Re: [PATCH v9 3/6] kasan: define and use MAX_PTRS_PER_* for early shadow tables

[Christophe Leroy]

Le 01/12/2020 à 17:16, Daniel Axtens a écrit :

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.le...@c-s.fr>

My neww address is : christophe.le...@csgroup.eu

Suggested-by: Balbir Singh <bsinghar...@gmail.com>
Reviewed-by: Christophe Leroy <christophe.le...@c-s.fr>

Same

Reviewed-by: Balbir Singh <bsinghar...@gmail.com>
Signed-off-by: Daniel Axtens <d...@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 3df66fdf6662..893d054aad6f 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -24,10 +24,22 @@ struct kunit_kasan_expectation {
  static inline bool kasan_arch_is_ready(void)  { return true; }
  #endif

+#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 fe6be0be1f76..42bca3d27db8 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)

  {