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

From: Daniel Axtens <[email-masked]>
Date: Fri, 29 Mar 2019 10:41:26 +1100

Hi Christophe,

> Daniel,
>
> This patch applies on top of my series.
>
> With this patch, I've managed to enable KASAN without the changes you 
> proposed on the KASAN core. This allows a full support of KASAN, ie not 
> limited to KASAN_MINIMAL.
>
> There is still some details to address, but it boots OK on qemu-e500.
>
> Can you have a try and tell me if it works on your side too ?
>
> It will likely fail for modules at the time being as I did nothing about it.
>
> Tell me if you continue working on it. I don't plan to spend more time 
> on it for the time being.

Thanks!! I will have a look - I've been trying to do something on 3s
Radix and was hoping to apply lessons learned from that to the 3e case.
So it may take a little while but I will eventually get back to this.

Regards,
Daniel
>
> Like I did on PPC32, it would be good to create an early_64.c file and 
> move into it the few functions from setup_64.c and paca.c that are 
> called before feature_fixups are done, in order to not disable KASAN on 
> the entire paca.c and setup_64.c
>
> I guess we could reduce a bit the size of the IOREMAP_AREA and put KASAN 
> on top of it instead of using VMEMMAP space, allthough I don't have a 
> clean view of how it would cooperate with VMEMMMAP if we keep it enabled.
>
> I've not been able to identify what is the largest size of the linear 
> mapping (ie the 0xc000000000000000 region).
>
> Christophe
>
> Le 28/03/2019 à 15:21, Christophe Leroy a écrit :
>> 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 <[email-masked]>
>> Signed-off-by: Christophe Leroy <[email-masked]>
>> ---
>>   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);
>> +}
>>