Re: [Xen-devel] Re: [Xen-changelog] [linux-2.6.18-xen] Add "#ifdefARCH_HAS_DEV_MEM" to archtecture specific file_operations.

[Akio Takebe <takebe_akio@jp.fujitsu.com>]

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Hi, Kama, Keir and Isaku

>On Wed, 11 Jul 2007 11:00:37 +0100
>Keir Fraser <keir@xensource.com> wrote:
>> The case of building drivers/xen/char/mem.c, yet not defining
>> ARCH_HAS_DEV_MEM, does not seem useful. Who will pick up and use the
>> mem_fops defined by drivers/xen/char/mem.c?
>> 
>> At the very least this seems abusive of ARCH_HAS_DEV_MEM, and you might be
>> better off defining a different macro name? But I think you need to explain
>> to us what it is you're actually trying to achieve.
>
>I would like to deal with the drivers/xen/char/mem.c as follows. How do
>you think about it? It will cause any problem?
>
>- I will post a patch, which removes definition of ARCH_HAS_DEV_MEM, to
>  xen-ia64-devel later.
>- If needed, I will post a revert patch of 
>  "xen-ia64-devel.hg c/s 12544:395aa5609e6d". (Creating the revert patch
>  may be difficult...)
Xen-ia64 already don't need to modify drivers/xen/char/mem.c.
But as you mentioned, current drivers/xen/char/mem.c has some parts
for xen-ia64. So we may need to cleanup drivers/xen/char/mem.c.

I made a attached revert patch of xen-unstablecs12513[1]
(same as xen-ia64 cs12544). Keir, Isaku, how about it?

If the patch is applied, we cannot compile linux-xen-ia64.
But I have a patch of reverting cs12873[2],
if the patch is also applied, we can compile linux-xen-ia64 again.
I think Kama will post this patch to xen-ia64-devel soon.

Signed-off-by: Akio Takebe <takebe_akio@jp.fujitsu.com>
Signed-off-by: Jun Kamada <kama@jp.fujitsu.com>

[1] cs12513
http://xenbits.xensource.com/xen-unstable.hg?rev/395aa5609e6d
[2] cs12873
http://xenbits.xensource.com/xen-unstable.hg?rev/e5e6893ec699

Best Regards,

Akio Takebe

[-- Attachment #2: revert_12513.patch --]
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diff -r 86ac3059ab67 drivers/xen/char/mem.c
--- a/drivers/xen/char/mem.c	Tue Jul 10 11:18:07 2007 -0600
+++ b/drivers/xen/char/mem.c	Thu Jul 12 23:49:29 2007 +0900
@@ -26,12 +26,13 @@
 #include <asm/io.h>
 #include <asm/hypervisor.h>
 
-#ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
-static inline int valid_phys_addr_range(unsigned long addr, size_t count)
+static inline int uncached_access(struct file *file)
 {
-	return 1;
+	if (file->f_flags & O_SYNC)
+		return 1;
+	/* Xen sets correct MTRR type on non-RAM for us. */
+	return 0;
 }
-#endif
 
 /*
  * This funcion reads the *physical* memory. The f_pos points directly to the 
@@ -44,9 +45,6 @@ static ssize_t read_mem(struct file * fi
 	ssize_t read = 0, sz;
 	void __iomem *v;
 
-	if (!valid_phys_addr_range(p, count))
-		return -EFAULT;
-
 	while (count > 0) {
 		/*
 		 * Handle first page in case it's not aligned
@@ -58,7 +56,7 @@ static ssize_t read_mem(struct file * fi
 
 		sz = min_t(unsigned long, sz, count);
 
-		v = xen_xlate_dev_mem_ptr(p, sz);
+		v = ioremap(p, sz);
 		if (IS_ERR(v) || v == NULL) {
 			/*
 			 * Some programs (e.g., dmidecode) groove off into
@@ -75,7 +73,7 @@ static ssize_t read_mem(struct file * fi
 		}
 
 		ignored = copy_to_user(buf, v, sz);
-		xen_xlate_dev_mem_ptr_unmap(v);
+		iounmap(v);
 		if (ignored)
 			return -EFAULT;
 		buf += sz;
@@ -95,9 +93,6 @@ static ssize_t write_mem(struct file * f
 	ssize_t written = 0, sz;
 	void __iomem *v;
 
-	if (!valid_phys_addr_range(p, count))
-		return -EFAULT;
-
 	while (count > 0) {
 		/*
 		 * Handle first page in case it's not aligned
@@ -109,7 +104,7 @@ static ssize_t write_mem(struct file * f
 
 		sz = min_t(unsigned long, sz, count);
 
