diff mbox series

[16/16] debug_vm_pgtable/ppc64: Add a variant of pfn_pte/pmd

Message ID 20200812063358.369514-16-aneesh.kumar@linux.ibm.com (mailing list archive)
State New, archived
Headers show
Series [01/16] powerpc/mm: Add DEBUG_VM WARN for pmd_clear | expand

Commit Message

Aneesh Kumar K.V Aug. 12, 2020, 6:33 a.m. UTC 
The tests do expect _PAGE_PTE bit set by different page table accessors.
This is not true for the kernel. Within the kernel, _PAGE_PTE bits are
usually set by set_pte_at(). To make the below tests work correctly add test
specific pfn_pte/pmd helpers that set _PAGE_PTE bit.

pte_t pte = pfn_pte(pfn, prot);
WARN_ON(!pte_devmap(pte_mkdevmap(pte)));
WARN_ON(!pte_savedwrite(pte_mk_savedwrite(pte_clear_savedwrite(pte))));

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
 mm/debug_vm_pgtable.c | 65 +++++++++++++++++++++++++++----------------
 1 file changed, 41 insertions(+), 24 deletions(-)

Comments

Anshuman Khandual Aug. 13, 2020, 5:30 a.m. UTC | #1 
On 08/12/2020 12:03 PM, Aneesh Kumar K.V wrote:
> The tests do expect _PAGE_PTE bit set by different page table accessors.
> This is not true for the kernel. Within the kernel, _PAGE_PTE bits are
> usually set by set_pte_at(). To make the below tests work correctly add test
> specific pfn_pte/pmd helpers that set _PAGE_PTE bit.
> 
> pte_t pte = pfn_pte(pfn, prot);
> WARN_ON(!pte_devmap(pte_mkdevmap(pte)));
> WARN_ON(!pte_savedwrite(pte_mk_savedwrite(pte_clear_savedwrite(pte))));
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> ---
>  mm/debug_vm_pgtable.c | 65 +++++++++++++++++++++++++++----------------
>  1 file changed, 41 insertions(+), 24 deletions(-)
> 
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index eea62d5e503b..153c925b5273 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -31,6 +31,23 @@
>  #include <asm/pgalloc.h>
>  #include <asm/tlbflush.h>
>  
> +#ifdef CONFIG_PPC_BOOK3S_64
> +static inline pte_t debug_vm_pfn_pte(unsigned long pfn, pgprot_t pgprot)
> +{
> +	pte_t pte = pfn_pte(pfn, pgprot);
> +	return __pte(pte_val(pte) | _PAGE_PTE);
> +
> +}
> +static inline pmd_t debug_vm_pfn_pmd(unsigned long pfn, pgprot_t pgprot)
> +{
> +	pmd_t pmd = pfn_pmd(pfn, pgprot);
> +	return __pmd(pmd_val(pmd) | _PAGE_PTE);
> +}
> +#else
> +#define debug_vm_pfn_pte(pfn, pgprot) pfn_pte(pfn, pgprot)
> +#define debug_vm_pfn_pmd(pfn, pgprot) pfn_pmd(pfn, pgprot)
> +#endif

