[PATCH v2 3/3] asm-generic/io.h: Fix !CONFIG_GENERIC_IOMAP pci_iounmap() implementation

[Lorenzo Pieralisi]

For arches that do not select CONFIG_GENERIC_IOMAP, the current
pci_iounmap() function does nothing causing obvious memory leaks
for mapped regions that are backed by MMIO physical space.

In order to detect if a mapped pointer is IO vs MMIO, a check must made
available to the pci_iounmap() function so that it can actually detect
whether the pointer has to be unmapped.

In configurations where CONFIG_HAS_IOPORT_MAP && !CONFIG_GENERIC_IOMAP,
a mapped port is detected using an ioport_map() stub defined in
asm-generic/io.h.

Use the same logic to implement a stub (ie __pci_ioport_unmap()) that
detects if the passed in pointer in pci_iounmap() is IO vs MMIO to
iounmap conditionally and call it in pci_iounmap() fixing the issue.

Leave __pci_ioport_unmap() as a NOP for all other config options.

Reported-by: George Cherian <george.cherian@xxxxxxxxxxx>
Link: https://lore.kernel.org/lkml/20200905024811.74701-1-yangyingliang@xxxxxxxxxx
Link: https://lore.kernel.org/lkml/20200824132046.3114383-1-george.cherian@xxxxxxxxxxx
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: George Cherian <george.cherian@xxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Yang Yingliang <yangyingliang@xxxxxxxxxx>
---
 include/asm-generic/io.h | 39 +++++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index dabf8cb7203b..9ea83d80eb6f 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -911,18 +911,6 @@ static inline void iowrite64_rep(volatile void __iomem *addr,
 #include <linux/vmalloc.h>
 #define __io_virt(x) ((void __force *)(x))
 
-#ifndef CONFIG_GENERIC_IOMAP
-struct pci_dev;
-extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max);
-
-#ifndef pci_iounmap
-#define pci_iounmap pci_iounmap
-static inline void pci_iounmap(struct pci_dev *dev, void __iomem *p)
-{
-}
-#endif
-#endif /* CONFIG_GENERIC_IOMAP */
-
 /*
  * Change virtual addresses to physical addresses and vv.
  * These are pretty trivial
@@ -1016,6 +1004,16 @@ static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
 	port &= IO_SPACE_LIMIT;
 	return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
 }
+#define __pci_ioport_unmap __pci_ioport_unmap
+static inline void __pci_ioport_unmap(void __iomem *p)
+{
+	uintptr_t start = (uintptr_t) PCI_IOBASE;
+	uintptr_t addr = (uintptr_t) p;
+
+	if (addr >= start && addr < start + IO_SPACE_LIMIT)
+		return;
+	iounmap(p);
+}
 #endif
 
 #ifndef ioport_unmap
@@ -1030,6 +1028,23 @@ extern void ioport_unmap(void __iomem *p);
 #endif /* CONFIG_GENERIC_IOMAP */
 #endif /* CONFIG_HAS_IOPORT_MAP */
 
+#ifndef CONFIG_GENERIC_IOMAP
+struct pci_dev;
+extern void __iomem *pci_iomap(struct pci_dev *dev, int bar, unsigned long max);
+
+#ifndef __pci_ioport_unmap
+static inline void __pci_ioport_unmap(void __iomem *p) {}
+#endif
+
+#ifndef pci_iounmap
+#define pci_iounmap pci_iounmap
+static inline void pci_iounmap(struct pci_dev *dev, void __iomem *p)
+{
+	__pci_ioport_unmap(p);
+}
+#endif
+#endif /* CONFIG_GENERIC_IOMAP */
+
 /*
  * Convert a virtual cached pointer to an uncached pointer
  */
-- 
2.26.1