[PATCH RFC v3 18/18] powerpc: KASAN for 64bit Book3E
Christophe Leroy
christophe.leroy at c-s.fr
Wed Mar 13 19:30:53 AEDT 2019
Any, the build is clean, see
http://kisskb.ellerman.id.au/kisskb/head/3e97aba429c769bd99ccd8d6f16eda98f7d378a7/
Only s390 defconfig and powerpc randconfig failed for unrelated reasons.
Christophe
Le 13/03/2019 à 08:02, Christophe Leroy a écrit :
> Why does snowpatch reports not being able to apply it to any branch ?
>
> I built the serie on top of merge branch, but it also cleanly applies on
> next branch.
>
> Could it be because the begining of the series is names 'v10' while the
> end of it is 'RFC v3' as it comes from Daniel's RFC v2 ?
>
> Christophe
>
> Le 12/03/2019 à 23:16, Christophe Leroy a écrit :
>> From: Daniel Axtens <dja at axtens.net>
>>
>> Wire up KASAN. Only outline instrumentation is supported.
>>
>> The KASAN shadow area is mapped into vmemmap space:
>> 0x8000 0400 0000 0000 to 0x8000 0600 0000 0000.
>> To do this we require that vmemmap be disabled. (This is the default
>> in the kernel config that QorIQ provides for the machine in their
>> SDK anyway - they use flat memory.)
>>
>> Only the kernel linear mapping (0xc000...) is checked. The vmalloc and
>> ioremap areas (also in 0x800...) are all mapped to the zero page. As
>> with the Book3S hash series, this requires overriding the memory <->
>> shadow mapping.
>>
>> Also, as with both previous 64-bit series, early instrumentation is not
>> supported. It would allow us to drop the check_return_arch_not_ready()
>> hook in the KASAN core, but it's tricky to get it set up early enough:
>> we need it setup before the first call to instrumented code like
>> printk().
>> Perhaps in the future.
>>
>> Only KASAN_MINIMAL works.
>>
>> Tested on e6500. KVM, kexec and xmon have not been tested.
>>
>> The test_kasan module fires warnings as expected, except for the
>> following tests:
>>
>> - Expected/by design:
>> kasan test: memcg_accounted_kmem_cache allocate memcg accounted object
>>
>> - Due to only supporting KASAN_MINIMAL:
>> kasan test: kasan_stack_oob out-of-bounds on stack
>> kasan test: kasan_global_oob out-of-bounds global variable
>> kasan test: kasan_alloca_oob_left out-of-bounds to left on alloca
>> kasan test: kasan_alloca_oob_right out-of-bounds to right on alloca
>> kasan test: use_after_scope_test use-after-scope on int
>> kasan test: use_after_scope_test use-after-scope on array
>>
>> Thanks to those who have done the heavy lifting over the past several
>> years:
>> - Christophe's 32 bit series:
>> https://lists.ozlabs.org/pipermail/linuxppc-dev/2019-February/185379.html
>> - Aneesh's Book3S hash series: https://lwn.net/Articles/655642/
>> - Balbir's Book3S radix series:
>> https://patchwork.ozlabs.org/patch/795211/
>>
>> Cc: Christophe Leroy <christophe.leroy at c-s.fr>
>> Cc: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
>> Cc: Balbir Singh <bsingharora at gmail.com>
>> Signed-off-by: Daniel Axtens <dja at axtens.net>
>> [- Removed EXPORT_SYMBOL of the static key
>> - Fixed most checkpatch problems
>> - Replaced kasan_zero_page[] by kasan_early_shadow_page[]
>> - Reduced casting mess by using intermediate locals
>> - Fixed build failure on pmac32_defconfig]
>> Signed-off-by: Christophe Leroy <christophe.leroy at c-s.fr>
>> ---
>> arch/powerpc/Kconfig | 1 +
>> arch/powerpc/Kconfig.debug | 2 +-
>> arch/powerpc/include/asm/kasan.h | 71
>> ++++++++++++++++++++++++++++
>> arch/powerpc/mm/Makefile | 2 +
>> arch/powerpc/mm/kasan/Makefile | 1 +
>> arch/powerpc/mm/kasan/kasan_init_book3e_64.c | 50 ++++++++++++++++++++
>> 6 files changed, 126 insertions(+), 1 deletion(-)
>> create mode 100644 arch/powerpc/mm/kasan/kasan_init_book3e_64.c
>>
