Re: [PATCH v2 2/4] kasan: use MAX_PTRS_PER_* for early shadow

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Le 10/12/2019 à 05:47, Daniel Axtens a écrit :
This helps with powerpc support, and should have no effect on
anything else.

As explained in previous patch, this patch is based on MAX_PTRS_PER_Pxx existing for every arch using KASAN, allthought all arches but powerpc will define it as PTRS_PER_Pxx.

I think instead of forcing all arches to define that value, just define a fallback in kasan.h (or somewhere else) would help keeping the changes to the minimum, see below.


Suggested-by: Christophe Leroy <christophe.leroy@xxxxxx>
Signed-off-by: Daniel Axtens <dja@xxxxxxxxxx>
---
  include/linux/kasan.h | 6 +++---
  mm/kasan/init.c       | 6 +++---
  2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index e18fe54969e9..d2f2a4ffcb12 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -15,9 +15,9 @@ struct task_struct;
  #include <asm/pgtable.h>

Add

#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

#ifndef MAX_PTRS_PER_P4D
#define MAX_PTRS_PER_P4D PTRS_PER_P4D
#endif

With that you don't need patch 1.

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)
  {


Christophe





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