* Re: [PATCH v6 00/12] mm/debug_vm_pgtable: Enhancements
[not found] ` <d96fa0d8-98d8-c924-99f7-bb9673fc2a13@redhat.com>
@ 2021-08-13 19:43 ` Vineet Gupta
2021-08-14 2:57 ` Gavin Shan
0 siblings, 1 reply; 2+ messages in thread
From: Vineet Gupta @ 2021-08-13 19:43 UTC (permalink / raw
To: Gavin Shan, Anshuman Khandual, linux-mm
Cc: linux-kernel, gerald.schaefer, aneesh.kumar, christophe.leroy,
cai, catalin.marinas, will, akpm, chuhu, shan.gavin, arcml
On 8/13/21 2:25 AM, Gavin Shan wrote:
> Hi Anshuman and Vineet,
>
> On 8/12/21 9:11 PM, Anshuman Khandual wrote:
>> On 8/9/21 2:56 PM, Gavin Shan wrote:
>>> There are couple of issues with current implementations and this series
>>> tries to resolve the issues:
>>>
>>> (a) All needed information are scattered in variables, passed to
>>> various
>>> test functions. The code is organized in pretty much relaxed
>>> fashion.
>>>
>>> (b) The page isn't allocated from buddy during page table entry
>>> modifying
>>> tests. The page can be invalid, conflicting to the
>>> implementations
>>> of set_xxx_at() on ARM64. The target page is accessed so that
>>> the
>>> iCache can be flushed when execution permission is given on
>>> ARM64.
>>> Besides, the target page can be unmapped and accessing to it
>>> causes
>>> kernel crash.
>>>
>>> "struct pgtable_debug_args" is introduced to address issue (a). For
>>> issue
>>> (b), the used page is allocated from buddy in page table entry
>>> modifying
>>> tests. The corresponding tets will be skipped if we fail to allocate
>>> the
>>> (huge) page. For other test cases, the original page around to kernel
>>> symbol (@start_kernel) is still used.
>>>
>>> The patches are organized as below. PATCH[2-10] could be combined to
>>> one
>>> patch, but it will make the review harder:
>>>
>>> PATCH[1] introduces "struct pgtable_debug_args" as place holder
>>> of all
>>> needed information. With it, the old and new implementation
>>> can coexist.
>>> PATCH[2-10] uses "struct pgtable_debug_args" in various test
>>> functions.
>>> PATCH[11] removes the unused code for old implementation.
>>> PATCH[12] fixes the issue of corrupted page flag for ARM64
>>>
>>> Changelog
>>> =========
>>> v6:
>>> * Populate saved page table entry pointers after
>>> they're allocated in init_args() (Anshuman)
>>> * Fix imbalanced preemption count issue by replacing
>>> pte_alloc_mmap() with pte_alloc() in init_args() (syzbot)
>>
>> + vgupta@kernel.org
Please also keep linux-snps-arc CC'ed for ARC changes.
>>
>> Hello Gavin/Vineet,
>>
>> This series still need to be tested on ARC ?
>>
>
> Yes, I'm unable to test ARC as it's not supported by QEMU yet.
> It would great if Vineet can give it a try on ARC :)
We do have a working QEMU (in the process of being upstreamed) you could try
https://github.com/foss-for-synopsys-dwc-arc-processors/qemu #master
Is this code in some shared git repo we can pull - instead of apply 8 files.
Thx,
-Vineet
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linux-snps-arc@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-snps-arc
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v6 00/12] mm/debug_vm_pgtable: Enhancements
2021-08-13 19:43 ` [PATCH v6 00/12] mm/debug_vm_pgtable: Enhancements Vineet Gupta
@ 2021-08-14 2:57 ` Gavin Shan
0 siblings, 0 replies; 2+ messages in thread
From: Gavin Shan @ 2021-08-14 2:57 UTC (permalink / raw
To: Vineet Gupta, Anshuman Khandual, linux-mm
Cc: linux-kernel, gerald.schaefer, aneesh.kumar, christophe.leroy,
cai, catalin.marinas, will, akpm, chuhu, shan.gavin, arcml
Hi Vineet,
On 8/14/21 5:43 AM, Vineet Gupta wrote:
> On 8/13/21 2:25 AM, Gavin Shan wrote:
>> On 8/12/21 9:11 PM, Anshuman Khandual wrote:
>>> On 8/9/21 2:56 PM, Gavin Shan wrote:
>>>> There are couple of issues with current implementations and this series
>>>> tries to resolve the issues:
>>>>
>>>> (a) All needed information are scattered in variables, passed to various
>>>> test functions. The code is organized in pretty much relaxed fashion.
