[PATCH v2 43/45] powerpc/8xx: Implement dedicated kasan_init_region()

[Christophe Leroy]

Implement a kasan_init_region() dedicated to 8xx that
allocates KASAN regions using huge pages.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
 arch/powerpc/mm/kasan/8xx.c    | 74 ++++++++++++++++++++++++++++++++++
 arch/powerpc/mm/kasan/Makefile |  1 +
 2 files changed, 75 insertions(+)
 create mode 100644 arch/powerpc/mm/kasan/8xx.c

diff --git a/arch/powerpc/mm/kasan/8xx.c b/arch/powerpc/mm/kasan/8xx.c
new file mode 100644
index 000000000000..db4ef44af22f
--- /dev/null
+++ b/arch/powerpc/mm/kasan/8xx.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define DISABLE_BRANCH_PROFILING
+
+#include <linux/kasan.h>
+#include <linux/memblock.h>
+#include <linux/hugetlb.h>
+#include <asm/pgalloc.h>
+
+static int __init
+kasan_init_shadow_8M(unsigned long k_start, unsigned long k_end, void *block)
+{
+	pmd_t *pmd = pmd_ptr_k(k_start);
+	unsigned long k_cur, k_next;
+
+	for (k_cur = k_start; k_cur != k_end; k_cur = k_next, pmd += 2, block += SZ_8M) {
+		pte_basic_t *new;
+
+		k_next = pgd_addr_end(k_cur, k_end);
+		k_next = pgd_addr_end(k_next, k_end);
+		if ((void *)pmd_page_vaddr(*pmd) != kasan_early_shadow_pte)
+			continue;
+
+		new = memblock_alloc(sizeof(pte_basic_t), SZ_4K);
+		if (!new)
+			return -ENOMEM;
+
+		*new = pte_val(pte_mkhuge(pfn_pte(PHYS_PFN(__pa(block)), PAGE_KERNEL)));
+
+		hugepd_populate_kernel((hugepd_t *)pmd, (pte_t *)new, PAGE_SHIFT_8M);
+		hugepd_populate_kernel((hugepd_t *)pmd + 1, (pte_t *)new, PAGE_SHIFT_8M);
+	}
+	return 0;
+}
+
+int __init kasan_init_region(void *start, size_t size)
+{
+	unsigned long k_start = (unsigned long)kasan_mem_to_shadow(start);
+	unsigned long k_end = (unsigned long)kasan_mem_to_shadow(start + size);
+	unsigned long k_cur;
+	int ret;
+	void *block;
+
+	block = memblock_alloc(k_end - k_start, SZ_8M);
+	if (!block)
+		return -ENOMEM;
+
+	if (IS_ALIGNED(k_start, SZ_8M)) {
+		kasan_init_shadow_8M(k_start, ALIGN_DOWN(k_end, SZ_8M), block);
+		k_cur = ALIGN_DOWN(k_end, SZ_8M);
+		if (k_cur == k_end)
+			goto finish;
+	} else {
+		k_cur = k_start;
+	}
+
+	ret = kasan_init_shadow_page_tables(k_start, k_end);
+	if (ret)
+		return ret;
+
+	for (; k_cur < k_end; k_cur += PAGE_SIZE) {
+		pmd_t *pmd = pmd_ptr_k(k_cur);
+		void *va = block + k_cur - k_start;
+		pte_t pte = pfn_pte(PHYS_PFN(__pa(va)), PAGE_KERNEL);
+
+		if (k_cur < ALIGN_DOWN(k_end, SZ_512K))
+			pte = pte_mkhuge(pte);
+
+		__set_pte_at(&init_mm, k_cur, pte_offset_kernel(pmd, k_cur), pte, 0);
+	}
+finish:
+	flush_tlb_kernel_range(k_start, k_end);
+	return 0;
+}
diff --git a/arch/powerpc/mm/kasan/Makefile b/arch/powerpc/mm/kasan/Makefile
index 6577897673dd..440038ea79f1 100644
--- a/arch/powerpc/mm/kasan/Makefile
+++ b/arch/powerpc/mm/kasan/Makefile
@@ -3,3 +3,4 @@
 KASAN_SANITIZE := n
 
 obj-$(CONFIG_PPC32)           += kasan_init_32.o
+obj-$(CONFIG_PPC_8xx)		+= 8xx.o
-- 
2.25.0