Re: [RFC PATCH] powerpc/book3e: KASAN Full support for 64bit

From: Daniel Axtens
Date: Thu May 30 2019 - 21:33:16 EST

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Hi Christophe,

I tried this on the t4240rdb and it fails to boot if KASAN is
enabled. It does boot with the patch applied but KASAN disabled, so that
narrows it down a little bit.

I need to focus on 3s first so I'll just drop 3e from my patch set for
now.

Regards,
Daniel

> 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@xxxxxxxxxx>
> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> ---
> 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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