riscv/kasan: add KASAN_VMALLOC support

It references to x86/s390 architecture.

So, it doesn't map the early shadow page to cover VMALLOC space.

Prepopulate top level page table for the range that would otherwise be
empty.

lower levels are filled dynamically upon memory allocation while
booting.

Signed-off-by: Nylon Chen <nylon7@andestech.com>
Signed-off-by: Nick Hu <nickhu@andestech.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

1 files changed, 56 insertions, 1 deletions

diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c
index 12ddd1f6bf70..4b9149f963d3 100644
--- a/arch/riscv/mm/kasan_init.c
+++ b/arch/riscv/mm/kasan_init.c
@@ -9,6 +9,19 @@
 #include <linux/pgtable.h>
 #include <asm/tlbflush.h>
 #include <asm/fixmap.h>
+#include <asm/pgalloc.h>
+
+static __init void *early_alloc(size_t size, int node)
+{
+	void *ptr = memblock_alloc_try_nid(size, size,
+		__pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, node);
+
+	if (!ptr)
+		panic("%pS: Failed to allocate %zu bytes align=%zx nid=%d from=%llx\n",
+			__func__, size, size, node, (u64)__pa(MAX_DMA_ADDRESS));
+
+	return ptr;
+}
 
 extern pgd_t early_pg_dir[PTRS_PER_PGD];
 asmlinkage void __init kasan_early_init(void)
@@ -83,6 +96,40 @@ static void __init populate(void *start, void *end)
 	memset(start, 0, end - start);
 }
 
+void __init kasan_shallow_populate(void *start, void *end)
+{
+	unsigned long vaddr = (unsigned long)start & PAGE_MASK;
+	unsigned long vend = PAGE_ALIGN((unsigned long)end);
+	unsigned long pfn;
+	int index;
+	void *p;
+	pud_t *pud_dir, *pud_k;
+	pgd_t *pgd_dir, *pgd_k;
+	p4d_t *p4d_dir, *p4d_k;
+
+	while (vaddr < vend) {
+		index = pgd_index(vaddr);
+		pfn = csr_read(CSR_SATP) & SATP_PPN;
+		pgd_dir = (pgd_t *)pfn_to_virt(pfn) + index;
+		pgd_k = init_mm.pgd + index;
+		pgd_dir = pgd_offset_k(vaddr);
+		set_pgd(pgd_dir, *pgd_k);
+
+		p4d_dir = p4d_offset(pgd_dir, vaddr);
+		p4d_k  = p4d_offset(pgd_k, vaddr);
+
+		vaddr = (vaddr + PUD_SIZE) & PUD_MASK;
+		pud_dir = pud_offset(p4d_dir, vaddr);
+		pud_k = pud_offset(p4d_k, vaddr);
+
+		if (pud_present(*pud_dir)) {
+			p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
+			pud_populate(&init_mm, pud_dir, p);
+		}
+		vaddr += PAGE_SIZE;
+	}
+}
+
 void __init kasan_init(void)
 {
 	phys_addr_t _start, _end;
@@ -90,7 +137,15 @@ void __init kasan_init(void)
 
 	kasan_populate_early_shadow((void *)KASAN_SHADOW_START,
 				    (void *)kasan_mem_to_shadow((void *)
-								VMALLOC_END));
+								VMEMMAP_END));
+	if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
+		kasan_shallow_populate(
+			(void *)kasan_mem_to_shadow((void *)VMALLOC_START),
+			(void *)kasan_mem_to_shadow((void *)VMALLOC_END));
+	else
+		kasan_populate_early_shadow(
+			(void *)kasan_mem_to_shadow((void *)VMALLOC_START),
+			(void *)kasan_mem_to_shadow((void *)VMALLOC_END));
 
 	for_each_mem_range(i, &_start, &_end) {
 		void *start = (void *)_start;