mm: stack based kmap_atomic()

Keep the current interface but ignore the KM_type and use a stack based
approach.

The advantage is that we get rid of crappy code like:

	#define __KM_PTE			\
		(in_nmi() ? KM_NMI_PTE : 	\
		 in_irq() ? KM_IRQ_PTE :	\
		 KM_PTE0)

and in general can stop worrying about what context we're in and what kmap
slots might be appropriate for that.

The downside is that FRV kmap_atomic() gets more expensive.

For now we use a CPP trick suggested by Andrew:

  #define kmap_atomic(page, args...) __kmap_atomic(page)

to avoid having to touch all kmap_atomic() users in a single patch.

[ not compiled on:
  - mn10300: the arch doesn't actually build with highmem to begin with ]

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix up drivers/gpu/drm/i915/intel_overlay.c]
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/arm/include/asm/highmem.h

@@ -35,9 +35,9 @@ extern void kunmap_high_l1_vipt(struct page *page, pte_t saved_pte);
 #ifdef CONFIG_HIGHMEM
 extern void *kmap(struct page *page);
 extern void kunmap(struct page *page);
-extern void *kmap_atomic(struct page *page, enum km_type type);
-extern void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type);
-extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
+extern void *__kmap_atomic(struct page *page);
+extern void __kunmap_atomic(void *kvaddr);
+extern void *kmap_atomic_pfn(unsigned long pfn);
 extern struct page *kmap_atomic_to_page(const void *ptr);
 #endif
 

arch/arm/mm/highmem.c

@@ -36,18 +36,17 @@ void kunmap(struct page *page)
 }
 EXPORT_SYMBOL(kunmap);
 
-void *kmap_atomic(struct page *page, enum km_type type)
+void *__kmap_atomic(struct page *page)
 {
 	unsigned int idx;
 	unsigned long vaddr;
 	void *kmap;
+	int type;
 
 	pagefault_disable();
 	if (!PageHighMem(page))
 		return page_address(page);
 
-	debug_kmap_atomic(type);
-
 #ifdef CONFIG_DEBUG_HIGHMEM
 	/*
 	 * There is no cache coherency issue when non VIVT, so force the
@@ -61,6 +60,8 @@ void *kmap_atomic(struct page *page, enum km_type type)
 	if (kmap)
 		return kmap;
 
+	type = kmap_atomic_idx_push();
+
 	idx = type + KM_TYPE_NR * smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
@@ -80,14 +81,17 @@ void *kmap_atomic(struct page *page, enum km_type type)
 
 	return (void *)vaddr;
 }
-EXPORT_SYMBOL(kmap_atomic);
+EXPORT_SYMBOL(__kmap_atomic);
 
-void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type)
+void __kunmap_atomic(void *kvaddr)
 {
 	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
-	unsigned int idx = type + KM_TYPE_NR * smp_processor_id();
+	int idx, type;
 
 	if (kvaddr >= (void *)FIXADDR_START) {
+		type = kmap_atomic_idx_pop();
+		idx = type + KM_TYPE_NR * smp_processor_id();
+
 		if (cache_is_vivt())
 			__cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE);
 #ifdef CONFIG_DEBUG_HIGHMEM
@@ -103,15 +107,16 @@ void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type)
 	}
 	pagefault_enable();
 }
-EXPORT_SYMBOL(kunmap_atomic_notypecheck);
+EXPORT_SYMBOL(__kunmap_atomic);
 
-void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
+void *kmap_atomic_pfn(unsigned long pfn)
 {
-	unsigned int idx;
 	unsigned long vaddr;
+	int idx, type;
 
 	pagefault_disable();
 
+	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR * smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 #ifdef CONFIG_DEBUG_HIGHMEM

arch/frv/include/asm/highmem.h

@@ -112,27 +112,18 @@ extern struct page *kmap_atomic_to_page(void *ptr);
 	(void *) damlr;										  \
 })
 