-		v = xen_xlate_dev_mem_ptr(p, sz);
+		v = ioremap(p, sz);
 		if (v == NULL)
 			break;
 		if (IS_ERR(v)) {
@@ -119,7 +114,7 @@ static ssize_t write_mem(struct file * f
 		}
 
 		ignored = copy_from_user(v, buf, sz);
-		xen_xlate_dev_mem_ptr_unmap(v);
+		iounmap(v);
 		if (ignored) {
 			written += sz - ignored;
 			if (written)
@@ -137,14 +132,6 @@ static ssize_t write_mem(struct file * f
 }
 
 #ifndef ARCH_HAS_DEV_MEM_MMAP_MEM
-static inline int uncached_access(struct file *file)
-{
-	if (file->f_flags & O_SYNC)
-		return 1;
-	/* Xen sets correct MTRR type on non-RAM for us. */
-	return 0;
-}
-
 static int xen_mmap_mem(struct file * file, struct vm_area_struct * vma)
 {
 	size_t size = vma->vm_end - vma->vm_start;
diff -r 86ac3059ab67 include/asm-i386/mach-xen/asm/io.h
--- a/include/asm-i386/mach-xen/asm/io.h	Tue Jul 10 11:18:07 2007 -0600
+++ b/include/asm-i386/mach-xen/asm/io.h	Thu Jul 12 23:47:18 2007 +0900
@@ -53,8 +53,7 @@
  * Convert a physical pointer to a virtual kernel pointer for /dev/mem
  * access
  */
-#define xen_xlate_dev_mem_ptr(p, sz)	ioremap(p, sz)
-#define xen_xlate_dev_mem_ptr_unmap(p)	iounmap(p)
+#define xen_xlate_dev_mem_ptr(p)	__va(p)
 
 /*
  * Convert a virtual cached pointer to an uncached pointer
diff -r 86ac3059ab67 include/asm-x86_64/mach-xen/asm/io.h
--- a/include/asm-x86_64/mach-xen/asm/io.h	Tue Jul 10 11:18:07 2007 -0600
+++ b/include/asm-x86_64/mach-xen/asm/io.h	Thu Jul 12 23:47:10 2007 +0900
@@ -315,8 +315,7 @@ extern int iommu_bio_merge;
  * Convert a physical pointer to a virtual kernel pointer for /dev/mem
  * access
  */
-#define xen_xlate_dev_mem_ptr(p, sz)	ioremap(p, sz)
-#define xen_xlate_dev_mem_ptr_unmap(p)	iounmap(p)
+#define xen_xlate_dev_mem_ptr(p)	__va(p)
 
 /*
  * Convert a virtual cached pointer to an uncached pointer

[-- Attachment #3: revert_12873.patch --]
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# HG changeset patch
# User root@pq480-rhel5.soft.fujitsu.com
# Date 1184254766 -32400
# Node ID c94d485e18d7fb33abab4c1e6761d9d62a192603
# Parent  02987ed7948ad0b0253fbc53991bf61ae2e305e4
revert 12873:[IA64] paraviatualize /dev/mem to enable X.
http://xenbits.xensource.com/xen-unstable.hg?rev/e5e6893ec699

diff -r 02987ed7948a -r c94d485e18d7 arch/ia64/Kconfig
--- a/arch/ia64/Kconfig	Fri Jul 13 00:00:44 2007 +0900
+++ b/arch/ia64/Kconfig	Fri Jul 13 00:39:26 2007 +0900
@@ -582,6 +582,9 @@ if XEN
 if XEN
 config XEN_SMPBOOT
 	default n
+
+config XEN_DEVMEM
+	default n
 endif
 
 source "drivers/xen/Kconfig"
diff -r 02987ed7948a -r c94d485e18d7 arch/ia64/xen/Makefile
--- a/arch/ia64/xen/Makefile	Fri Jul 13 00:00:44 2007 +0900
+++ b/arch/ia64/xen/Makefile	Fri Jul 13 00:39:26 2007 +0900
@@ -4,6 +4,6 @@
 
 obj-y := hypercall.o xenivt.o xenentry.o xensetup.o xenpal.o xenhpski.o \
 	 hypervisor.o util.o xencomm.o xcom_hcall.o xcom_mini.o \
-	 xcom_privcmd.o mem.o xen_dma.o
+	 xcom_privcmd.o xen_dma.o
 
