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>

4 files changed, 61 insertions, 26 deletions

diff --git a/arch/frv/include/asm/highmem.h b/arch/frv/include/asm/highmem.h
index cb4c317eaecc..a8d6565d415d 100644
--- a/arch/frv/include/asm/highmem.h
+++ b/arch/frv/include/asm/highmem.h
@@ -112,12 +112,11 @@ 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) {
@@ -125,14 +124,6 @@ static inline void *kmap_atomic(struct page *page, enum km_type type)
         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();
@@ -152,22 +143,13 @@ 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();
@@ -175,6 +157,9 @@ static inline void kunmap_atomic_notypecheck(void *kvaddr, enum km_type type)
         pagefault_enable();
 }
 
+void *__kmap_atomic(struct page *page);
+void __kunmap_atomic(void *kvaddr);
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __KERNEL__ */
diff --git a/arch/frv/mb93090-mb00/pci-dma.c b/arch/frv/mb93090-mb00/pci-dma.c
index 85d110b71cf7..41098a3803a2 100644
--- a/arch/frv/mb93090-mb00/pci-dma.c
+++ b/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);
diff --git a/arch/frv/mm/cache-page.c b/arch/frv/mm/cache-page.c
index 0261cbe153b5..b24ade27a0f0 100644
--- a/arch/frv/mm/cache-page.c
+++ b/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);
diff --git a/arch/frv/mm/highmem.c b/arch/frv/mm/highmem.c
index eadd07658075..61088dcc1594 100644
--- a/arch/frv/mm/highmem.c
+++ b/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);