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Subject[RFC PATCH] powerpc/book3e: KASAN Full support for 64bit
Date
The KASAN shadow area is mapped into vmemmap space:
0x8000 0400 0000 0000 to 0x8000 0600 0000 0000.
For this vmemmap has to be disabled.

Cc: Daniel Axtens <dja@axtens.net>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/Kconfig.debug | 3 +-
arch/powerpc/include/asm/kasan.h | 11 +++
arch/powerpc/kernel/Makefile | 2 +
arch/powerpc/kernel/head_64.S | 3 +
arch/powerpc/kernel/setup_64.c | 20 +++---
arch/powerpc/mm/kasan/Makefile | 1 +
arch/powerpc/mm/kasan/kasan_init_64.c | 129 ++++++++++++++++++++++++++++++++++
8 files changed, 159 insertions(+), 11 deletions(-)
create mode 100644 arch/powerpc/mm/kasan/kasan_init_64.c

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 1a2fb50126b2..e0b7c45e4dc7 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -174,6 +174,7 @@ config PPC
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_KASAN if PPC32
+ select HAVE_ARCH_KASAN if PPC_BOOK3E_64 && !SPARSEMEM_VMEMMAP
select HAVE_ARCH_KGDB
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index 61febbbdd02b..b4140dd6b4e4 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -370,4 +370,5 @@ config PPC_FAST_ENDIAN_SWITCH
config KASAN_SHADOW_OFFSET
hex
depends on KASAN
- default 0xe0000000
+ default 0xe0000000 if PPC32
+ default 0x6800040000000000 if PPC64
diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h
index 296e51c2f066..756b3d58f921 100644
--- a/arch/powerpc/include/asm/kasan.h
+++ b/arch/powerpc/include/asm/kasan.h
@@ -23,10 +23,21 @@

#define KASAN_SHADOW_OFFSET ASM_CONST(CONFIG_KASAN_SHADOW_OFFSET)

+#ifdef CONFIG_PPC32
#define KASAN_SHADOW_END 0UL

#define KASAN_SHADOW_SIZE (KASAN_SHADOW_END - KASAN_SHADOW_START)

+#else
+
+#include <asm/pgtable.h>
+
+#define KASAN_SHADOW_SIZE (KERN_VIRT_SIZE >> KASAN_SHADOW_SCALE_SHIFT)
+
+#define KASAN_SHADOW_END (KASAN_SHADOW_START + KASAN_SHADOW_SIZE)
+
+#endif /* CONFIG_PPC32 */
+
#ifdef CONFIG_KASAN
void kasan_early_init(void);
void kasan_mmu_init(void);
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 0ea6c4aa3a20..7f232c06f11d 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -35,6 +35,8 @@ KASAN_SANITIZE_early_32.o := n
KASAN_SANITIZE_cputable.o := n
KASAN_SANITIZE_prom_init.o := n
KASAN_SANITIZE_btext.o := n
+KASAN_SANITIZE_paca.o := n
+KASAN_SANITIZE_setup_64.o := n

ifdef CONFIG_KASAN
CFLAGS_early_32.o += -DDISABLE_BRANCH_PROFILING
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 3fad8d499767..80fbd8024fb2 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -966,6 +966,9 @@ start_here_multiplatform:
* and SLB setup before we turn on relocation.
*/

+#ifdef CONFIG_KASAN
+ bl kasan_early_init
+#endif
/* Restore parameters passed from prom_init/kexec */
mr r3,r31
bl early_setup /* also sets r13 and SPRG_PACA */
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index ba404dd9ce1d..d2bf860dd966 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -311,6 +311,16 @@ void __init early_setup(unsigned long dt_ptr)
DBG(" -> early_setup(), dt_ptr: 0x%lx\n", dt_ptr);

/*
+ * Configure exception handlers. This include setting up trampolines
+ * if needed, setting exception endian mode, etc...
+ */
+ configure_exceptions();
+
+ /* Apply all the dynamic patching */
+ apply_feature_fixups();
+ setup_feature_keys();
+
+ /*
* Do early initialization using the flattened device
* tree, such as retrieving the physical memory map or
* calculating/retrieving the hash table size.
@@ -325,16 +335,6 @@ void __init early_setup(unsigned long dt_ptr)
setup_paca(paca_ptrs[boot_cpuid]);
fixup_boot_paca();

- /*
- * Configure exception handlers. This include setting up trampolines
- * if needed, setting exception endian mode, etc...
- */
- configure_exceptions();
-
- /* Apply all the dynamic patching */
- apply_feature_fixups();
- setup_feature_keys();
-
/* Initialize the hash table or TLB handling */
early_init_mmu();

