{x86,powerpc,microblaze}/kmap: move preempt disable

During this kmap() conversion series we must maintain bisect-ability.  To
do this, kmap_atomic_prot() in x86, powerpc, and microblaze need to remain
functional.

Create a temporary inline version of kmap_atomic_prot within these
architectures so we can rework their kmap_atomic() calls and then lift
kmap_atomic_prot() to the core.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian König <christian.koenig@amd.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20200507150004.1423069-6-ira.weiny@intel.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/microblaze/include/asm/highmem.h

@@ -51,7 +51,16 @@ extern pte_t *pkmap_page_table;
 #define PKMAP_NR(virt)  ((virt - PKMAP_BASE) >> PAGE_SHIFT)
 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
 
-extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
+extern void *kmap_atomic_high_prot(struct page *page, pgprot_t prot);
+static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot)
+{
+	preempt_disable();
+	pagefault_disable();
+	if (!PageHighMem(page))
+		return page_address(page);
+
+	return kmap_atomic_high_prot(page, prot);
+}
 extern void __kunmap_atomic(void *kvaddr);
 
 static inline void *kmap_atomic(struct page *page)

arch/microblaze/mm/highmem.c

@@ -32,18 +32,12 @@
  */
 #include <asm/tlbflush.h>
 
-void *kmap_atomic_prot(struct page *page, pgprot_t prot)
+void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
 {
 
 	unsigned long vaddr;
 	int idx, type;
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
-
-
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
@@ -55,7 +49,7 @@ void *kmap_atomic_prot(struct page *page, pgprot_t prot)
 
 	return (void *) vaddr;
 }
-EXPORT_SYMBOL(kmap_atomic_prot);
+EXPORT_SYMBOL(kmap_atomic_high_prot);
 
 void __kunmap_atomic(void *kvaddr)
 {

arch/powerpc/include/asm/highmem.h

@@ -59,7 +59,16 @@ extern pte_t *pkmap_page_table;
 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
 
-extern void *kmap_atomic_prot(struct page *page, pgprot_t prot);
+extern void *kmap_atomic_high_prot(struct page *page, pgprot_t prot);
+static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot)
+{
+	preempt_disable();
+	pagefault_disable();
+	if (!PageHighMem(page))
+		return page_address(page);
+
+	return kmap_atomic_high_prot(page, prot);
+}
 extern void __kunmap_atomic(void *kvaddr);
 
 static inline void *kmap_atomic(struct page *page)

arch/powerpc/mm/highmem.c

@@ -30,16 +30,11 @@
  * be used in IRQ contexts, so in some (very limited) cases we need
  * it.
  */
-void *kmap_atomic_prot(struct page *page, pgprot_t prot)
+void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
 {
 	unsigned long vaddr;
 	int idx, type;
 
-	preempt_disable();
-	pagefault_disable();
-	if (!PageHighMem(page))
-		return page_address(page);
-
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
@@ -49,7 +44,7 @@ void *kmap_atomic_prot(struct page *page, pgprot_t prot)
 
 	return (void*) vaddr;
 }
-EXPORT_SYMBOL(kmap_atomic_prot);
+EXPORT_SYMBOL(kmap_atomic_high_prot);
 
 void __kunmap_atomic(void *kvaddr)
 {

arch/x86/include/asm/highmem.h

@@ -58,7 +58,16 @@ extern unsigned long highstart_pfn, highend_pfn;
 #define PKMAP_NR(virt)  ((virt-PKMAP_BASE) >> PAGE_SHIFT)
 #define PKMAP_ADDR(nr)  (PKMAP_BASE + ((nr) << PAGE_SHIFT))
 
-void *kmap_atomic_prot(struct page *page, pgprot_t prot);
+extern void *kmap_atomic_high_prot(struct page *page, pgprot_t prot);
+static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot)
+{
+	preempt_disable();
+	pagefault_disable();
+	if (!PageHighMem(page))
+		return page_address(page);
+
+	return kmap_atomic_high_prot(page, prot);
+}
 void *kmap_atomic(struct page *page);
 void __kunmap_atomic(void *kvaddr);
 void *kmap_atomic_pfn(unsigned long pfn);

arch/x86/mm/highmem_32.c

@@ -12,17 +12,11 @@
  * However when holding an atomic kmap it is not legal to sleep, so atomic
  * kmaps are appropriate for short, tight code paths only.
  */
-void *kmap_atomic_prot(struct page *page, pgprot_t prot)
+void *kmap_atomic_high_prot(struct page *page, pgprot_t prot)
 {
 	unsigned long vaddr;
 	int idx, type;
 
-	preempt_disable();
-	pagefault_disable();
-
-	if (!PageHighMem(page))
-		return page_address(page);
-
 	type = kmap_atomic_idx_push();
 	idx = type + KM_TYPE_NR*smp_processor_id();
 	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
@@ -32,7 +26,7 @@ void *kmap_atomic_prot(struct page *page, pgprot_t prot)
 
 	return (void *)vaddr;
 }
-EXPORT_SYMBOL(kmap_atomic_prot);
+EXPORT_SYMBOL(kmap_atomic_high_prot);
 
 void *kmap_atomic(struct page *page)
 {