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

From: Daniel Axtens
Date: Mon Jun 10 2019 - 21:26:23 EST

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Christophe Leroy <christophe.leroy@xxxxxx> writes:

> On 06/03/2019 11:50 PM, Daniel Axtens wrote:
>> Christophe Leroy <christophe.leroy@xxxxxx> writes:
>>
>>> Hi,
>>>
>>> Ok, can you share your .config ?
>>
>> Sure! This one is with kasan off as the last build I did was testing to
>> see if the code reorgisation was the cause of the issues. (it was not)
>>
>>
>>
>>
>> This was the kasan-enabled config that failed to boot:
>>
>>
>
> Same issue with your .config under QEMU:
>
> A go with gdb shows:
>
> Breakpoint 3, 0xc000000000027b6c in exc_0x700_common ()
> => 0xc000000000027b6c <exc_0x700_common+0>: f8 01 00 70 std r0,112(r1)
> (gdb) bt
> #0 0xc000000000027b6c in exc_0x700_common ()
> #1 0xc00000000136f80c in .udbg_init_memcons ()
>

Thanks for debugging this!

> Without CONFIG_PPC_EARLY_DEBUG, it boots fine for me. Can you check on
> your side ?

Yes, that works on my side.

> Deactivating KASAN for arch/powerpc/kernel/udbg.o and
> arch/powerpc/sysdev/udbg_memcons.o is not enough, we hit a call to
> strstr() in register_early_udbg_console(), and once we get rid of it (in
> the same way as in prom_init.c) the next issue is register_console() and
> I don't know what to do about that one.

Disabling early debug seems like a reasonable restriction to add.

I'll have a look at modules across this and book3s next.

Regards,
Daniel

>
> Christophe
>
>>
>>
>> Regards,
>> Daniel
>>
>>>
>>> Christophe
>>>
>>> Le 31/05/2019 Ã 03:29, Daniel Axtens a ÃcritÂ:
>>>> 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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