Again, no platform specific constructs please. This defeats the whole purpose of
this test. If __PAGE_PTE is required for the helpers, then pfn_pmd/pte() could
be modified to accommodate that. We dont see similar issues on other platforms,
hence could you please explain why ppc64 is different here.
Aneesh Kumar K.V Aug. 13, 2020, 6:37 a.m. UTC | #2 
On 8/13/20 11:00 AM, Anshuman Khandual wrote:
> 
> On 08/12/2020 12:03 PM, Aneesh Kumar K.V wrote:
>> The tests do expect _PAGE_PTE bit set by different page table accessors.
>> This is not true for the kernel. Within the kernel, _PAGE_PTE bits are
>> usually set by set_pte_at(). To make the below tests work correctly add test
>> specific pfn_pte/pmd helpers that set _PAGE_PTE bit.
>>
>> pte_t pte = pfn_pte(pfn, prot);
>> WARN_ON(!pte_devmap(pte_mkdevmap(pte)));
>> WARN_ON(!pte_savedwrite(pte_mk_savedwrite(pte_clear_savedwrite(pte))));
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>> ---
>>   mm/debug_vm_pgtable.c | 65 +++++++++++++++++++++++++++----------------
>>   1 file changed, 41 insertions(+), 24 deletions(-)
>>
>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
>> index eea62d5e503b..153c925b5273 100644
>> --- a/mm/debug_vm_pgtable.c
>> +++ b/mm/debug_vm_pgtable.c
>> @@ -31,6 +31,23 @@
>>   #include <asm/pgalloc.h>
>>   #include <asm/tlbflush.h>
>>   
>> +#ifdef CONFIG_PPC_BOOK3S_64
>> +static inline pte_t debug_vm_pfn_pte(unsigned long pfn, pgprot_t pgprot)
>> +{
>> +	pte_t pte = pfn_pte(pfn, pgprot);
>> +	return __pte(pte_val(pte) | _PAGE_PTE);
>> +
>> +}
>> +static inline pmd_t debug_vm_pfn_pmd(unsigned long pfn, pgprot_t pgprot)
>> +{
>> +	pmd_t pmd = pfn_pmd(pfn, pgprot);
>> +	return __pmd(pmd_val(pmd) | _PAGE_PTE);
>> +}
>> +#else
>> +#define debug_vm_pfn_pte(pfn, pgprot) pfn_pte(pfn, pgprot)
>> +#define debug_vm_pfn_pmd(pfn, pgprot) pfn_pmd(pfn, pgprot)
>> +#endif
> 
> Again, no platform specific constructs please. This defeats the whole purpose of
> this test. If __PAGE_PTE is required for the helpers, then pfn_pmd/pte() could
> be modified to accommodate that. We dont see similar issues on other platforms,
> hence could you please explain why ppc64 is different here.
> 

It is not platform specific. set_pte_at is the one that set the 
_PAGE_PTE bit. We don't call that in the test.  The test seems to make 
the assumption that pfn_pte returns a proper pte which is not true.

-aneesh
Anshuman Khandual Aug. 14, 2020, 8:29 a.m. UTC | #3 
On 08/13/2020 12:07 PM, Aneesh Kumar K.V wrote:
> On 8/13/20 11:00 AM, Anshuman Khandual wrote:
>>
>> On 08/12/2020 12:03 PM, Aneesh Kumar K.V wrote:
>>> The tests do expect _PAGE_PTE bit set by different page table accessors.
>>> This is not true for the kernel. Within the kernel, _PAGE_PTE bits are
>>> usually set by set_pte_at(). To make the below tests work correctly add test
>>> specific pfn_pte/pmd helpers that set _PAGE_PTE bit.
>>>
>>> pte_t pte = pfn_pte(pfn, prot);
>>> WARN_ON(!pte_devmap(pte_mkdevmap(pte)));
>>> WARN_ON(!pte_savedwrite(pte_mk_savedwrite(pte_clear_savedwrite(pte))));
>>>
>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>>> ---
>>>   mm/debug_vm_pgtable.c | 65 +++++++++++++++++++++++++++----------------
>>>   1 file changed, 41 insertions(+), 24 deletions(-)
>>>
>>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
>>> index eea62d5e503b..153c925b5273 100644
>>> --- a/mm/debug_vm_pgtable.c
>>> +++ b/mm/debug_vm_pgtable.c
>>> @@ -31,6 +31,23 @@
>>>   #include <asm/pgalloc.h>
>>>   #include <asm/tlbflush.h>
>>>   +#ifdef CONFIG_PPC_BOOK3S_64
>>> +static inline pte_t debug_vm_pfn_pte(unsigned long pfn, pgprot_t pgprot)
>>> +{
>>> +    pte_t pte = pfn_pte(pfn, pgprot);
>>> +    return __pte(pte_val(pte) | _PAGE_PTE);
>>> +
>>> +}
>>> +static inline pmd_t debug_vm_pfn_pmd(unsigned long pfn, pgprot_t pgprot)
>>> +{
>>> +    pmd_t pmd = pfn_pmd(pfn, pgprot);
>>> +    return __pmd(pmd_val(pmd) | _PAGE_PTE);
>>> +}
>>> +#else
>>> +#define debug_vm_pfn_pte(pfn, pgprot) pfn_pte(pfn, pgprot)
>>> +#define debug_vm_pfn_pmd(pfn, pgprot) pfn_pmd(pfn, pgprot)
>>> +#endif
>>
>> Again, no platform specific constructs please. This defeats the whole purpose of
>> this test. If __PAGE_PTE is required for the helpers, then pfn_pmd/pte() could
>> be modified to accommodate that. We dont see similar issues on other platforms,
>> hence could you please explain why ppc64 is different here.
>>
> 
> It is not platform specific. set_pte_at is the one that set the _PAGE_PTE bit. We don't call that in the test.  The test seems to make the assumption that pfn_pte returns a proper pte which is not true.

