn(*ptep));
...	...	@@ -200,7 +200,7 @@
200	200	#else
201	201	va = __fix_to_virt(FIX_HOMECACHE_BEGIN + smp_processor_id());
202	202	#endif
203		- ptep = virt_to_pte(NULL, (unsigned long)va);
	203	+ ptep = virt_to_kpte(va);
204	204	pte = pfn_pte(page_to_pfn(page), PAGE_KERNEL);
205	205	__set_pte(ptep, pte_set_home(pte, home));
206	206	homecache_finv_page_va((void *)va, home);
...	...	@@ -385,7 +385,7 @@
385	385	return initial_page_home();
386	386	} else {
387	387	unsigned long kva = (unsigned long)page_address(page);
388		- return pte_to_home(*virt_to_pte(NULL, kva));
	388	+ return pte_to_home(*virt_to_kpte(kva));
389	389	}
390	390	}
391	391	EXPORT_SYMBOL(page_home);
...	...	@@ -404,7 +404,7 @@
404	404	NULL, 0);
405	405
406	406	for (i = 0; i < pages; ++i, kva += PAGE_SIZE) {
407		- pte_t *ptep = virt_to_pte(NULL, kva);
	407	+ pte_t *ptep = virt_to_kpte(kva);
408	408	pte_t pteval = *ptep;
409	409	BUG_ON(!pte_present(pteval) \|\| pte_huge(pteval));
410	410	__set_pte(ptep, pte_set_home(pteval, home));
...	...	@@ -951,7 +951,7 @@
951	951	BUG_ON((addr & (PAGE_SIZE-1)) != 0);
952	952	for (; addr <= (unsigned long)__w1data_end - 1; addr += PAGE_SIZE) {
953	953	unsigned long pfn = kaddr_to_pfn((void *)addr);
954		- pte_t *ptep = virt_to_pte(NULL, addr);
	954	+ pte_t *ptep = virt_to_kpte(addr);
955	955	BUG_ON(pte_huge(ptep)); / not relevant for kdata_huge */
956	956	set_pte_at(&init_mm, addr, ptep, pfn_pte(pfn, PAGE_KERNEL_RO));
957	957	}
...	...	@@ -997,7 +997,7 @@
997	997	*/
998	998	int pfn = kaddr_to_pfn((void *)addr);
999	999	struct page *page = pfn_to_page(pfn);
1000		- pte_t *ptep = virt_to_pte(NULL, addr);
	1000	+ pte_t *ptep = virt_to_kpte(addr);
1001	1001	if (!initfree) {
1002	1002	/*
1003	1003	* If debugging page accesses then do not free
...	...	@@ -325,6 +325,17 @@
325	325
326	326	#endif
327	327
	328	+/*
	329	+ * Return a pointer to the PTE that corresponds to the given
	330	+ * address in the given page table. A NULL page table just uses
	331	+ * the standard kernel page table; the preferred API in this case
	332	+ * is virt_to_kpte().
	333	+ *
	334	+ * The returned pointer can point to a huge page in other levels
	335	+ * of the page table than the bottom, if the huge page is present
	336	+ * in the page table. For bottom-level PTEs, the returned pointer
	337	+ * can point to a PTE that is either present or not.
	338	+ */
328	339	pte_t virt_to_pte(struct mm_struct mm, unsigned long addr)
329	340	{
330	341	pgd_t *pgd;
331	342
332	343
...	...	@@ -341,13 +352,20 @@
341	352	if (pud_huge_page(*pud))
342	353	return (pte_t *)pud;
343	354	pmd = pmd_offset(pud, addr);
344		- if (pmd_huge_page(*pmd))
345		- return (pte_t *)pmd;
346	355	if (!pmd_present(*pmd))
347	356	return NULL;
	357	+ if (pmd_huge_page(*pmd))
	358	+ return (pte_t *)pmd;
348	359	return pte_offset_kernel(pmd, addr);
349	360	}
350	361	EXPORT_SYMBOL(virt_to_pte);
	362	+
	363	+pte_t *virt_to_kpte(unsigned long kaddr)
	364	+{
	365	+ BUG_ON(kaddr < PAGE_OFFSET);
	366	+ return virt_to_pte(NULL, kaddr);
	367	+}
	368	+EXPORT_SYMBOL(virt_to_kpte);
351	369
352	370	pgprot_t set_remote_cache_cpu(pgprot_t prot, int cpu)
353	371	{