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kasan: Move generic KASAN page tables out of BSS too

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Make sure that all KASAN page tables are emitted into the .pgtbl section
(provided that the arch has one - otherwise, fall back to page aligned
BSS)

This is needed because BSS itself is no longer accessible via the linear
map on arm64.

Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: kasan-dev@googlegroups.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ard Biesheuvel 2026-06-04 17:11:54 +02:00 committed by Will Deacon
parent 9c401fa739
commit 9f7f685758
2 changed files with 9 additions and 5 deletions
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4
include/linux/linkage.h
View File

@ -39,6 +39,10 @@
#define __page_aligned_data __section(".data..page_aligned") __aligned(PAGE_SIZE)
#define __page_aligned_bss __section(".bss..page_aligned") __aligned(PAGE_SIZE)
#ifndef __bss_pgtbl
#define __bss_pgtbl __page_aligned_bss
#endif
/*
* For assembly routines.
*

10
mm/kasan/init.c
View File

@ -26,10 +26,10 @@
* - Latter it reused it as zero shadow to cover large ranges of memory
* that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
*/
unsigned char kasan_early_shadow_page[PAGE_SIZE] __page_aligned_bss;
unsigned char kasan_early_shadow_page[PAGE_SIZE] __bss_pgtbl;
#if CONFIG_PGTABLE_LEVELS > 4
p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __bss_pgtbl;
static inline bool kasan_p4d_table(pgd_t pgd)
{
return pgd_page(pgd) == virt_to_page(lm_alias(kasan_early_shadow_p4d));
@ -41,7 +41,7 @@ static inline bool kasan_p4d_table(pgd_t pgd)
}
#endif
#if CONFIG_PGTABLE_LEVELS > 3
pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD] __page_aligned_bss;
pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD] __bss_pgtbl;
static inline bool kasan_pud_table(p4d_t p4d)
{
return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
@ -53,7 +53,7 @@ static inline bool kasan_pud_table(p4d_t p4d)
}
#endif
#if CONFIG_PGTABLE_LEVELS > 2
pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD] __page_aligned_bss;
pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD] __bss_pgtbl;
static inline bool kasan_pmd_table(pud_t pud)
{
return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
@ -65,7 +65,7 @@ static inline bool kasan_pmd_table(pud_t pud)
}
#endif
pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE + PTE_HWTABLE_PTRS]
__page_aligned_bss;
__bss_pgtbl;
static inline bool kasan_pte_table(pmd_t pmd)
{