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Subject[PATCH v4 4/6] mm: ioremap: Add ioremap/iounmap_allowed()
Date
Add special hook for architecture to verify addr, size or prot
when ioremap() or iounmap(), which will make the generic ioremap
more useful.

ioremap_allowed() return an int,
- NULL means continue to remap
- error code means skip remap and return directly
iounmap_allowed() return an int,
- 0 means continue to vunmap
- error code means skip vunmap and return directly

Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
include/asm-generic/io.h | 25 +++++++++++++++++++++++++
mm/ioremap.c | 13 ++++++++++---
2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index e6ffa2519f08..9429387a3e65 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -964,6 +964,31 @@ static inline void iounmap(volatile void __iomem *addr)
#elif defined(CONFIG_GENERIC_IOREMAP)
#include <linux/pgtable.h>

+/*
+ * Arch code can implement the following two special hooks when using GENERIC_IOREMAP
+ * ioremap_allowed() return an int,
+ * - 0 means continue to remap
+ * - error code means skip remap and return directly
+ * iounmap_allowed() return an int,
+ * - 0 means continue to vunmap
+ * - error code means skip vunmap and return directly
+ */
+#ifndef ioremap_allowed
+#define ioremap_allowed ioremap_allowed
+static inline int ioremap_allowed(phys_addr_t phys_addr, size_t size, unsigned long prot)
+{
+ return 0;
+}
+#endif
+
+#ifndef iounmap_allowed
+#define iounmap_allowed iounmap_allowed
+static inline int iounmap_allowed(void __iomem *addr)
+{
+ return 0;
+}
+#endif
+
void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size, unsigned long prot);
void iounmap(volatile void __iomem *addr);

diff --git a/mm/ioremap.c b/mm/ioremap.c
index 7cb9996b0c12..196c93c0beb8 100644
--- a/mm/ioremap.c
+++ b/mm/ioremap.c
@@ -27,8 +27,10 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size, unsigned long pro
phys_addr -= offset;
size = PAGE_ALIGN(size + offset);

- area = get_vm_area_caller(size, VM_IOREMAP,
- __builtin_return_address(0));
+ if (ioremap_allowed(phys_addr, size, prot))
+ return NULL;
+
+ area = get_vm_area_caller(size, VM_IOREMAP, __builtin_return_address(0));
if (!area)
return NULL;
vaddr = (unsigned long)area->addr;
@@ -45,6 +47,11 @@ EXPORT_SYMBOL(ioremap_prot);

void iounmap(volatile void __iomem *addr)
{
- vunmap((void *)((unsigned long)addr & PAGE_MASK));
+ void __iomem *vaddr = (void __iomem *)((unsigned long)addr & PAGE_MASK);
+
+ if (iounmap_allowed(vaddr))
+ return;
+
+ vunmap((void __force *)vaddr);
}
EXPORT_SYMBOL(iounmap);
--
2.35.3
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