powerpc/mm: refactor ioremap vm area setup.

PPC32 and PPC64 are doing the same once SLAB is available.
Create a do_ioremap() function that calls get_vm_area and
do the mapping.

For PPC64, we add the 4K PFN hack sanity check to __ioremap_caller()
in order to avoid using __ioremap_at(). Other checks in __ioremap_at()
are irrelevant for __ioremap_caller().

On PPC64, VM area is allocated in the range [ioremap_bot ; IOREMAP_END]
On PPC32, VM area is allocated in the range [VMALLOC_START ; VMALLOC_END]

Lets define IOREMAP_START is ioremap_bot for PPC64, and alias
IOREMAP_START/END to VMALLOC_START/END on PPC32

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/42e7e36ad32e0fdf76692426cc642799c9f689b8.1566309263.git.christophe.leroy@c-s.fr

arch/powerpc/include/asm/book3s/32/pgtable.h

@@ -165,6 +165,10 @@ int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
 #define IOREMAP_TOP	KVIRT_TOP
 #endif
 
+/* PPC32 shares vmalloc area with ioremap */
+#define IOREMAP_START	VMALLOC_START
+#define IOREMAP_END	VMALLOC_END
+
 /*
  * Just any arbitrary offset to the start of the vmalloc VM area: the
  * current 16MB value just means that there will be a 64MB "hole" after the

arch/powerpc/include/asm/book3s/64/pgtable.h

@@ -316,6 +316,7 @@ extern unsigned long pci_io_base;
 #define  PHB_IO_BASE	(ISA_IO_END)
 #define  PHB_IO_END	(KERN_IO_START + FULL_IO_SIZE)
 #define IOREMAP_BASE	(PHB_IO_END)
+#define IOREMAP_START	(ioremap_bot)
 #define IOREMAP_END	(KERN_IO_END)
 
 /* Advertise special mapping type for AGP */

arch/powerpc/include/asm/io.h

@@ -723,6 +723,8 @@ void __iomem *ioremap_coherent(phys_addr_t address, unsigned long size);
 extern void iounmap(volatile void __iomem *addr);
 
 int ioremap_range(unsigned long ea, phys_addr_t pa, unsigned long size, pgprot_t prot);
+void __iomem *do_ioremap(phys_addr_t pa, phys_addr_t offset, unsigned long size,
+			 pgprot_t prot, void *caller);
 
 extern void __iomem *__ioremap_caller(phys_addr_t, unsigned long size,
 				      pgprot_t prot, void *caller);

arch/powerpc/include/asm/nohash/32/pgtable.h

@@ -93,6 +93,10 @@ int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
 #define IOREMAP_TOP	KVIRT_TOP
 #endif
 
+/* PPC32 shares vmalloc area with ioremap */
+#define IOREMAP_START	VMALLOC_START
+#define IOREMAP_END	VMALLOC_END
+
 /*
  * Just any arbitrary offset to the start of the vmalloc VM area: the
  * current 16MB value just means that there will be a 64MB "hole" after the

arch/powerpc/include/asm/nohash/64/pgtable.h

@@ -53,6 +53,7 @@
 #define  PHB_IO_BASE	(ISA_IO_END)
 #define  PHB_IO_END	(KERN_IO_START + FULL_IO_SIZE)
 #define IOREMAP_BASE	(PHB_IO_END)
+#define IOREMAP_START	(ioremap_bot)
 #define IOREMAP_END	(KERN_VIRT_START + KERN_VIRT_SIZE)
 