diff --git a/arch/powerpc/mm/kasan/Makefile b/arch/powerpc/mm/kasan/Makefile
index 6577897673dd..0bfbe3892808 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_PPC64) += kasan_init_64.o
diff --git a/arch/powerpc/mm/kasan/kasan_init_64.c b/arch/powerpc/mm/kasan/kasan_init_64.c
new file mode 100644
index 000000000000..7fd71b8e883b
--- /dev/null
+++ b/arch/powerpc/mm/kasan/kasan_init_64.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define DISABLE_BRANCH_PROFILING
+
+#include <linux/kasan.h>
+#include <linux/printk.h>
+#include <linux/memblock.h>
+#include <linux/sched/task.h>
+#include <asm/pgalloc.h>
+
+static void __init kasan_populate_pte(pte_t *ptep, pgprot_t prot)
+{
+ unsigned long va = (unsigned long)kasan_early_shadow_page;
+ phys_addr_t pa = __pa(kasan_early_shadow_page);
+ int i;
+
+ for (i = 0; i < PTRS_PER_PTE; i++, ptep++)
+ __set_pte_at(&init_mm, va, ptep, pfn_pte(PHYS_PFN(pa), prot), 0);
+}
+
+static void __init kasan_populate_pmd(pmd_t *pmdp)
+{
+ int i;
+
+ for (i = 0; i < PTRS_PER_PMD; i++)
+ pmd_populate_kernel(&init_mm, pmdp + i, kasan_early_shadow_pte);
+}
+
+static void __init kasan_populate_pud(pud_t *pudp)
+{
+ int i;
+
+ for (i = 0; i < PTRS_PER_PUD; i++)
+ pud_populate(&init_mm, pudp + i, kasan_early_shadow_pmd);
+}
+
+static void __init *kasan_alloc_pgtable(unsigned long size)
+{
+ void *ptr = memblock_alloc_try_nid(size, size, MEMBLOCK_LOW_LIMIT,
+ __pa(MAX_DMA_ADDRESS), NUMA_NO_NODE);
+
+ if (!ptr)
+ panic("%s: Failed to allocate %lu bytes align=0x%lx max_addr=%lx\n",
+ __func__, size, size, __pa(MAX_DMA_ADDRESS));
+
+ return ptr;
+}
+
+static int __init kasan_map_page(unsigned long va, unsigned long pa, pgprot_t prot)
+{
+ pgd_t *pgdp = pgd_offset_k(va);
+ pud_t *pudp;
+ pmd_t *pmdp;
+ pte_t *ptep;
+
+ if (pgd_none(*pgdp) || (void *)pgd_page_vaddr(*pgdp) == kasan_early_shadow_pud) {
+ pudp = kasan_alloc_pgtable(PUD_TABLE_SIZE);
+ kasan_populate_pud(pudp);
+ pgd_populate(&init_mm, pgdp, pudp);
+ }
+ pudp = pud_offset(pgdp, va);
+ if (pud_none(*pudp) || (void *)pud_page_vaddr(*pudp) == kasan_early_shadow_pmd) {
+ pmdp = kasan_alloc_pgtable(PMD_TABLE_SIZE);
+ kasan_populate_pmd(pmdp);
+ pud_populate(&init_mm, pudp, pmdp);
+ }
+ pmdp = pmd_offset(pudp, va);
+ if (!pmd_present(*pmdp) || (void *)pmd_page_vaddr(*pmdp) == kasan_early_shadow_pte) {
+ ptep = kasan_alloc_pgtable(PTE_TABLE_SIZE);
+ kasan_populate_pte(ptep, PAGE_KERNEL);
+ pmd_populate_kernel(&init_mm, pmdp, ptep);
+ }
+ ptep = pte_offset_kernel(pmdp, va);
+
+ __set_pte_at(&init_mm, va, ptep, pfn_pte(pa >> PAGE_SHIFT, prot), 0);
+
+ return 0;
+}
+
+static void __init kasan_init_region(struct memblock_region *reg)
+{
+ void *start = __va(reg->base);
+ void *end = __va(reg->base + reg->size);
+ unsigned long k_start, k_end, k_cur;
+
+ if (start >= end)
+ return;
+
+ k_start = (unsigned long)kasan_mem_to_shadow(start);
+ k_end = (unsigned long)kasan_mem_to_shadow(end);
+
+ for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE) {
+ void *va = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+
+ kasan_map_page(k_cur, __pa(va), PAGE_KERNEL);
+ }
+ flush_tlb_kernel_range(k_start, k_end);
+}
+
+void __init kasan_init(void)
+{
+ struct memblock_region *reg;
+
+ for_each_memblock(memory, reg)
+ kasan_init_region(reg);
+
+ /* It's too early to use clear_page() ! */
+ memset(kasan_early_shadow_page, 0, sizeof(kasan_early_shadow_page));
+
+ /* Enable error messages */
+ init_task.kasan_depth = 0;
+ pr_info("KASAN init done\n");
+}
+
+/* The early shadow maps everything to a single page of zeroes */
+asmlinkage void __init kasan_early_init(void)
+{
+ unsigned long addr = KASAN_SHADOW_START;
+ unsigned long end = KASAN_SHADOW_END;
+ pgd_t *pgdp = pgd_offset_k(addr);
+
+ kasan_populate_pte(kasan_early_shadow_pte, PAGE_KERNEL);
+ kasan_populate_pmd(kasan_early_shadow_pmd);
+ kasan_populate_pud(kasan_early_shadow_pud);
+
+ do {
+ pgd_populate(&init_mm, pgdp, kasan_early_shadow_pud);
+ } while (pgdp++, addr = pgd_addr_end(addr, end), addr != end);
+}
--
2.13.3
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