-static inline void *kmap_atomic(struct page *page, enum km_type type)
+static inline void *kmap_atomic_primary(struct page *page, enum km_type type)
 {
 	unsigned long paddr;
 
 	pagefault_disable();
-	debug_kmap_atomic(type);
 	paddr = page_to_phys(page);
 
 	switch (type) {
         case 0:		return __kmap_atomic_primary(0, paddr, 2);
         case 1:		return __kmap_atomic_primary(1, paddr, 3);
         case 2:		return __kmap_atomic_primary(2, paddr, 4);
         case 3:		return __kmap_atomic_primary(3, paddr, 5);
-        case 4:		return __kmap_atomic_primary(4, paddr, 6);
-        case 5:		return __kmap_atomic_primary(5, paddr, 7);
-        case 6:		return __kmap_atomic_primary(6, paddr, 8);
-        case 7:		return __kmap_atomic_primary(7, paddr, 9);
-        case 8:		return __kmap_atomic_primary(8, paddr, 10);
-
-	case 9 ... 9 + NR_TLB_LINES - 1:
-		return __kmap_atomic_secondary(type - 9, paddr);
 
 	default:
 		BUG();
@@ -152,29 +143,23 @@ do {									\
 	asm volatile("tlbpr %0,gr0,#4,#1" : : "r"(vaddr) : "memory");	\
 } while(0)
 
-static inline void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type)
+static inline void kunmap_atomic_primary(void *kvaddr, enum km_type type)
 {
 	switch (type) {
         case 0:		__kunmap_atomic_primary(0, 2);	break;
         case 1:		__kunmap_atomic_primary(1, 3);	break;
         case 2:		__kunmap_atomic_primary(2, 4);	break;
         case 3:		__kunmap_atomic_primary(3, 5);	break;
-        case 4:		__kunmap_atomic_primary(4, 6);	break;
-        case 5:		__kunmap_atomic_primary(5, 7);	break;
-        case 6:		__kunmap_atomic_primary(6, 8);	break;
-        case 7:		__kunmap_atomic_primary(7, 9);	break;
-        case 8:		__kunmap_atomic_primary(8, 10);	break;
-
-	case 9 ... 9 + NR_TLB_LINES - 1:
-		__kunmap_atomic_secondary(type - 9, kvaddr);
-		break;
 
 	default:
 		BUG();
 	}
 	pagefault_enable();
 }
 
+void *__kmap_atomic(struct page *page);
+void __kunmap_atomic(void *kvaddr);
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __KERNEL__ */

arch/frv/mb93090-mb00/pci-dma.c

@@ -61,14 +61,14 @@ int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 	dampr2 = __get_DAMPR(2);
 
 	for (i = 0; i < nents; i++) {
-		vaddr = kmap_atomic(sg_page(&sg[i]), __KM_CACHE);
+		vaddr = kmap_atomic_primary(sg_page(&sg[i]), __KM_CACHE);
 
 		frv_dcache_writeback((unsigned long) vaddr,
 				     (unsigned long) vaddr + PAGE_SIZE);
 
 	}
 
-	kunmap_atomic(vaddr, __KM_CACHE);
+	kunmap_atomic_primary(vaddr, __KM_CACHE);
 	if (dampr2) {
 		__set_DAMPR(2, dampr2);
 		__set_IAMPR(2, dampr2);

arch/frv/mm/cache-page.c

@@ -26,11 +26,11 @@ void flush_dcache_page(struct page *page)
 
 	dampr2 = __get_DAMPR(2);
 
-	vaddr = kmap_atomic(page, __KM_CACHE);
+	vaddr = kmap_atomic_primary(page, __KM_CACHE);
 
 	frv_dcache_writeback((unsigned long) vaddr, (unsigned long) vaddr + PAGE_SIZE);
 
