[PATCH] [v2] xen: avoid link error on ARM

[PATCH] [v2] xen: avoid link error on ARM

[Arnd Bergmann]

Building the privcmd code as a loadable module on ARM, we get
a link error due to the private cache management functions:

ERROR: "__sync_icache_dcache" [drivers/xen/xen-privcmd.ko] undefined!

Move the code into a new file that is always built in when Xen
is enabled, as suggested by Juergen Gross. Additional code will
be moved into this file later.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: rename mm.o to xen-builtin.o, make it unconditional
---
 drivers/xen/Makefile      |  1 +
 drivers/xen/privcmd.c     | 30 +---------------------------
 drivers/xen/xen-builtin.c | 41 +++++++++++++++++++++++++++++++++++++++
 include/xen/xen-ops.h     |  3 +++
 4 files changed, 46 insertions(+), 29 deletions(-)
 create mode 100644 drivers/xen/xen-builtin.c

diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index ad3844d9f876..c3cbfcf30d38 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -2,6 +2,7 @@
 obj-$(CONFIG_HOTPLUG_CPU)		+= cpu_hotplug.o
 obj-y	+= grant-table.o features.o balloon.o manage.o preempt.o time.o
 obj-y	+= mem-reservation.o
+obj-y	+= xen-builtin.o
 obj-y	+= events/
 obj-y	+= xenbus/
 
diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index b24ddac1604b..290b6aca7e1d 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -723,26 +723,6 @@ static long privcmd_ioctl_restrict(struct file *file, void __user *udata)
 	return 0;
 }
 
-struct remap_pfn {
-	struct mm_struct *mm;
-	struct page **pages;
-	pgprot_t prot;
-	unsigned long i;
-};
-
-static int remap_pfn_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
-			void *data)
-{
-	struct remap_pfn *r = data;
-	struct page *page = r->pages[r->i];
-	pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot));
-
-	set_pte_at(r->mm, addr, ptep, pte);
-	r->i++;
-
-	return 0;
-}
-
 static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
 {
 	struct privcmd_data *data = file->private_data;
@@ -809,15 +789,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
 		goto out;
 
 	if (xen_feature(XENFEAT_auto_translated_physmap)) {
-		struct remap_pfn r = {
-			.mm = vma->vm_mm,
-			.pages = vma->vm_private_data,
-			.prot = vma->vm_page_prot,
-		};
-
-		rc = apply_to_page_range(r.mm, kdata.addr,
-					 kdata.num << PAGE_SHIFT,
-					 remap_pfn_fn, &r);
+		rc = xen_remap_vma_range(vma, kdata.addr, kdata.num << PAGE_SHIFT);
 	} else {
 		unsigned int domid =
 			(xdata.flags & XENMEM_rsrc_acq_caller_owned) ?
diff --git a/drivers/xen/xen-builtin.c b/drivers/xen/xen-builtin.c
new file mode 100644
index 000000000000..8ad0d4900588
--- /dev/null
+++ b/drivers/xen/xen-builtin.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Architecture independent helper functions for memory management
+ *
+ * Written by Paul Durrant <paul.durrant@citrix.com>
+ */
+#include <linux/mm.h>
+#include <linux/export.h>
+
+struct remap_pfn {
+	struct mm_struct *mm;
+	struct page **pages;
+	pgprot_t prot;
+	unsigned long i;
+};
+
+static int remap_pfn_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
+			void *data)
+{
+	struct remap_pfn *r = data;
+	struct page *page = r->pages[r->i];
+	pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot));
+
+	set_pte_at(r->mm, addr, ptep, pte);
+	r->i++;
+
+	return 0;
+}
+
+/* Used by the privcmd module, but has to be built-in on ARM */
+int xen_remap_vma_range(struct vm_area_struct *vma, unsigned long addr, unsigned long len)
+{
+	struct remap_pfn r = {
+		.mm = vma->vm_mm,
+		.pages = vma->vm_private_data,
+		.prot = vma->vm_page_prot,
+	};
+
+	return apply_to_page_range(vma->vm_mm, addr, len, remap_pfn_fn, &r);
+}
+EXPORT_SYMBOL_GPL(xen_remap_vma_range);
diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index 4969817124a8..98b30c1613b2 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -109,6 +109,9 @@ static inline int xen_xlate_unmap_gfn_range(struct vm_area_struct *vma,
 }
 #endif
 
