On 08/04/22 at 06:02pm, Alexander Gordeev wrote:

On Mon, Aug 01, 2022 at 10:40:20PM +0800, Baoquan He wrote:

quoted

This is a preparation patch, no functionality change.

There is, please see below.

quoted

@@ -3,11 +3,17 @@
 #include <linux/mm.h>
 #include <linux/io.h>
 
-void __iomem *ioremap_allowed(phys_addr_t phys_addr, size_t size, unsigned long prot)
+void __iomem *
+ioremap_allowed(phys_addr_t *paddr, size_t size, unsigned long *prot_val)
 {
-	unsigned long last_addr = phys_addr + size - 1;
+	unsigned long last_addr, offset, phys_addr = *paddr;
 	int ret = -EINVAL;
 
+	offset = phys_addr & (~PAGE_MASK);
+	phys_addr -= offset;

FWIW, phys_addr &= PAGE_MASK looks much more usual.

Sure, will change.

quoted

@@ -11,13 +11,20 @@
 #include <linux/io.h>
 #include <linux/export.h>
 
-void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
+void __iomem *ioremap_prot(phys_addr_t paddr, size_t size,
 			   unsigned long prot)
 {
 	unsigned long offset, vaddr;
-	phys_addr_t last_addr;
+	phys_addr_t last_addr, phys_addr = paddr;
 	struct vm_struct *area;
 	void __iomem *base;
+	unsigned long prot_val = prot;

Why prot_val is needed?

I will remove it and pass &prot to ioremap_allowed(). I could think too
much when I made change here. Thanks.

quoted

+	base = ioremap_allowed(&phys_addr, size, &prot_val);
+	if (IS_ERR(base))
+		return NULL;
+	else if (base)
+		return base;

By moving ioremap_allowed() here you allow it to be called
before the wrap-around check, including architectures that
do not do fixups.

Yes, just as you say.

And now ioremap_allowed() semantics, prototype and name turn
less than obvious. Why not introduce a separate fixup callback?

I can do that, while a little worried if too many hooks introduced.
I will introduce another fixup hook in v2 if no other suggestion or
concern. Thanks.

quoted

 	/* Disallow wrap-around or zero size */
 	last_addr = phys_addr + size - 1;

@@ -29,12 +36,6 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size,
 	phys_addr -= offset;
 	size = PAGE_ALIGN(size + offset);
 
-	base = ioremap_allowed(phys_addr, size, prot);
-	if (IS_ERR(base))
-		return NULL;
-	else if (base)
-		return base;
-
 	area = get_vm_area_caller(size, VM_IOREMAP,
 			__builtin_return_address(0));
 	if (!area)

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