riscv: mm: add missing memcpy in kasan_init

Hi Atish,

It seems that the panic is due to the missing memcpy during kasan_init.
Could you please check whether this patch is helpful?

When doing kasan_populate, the new allocated base_pud/base_p4d should
contain kasan_early_shadow_{pud, p4d}'s content. Add the missing memcpy
to avoid page fault when read/write kasan shadow region.

Tested on:
 - qemu with sv57 and CONFIG_KASAN on.
 - qemu with sv48 and CONFIG_KASAN on.

Signed-off-by: Qinglin Pan <panqinglin2020@iscas.ac.cn>
Tested-by: Atish Patra <atishp@rivosinc.com>
Fixes: 8fbdccd2b173 ("riscv: mm: Support kasan for sv57")
Link: https://lore.kernel.org/r/20221009083050.3814850-1-panqinglin2020@iscas.ac.cn
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index a22e418..e122670 100644 (file)
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -113,6 +113,8 @@ static void __init kasan_populate_pud(pgd_t *pgd,
                base_pud = pt_ops.get_pud_virt(pfn_to_phys(_pgd_pfn(*pgd)));
        } else if (pgd_none(*pgd)) {
                base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
+               memcpy(base_pud, (void *)kasan_early_shadow_pud,
+                       sizeof(pud_t) * PTRS_PER_PUD);
        } else {
                base_pud = (pud_t *)pgd_page_vaddr(*pgd);
                if (base_pud == lm_alias(kasan_early_shadow_pud)) {
@@ -173,8 +175,11 @@ static void __init kasan_populate_p4d(pgd_t *pgd,
                base_p4d = pt_ops.get_p4d_virt(pfn_to_phys(_pgd_pfn(*pgd)));
        } else {
                base_p4d = (p4d_t *)pgd_page_vaddr(*pgd);
-               if (base_p4d == lm_alias(kasan_early_shadow_p4d))
+               if (base_p4d == lm_alias(kasan_early_shadow_p4d)) {
                        base_p4d = memblock_alloc(PTRS_PER_PUD * sizeof(p4d_t), PAGE_SIZE);
+                       memcpy(base_p4d, (void *)kasan_early_shadow_p4d,
+                               sizeof(p4d_t) * PTRS_PER_P4D);
+               }
        }
 
        p4dp = base_p4d + p4d_index(vaddr);