+int xen_remap_vma_range(struct vm_area_struct *vma, unsigned long addr,
+			unsigned long len);
+
 /*
  * xen_remap_domain_gfn_array() - map an array of foreign frames by gfn
  * @vma:     VMA to map the pages into
-- 
2.20.0

Re: [PATCH] [v2] xen: avoid link error on ARM

[Juergen Gross]

On 05/03/2019 14:30, Arnd Bergmann wrote:
> Building the privcmd code as a loadable module on ARM, we get
> a link error due to the private cache management functions:
> 
> ERROR: "__sync_icache_dcache" [drivers/xen/xen-privcmd.ko] undefined!
> 
> Move the code into a new file that is always built in when Xen
> is enabled, as suggested by Juergen Gross. Additional code will
> be moved into this file later.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> v2: rename mm.o to xen-builtin.o, make it unconditional
> ---
>  drivers/xen/Makefile      |  1 +
>  drivers/xen/privcmd.c     | 30 +---------------------------
>  drivers/xen/xen-builtin.c | 41 +++++++++++++++++++++++++++++++++++++++
>  include/xen/xen-ops.h     |  3 +++
>  4 files changed, 46 insertions(+), 29 deletions(-)
>  create mode 100644 drivers/xen/xen-builtin.c
> 
> diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
> index ad3844d9f876..c3cbfcf30d38 100644
> --- a/drivers/xen/Makefile
> +++ b/drivers/xen/Makefile
> @@ -2,6 +2,7 @@
>  obj-$(CONFIG_HOTPLUG_CPU)		+= cpu_hotplug.o
>  obj-y	+= grant-table.o features.o balloon.o manage.o preempt.o time.o
>  obj-y	+= mem-reservation.o
> +obj-y	+= xen-builtin.o
>  obj-y	+= events/
>  obj-y	+= xenbus/
>  
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index b24ddac1604b..290b6aca7e1d 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -723,26 +723,6 @@ static long privcmd_ioctl_restrict(struct file *file, void __user *udata)
>  	return 0;
>  }
>  
> -struct remap_pfn {
> -	struct mm_struct *mm;
> -	struct page **pages;
> -	pgprot_t prot;
> -	unsigned long i;
> -};
> -
> -static int remap_pfn_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
> -			void *data)
> -{
> -	struct remap_pfn *r = data;
> -	struct page *page = r->pages[r->i];
> -	pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot));
> -
> -	set_pte_at(r->mm, addr, ptep, pte);
> -	r->i++;
> -
> -	return 0;
> -}
> -
>  static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
>  {
>  	struct privcmd_data *data = file->private_data;
> @@ -809,15 +789,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
>  		goto out;
>  
>  	if (xen_feature(XENFEAT_auto_translated_physmap)) {
> -		struct remap_pfn r = {
> -			.mm = vma->vm_mm,
> -			.pages = vma->vm_private_data,
> -			.prot = vma->vm_page_prot,
> -		};
> -
> -		rc = apply_to_page_range(r.mm, kdata.addr,
> -					 kdata.num << PAGE_SHIFT,
> -					 remap_pfn_fn, &r);
> +		rc = xen_remap_vma_range(vma, kdata.addr, kdata.num << PAGE_SHIFT);
>  	} else {
>  		unsigned int domid =
>  			(xdata.flags & XENMEM_rsrc_acq_caller_owned) ?
> diff --git a/drivers/xen/xen-builtin.c b/drivers/xen/xen-builtin.c
> new file mode 100644
> index 000000000000..8ad0d4900588
> --- /dev/null
> +++ b/drivers/xen/xen-builtin.c
> @@ -0,0 +1,41 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Architecture independent helper functions for memory management
> + *
> + * Written by Paul Durrant <paul.durrant@citrix.com>
> + */
> +#include <linux/mm.h>
> +#include <linux/export.h>

Shouldn't you #include xen/xen-ops.h here as well?