-	kunmap_atomic(vaddr, __KM_CACHE);
+	kunmap_atomic_primary(vaddr, __KM_CACHE);
 
 	if (dampr2) {
 		__set_DAMPR(2, dampr2);
@@ -54,12 +54,12 @@ void flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
 
 	dampr2 = __get_DAMPR(2);
 
-	vaddr = kmap_atomic(page, __KM_CACHE);
+	vaddr = kmap_atomic_primary(page, __KM_CACHE);
 
 	start = (start & ~PAGE_MASK) | (unsigned long) vaddr;
 	frv_cache_wback_inv(start, start + len);
 
-	kunmap_atomic(vaddr, __KM_CACHE);
+	kunmap_atomic_primary(vaddr, __KM_CACHE);
 
 	if (dampr2) {
 		__set_DAMPR(2, dampr2);

arch/frv/mm/highmem.c

@@ -36,3 +36,53 @@ struct page *kmap_atomic_to_page(void *ptr)
 {
 	return virt_to_page(ptr);
 }
+
+void *__kmap_atomic(struct page *page)
+{
+	unsigned long paddr;
+	int type;
+
+	pagefault_disable();
+	type = kmap_atomic_idx_push();
+	paddr = page_to_phys(page);
+
+	switch (type) {
+	/*
+	 * The first 4 primary maps are reserved for architecture code
+	 */
+	case 0:		return __kmap_atomic_primary(4, paddr, 6);
+	case 1:		return __kmap_atomic_primary(5, paddr, 7);
+	case 2:		return __kmap_atomic_primary(6, paddr, 8);
+	case 3:		return __kmap_atomic_primary(7, paddr, 9);
+	case 4:		return __kmap_atomic_primary(8, paddr, 10);
+
+	case 5 ... 5 + NR_TLB_LINES - 1:
+		return __kmap_atomic_secondary(type - 5, paddr);
+
+	default:
+		BUG();
+		return NULL;
+	}
+}
+EXPORT_SYMBOL(__kmap_atomic);
+
+void __kunmap_atomic(void *kvaddr)
+{
+	int type = kmap_atomic_idx_pop();
+	switch (type) {
+	case 0:		__kunmap_atomic_primary(4, 6);	break;
+	case 1:		__kunmap_atomic_primary(5, 7);	break;
+	case 2:		__kunmap_atomic_primary(6, 8);	break;
+	case 3:		__kunmap_atomic_primary(7, 9);	break;
+	case 4:		__kunmap_atomic_primary(8, 10);	break;
+
+	case 5 ... 5 + NR_TLB_LINES - 1:
+		__kunmap_atomic_secondary(type - 5, kvaddr);
+		break;
+
+	default:
+		BUG();
+	}
+	pagefault_enable();
+}
+EXPORT_SYMBOL(__kunmap_atomic);

arch/mips/include/asm/highmem.h

@@ -45,18 +45,12 @@ extern pte_t *pkmap_page_table;
 extern void * kmap_high(struct page *page);
 extern void kunmap_high(struct page *page);
 
-extern void *__kmap(struct page *page);
-extern void __kunmap(struct page *page);
-extern void *__kmap_atomic(struct page *page, enum km_type type);
-extern void __kunmap_atomic_notypecheck(void *kvaddr, enum km_type type);
-extern void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
-extern struct page *__kmap_atomic_to_page(void *ptr);
-
-#define kmap			__kmap
-#define kunmap			__kunmap
-#define kmap_atomic		__kmap_atomic
-#define kunmap_atomic_notypecheck		__kunmap_atomic_notypecheck
-#define kmap_atomic_to_page	__kmap_atomic_to_page
+extern void *kmap(struct page *page);
+extern void kunmap(struct page *page);
+extern void *__kmap_atomic(struct page *page);
+extern void __kunmap_atomic(void *kvaddr);
+extern void *kmap_atomic_pfn(unsigned long pfn);
+extern struct page *kmap_atomic_to_page(void *ptr);
 
