Attachment 151667 Details for Bug 234069 – use ioremap_page_range() to avoid unsupported attributes

[patch] use ioremap_page_range() to avoid unsupported attributes

ia64-ioremap (text/plain), 4.72 KB, created by Bjorn Helgaas on 2007-04-04 15:29:05 UTC

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Creator: Bjorn Helgaas

Created: 2007-04-04 15:29:05 UTC

Size: 4.72 KB

patch

obsolete

>[PATCH] ia64: make ioremap avoid unsupported attributes
>
>Example memory map (from HP sx1000 with VGA enabled):
>    0x00000 - 0x9FFFF supports only WB (cacheable) access
>    0xA0000 - 0xBFFFF supports only UC (uncacheable) access
>    0xC0000 - 0xFFFFF supports only WB (cacheable) access
>
>pci_read_rom() indirectly uses ioremap(0xC0000) to read the shadow VGA option
>ROM.  ioremap() used to default to a 16MB or 64MB UC kernel identity mapping,
>which would cause an MCA when reading 0xC0000 since only WB is supported there.
>
>X uses reads the option ROM to initialize devices.  A smaller test case is:
>  # echo 1 > /sys/bus/pci/devices/0000:aa:03.0/rom
>  # cp /sys/bus/pci/devices/0000:aa:03.0/rom x
>
>To avoid this, we can use the same ioremap_page_range() strategy that most
>architectures use for all ioremaps.  These page table mappings come out of the
>vmalloc area.  On ia64, these are in region 5 (0xA... addresses) and typically
>use 16KB or 64KB mappings instead of 16MB or 64MB mappings.  The smaller
>mappings give more flexibility to use the correct attributes.
>
>Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
>
>Index: linux-2.6.18.ia64/arch/ia64/mm/ioremap.c
>===================================================================
>--- linux-2.6.18.ia64.orig/arch/ia64/mm/ioremap.c	2007-04-04 03:25:52.000000000 -0600
>+++ linux-2.6.18.ia64/arch/ia64/mm/ioremap.c	2007-04-04 03:27:36.000000000 -0600
>@@ -1,5 +1,5 @@
> /*
>- * (c) Copyright 2006 Hewlett-Packard Development Company, L.P.
>+ * (c) Copyright 2006, 2007 Hewlett-Packard Development Company, L.P.
>  *	Bjorn Helgaas <bjorn.helgaas@hp.com>
>  *
>  * This program is free software; you can redistribute it and/or modify
>@@ -10,11 +10,13 @@
> #include <linux/compiler.h>
> #include <linux/module.h>
> #include <linux/efi.h>
>+#include <linux/io.h>
>+#include <linux/vmalloc.h>
> #include <asm/io.h>
> #include <asm/meminit.h>
> 
> static inline void __iomem *
>-__ioremap (unsigned long phys_addr, unsigned long size)
>+__ioremap (unsigned long phys_addr)
> {
> #ifdef CONFIG_XEN
> 	offset = HYPERVISOR_ioremap(phys_addr, size);
>@@ -25,8 +27,13 @@
> void __iomem *
> ioremap (unsigned long phys_addr, unsigned long size)
> {
>+	void __iomem *addr;
>+	struct vm_struct *area;
>+	unsigned long offset;
>+	pgprot_t prot;
> 	u64 attr;
> 	unsigned long gran_base, gran_size;
>+	unsigned long page_base;
> 
> 	/*
> 	 * For things in kern_memmap, we must use the same attribute
>@@ -37,7 +44,7 @@
> 	if (attr & EFI_MEMORY_WB)
> 		return (void __iomem *) phys_to_virt(phys_addr);
> 	else if (attr & EFI_MEMORY_UC)
>-		return __ioremap(phys_addr, size);
>+		return __ioremap(phys_addr);
> 
> 	/*
> 	 * Some chipsets don't support UC access to memory.  If
>@@ -48,7 +55,42 @@
> 	if (efi_mem_attribute(gran_base, gran_size) & EFI_MEMORY_WB)
> 		return (void __iomem *) phys_to_virt(phys_addr);
> 
>-	return __ioremap(phys_addr, size);
>+	/*
>+	 * WB is not supported for the whole granule, so we can't use
>+	 * the region 7 identity mapping.  If we can safely cover the
>+	 * area with kernel page table mappings, we can use those
>+	 * instead.
>+	 */
>+	page_base = phys_addr & PAGE_MASK;
>+	size = PAGE_ALIGN(phys_addr + size) - page_base;
>+	if (efi_mem_attribute(page_base, size) & EFI_MEMORY_WB) {
>+		prot = PAGE_KERNEL;
>+
>+		/*
>+		 * Mappings have to be page-aligned
>+		 */
>+		offset = phys_addr & ~PAGE_MASK;
>+		phys_addr &= PAGE_MASK;
>+
>+		/*
>+		 * Ok, go for it..
>+		 */
>+		area = get_vm_area(size, VM_IOREMAP);
>+		if (!area)
>+			return NULL;
>+
>+		area->phys_addr = phys_addr;
>+		addr = (void __iomem *) area->addr;
>+		if (ioremap_page_range((unsigned long) addr,
>+				(unsigned long) addr + size, phys_addr, prot)) {
>+			vunmap((void __force *) addr);
>+			return NULL;
>+		}
>+
>+		return (void __iomem *) (offset + (char __iomem *)addr);
>+	}
>+
>+	return __ioremap(phys_addr);
> }
> EXPORT_SYMBOL(ioremap);
> 
>@@ -58,6 +100,14 @@
> 	if (kern_mem_attribute(phys_addr, size) & EFI_MEMORY_WB)
> 		return NULL;
> 
>-	return __ioremap(phys_addr, size);
>+	return __ioremap(phys_addr);
> }
> EXPORT_SYMBOL(ioremap_nocache);
>+
>+void
>+iounmap (volatile void __iomem *addr)
>+{
>+	if (REGION_NUMBER(addr) == RGN_GATE)
>+		vunmap((void *) ((unsigned long) addr & PAGE_MASK));
>+}
>+EXPORT_SYMBOL(iounmap);
>Index: linux-2.6.18.ia64/include/asm-ia64/io.h
>===================================================================
>--- linux-2.6.18.ia64.orig/include/asm-ia64/io.h	2007-04-04 03:24:01.000000000 -0600
>+++ linux-2.6.18.ia64/include/asm-ia64/io.h	2007-04-04 03:25:53.000000000 -0600
>@@ -453,11 +453,7 @@
> 
> extern void __iomem * ioremap(unsigned long offset, unsigned long size);
> extern void __iomem * ioremap_nocache (unsigned long offset, unsigned long size);
>-
>-static inline void
>-iounmap (volatile void __iomem *addr)
>-{
>-}
>+extern void iounmap (volatile void __iomem *addr);
> 
> /* Use normal IO mappings for DMI */
> #define dmi_ioremap ioremap

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Attachments on bug 234069: 151665 | 151666 | 151667 | 151668 | 151669