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x86/kasan: Fix KASAN shadow region page tables

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Currently KASAN shadow region page tables created without
respect of physical offset (phys_base). This causes kernel halt
when phys_base is not zero.

So let's initialize KASAN shadow region page tables in
kasan_early_init() using __pa_nodebug() which considers
phys_base.

This patch also separates x86_64_start_kernel() from KASAN low
level details by moving kasan_map_early_shadow(init_level4_pgt)
into kasan_early_init().

Remove the comment before clear_bss() which stopped bringing
much profit to the code readability. Otherwise describing all
the new order dependencies would be too verbose.

Signed-off-by: Alexander Popov <alpopov@ptsecurity.com>
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: <stable@vger.kernel.org> # 4.0+
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1435828178-10975-3-git-send-email-a.ryabinin@samsung.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Alexander Popov
2015-07-02 12:09:34 +03:00
committed by Ingo Molnar
parent d0f77d4d04
commit 5d5aa3cfca
4 changed files with 38 additions and 42 deletions
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36
arch/x86/mm/kasan_init_64.c
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@@ -11,7 +11,19 @@
extern pgd_t early_level4_pgt[PTRS_PER_PGD];
extern struct range pfn_mapped[E820_X_MAX];
extern unsigned char kasan_zero_page[PAGE_SIZE];
static pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
static pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
static pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
/*
* This page used as early shadow. We don't use empty_zero_page
* at early stages, stack instrumentation could write some garbage
* to this page.
* Latter we reuse it as zero shadow for large ranges of memory
* that allowed to access, but not instrumented by kasan
* (vmalloc/vmemmap ...).
*/
static unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
static int __init map_range(struct range *range)
{
@@ -36,7 +48,7 @@ static void __init clear_pgds(unsigned long start,
pgd_clear(pgd_offset_k(start));
}
void __init kasan_map_early_shadow(pgd_t *pgd)
static void __init kasan_map_early_shadow(pgd_t *pgd)
{
int i;
unsigned long start = KASAN_SHADOW_START;
@@ -166,6 +178,26 @@ static struct notifier_block kasan_die_notifier = {
};
#endif
void __init kasan_early_init(void)
{
int i;
pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL;
pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
for (i = 0; i < PTRS_PER_PTE; i++)
kasan_zero_pte[i] = __pte(pte_val);
for (i = 0; i < PTRS_PER_PMD; i++)
kasan_zero_pmd[i] = __pmd(pmd_val);
for (i = 0; i < PTRS_PER_PUD; i++)
kasan_zero_pud[i] = __pud(pud_val);
kasan_map_early_shadow(early_level4_pgt);
kasan_map_early_shadow(init_level4_pgt);
}
void __init kasan_init(void)
{
int i;