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Subject[PATCH v5 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 a bool,
- true means continue to remap
- false means skip remap and return directly
iounmap_allowed() return a bool,
- true means continue to vunmap
- false code means skip vunmap and return directly

Meanwhile, only vunmap the address when it is in vmalloc area
as the generic ioremap only returns vmalloc addresses.

Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
include/asm-generic/io.h | 26 ++++++++++++++++++++++++++
mm/ioremap.c | 11 ++++++++++-
2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index b76379628a02..db5b890eaff7 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -964,6 +964,32 @@ static inline void iounmap(volatile void __iomem *addr)
#elif defined(CONFIG_GENERIC_IOREMAP)
#include <linux/pgtable.h>

+/*
+ * Arch code can implement the following two hooks when using GENERIC_IOREMAP
+ * ioremap_allowed() return a bool,
+ * - true means continue to remap
+ * - false means skip remap and return directly
+ * iounmap_allowed() return a bool,
+ * - true means continue to vunmap
+ * - false means skip vunmap and return directly
+ */
+#ifndef ioremap_allowed
+#define ioremap_allowed ioremap_allowed
+static inline bool ioremap_allowed(phys_addr_t phys_addr, size_t size,
+ unsigned long prot)
+{
+ return true;
+}
+#endif
+
+#ifndef iounmap_allowed
+#define iounmap_allowed iounmap_allowed
+static inline bool iounmap_allowed(void *addr)
+{
+ return true;
+}
+#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 e1d008e8f87f..8652426282cc 100644
--- a/mm/ioremap.c
+++ b/mm/ioremap.c
@@ -28,6 +28,9 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
phys_addr -= offset;
size = PAGE_ALIGN(size + offset);

+ if (!ioremap_allowed(phys_addr, size, prot))
+ return NULL;
+
area = get_vm_area_caller(size, VM_IOREMAP,
__builtin_return_address(0));
if (!area)
@@ -47,6 +50,12 @@ 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 (!iounmap_allowed(vaddr))
+ return;
+
+ if (is_vmalloc_addr(vaddr))
+ vunmap(vaddr);
}
EXPORT_SYMBOL(iounmap);
--
2.35.3
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