 #define flush_cache_kmaps()	flush_cache_all()
 

arch/mips/mm/highmem.c

@@ -9,7 +9,7 @@ static pte_t *kmap_pte;
 
 unsigned long highstart_pfn, highend_pfn;
 
-void *__kmap(struct page *page)
+void *kmap(struct page *page)
 {
 	void *addr;
 
@@ -21,16 +21,16 @@ void *__kmap(struct page *page)
 
 	return addr;
 }
-EXPORT_SYMBOL(__kmap);
+EXPORT_SYMBOL(kmap);
 
-void __kunmap(struct page *page)
+void kunmap(struct page *page)
 {
 	BUG_ON(in_interrupt());
 	if (!PageHighMem(page))
 		return;
 	kunmap_high(page);
 }
-EXPORT_SYMBOL(__kunmap);
+EXPORT_SYMBOL(kunmap);
 
 /*
  * kmap_atomic/kunmap_atomic is significantly faster than kmap/kunmap because
@@ -41,17 +41,17 @@ EXPORT_SYMBOL(__kunmap);
  * kmaps are appropriate for short, tight code paths only.
  */
 
-void *__kmap_atomic(struct page *page, enum km_type type)
+void *__kmap_atomic(struct page *page)
 {
-	enum fixed_addresses idx;
 	unsigned long vaddr;
+	int idx, type;
 
 	/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
 	pagefault_disable();
 	if (!PageHighMem(page))
 		return page_address(page);
 
-	debug_kmap_atomic(type);
+	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 #ifdef CONFIG_DEBUG_HIGHMEM
@@ -64,43 +64,47 @@ void *__kmap_atomic(struct page *page, enum km_type type)
 }
 EXPORT_SYMBOL(__kmap_atomic);
 
-void __kunmap_atomic_notypecheck(void *kvaddr, enum km_type type)
+void __kunmap_atomic(void *kvaddr)
 {
-#ifdef CONFIG_DEBUG_HIGHMEM
 	unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
-	enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
+	int type;
 
 	if (vaddr < FIXADDR_START) { // FIXME
 		pagefault_enable();
 		return;
 	}
 
-	BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
+	type = kmap_atomic_idx_pop();
+#ifdef CONFIG_DEBUG_HIGHMEM
+	{
+		int idx = type + KM_TYPE_NR * smp_processor_id();
 
-	/*
-	 * force other mappings to Oops if they'll try to access
-	 * this pte without first remap it
-	 */
-	pte_clear(&init_mm, vaddr, kmap_pte-idx);
-	local_flush_tlb_one(vaddr);
-#endif
+		BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
 
+		/*
+		 * force other mappings to Oops if they'll try to access
+		 * this pte without first remap it
+		 */
+		pte_clear(&init_mm, vaddr, kmap_pte-idx);
+		local_flush_tlb_one(vaddr);
+	}
+#endif
 	pagefault_enable();
 }
-EXPORT_SYMBOL(__kunmap_atomic_notypecheck);
+EXPORT_SYMBOL(__kunmap_atomic);
 
 /*
  * This is the same as kmap_atomic() but can map memory that doesn't
  * have a struct page associated with it.
  */
-void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
+void *kmap_atomic_pfn(unsigned long pfn)
 {
-	enum fixed_addresses idx;
 	unsigned long vaddr;
+	int idx, type;
 
 	pagefault_disable();
 
-	debug_kmap_atomic(type);
+	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
 	set_pte(kmap_pte-idx, pfn_pte(pfn, PAGE_KERNEL));
@@ -109,7 +113,7 @@ void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
 	return (void*) vaddr;
 }
 
-struct page *__kmap_atomic_to_page(void *ptr)
+struct page *kmap_atomic_to_page(void *ptr)
 {
 	unsigned long idx, vaddr = (unsigned long)ptr;
 	pte_t *pte;