From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>,
linux-mm@kvack.org, akpm@linux-foundation.org
Cc: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org,
linux-snps-arc@lists.infradead.org, x86@kernel.org,
linux-arch@vger.kernel.org,
Gerald Schaefer <gerald.schaefer@de.ibm.com>,
Christophe Leroy <christophe.leroy@c-s.fr>,
Vineet Gupta <vgupta@synopsys.com>,
Mike Rapoport <rppt@linux.ibm.com>, Qian Cai <cai@lca.pw>
Subject: Re: [PATCH v3 03/13] mm/debug_vm_pgtable/ppc64: Avoid setting top bits in radom value
Date: Tue, 1 Sep 2020 13:06:28 +0530 [thread overview]
Message-ID: <e5d32d12-d904-ed8c-8963-d43d2c3744d9@linux.ibm.com> (raw)
In-Reply-To: <75771782-734b-69f6-4a07-2d3542458319@arm.com>
On 9/1/20 1:02 PM, Anshuman Khandual wrote:
>
>
> On 09/01/2020 11:51 AM, Aneesh Kumar K.V wrote:
>> On 9/1/20 8:45 AM, Anshuman Khandual wrote:
>>>
>>>
>>> On 08/27/2020 01:34 PM, Aneesh Kumar K.V wrote:
>>>> ppc64 use bit 62 to indicate a pte entry (_PAGE_PTE). Avoid setting that bit in
>>>> random value.
>>>>
>>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>>>> ---
>>>> mm/debug_vm_pgtable.c | 13 ++++++++++---
>>>> 1 file changed, 10 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
>>>> index 086309fb9b6f..bbf9df0e64c6 100644
>>>> --- a/mm/debug_vm_pgtable.c
>>>> +++ b/mm/debug_vm_pgtable.c
>>>> @@ -44,10 +44,17 @@
>>>> * entry type. But these bits might affect the ability to clear entries with
>>>> * pxx_clear() because of how dynamic page table folding works on s390. So
>>>> * while loading up the entries do not change the lower 4 bits. It does not
>>>> - * have affect any other platform.
>>>> + * have affect any other platform. Also avoid the 62nd bit on ppc64 that is
>>>> + * used to mark a pte entry.
>>>> */
>>>> -#define S390_MASK_BITS 4
>>>> -#define RANDOM_ORVALUE GENMASK(BITS_PER_LONG - 1, S390_MASK_BITS)
>>>> +#define S390_SKIP_MASK GENMASK(3, 0)
>>>> +#ifdef CONFIG_PPC_BOOK3S_64
>>>> +#define PPC64_SKIP_MASK GENMASK(62, 62)
>>>> +#else
>>>> +#define PPC64_SKIP_MASK 0x0
>>>> +#endif
>>>
>>> Please drop the #ifdef CONFIG_PPC_BOOK3S_64 here. We already accommodate skip
>>> bits for a s390 platform requirement and can also do so for ppc64 as well. As
>>> mentioned before, please avoid adding any platform specific constructs in the
>>> test.
>>>
>>
>>
>> that is needed so that it can be built on 32 bit architectures.I did face build errors with arch-linux
>
> Could not (#if __BITS_PER_LONG == 32) be used instead or something like
> that. But should be a generic conditional check identifying 32 bit arch
> not anything platform specific.
>
that _PAGE_PTE bit is pretty much specific to PPC BOOK3S_64. Not sure
why other architectures need to bothered about ignoring bit 62.
-aneesh
next prev parent reply other threads:[~2020-09-01 7:36 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-27 8:04 [PATCH v3 00/13] mm/debug_vm_pgtable fixes Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 01/13] powerpc/mm: Add DEBUG_VM WARN for pmd_clear Aneesh Kumar K.V
2020-09-01 3:12 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 02/13] powerpc/mm: Move setting pte specific flags to pfn_pte Aneesh Kumar K.V
2020-09-01 3:13 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 03/13] mm/debug_vm_pgtable/ppc64: Avoid setting top bits in radom value Aneesh Kumar K.V
2020-09-01 3:15 ` Anshuman Khandual
2020-09-01 6:21 ` Aneesh Kumar K.V
2020-09-01 7:32 ` Anshuman Khandual
2020-09-01 7:36 ` Aneesh Kumar K.V [this message]
2020-09-01 7:46 ` Anshuman Khandual
2020-09-01 7:55 ` Aneesh Kumar K.V
2020-09-02 3:45 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 04/13] mm/debug_vm_pgtables/hugevmap: Use the arch helper to identify huge vmap support Aneesh Kumar K.V
2020-09-01 3:16 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 05/13] mm/debug_vm_pgtable/savedwrite: Enable savedwrite test with CONFIG_NUMA_BALANCING Aneesh Kumar K.V
2020-09-01 3:18 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 06/13] mm/debug_vm_pgtable/THP: Mark the pte entry huge before using set_pmd/pud_at Aneesh Kumar K.V
2020-09-01 3:21 ` Anshuman Khandual
2020-09-01 6:23 ` Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 07/13] mm/debug_vm_pgtable/set_pte/pmd/pud: Don't use set_*_at to update an existing pte entry Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 08/13] mm/debug_vm_pgtable/thp: Use page table depost/withdraw with THP Aneesh Kumar K.V
2020-09-01 3:22 ` Anshuman Khandual
2020-09-01 6:25 ` Aneesh Kumar K.V
2020-09-01 6:50 ` Christophe Leroy
2020-09-01 7:40 ` Aneesh Kumar K.V
2020-09-01 7:51 ` Christophe Leroy
2020-09-02 3:45 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 09/13] mm/debug_vm_pgtable/locks: Move non page table modifying test together Aneesh Kumar K.V
2020-09-01 3:41 ` Anshuman Khandual
2020-09-01 6:38 ` Aneesh Kumar K.V
2020-09-01 9:33 ` Anshuman Khandual
2020-09-01 9:36 ` Aneesh Kumar K.V
2020-09-01 9:58 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 10/13] mm/debug_vm_pgtable/locks: Take correct page table lock Aneesh Kumar K.V
2020-09-01 3:44 ` Anshuman Khandual
2020-08-27 8:04 ` [PATCH v3 11/13] mm/debug_vm_pgtable/pmd_clear: Don't use pmd/pud_clear on pte entries Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 12/13] mm/debug_vm_pgtable/hugetlb: Disable hugetlb test on ppc64 Aneesh Kumar K.V
2020-09-01 4:03 ` Anshuman Khandual
2020-09-01 6:30 ` Aneesh Kumar K.V
2020-09-01 7:59 ` Christophe Leroy
2020-09-02 13:05 ` Anshuman Khandual
2020-09-02 13:20 ` Aneesh Kumar K.V
2020-08-27 8:04 ` [PATCH v3 13/13] mm/debug_vm_pgtable: populate a pte entry before fetching it Aneesh Kumar K.V
2020-08-27 12:17 ` kernel test robot
2020-09-01 3:25 ` Anshuman Khandual
2020-09-01 6:37 ` Aneesh Kumar K.V
2020-09-01 7:38 ` Anshuman Khandual
2020-09-01 9:58 ` Aneesh Kumar K.V
2020-09-02 3:49 ` Anshuman Khandual
2020-09-02 3:58 ` Aneesh Kumar K.V
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