Re: [PATCH 4/4 v2] LoongArch: Add KFENCE support

[Enze Li <lienze@kylinos.cn>]

On Tue, Jul 25 2023 at 10:34:50 PM +0800, Jackie Liu wrote:

> 在 2023/7/25 14:14, Enze Li 写道:
>> The LoongArch architecture is quite different from other architectures.
>> When the allocating of KFENCE itself is done, it is mapped to the direct
>> mapping configuration window [1] by default on LoongArch.  It means that
>> it is not possible to use the page table mapped mode which required by
>> the KFENCE system and therefore it should be remapped to the appropriate
>> region.
>>
>> This patch adds architecture specific implementation details for KFENCE.
>> In particular, this implements the required interface in <asm/kfence.h>.
>>
>> Tested this patch by running the testcases and all passed.
>>
>> [1] https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#virtual-address-space-and-address-translation-mode
>>
>> Signed-off-by: Enze Li <lienze@kylinos.cn>
>> ---
>>   arch/loongarch/Kconfig               |  1 +
>>   arch/loongarch/include/asm/kfence.h  | 62 ++++++++++++++++++++++++++++
>>   arch/loongarch/include/asm/pgtable.h | 14 ++++++-
>>   arch/loongarch/mm/fault.c            | 22 ++++++----
>>   4 files changed, 90 insertions(+), 9 deletions(-)
>>   create mode 100644 arch/loongarch/include/asm/kfence.h
>>
>> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
>> index 70635ea3d1e4..5b63b16be49e 100644
>> --- a/arch/loongarch/Kconfig
>> +++ b/arch/loongarch/Kconfig
>> @@ -91,6 +91,7 @@ config LOONGARCH
>>   	select HAVE_ARCH_AUDITSYSCALL
>>   	select HAVE_ARCH_JUMP_LABEL
>>   	select HAVE_ARCH_JUMP_LABEL_RELATIVE
>> +	select HAVE_ARCH_KFENCE
>>   	select HAVE_ARCH_MMAP_RND_BITS if MMU
>>   	select HAVE_ARCH_SECCOMP_FILTER
>>   	select HAVE_ARCH_TRACEHOOK
>> diff --git a/arch/loongarch/include/asm/kfence.h b/arch/loongarch/include/asm/kfence.h
>> new file mode 100644
>> index 000000000000..fb39076fe4d7
>> --- /dev/null
>> +++ b/arch/loongarch/include/asm/kfence.h
>> @@ -0,0 +1,62 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * KFENCE support for LoongArch.
>> + *
>> + * Author: Enze Li <lienze@kylinos.cn>
>> + * Copyright (C) 2022-2023 KylinSoft Corporation.
>> + */
>> +
>> +#ifndef _ASM_LOONGARCH_KFENCE_H
>> +#define _ASM_LOONGARCH_KFENCE_H
>> +
>> +#include <linux/kfence.h>
>> +#include <asm/pgtable.h>
>> +#include <asm/tlb.h>
>> +
>> +static inline bool arch_kfence_init_pool(void)
>> +{
>> +	char *kfence_pool = __kfence_pool;
>> +	struct vm_struct *area;
>> +	int err;
>> +
>> +	area = __get_vm_area_caller(KFENCE_POOL_SIZE, VM_IOREMAP,
>> +				    KFENCE_AREA_START, KFENCE_AREA_END,
>> +				    __builtin_return_address(0));
>> +	if (!area)
>> +		return false;
>> +
>> +	__kfence_pool = (char *)area->addr;
>
> I think there should be something wrong here.
>
>> +	err = ioremap_page_range((unsigned long)__kfence_pool,
>> +				 (unsigned long)__kfence_pool + KFENCE_POOL_SIZE,
>> +				 virt_to_phys((void *)kfence_pool),
>> +				 PAGE_KERNEL);
>> +	if (err) {
>> +		free_vm_area(area);
>
> If err > 0, return area->addr here, It's not correct.

Hi Jackie,

Good catch!  I'll fix this issue in v3.

Cheers!
Enze