'#ifdef CONFIG_PPC_BOOK3S_64' definitely makes it platform specific. Here is how
set_pte_at() updates an entry on other platforms without changing the pte value.
_PAGE_PTE bit update during set_pte_at() on ppc64 seems to be a deviation.

1. set_pte_at() on arm64 directly update the entry after TLB, cache maintenance
2. set_pte_at() on s390 directly updates the entry for !CONFIG_PGSTE
3. set_pte_at() on arc directly updates the entry via set_pte()
4. set_pte_at() on x86 directly update the entry via native_set_pte()

set_pte_at() does take a pte created with pfn_pte().

As an example do_anonymous_page() does the same.

......
entry = mk_pte(page, vma->vm_page_prot);	/* Call pfn_pte() */
entry = pte_sw_mkyoung(entry);
if (vma->vm_flags & VM_WRITE)
	entry = pte_mkwrite(pte_mkdirty(entry));
.....
set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
.....
diff mbox series

Patch

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index eea62d5e503b..153c925b5273 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -31,6 +31,23 @@ 
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 
+#ifdef CONFIG_PPC_BOOK3S_64
+static inline pte_t debug_vm_pfn_pte(unsigned long pfn, pgprot_t pgprot)
+{
+	pte_t pte = pfn_pte(pfn, pgprot);
+	return __pte(pte_val(pte) | _PAGE_PTE);
+
+}
+static inline pmd_t debug_vm_pfn_pmd(unsigned long pfn, pgprot_t pgprot)
+{
+	pmd_t pmd = pfn_pmd(pfn, pgprot);
+	return __pmd(pmd_val(pmd) | _PAGE_PTE);
+}
+#else
+#define debug_vm_pfn_pte(pfn, pgprot) pfn_pte(pfn, pgprot)
+#define debug_vm_pfn_pmd(pfn, pgprot) pfn_pmd(pfn, pgprot)
+#endif
+
 /*
  * Please refer Documentation/vm/arch_pgtable_helpers.rst for the semantics
  * expectations that are being validated here. All future changes in here
@@ -55,7 +72,7 @@ 
 
 static void __init pte_basic_tests(unsigned long pfn, pgprot_t prot)
 {
-	pte_t pte = pfn_pte(pfn, prot);
+	pte_t pte = debug_vm_pfn_pte(pfn, prot);
 
 	pr_debug("Validating PTE basic\n");
 	WARN_ON(!pte_same(pte, pte));
@@ -72,10 +89,10 @@  static void __init pte_advanced_tests(struct mm_struct *mm,
 				      unsigned long pfn, unsigned long vaddr,
 				      pgprot_t prot)
 {
-	pte_t pte = pfn_pte(pfn, prot);
+	pte_t pte = debug_vm_pfn_pte(pfn, prot);
 
 	pr_debug("Validating PTE advanced\n");
-	pte = pfn_pte(pfn, prot);
+	pte = debug_vm_pfn_pte(pfn, prot);
 	set_pte_at(mm, vaddr, ptep, pte);
 	ptep_set_wrprotect(mm, vaddr, ptep);
 	pte = ptep_get(ptep);
@@ -85,7 +102,7 @@  static void __init pte_advanced_tests(struct mm_struct *mm,
 	pte = ptep_get(ptep);
 	WARN_ON(!pte_none(pte));
 
-	pte = pfn_pte(pfn, prot);
+	pte = debug_vm_pfn_pte(pfn, prot);
 	pte = pte_wrprotect(pte);
 	pte = pte_mkclean(pte);
 	set_pte_at(mm, vaddr, ptep, pte);
@@ -113,7 +130,7 @@  static void __init pte_advanced_tests(struct mm_struct *mm,
 #ifdef CONFIG_NUMA_BALANCING
 static void __init pte_savedwrite_tests(unsigned long pfn, pgprot_t prot)
 {
-	pte_t pte = pfn_pte(pfn, prot);
+	pte_t pte = debug_vm_pfn_pte(pfn, prot);
 
