Christophe Leroy <christophe.le...@c-s.fr> writes:
> Le 07/08/2019 à 01:38, Daniel Axtens a écrit :
>> powerpc supports several different MMUs. In particular, book3s
>> machines support both a hash-table based MMU and a radix MMU.
>> These MMUs support different numbers of entries per directory
>> level: the PTES_PER_* defines evaluate to variables, not constants.
>> This leads to complier errors as global variables must have constant
>> sizes.
>>
>> Allow architectures to manage their own early shadow variables so we
>> can work around this on powerpc.
>
> This seems rather strange to move the early shadow tables out of
> mm/kasan/init.c allthough they are used there still.
>
> What about doing for all what is already done for
> kasan_early_shadow_p4d[], in extenso define constant max sizes
> MAX_PTRS_PER_PTE, MAX_PTRS_PER_PMD and MAX_PTRS_PER_PUD ?
I have added this. I haven't tried the ifndef magic, I've just defined
the constant for all arches that implement KASAN.
Regards,
Daniel
>
> With a set of the following, it would remain transparent for other arches.
> #ifndef MAX_PTRS_PER_PXX
> #define MAX_PTRS_PER_PXX PTRS_PER_PXX
> #endif
>
> Then you would just need to do the following for Radix:
>
> #define MAX_PTRS_PER_PTE (1 << RADIX_PTE_INDEX_SIZE)
> #define MAX_PTRS_PER_PMD (1 << RADIX_PMD_INDEX_SIZE)
> #define MAX_PTRS_PER_PUD (1 << RADIX_PUD_INDEX_SIZE)
>
>
> For the kasan_early_shadow_page[], I don't think we have variable
> PAGE_SIZE, have we ?
>
> Christophe
>
>
>>
>> Signed-off-by: Daniel Axtens <d...@axtens.net>
>>
>> ---
>> Changes from RFC:
>>
>> - To make checkpatch happy, move ARCH_HAS_KASAN_EARLY_SHADOW from
>> a random #define to a config option selected when building for
>> ppc64 book3s
>> ---
>> include/linux/kasan.h | 2 ++
>> lib/Kconfig.kasan | 3 +++
>> mm/kasan/init.c | 10 ++++++++++
>> 3 files changed, 15 insertions(+)
>>
>> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
>> index ec81113fcee4..15933da52a3e 100644
>> --- a/include/linux/kasan.h
>> +++ b/include/linux/kasan.h
>> @@ -14,11 +14,13 @@ struct task_struct;
>> #include <asm/kasan.h>
>> #include <asm/pgtable.h>
>>
>> +#ifndef CONFIG_ARCH_HAS_KASAN_EARLY_SHADOW
>> extern unsigned char kasan_early_shadow_page[PAGE_SIZE];
>> extern pte_t kasan_early_shadow_pte[PTRS_PER_PTE];
>> extern pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD];
>> extern pud_t kasan_early_shadow_pud[PTRS_PER_PUD];
>> extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D];
>> +#endif
>>
>> int kasan_populate_early_shadow(const void *shadow_start,
>> const void *shadow_end);
>> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
>> index a320dc2e9317..0621a0129c04 100644
>> --- a/lib/Kconfig.kasan
>> +++ b/lib/Kconfig.kasan
>> @@ -9,6 +9,9 @@ config HAVE_ARCH_KASAN_SW_TAGS
>> config HAVE_ARCH_KASAN_VMALLOC
>> bool
>>
>> +config ARCH_HAS_KASAN_EARLY_SHADOW
>> + bool
>> +
>> config CC_HAS_KASAN_GENERIC
>> def_bool $(cc-option, -fsanitize=kernel-address)
>>
>> diff --git a/mm/kasan/init.c b/mm/kasan/init.c
>> index ce45c491ebcd..7ef2b87a7988 100644
>> --- a/mm/kasan/init.c
>> +++ b/mm/kasan/init.c
>> @@ -31,10 +31,14 @@
>> * - Latter it reused it as zero shadow to cover large ranges of memory
>> * that allowed to access, but not handled by kasan (vmalloc/vmemmap
>> ...).
>> */
>> +#ifndef CONFIG_ARCH_HAS_KASAN_EARLY_SHADOW
>> unsigned char kasan_early_shadow_page[PAGE_SIZE] __page_aligned_bss;
>> +#endif
>>
>> #if CONFIG_PGTABLE_LEVELS > 4
>> +#ifndef CONFIG_ARCH_HAS_KASAN_EARLY_SHADOW
>> p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
>> +#endif
>> static inline bool kasan_p4d_table(pgd_t pgd)
>> {
>> return pgd_page(pgd) == virt_to_page(lm_alias(kasan_early_shadow_p4d));
>> @@ -46,7 +50,9 @@ static inline bool kasan_p4d_table(pgd_t pgd)
>> }
>> #endif
>> #if CONFIG_PGTABLE_LEVELS > 3
>> +#ifndef CONFIG_ARCH_HAS_KASAN_EARLY_SHADOW
>> pud_t kasan_early_shadow_pud[PTRS_PER_PUD] __page_aligned_bss;
>> +#endif
>> static inline bool kasan_pud_table(p4d_t p4d)
>> {
>> return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
>> @@ -58,7 +64,9 @@ static inline bool kasan_pud_table(p4d_t p4d)
>> }
>> #endif
>> #if CONFIG_PGTABLE_LEVELS > 2
>> +#ifndef CONFIG_ARCH_HAS_KASAN_EARLY_SHADOW
>> pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD] __page_aligned_bss;
>> +#endif
>> static inline bool kasan_pmd_table(pud_t pud)
>> {
>> return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
>> @@ -69,7 +77,9 @@ static inline bool kasan_pmd_table(pud_t pud)
>> return false;
>> }
>> #endif
>> +#ifndef CONFIG_ARCH_HAS_KASAN_EARLY_SHADOW
>> pte_t kasan_early_shadow_pte[PTRS_PER_PTE] __page_aligned_bss;
>> +#endif
>>
>> static inline bool kasan_pte_table(pmd_t pmd)
>> {
>>