 

arch/powerpc/mm/ioremap.c

@@ -80,3 +80,23 @@ int ioremap_range(unsigned long ea, phys_addr_t pa, unsigned long size, pgprot_t
 
 	return 0;
 }
+
+void __iomem *do_ioremap(phys_addr_t pa, phys_addr_t offset, unsigned long size,
+			 pgprot_t prot, void *caller)
+{
+	struct vm_struct *area;
+	int ret;
+
+	area = __get_vm_area_caller(size, VM_IOREMAP, IOREMAP_START, IOREMAP_END, caller);
+	if (area == NULL)
+		return NULL;
+
+	area->phys_addr = pa;
+	ret = ioremap_range((unsigned long)area->addr, pa, size, prot);
+	if (!ret)
+		return (void __iomem *)area->addr + offset;
+
+	free_vm_area(area);
+
+	return NULL;
+}

arch/powerpc/mm/ioremap_32.c

@@ -18,7 +18,7 @@ void __iomem *
 __ioremap_caller(phys_addr_t addr, unsigned long size, pgprot_t prot, void *caller)
 {
 	unsigned long v;
-	phys_addr_t p;
+	phys_addr_t p, offset;
 	int err;
 
 	/*
@@ -28,6 +28,7 @@ __ioremap_caller(phys_addr_t addr, unsigned long size, pgprot_t prot, void *call
 	 * (ioremap_bot records where we're up to).
 	 */
 	p = addr & PAGE_MASK;
+	offset = addr & ~PAGE_MASK;
 	size = PAGE_ALIGN(addr + size) - p;
 
 	/*
@@ -62,12 +63,7 @@ __ioremap_caller(phys_addr_t addr, unsigned long size, pgprot_t prot, void *call
 		goto out;
 
 	if (slab_is_available()) {
-		struct vm_struct *area;
+		return do_ioremap(p, offset, size, prot, caller);
-		area = get_vm_area_caller(size, VM_IOREMAP, caller);
-		if (area == 0)
-			return NULL;
-		area->phys_addr = p;
-		v = (unsigned long)area->addr;
 	} else {
 		v = (ioremap_bot -= size);
 	}
@@ -77,11 +73,8 @@ __ioremap_caller(phys_addr_t addr, unsigned long size, pgprot_t prot, void *call
 	 */
 
 	err = ioremap_range((unsigned long)v, p, size, prot);
-	if (err) {
+	if (err)
-		if (slab_is_available())
-			vunmap((void *)v);
 		return NULL;
-	}
 
 out:
 	return (void __iomem *)(v + ((unsigned long)addr & ~PAGE_MASK));

arch/powerpc/mm/ioremap_64.c

@@ -46,9 +46,13 @@ EXPORT_SYMBOL(__iounmap_at);
 void __iomem *__ioremap_caller(phys_addr_t addr, unsigned long size,
 			       pgprot_t prot, void *caller)
 {
-	phys_addr_t paligned;
+	phys_addr_t paligned, offset;
 	void __iomem *ret;
 
+	/* We don't support the 4K PFN hack with ioremap */
+	if (pgprot_val(prot) & H_PAGE_4K_PFN)
+		return NULL;
+
 	/*
 	 * Choose an address to map it to. Once the vmalloc system is running,
 	 * we use it. Before that, we map using addresses going up from
@@ -56,21 +60,14 @@ void __iomem *__ioremap_caller(phys_addr_t addr, unsigned long size,
 	 * through ioremap_bot.
 	 */
 	paligned = addr & PAGE_MASK;
+	offset = addr & ~PAGE_MASK;
 	size = PAGE_ALIGN(addr + size) - paligned;
 
 	if (size == 0 || paligned == 0)
 		return NULL;
 
 	if (slab_is_available()) {
-		struct vm_struct *area;
+		return do_ioremap(paligned, offset, size, prot, caller);
-
-		area = __get_vm_area_caller(size, VM_IOREMAP, ioremap_bot,
-					    IOREMAP_END, caller);
-		if (area == NULL)
-			return NULL;
-
-		area->phys_addr = paligned;
-		ret = __ioremap_at(paligned, area->addr, size, prot);
 	} else {
 		ret = __ioremap_at(paligned, (void *)ioremap_bot, size, prot);
 		if (ret)