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authorAlexandre Ghiti <alex@ghiti.fr>2021-02-08 14:30:16 -0500
committerPalmer Dabbelt <palmerdabbelt@google.com>2021-02-22 18:45:12 -0800
commitd127c19c7bea6150a247ffcd529c9a176877e422 (patch)
treea6139522f0e683fd3bc8e346c87f820cc0a1bfa2 /arch/riscv
parent9484e2aef45bbc27cd23519917f27031e2857a6f (diff)
downloadlinux-d127c19c7bea6150a247ffcd529c9a176877e422.tar.gz
riscv: Improve kasan population function
Current population code populates a whole page table without taking care of what could have been already allocated and without taking into account possible index in page table, assuming the virtual address to map is always aligned on the page table size, which, for example, won't be the case when the kernel will get pushed to the end of the address space. Address those problems by rewriting the kasan population function, splitting it into subfunctions for each different page table level. Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Diffstat (limited to 'arch/riscv')
-rw-r--r--arch/riscv/mm/kasan_init.c91
1 files changed, 63 insertions, 28 deletions
diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index 8f23799fcbe6..a97df4fdce09 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -60,37 +60,72 @@ asmlinkage void __init kasan_early_init(void)
local_flush_tlb_all();
}
-static void __init populate(void *start, void *end)
+static void kasan_populate_pte(pmd_t *pmd, unsigned long vaddr, unsigned long end)
+{
+ phys_addr_t phys_addr;
+ pte_t *ptep, *base_pte;
+
+ if (pmd_none(*pmd))
+ base_pte = memblock_alloc(PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE);
+ else
+ base_pte = (pte_t *)pmd_page_vaddr(*pmd);
+
+ ptep = base_pte + pte_index(vaddr);
+
+ do {
+ if (pte_none(*ptep)) {
+ phys_addr = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
+ set_pte(ptep, pfn_pte(PFN_DOWN(phys_addr), PAGE_KERNEL));
+ }
+ } while (ptep++, vaddr += PAGE_SIZE, vaddr != end);
+
+ set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(base_pte)), PAGE_TABLE));
+}
+
+static void kasan_populate_pmd(pgd_t *pgd, unsigned long vaddr, unsigned long end)
+{
+ phys_addr_t phys_addr;
+ pmd_t *pmdp, *base_pmd;
+ unsigned long next;
+
+ base_pmd = (pmd_t *)pgd_page_vaddr(*pgd);
+ if (base_pmd == lm_alias(kasan_early_shadow_pmd))
+ base_pmd = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
+
+ pmdp = base_pmd + pmd_index(vaddr);
+
+ do {
+ next = pmd_addr_end(vaddr, end);
+ kasan_populate_pte(pmdp, vaddr, next);
+ } while (pmdp++, vaddr = next, vaddr != end);
+
+ /*
+ * Wait for the whole PGD to be populated before setting the PGD in
+ * the page table, otherwise, if we did set the PGD before populating
+ * it entirely, memblock could allocate a page at a physical address
+ * where KASAN is not populated yet and then we'd get a page fault.
+ */
+ set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(base_pmd)), PAGE_TABLE));
+}
+
+static void kasan_populate_pgd(unsigned long vaddr, unsigned long end)
+{
+ phys_addr_t phys_addr;
+ pgd_t *pgdp = pgd_offset_k(vaddr);
+ unsigned long next;
+
+ do {
+ next = pgd_addr_end(vaddr, end);
+ kasan_populate_pmd(pgdp, vaddr, next);
+ } while (pgdp++, vaddr = next, vaddr != end);
+}
+
+static void __init kasan_populate(void *start, void *end)
{
- unsigned long i, offset;
unsigned long vaddr = (unsigned long)start & PAGE_MASK;
unsigned long vend = PAGE_ALIGN((unsigned long)end);
- unsigned long n_pages = (vend - vaddr) / PAGE_SIZE;
- unsigned long n_ptes =
- ((n_pages + PTRS_PER_PTE) & -PTRS_PER_PTE) / PTRS_PER_PTE;
- unsigned long n_pmds =
- ((n_ptes + PTRS_PER_PMD) & -PTRS_PER_PMD) / PTRS_PER_PMD;
-
- pte_t *pte =
- memblock_alloc(n_ptes * PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE);
- pmd_t *pmd =
- memblock_alloc(n_pmds * PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
- pgd_t *pgd = pgd_offset_k(vaddr);
-
- for (i = 0; i < n_pages; i++) {
- phys_addr_t phys = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
- set_pte(&pte[i], pfn_pte(PHYS_PFN(phys), PAGE_KERNEL));
- }
-
- for (i = 0, offset = 0; i < n_ptes; i++, offset += PTRS_PER_PTE)
- set_pmd(&pmd[i],
- pfn_pmd(PFN_DOWN(__pa(&pte[offset])),
- __pgprot(_PAGE_TABLE)));
- for (i = 0, offset = 0; i < n_pmds; i++, offset += PTRS_PER_PMD)
- set_pgd(&pgd[i],
- pfn_pgd(PFN_DOWN(__pa(&pmd[offset])),
- __pgprot(_PAGE_TABLE)));
+ kasan_populate_pgd(vaddr, vend);
local_flush_tlb_all();
memset(start, KASAN_SHADOW_INIT, end - start);
@@ -154,7 +189,7 @@ void __init kasan_init(void)
if (start >= end)
break;
- populate(kasan_mem_to_shadow(start), kasan_mem_to_shadow(end));
+ kasan_populate(kasan_mem_to_shadow(start), kasan_mem_to_shadow(end));
};
for (i = 0; i < PTRS_PER_PTE; i++)