 	pr_debug("Validating PTE saved write\n");
 	WARN_ON(!pte_savedwrite(pte_mk_savedwrite(pte_clear_savedwrite(pte))));
@@ -124,7 +141,7 @@  static void __init pte_savedwrite_tests(unsigned long pfn, pgprot_t prot)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot)
 {
-	pmd_t pmd = pfn_pmd(pfn, prot);
+	pmd_t pmd = debug_vm_pfn_pmd(pfn, prot);
 
 	if (!has_transparent_hugepage())
 		return;
@@ -160,7 +177,7 @@  static void __init pmd_advanced_tests(struct mm_struct *mm,
 
 	pgtable_trans_huge_deposit(mm, pmdp, pgtable);
 
-	pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
+	pmd = pmd_mkhuge(debug_vm_pfn_pmd(pfn, prot));
 	set_pmd_at(mm, vaddr, pmdp, pmd);
 	pmdp_set_wrprotect(mm, vaddr, pmdp);
 	pmd = READ_ONCE(*pmdp);
@@ -170,7 +187,7 @@  static void __init pmd_advanced_tests(struct mm_struct *mm,
 	pmd = READ_ONCE(*pmdp);
 	WARN_ON(!pmd_none(pmd));
 
-	pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
+	pmd = pmd_mkhuge(debug_vm_pfn_pmd(pfn, prot));
 	pmd = pmd_wrprotect(pmd);
 	pmd = pmd_mkclean(pmd);
 	set_pmd_at(mm, vaddr, pmdp, pmd);
@@ -184,7 +201,7 @@  static void __init pmd_advanced_tests(struct mm_struct *mm,
 	pmd = READ_ONCE(*pmdp);
 	WARN_ON(!pmd_none(pmd));
 
-	pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
+	pmd = pmd_mkhuge(debug_vm_pfn_pmd(pfn, prot));
 	pmd = pmd_mkyoung(pmd);
 	set_pmd_at(mm, vaddr, pmdp, pmd);
 	pmdp_test_and_clear_young(vma, vaddr, pmdp);
@@ -198,7 +215,7 @@  static void __init pmd_advanced_tests(struct mm_struct *mm,
 
 static void __init pmd_leaf_tests(unsigned long pfn, pgprot_t prot)
 {
-	pmd_t pmd = pfn_pmd(pfn, prot);
+	pmd_t pmd = debug_vm_pfn_pmd(pfn, prot);
 
 	pr_debug("Validating PMD leaf\n");
 	/*
@@ -230,7 +247,7 @@  static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot)
 #ifdef CONFIG_NUMA_BALANCING
 static void __init pmd_savedwrite_tests(unsigned long pfn, pgprot_t prot)
 {
-	pmd_t pmd = pfn_pmd(pfn, prot);
+	pmd_t pmd = debug_vm_pfn_pmd(pfn, prot);
 
 	pr_debug("Validating PMD saved write\n");
 	WARN_ON(!pmd_savedwrite(pmd_mk_savedwrite(pmd_clear_savedwrite(pmd))));
@@ -573,7 +590,7 @@  static void __init pmd_populate_tests(struct mm_struct *mm, pmd_t *pmdp,
 
 static void __init pte_special_tests(unsigned long pfn, pgprot_t prot)
 {
-	pte_t pte = pfn_pte(pfn, prot);
+	pte_t pte = debug_vm_pfn_pte(pfn, prot);
 
 	if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL))
 		return;
@@ -584,7 +601,7 @@  static void __init pte_special_tests(unsigned long pfn, pgprot_t prot)
 
 static void __init pte_protnone_tests(unsigned long pfn, pgprot_t prot)
 {
-	pte_t pte = pfn_pte(pfn, prot);
+	pte_t pte = debug_vm_pfn_pte(pfn, prot);
 
 	if (!IS_ENABLED(CONFIG_NUMA_BALANCING))
 		return;
@@ -597,7 +614,7 @@  static void __init pte_protnone_tests(unsigned long pfn, pgprot_t prot)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static void __init pmd_protnone_tests(unsigned long pfn, pgprot_t prot)
 {
-	pmd_t pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
+	pmd_t pmd = pmd_mkhuge(debug_vm_pfn_pmd(pfn, prot));
 
