io-mapping: Cleanup atomic iomap

Switch the atomic iomap implementation over to kmap_local and stick the
preempt/pagefault mechanics into the generic code similar to the
kmap_atomic variants.

Rename the x86 map function in preparation for a non-atomic variant.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20201103095858.625310005@linutronix.de

arch/x86/include/asm/iomap.h

@@ -13,14 +13,7 @@
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 
-void __iomem *iomap_atomic_pfn_prot(unsigned long pfn, pgprot_t prot);
-
-static inline void iounmap_atomic(void __iomem *vaddr)
-{
-	kunmap_local_indexed((void __force *)vaddr);
-	pagefault_enable();
-	preempt_enable();
-}
+void __iomem *__iomap_local_pfn_prot(unsigned long pfn, pgprot_t prot);
 
 int iomap_create_wc(resource_size_t base, unsigned long size, pgprot_t *prot);
 

arch/x86/mm/iomap_32.c

@@ -44,7 +44,7 @@ void iomap_free(resource_size_t base, unsigned long size)
 }
 EXPORT_SYMBOL_GPL(iomap_free);
 
-void __iomem *iomap_atomic_pfn_prot(unsigned long pfn, pgprot_t prot)
+void __iomem *__iomap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
 {
 	/*
 	 * For non-PAT systems, translate non-WB request to UC- just in
@@ -60,8 +60,6 @@ void __iomem *iomap_atomic_pfn_prot(unsigned long pfn, pgprot_t prot)
 	/* Filter out unsupported __PAGE_KERNEL* bits: */
 	pgprot_val(prot) &= __default_kernel_pte_mask;
 
-	preempt_disable();
-	pagefault_disable();
 	return (void __force __iomem *)__kmap_local_pfn_prot(pfn, prot);
 }
-EXPORT_SYMBOL_GPL(iomap_atomic_pfn_prot);
+EXPORT_SYMBOL_GPL(__iomap_local_pfn_prot);

include/linux/io-mapping.h

@@ -69,13 +69,17 @@ io_mapping_map_atomic_wc(struct io_mapping *mapping,
 
 	BUG_ON(offset >= mapping->size);
 	phys_addr = mapping->base + offset;
-	return iomap_atomic_pfn_prot(PHYS_PFN(phys_addr), mapping->prot);
+	preempt_disable();
+	pagefault_disable();
+	return __iomap_local_pfn_prot(PHYS_PFN(phys_addr), mapping->prot);
 }
 
 static inline void
 io_mapping_unmap_atomic(void __iomem *vaddr)
 {
-	iounmap_atomic(vaddr);
+	kunmap_local_indexed((void __force *)vaddr);
+	pagefault_enable();
+	preempt_enable();
 }
 
 static inline void __iomem *