>>>>
>>>> (b) The page isn't allocated from buddy during page table entry modifying
>>>> tests. The page can be invalid, conflicting to the implementations
>>>> of set_xxx_at() on ARM64. The target page is accessed so that the
>>>> iCache can be flushed when execution permission is given on ARM64.
>>>> Besides, the target page can be unmapped and accessing to it causes
>>>> kernel crash.
>>>>
>>>> "struct pgtable_debug_args" is introduced to address issue (a). For issue
>>>> (b), the used page is allocated from buddy in page table entry modifying
>>>> tests. The corresponding tets will be skipped if we fail to allocate the
>>>> (huge) page. For other test cases, the original page around to kernel
>>>> symbol (@start_kernel) is still used.
>>>>
>>>> The patches are organized as below. PATCH[2-10] could be combined to one
>>>> patch, but it will make the review harder:
>>>>
>>>> PATCH[1] introduces "struct pgtable_debug_args" as place holder of all
>>>> needed information. With it, the old and new implementation
>>>> can coexist.
>>>> PATCH[2-10] uses "struct pgtable_debug_args" in various test functions.
>>>> PATCH[11] removes the unused code for old implementation.
>>>> PATCH[12] fixes the issue of corrupted page flag for ARM64
>>>>
>>>> Changelog
>>>> =========
>>>> v6:
>>>> * Populate saved page table entry pointers after
>>>> they're allocated in init_args() (Anshuman)
>>>> * Fix imbalanced preemption count issue by replacing
>>>> pte_alloc_mmap() with pte_alloc() in init_args() (syzbot)
>>>
>>> + vgupta@kernel.org
>
> Please also keep linux-snps-arc CC'ed for ARC changes.
>
Sure.
>>>
>>> Hello Gavin/Vineet,
>>>
>>> This series still need to be tested on ARC ?
>>>
>>
>> Yes, I'm unable to test ARC as it's not supported by QEMU yet.
>> It would great if Vineet can give it a try on ARC :)
>
> We do have a working QEMU (in the process of being upstreamed) you could try
> https://github.com/foss-for-synopsys-dwc-arc-processors/qemu #master
>
> Is this code in some shared git repo we can pull - instead of apply 8 files.
>
Here is repo with v6 series included. Please help to have
a try.
https://github.com/gwshan/linux # kvm/arm64_debug
I tried to build the cross-compiler with buildroot with following
2 repos. Unfortunately, none of them worked for me. The QEMU
binary can be built successfully with the provided repo though.
[1] git://github.com/foss-for-synopsys-dwc-arc-processors/buildroot.git
(branch: master)
There are build errors after choosing little-endian ARM from
"make menuconfig"
[2] https://github.com/buildroot/buildroot
(branch: master)
The build is successful, but the kernel can't be built because
of the following errors:
# make ARCH=arc CROSS_COMPILE=arc-linux- axs103_smp_defconfig
# make -j 40
:
LD vmlinux.o
arc-linux-ld: error: attempting to link /home/gavin/sandbox/buildroot/buildroot.arc/output/host/lib
/gcc/arc-buildroot-linux-uclibc/10.2.0/libgcc.a(_muldi3.o) with a binary vmlinux.o of different
architecture
Thanks,
Gavin
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2021-08-13 19:43 ` [PATCH v6 00/12] mm/debug_vm_pgtable: Enhancements Vineet Gupta
2021-08-14 2:57 ` Gavin Shan
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