 	if (!IS_ENABLED(CONFIG_NUMA_BALANCING))
 		return;
@@ -613,7 +630,7 @@  static void __init pmd_protnone_tests(unsigned long pfn, pgprot_t prot) { }
 #ifdef CONFIG_ARCH_HAS_PTE_DEVMAP
 static void __init pte_devmap_tests(unsigned long pfn, pgprot_t prot)
 {
-	pte_t pte = pfn_pte(pfn, prot);
+	pte_t pte = debug_vm_pfn_pte(pfn, prot);
 
 	pr_debug("Validating PTE devmap\n");
 	WARN_ON(!pte_devmap(pte_mkdevmap(pte)));
@@ -622,7 +639,7 @@  static void __init pte_devmap_tests(unsigned long pfn, pgprot_t prot)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static void __init pmd_devmap_tests(unsigned long pfn, pgprot_t prot)
 {
-	pmd_t pmd = pfn_pmd(pfn, prot);
+	pmd_t pmd = debug_vm_pfn_pmd(pfn, prot);
 
 	pr_debug("Validating PMD devmap\n");
 	WARN_ON(!pmd_devmap(pmd_mkdevmap(pmd)));
@@ -651,7 +668,7 @@  static void __init pud_devmap_tests(unsigned long pfn, pgprot_t prot) { }
 
 static void __init pte_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
 {
-	pte_t pte = pfn_pte(pfn, prot);
+	pte_t pte = debug_vm_pfn_pte(pfn, prot);
 
 	if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
 		return;
@@ -663,7 +680,7 @@  static void __init pte_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
 
 static void __init pte_swap_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
 {
-	pte_t pte = pfn_pte(pfn, prot);
+	pte_t pte = debug_vm_pfn_pte(pfn, prot);
 
 	if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
 		return;
@@ -676,7 +693,7 @@  static void __init pte_swap_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static void __init pmd_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
 {
-	pmd_t pmd = pfn_pmd(pfn, prot);
+	pmd_t pmd = debug_vm_pfn_pmd(pfn, prot);
 
 	if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY))
 		return;
@@ -688,7 +705,7 @@  static void __init pmd_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
 
 static void __init pmd_swap_soft_dirty_tests(unsigned long pfn, pgprot_t prot)
 {
-	pmd_t pmd = pfn_pmd(pfn, prot);
+	pmd_t pmd = debug_vm_pfn_pmd(pfn, prot);
 
 	if (!IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) ||
 		!IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION))
@@ -711,7 +728,7 @@  static void __init pte_swap_tests(unsigned long pfn, pgprot_t prot)
 	pte_t pte;
 
 	pr_debug("Validating PTE swap\n");
-	pte = pfn_pte(pfn, prot);
+	pte = debug_vm_pfn_pte(pfn, prot);
 	swp = __pte_to_swp_entry(pte);
 	pte = __swp_entry_to_pte(swp);
 	WARN_ON(pfn != pte_pfn(pte));
@@ -724,7 +741,7 @@  static void __init pmd_swap_tests(unsigned long pfn, pgprot_t prot)
 	pmd_t pmd;
 
 	pr_debug("Validating PMD swap\n");
-	pmd = pfn_pmd(pfn, prot);
+	pmd = debug_vm_pfn_pmd(pfn, prot);
 	swp = __pmd_to_swp_entry(pmd);
 	pmd = __swp_entry_to_pmd(swp);
 	WARN_ON(pfn != pmd_pfn(pmd));
@@ -794,7 +811,7 @@  static void __init hugetlb_basic_tests(unsigned long pfn, pgprot_t prot)
 	WARN_ON(huge_pte_write(huge_pte_wrprotect(huge_pte_mkwrite(pte))));
 
 #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB
-	pte = pfn_pte(pfn, prot);
+	pte = debug_vm_pfn_pte(pfn, prot);
 
 	WARN_ON(!pte_huge(pte_mkhuge(pte)));
 #endif /* CONFIG_ARCH_WANT_GENERAL_HUGETLB */
@@ -874,7 +891,7 @@  static void __init pmd_thp_tests(unsigned long pfn, pgprot_t prot)
 	 * needs to return true. pmd_present() should be true whenever
 	 * pmd_trans_huge() returns true.
 	 */
-	pmd = pfn_pmd(pfn, prot);
+	pmd = debug_vm_pfn_pmd(pfn, prot);
 	WARN_ON(!pmd_trans_huge(pmd_mkhuge(pmd)));
 
 #ifndef __HAVE_ARCH_PMDP_INVALIDATE