 obj-$(CONFIG_IA64_GENERIC) += machvec.o
diff -r 02987ed7948a -r c94d485e18d7 arch/ia64/xen/mem.c
--- a/arch/ia64/xen/mem.c	Fri Jul 13 00:00:44 2007 +0900
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,75 +0,0 @@
-/*
- *  Originally from linux/drivers/char/mem.c
- *
- *  Copyright (C) 1991, 1992  Linus Torvalds
- *
- *  Added devfs support. 
- *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
- *  Shared /dev/zero mmaping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
- */
-/*
- * taken from
- * linux/drivers/char/mem.c and linux-2.6-xen-sparse/drivers/xen/char/mem.c.
- * adjusted for IA64 and made transparent.
- * Copyright (c) 2006 Isaku Yamahata <yamahata at valinux co jp>
- *                    VA Linux Systems Japan K.K.
- */
-
-#include <linux/mm.h>
-#include <linux/efi.h>
-
-/*
- * Architectures vary in how they handle caching for addresses
- * outside of main memory.
- *
- */
-static inline int uncached_access(struct file *file, unsigned long addr)
-{
-	/*
-	 * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
-	 */
-	return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
-}
-
-int xen_mmap_mem(struct file * file, struct vm_area_struct * vma)
-{
-	unsigned long addr = vma->vm_pgoff << PAGE_SHIFT;
-	size_t size = vma->vm_end - vma->vm_start;
-
-
-#if 0
-	/*
-	 *XXX FIXME: linux-2.6.16.29, linux-2.6.17
-	 *    valid_mmap_phys_addr_range() in linux/arch/ia64/kernel/efi.c
-	 *    fails checks.
-	 *    linux-2.6.18.1's returns always 1. 
-	 *    Its comments says
-	 *
-         * MMIO regions are often missing from the EFI memory map.
-         * We must allow mmap of them for programs like X, so we
-         * currently can't do any useful validation.
-         */
-	if (!valid_mmap_phys_addr_range(addr, &size))
-		return -EINVAL;
-	if (size < vma->vm_end - vma->vm_start)
-		return -EINVAL;
-#endif
-
-	if (is_running_on_xen()) {
-		unsigned long offset = HYPERVISOR_ioremap(addr, size);
-		if (IS_ERR_VALUE(offset))
-			return offset;
-	}
-
-	if (uncached_access(file, vma->vm_pgoff << PAGE_SHIFT))
-		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-
-        /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
-        if (remap_pfn_range(vma,
-                            vma->vm_start,
-                            vma->vm_pgoff,
-                            size,
-                            vma->vm_page_prot))
-                return -EAGAIN;
-        return 0;
-}
diff -r 02987ed7948a -r c94d485e18d7 include/asm-ia64/io.h
--- a/include/asm-ia64/io.h	Fri Jul 13 00:00:44 2007 +0900
+++ b/include/asm-ia64/io.h	Fri Jul 13 00:39:26 2007 +0900
@@ -129,10 +129,6 @@ extern int valid_mmap_phys_addr_range (u
 	 ((bvec_to_pseudophys((vec1)) + (vec1)->bv_len) ==		\
 	  bvec_to_pseudophys((vec2))))
 
-/* We will be supplying our own /dev/mem implementation */
-#define ARCH_HAS_DEV_MEM
-#define ARCH_HAS_DEV_MEM_MMAP_MEM
-int xen_mmap_mem(struct file * file, struct vm_area_struct * vma);
 #endif /* CONFIG_XEN */
 
 # endif /* KERNEL */
diff -r 02987ed7948a -r c94d485e18d7 include/asm-ia64/uaccess.h
--- a/include/asm-ia64/uaccess.h	Fri Jul 13 00:00:44 2007 +0900
+++ b/include/asm-ia64/uaccess.h	Fri Jul 13 00:39:26 2007 +0900
@@ -365,7 +365,6 @@ ia64_done_with_exception (struct pt_regs
 }
 
 #define ARCH_HAS_TRANSLATE_MEM_PTR	1
-#ifndef CONFIG_XEN
 static __inline__ char *
 xlate_dev_mem_ptr (unsigned long p)
 {
@@ -380,25 +379,6 @@ xlate_dev_mem_ptr (unsigned long p)
 
 	return ptr;
 }
-#else
-static __inline__ char *
-xen_xlate_dev_mem_ptr (unsigned long p, ssize_t sz)
-{
-	unsigned long pfn = p >> PAGE_SHIFT;
-
-	if (pfn_valid(pfn) && !PageUncached(pfn_to_page(pfn)))
-		return __va(p);
-
-	return ioremap(p, sz);
-}
-
-static __inline__ void
-xen_xlate_dev_mem_ptr_unmap (char* v)
-{
-	if (REGION_NUMBER(v) == RGN_UNCACHED)
-		iounmap(v);
-}
-#endif
 
 /*
  * Convert a virtual cached kernel memory pointer to an uncached pointer

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