Juergen

Re: [PATCH] [v2] xen: avoid link error on ARM

[Boris Ostrovsky]

On 3/5/19 8:30 AM, Arnd Bergmann wrote:
>  
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index b24ddac1604b..290b6aca7e1d 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -723,26 +723,6 @@ static long privcmd_ioctl_restrict(struct file *file, void __user *udata)
>  	return 0;
>  }
>  
> -struct remap_pfn {
> -	struct mm_struct *mm;
> -	struct page **pages;
> -	pgprot_t prot;
> -	unsigned long i;
> -};
> -
> -static int remap_pfn_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
> -			void *data)
> -{
> -	struct remap_pfn *r = data;
> -	struct page *page = r->pages[r->i];
> -	pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot));
> -
> -	set_pte_at(r->mm, addr, ptep, pte);
> -	r->i++;
> -
> -	return 0;
> -}
> -
>  static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
>  {
>  	struct privcmd_data *data = file->private_data;
> @@ -809,15 +789,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
>  		goto out;
>  
>  	if (xen_feature(XENFEAT_auto_translated_physmap)) {
> -		struct remap_pfn r = {
> -			.mm = vma->vm_mm,
> -			.pages = vma->vm_private_data,
> -			.prot = vma->vm_page_prot,
> -		};
> -
> -		rc = apply_to_page_range(r.mm, kdata.addr,
> -					 kdata.num << PAGE_SHIFT,
> -					 remap_pfn_fn, &r);
> +		rc = xen_remap_vma_range(vma, kdata.addr, kdata.num << PAGE_SHIFT);

I wonder whether drivers/xen/xlate_mmu.c might be a good place for these
routines.

-boris

Re: [PATCH] [v2] xen: avoid link error on ARM

[Juergen Gross]

On 05/03/2019 14:43, Boris Ostrovsky wrote:
> On 3/5/19 8:30 AM, Arnd Bergmann wrote:
>>  
>> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
>> index b24ddac1604b..290b6aca7e1d 100644
>> --- a/drivers/xen/privcmd.c
>> +++ b/drivers/xen/privcmd.c
>> @@ -723,26 +723,6 @@ static long privcmd_ioctl_restrict(struct file *file, void __user *udata)
>>  	return 0;
>>  }
>>  
>> -struct remap_pfn {
>> -	struct mm_struct *mm;
>> -	struct page **pages;
>> -	pgprot_t prot;
>> -	unsigned long i;
>> -};
>> -
>> -static int remap_pfn_fn(pte_t *ptep, pgtable_t token, unsigned long addr,
>> -			void *data)
>> -{
>> -	struct remap_pfn *r = data;
>> -	struct page *page = r->pages[r->i];
>> -	pte_t pte = pte_mkspecial(pfn_pte(page_to_pfn(page), r->prot));
>> -
>> -	set_pte_at(r->mm, addr, ptep, pte);
>> -	r->i++;
>> -
>> -	return 0;
>> -}
>> -
>>  static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
>>  {
>>  	struct privcmd_data *data = file->private_data;
>> @@ -809,15 +789,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
>>  		goto out;
>>  
>>  	if (xen_feature(XENFEAT_auto_translated_physmap)) {
>> -		struct remap_pfn r = {
>> -			.mm = vma->vm_mm,
>> -			.pages = vma->vm_private_data,
>> -			.prot = vma->vm_page_prot,
>> -		};
>> -
>> -		rc = apply_to_page_range(r.mm, kdata.addr,
>> -					 kdata.num << PAGE_SHIFT,
>> -					 remap_pfn_fn, &r);
>> +		rc = xen_remap_vma_range(vma, kdata.addr, kdata.num << PAGE_SHIFT);
> 
> I wonder whether drivers/xen/xlate_mmu.c might be a good place for these
> routines.

