[PATCH 2/4] mm: ioremap: Add arch_ioremap/iounmap_check()

[Kefeng Wang]

Add special check hook for architecture to verify addr, size
or prot when ioremap() or iounmap(), which will make the generic
ioremap more useful.

Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
---
 include/asm-generic/io.h |  3 +++
 mm/ioremap.c             | 20 +++++++++++++++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 7ce93aaf69f8..26924fded7c3 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -964,6 +964,9 @@ static inline void iounmap(volatile void __iomem *addr)
 #elif defined(CONFIG_GENERIC_IOREMAP)
 #include <linux/pgtable.h>
 
+bool arch_ioremap_check(phys_addr_t addr, size_t size, unsigned long prot);
+bool arch_iounmap_check(void __iomem *addr);
+
 void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot);
 void iounmap(volatile void __iomem *addr);
 
diff --git a/mm/ioremap.c b/mm/ioremap.c
index 522ef899c35f..d1117005dcc7 100644
--- a/mm/ioremap.c
+++ b/mm/ioremap.c
@@ -11,6 +11,16 @@
 #include <linux/io.h>
 #include <linux/export.h>
 
+bool __weak arch_ioremap_check(phys_addr_t addr, size_t size, unsigned long prot)
+{
+	return true;
+}
+
+bool __weak arch_iounmap_check(void __iomem *addr)
+{
+	return true;
+}
+
 void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot)
 {
 	unsigned long offset, vaddr;
@@ -27,6 +37,9 @@ void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot)
 	addr -= offset;
 	size = PAGE_ALIGN(size + offset);
 
+	if (!arch_ioremap_check(addr, size, prot))
+		return NULL;
+
 	area = get_vm_area_caller(size, VM_IOREMAP,
 			__builtin_return_address(0));
 	if (!area)
@@ -45,6 +58,11 @@ EXPORT_SYMBOL(ioremap_prot);
 
 void iounmap(volatile void __iomem *addr)
 {
-	vunmap((void *)((unsigned long)addr & PAGE_MASK));
+	void *vaddr = (void *)((unsigned long)addr & PAGE_MASK);
+
+	if (!arch_iounmap_check(vaddr))
+		return;
+
+	vunmap(vaddr);
 }
 EXPORT_SYMBOL(iounmap);
-- 
2.26.2