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    Subject[PATCH v7 1/4] kasan: define and use MAX_PTRS_PER_* for early shadow tables
    Date
    powerpc has a variable number of PTRS_PER_*, set at runtime based
    on the MMU that the kernel is booted under.

    This means the PTRS_PER_* are no longer constants, and therefore
    breaks the build.

    Define default MAX_PTRS_PER_*s in the same style as MAX_PTRS_PER_P4D.
    As KASAN is the only user at the moment, just define them in the kasan
    header, and have them default to PTRS_PER_* unless overridden in arch
    code.

    Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
    Suggested-by: Balbir Singh <bsingharora@gmail.com>
    Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
    Reviewed-by: Balbir Singh <bsingharora@gmail.com>
    Signed-off-by: Daniel Axtens <dja@axtens.net>
    ---
    include/linux/kasan.h | 18 +++++++++++++++---
    mm/kasan/init.c | 6 +++---
    2 files changed, 18 insertions(+), 6 deletions(-)

    diff --git a/include/linux/kasan.h b/include/linux/kasan.h
    index 5cde9e7c2664..b3a4500633f5 100644
    --- a/include/linux/kasan.h
    +++ b/include/linux/kasan.h
    @@ -14,10 +14,22 @@ struct task_struct;
    #include <asm/kasan.h>
    #include <asm/pgtable.h>

    +#ifndef MAX_PTRS_PER_PTE
    +#define MAX_PTRS_PER_PTE PTRS_PER_PTE
    +#endif
    +
    +#ifndef MAX_PTRS_PER_PMD
    +#define MAX_PTRS_PER_PMD PTRS_PER_PMD
    +#endif
    +
    +#ifndef MAX_PTRS_PER_PUD
    +#define MAX_PTRS_PER_PUD PTRS_PER_PUD
    +#endif
    +
    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 pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE];
    +extern pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD];
    +extern pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD];
    extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D];

    int kasan_populate_early_shadow(const void *shadow_start,
    diff --git a/mm/kasan/init.c b/mm/kasan/init.c
    index ce45c491ebcd..8b54a96d3b3e 100644
    --- a/mm/kasan/init.c
    +++ b/mm/kasan/init.c
    @@ -46,7 +46,7 @@ static inline bool kasan_p4d_table(pgd_t pgd)
    }
    #endif
    #if CONFIG_PGTABLE_LEVELS > 3
    -pud_t kasan_early_shadow_pud[PTRS_PER_PUD] __page_aligned_bss;
    +pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD] __page_aligned_bss;
    static inline bool kasan_pud_table(p4d_t p4d)
    {
    return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
    @@ -58,7 +58,7 @@ static inline bool kasan_pud_table(p4d_t p4d)
    }
    #endif
    #if CONFIG_PGTABLE_LEVELS > 2
    -pmd_t kasan_early_shadow_pmd[PTRS_PER_PMD] __page_aligned_bss;
    +pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD] __page_aligned_bss;
    static inline bool kasan_pmd_table(pud_t pud)
    {
    return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
    @@ -69,7 +69,7 @@ static inline bool kasan_pmd_table(pud_t pud)
    return false;
    }
    #endif
    -pte_t kasan_early_shadow_pte[PTRS_PER_PTE] __page_aligned_bss;
    +pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE] __page_aligned_bss;

    static inline bool kasan_pte_table(pmd_t pmd)
    {
    --
    2.20.1
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