Hmm, probably. This would require a stub in the header to avoid
problems in case of CONFIG_XEN_AUTO_XLATE not defined, though
(the #ifdef is already there).

I think this is the cleanest solution.


Juergen

Re: [PATCH] [v2] xen: avoid link error on ARM

[Arnd Bergmann]

On Tue, Mar 5, 2019 at 3:57 PM Juergen Gross <jgross@suse.com> wrote:
> On 05/03/2019 14:43, Boris Ostrovsky wrote:
> > On 3/5/19 8:30 AM, Arnd Bergmann wrote:

> >> @@ -809,15 +789,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
> >>              goto out;
> >>
> >>      if (xen_feature(XENFEAT_auto_translated_physmap)) {
> >> -            struct remap_pfn r = {
> >> -                    .mm = vma->vm_mm,
> >> -                    .pages = vma->vm_private_data,
> >> -                    .prot = vma->vm_page_prot,
> >> -            };
> >> -
> >> -            rc = apply_to_page_range(r.mm, kdata.addr,
> >> -                                     kdata.num << PAGE_SHIFT,
> >> -                                     remap_pfn_fn, &r);
> >> +            rc = xen_remap_vma_range(vma, kdata.addr, kdata.num << PAGE_SHIFT);
> >
> > I wonder whether drivers/xen/xlate_mmu.c might be a good place for these
> > routines.
>
> Hmm, probably. This would require a stub in the header to avoid
> problems in case of CONFIG_XEN_AUTO_XLATE not defined, though
> (the #ifdef is already there).
>
> I think this is the cleanest solution.

Putting it into xlate_mmu.c was my first attempt, but I was not sure how to
solve the dependency on CONFIG_XEN_AUTO_XLATE. So
xen_feature(XENFEAT_auto_translated_physmap)) would be guaranteed
to return false if CONFIG_XEN_AUTO_XLATE is disabled?

       Arnd

Re: [PATCH] [v2] xen: avoid link error on ARM

[Juergen Gross]

On 05/03/2019 17:49, Arnd Bergmann wrote:
> On Tue, Mar 5, 2019 at 3:57 PM Juergen Gross <jgross@suse.com> wrote:
>> On 05/03/2019 14:43, Boris Ostrovsky wrote:
>>> On 3/5/19 8:30 AM, Arnd Bergmann wrote:
> 
>>>> @@ -809,15 +789,7 @@ static long privcmd_ioctl_mmap_resource(struct file *file, void __user *udata)
>>>>              goto out;
>>>>
>>>>      if (xen_feature(XENFEAT_auto_translated_physmap)) {
>>>> -            struct remap_pfn r = {
>>>> -                    .mm = vma->vm_mm,
>>>> -                    .pages = vma->vm_private_data,
>>>> -                    .prot = vma->vm_page_prot,
>>>> -            };
>>>> -
>>>> -            rc = apply_to_page_range(r.mm, kdata.addr,
>>>> -                                     kdata.num << PAGE_SHIFT,
>>>> -                                     remap_pfn_fn, &r);
>>>> +            rc = xen_remap_vma_range(vma, kdata.addr, kdata.num << PAGE_SHIFT);
>>>
>>> I wonder whether drivers/xen/xlate_mmu.c might be a good place for these
>>> routines.
>>
>> Hmm, probably. This would require a stub in the header to avoid
>> problems in case of CONFIG_XEN_AUTO_XLATE not defined, though
>> (the #ifdef is already there).
>>
>> I think this is the cleanest solution.
> 
> Putting it into xlate_mmu.c was my first attempt, but I was not sure how to
> solve the dependency on CONFIG_XEN_AUTO_XLATE. So
> xen_feature(XENFEAT_auto_translated_physmap)) would be guaranteed
> to return false if CONFIG_XEN_AUTO_XLATE is disabled?

Yes.


Juergen