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

3 files changed, 31 insertions, 21 deletions

diff --git a/arch/powerpc/mm/ioremap.c b/arch/powerpc/mm/ioremap.c
index 50ee6544d0b7..57630325846c 100644
--- a/arch/powerpc/mm/ioremap.c
+++ b/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;
+}
diff --git a/arch/powerpc/mm/ioremap_32.c b/arch/powerpc/mm/ioremap_32.c
index 85b90a62e084..fcf343dbf2bf 100644
--- a/arch/powerpc/mm/ioremap_32.c
+++ b/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;
-		area = get_vm_area_caller(size, VM_IOREMAP, caller);
-		if (area == 0)
-			return NULL;
-		area->phys_addr = p;
-		v = (unsigned long)area->addr;
+		return do_ioremap(p, offset, size, prot, caller);
 	} 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 (slab_is_available())
-			vunmap((void *)v);
+	if (err)
 		return NULL;
-	}
 
 out:
 	return (void __iomem *)(v + ((unsigned long)addr & ~PAGE_MASK));
diff --git a/arch/powerpc/mm/ioremap_64.c b/arch/powerpc/mm/ioremap_64.c
index d132ce1e538d..e37b68b7f0e8 100644
--- a/arch/powerpc/mm/ioremap_64.c
+++ b/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;
-
-		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);
+		return do_ioremap(paligned, offset, size, prot, caller);
 	} else {
 		ret = __ioremap_at(paligned, (void *)ioremap_bot, size, prot);
 		if (ret)