Xen devel - Feb 2009 - [PATCH] xen: fix 32-bit build resulting from mmu move

Moving the mmu code from enlighten.c to mmu.c inadvertently broke the
32-bit build.  Fix it.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
 arch/x86/xen/mmu.c |   37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

==================================================================---
a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1388,6 +1388,43 @@
 #endif
 }
 
+#ifdef CONFIG_HIGHPTE
+static void *xen_kmap_atomic_pte(struct page *page, enum km_type type)
+{
+	pgprot_t prot = PAGE_KERNEL;
+
+	if (PagePinned(page))
+		prot = PAGE_KERNEL_RO;
+
+	if (0 && PageHighMem(page))
+		printk("mapping highpte %lx type %d prot %s\n",
+		       page_to_pfn(page), type,
+		       (unsigned long)pgprot_val(prot) & _PAGE_RW ? "WRITE" :
"READ");
+
+	return kmap_atomic_prot(page, type, prot);
+}
+#endif
+
+#ifdef CONFIG_X86_32
+static __init pte_t mask_rw_pte(pte_t *ptep, pte_t pte)
+{
+	/* If there''s an existing pte, then don''t allow _PAGE_RW to
be set */
+	if (pte_val_ma(*ptep) & _PAGE_PRESENT)
+		pte = __pte_ma(((pte_val_ma(*ptep) & _PAGE_RW) | ~_PAGE_RW) &
+			       pte_val_ma(pte));
+
+	return pte;
+}
+
+/* Init-time set_pte while constructing initial pagetables, which
+   doesn''t allow RO pagetable pages to be remapped RW */
+static __init void xen_set_pte_init(pte_t *ptep, pte_t pte)
+{
+	pte = mask_rw_pte(ptep, pte);
+
+	xen_set_pte(ptep, pte);
+}
+#endif
 
 /* Early in boot, while setting up the initial pagetable, assume
    everything is pinned. */



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* Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> Moving the mmu code from enlighten.c to mmu.c inadvertently broke the
> 32-bit build.  Fix it.
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> ---
> arch/x86/xen/mmu.c |   37 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 37 insertions(+)
that goes on top of the recent tip/x86/paravirt changes, right? No 
objections, i''m wondering why my testing didnt find any build breakage.
Could you send me a .config that triggers the breakage?

	Ingo

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Ingo Molnar wrote:
> * Jeremy Fitzhardinge <jeremy@goop.org> wrote:
>
>   
>> Moving the mmu code from enlighten.c to mmu.c inadvertently broke the
>> 32-bit build.  Fix it.
>>
>> Signed-off-by: Jeremy Fitzhardinge
<jeremy.fitzhardinge@citrix.com>
>> ---
>> arch/x86/xen/mmu.c |   37 +++++++++++++++++++++++++++++++++++++
>> 1 file changed, 37 insertions(+)
>>     
>
> that goes on top of the recent tip/x86/paravirt changes, right? No 
> objections, i''m wondering why my testing didnt find any build
breakage.
> Could you send me a .config that triggers the breakage?
>   
Any x86-32 + Xen build would hit it. +highmem+highpte would break a bit 
more.

    J

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* Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> Ingo Molnar wrote:
>> * Jeremy Fitzhardinge <jeremy@goop.org> wrote:
>>
>>   
>>> Moving the mmu code from enlighten.c to mmu.c inadvertently broke
the
>>> 32-bit build.  Fix it.
>>>
>>> Signed-off-by: Jeremy Fitzhardinge
<jeremy.fitzhardinge@citrix.com>
>>> ---
>>> arch/x86/xen/mmu.c |   37 +++++++++++++++++++++++++++++++++++++
>>> 1 file changed, 37 insertions(+)
>>>     
>>
>> that goes on top of the recent tip/x86/paravirt changes, right? No  
>> objections, i''m wondering why my testing didnt find any build
breakage.
>> Could you send me a .config that triggers the breakage?
>
> Any x86-32 + Xen build would hit it. +highmem+highpte would break a bit 
> more.
i have a lot of successful builds with that pattern, that''s why i asked
for
a specific config from you that definitely triggers it - i''d like to 
investigate how it escaped my testing procedures.

	Ingo

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Ingo Molnar wrote:
> i have a lot of successful builds with that pattern, that''s why i
asked for
> a specific config from you that definitely triggers it - i''d like
to
> investigate how it escaped my testing procedures.
>   
Hm, I don''t see how you could be; the functions are just outright 
missing.  Without the patch, the attached config fails with:

$ make ''ARCH=i386'' arch/x86/xen/mmu.o
[...]
  CC      arch/x86/xen/mmu.o
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1810: error:
''xen_kmap_atomic_pte'' undeclared here (not in a function)
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1816: error:
''xen_set_pte_init'' undeclared here (not in a function)
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1824: error: initializer
element is not constant
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1824: error: (near
initialization for ''xen_mmu_ops.pte_val'')
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1825: error: initializer
element is not constant
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1825: error: (near
initialization for ''xen_mmu_ops.pgd_val'')
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1827: error: initializer
element is not constant
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1827: error: (near
initialization for ''xen_mmu_ops.make_pte'')
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1828: error: initializer
element is not constant
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1828: error: (near
initialization for ''xen_mmu_ops.make_pgd'')
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1838: error: initializer
element is not constant
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1838: error: (near
initialization for ''xen_mmu_ops.make_pmd'')
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1839: error: initializer
element is not constant
/home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1839: error: (near
initialization for ''xen_mmu_ops.pmd_val'')
make[3]: *** [arch/x86/xen/mmu.o] Error 1
make[2]: *** [arch/x86/xen/mmu.o] Error 2
make[1]: *** [sub-make] Error 2
make: *** [all] Error 2


(The errors from 1824 onwards seem to be spurious.)

With the patch the file compiles properly.

    J


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* Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> Ingo Molnar wrote:
>> i have a lot of successful builds with that pattern, that''s
why i asked
>> for a specific config from you that definitely triggers it -
i''d like
>> to investigate how it escaped my testing procedures.
>>   
>
> Hm, I don''t see how you could be; the functions are just outright
> missing.  Without the patch, the attached config fails with:
>
> $ make ''ARCH=i386'' arch/x86/xen/mmu.o
> [...]
>  CC      arch/x86/xen/mmu.o
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1810: error:
''xen_kmap_atomic_pte'' undeclared here (not in a function)
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1816: error:
''xen_set_pte_init'' undeclared here (not in a function)
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1824: error:
initializer element is not constant
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1824: error: (near
initialization for ''xen_mmu_ops.pte_val'')
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1825: error:
initializer element is not constant
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1825: error: (near
initialization for ''xen_mmu_ops.pgd_val'')
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1827: error:
initializer element is not constant
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1827: error: (near
initialization for ''xen_mmu_ops.make_pte'')
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1828: error:
initializer element is not constant
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1828: error: (near
initialization for ''xen_mmu_ops.make_pgd'')
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1838: error:
initializer element is not constant
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1838: error: (near
initialization for ''xen_mmu_ops.make_pmd'')
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1839: error:
initializer element is not constant
> /home/jeremy/hg/xen/paravirt/linux/arch/x86/xen/mmu.c:1839: error: (near
initialization for ''xen_mmu_ops.pmd_val'')
> make[3]: *** [arch/x86/xen/mmu.o] Error 1
> make[2]: *** [arch/x86/xen/mmu.o] Error 2
> make[1]: *** [sub-make] Error 2
> make: *** [all] Error 2
>
hm, it triggers here too. Maybe the count of 32-bit tests wasnt high enough 
yet to hit this.

	Ingo

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