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index d9364368329b..51ef9fac6c5d 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..fc1f5fa7554e 100644
>> --- a/arch/powerpc/Kconfig.debug
>> +++ b/arch/powerpc/Kconfig.debug
>> @@ -369,5 +369,5 @@ config PPC_FAST_ENDIAN_SWITCH
>> config KASAN_SHADOW_OFFSET
>> hex
>> - depends on KASAN
>> + depends on KASAN && PPC32
>> default 0xe0000000
>> diff --git a/arch/powerpc/include/asm/kasan.h
>> b/arch/powerpc/include/asm/kasan.h
>> index 296e51c2f066..ae410f0e060d 100644
>> --- a/arch/powerpc/include/asm/kasan.h
>> +++ b/arch/powerpc/include/asm/kasan.h
>> @@ -21,12 +21,15 @@
>> #define KASAN_SHADOW_START (KASAN_SHADOW_OFFSET + \
>> (PAGE_OFFSET >> KASAN_SHADOW_SCALE_SHIFT))
>> +#ifdef CONFIG_PPC32
>> #define KASAN_SHADOW_OFFSET ASM_CONST(CONFIG_KASAN_SHADOW_OFFSET)
>> #define KASAN_SHADOW_END 0UL
>> #define KASAN_SHADOW_SIZE (KASAN_SHADOW_END - KASAN_SHADOW_START)
>> +#endif /* CONFIG_PPC32 */
>> +
>> #ifdef CONFIG_KASAN
>> void kasan_early_init(void);
>> void kasan_mmu_init(void);
>> @@ -36,5 +39,73 @@ static inline void kasan_init(void) { }
>> static inline void kasan_mmu_init(void) { }
>> #endif
>> +#ifdef CONFIG_PPC_BOOK3E_64
>> +#include <asm/pgtable.h>
>> +#include <linux/jump_label.h>
>> +
>> +/*
>> + * We don't put this in Kconfig as we only support KASAN_MINIMAL, and
>> + * that will be disabled if the symbol is available in Kconfig
>> + */
>> +#define KASAN_SHADOW_OFFSET ASM_CONST(0x6800040000000000)
>> +
>> +#define KASAN_SHADOW_SIZE (KERN_VIRT_SIZE >>
>> KASAN_SHADOW_SCALE_SHIFT)
>> +
>> +extern struct static_key_false powerpc_kasan_enabled_key;
>> +extern unsigned char kasan_early_shadow_page[];
>> +
>> +static inline bool kasan_arch_is_ready_book3e(void)
>> +{
>> + if (static_branch_likely(&powerpc_kasan_enabled_key))
>> + return true;
>> + return false;
>> +}
>> +#define kasan_arch_is_ready kasan_arch_is_ready_book3e
>> +
>> +static inline void *kasan_mem_to_shadow_book3e(const void *ptr)
>> +{
>> + unsigned long addr = (unsigned long)ptr;
>> +
>> + if (addr >= KERN_VIRT_START && addr < KERN_VIRT_START +
>> KERN_VIRT_SIZE)
>> + return kasan_early_shadow_page;
>> +
>> + return (void *)(addr >> KASAN_SHADOW_SCALE_SHIFT) +
>> KASAN_SHADOW_OFFSET;
>> +}
>> +#define kasan_mem_to_shadow kasan_mem_to_shadow_book3e
>> +
>> +static inline void *kasan_shadow_to_mem_book3e(const void *shadow_addr)
>> +{
>> + /*
>> + * We map the entire non-linear virtual mapping onto the zero
>> page so if
>> + * we are asked to map the zero page back just pick the beginning
>> of that
>> + * area.
>> + */
>> + if (shadow_addr >= (void *)kasan_early_shadow_page &&
>> + shadow_addr < (void *)(kasan_early_shadow_page + PAGE_SIZE))
>> + return (void *)KERN_VIRT_START;
>> +
>> + return (void *)(((unsigned long)shadow_addr -
>> KASAN_SHADOW_OFFSET) <<
>> + KASAN_SHADOW_SCALE_SHIFT);
>> +}
>> +#define kasan_shadow_to_mem kasan_shadow_to_mem_book3e
>> +
>> +static inline bool kasan_addr_has_shadow_book3e(const void *ptr)
>> +{
>> + unsigned long addr = (unsigned long)ptr;
>> +
>> + /*
>> + * We want to specifically assert that the addresses in the
>> 0x8000...
>> + * region have a shadow, otherwise they are considered by the kasan
>> + * core to be wild pointers
>> + */
>> + if (addr >= KERN_VIRT_START && addr < (KERN_VIRT_START +
>> KERN_VIRT_SIZE))
>> + return true;
>> +
>> + return (ptr >= kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
>> +}
>> +#define kasan_addr_has_shadow kasan_addr_has_shadow_book3e
>> +
>> +#endif /* CONFIG_PPC_BOOK3E_64 */
>> +
>> #endif /* __ASSEMBLY */
>> #endif
>> diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
>> index 80382a2d169b..fc49231f807c 100644
>> --- a/arch/powerpc/mm/Makefile
>> +++ b/arch/powerpc/mm/Makefile
>> @@ -8,9 +8,11 @@ ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
>> CFLAGS_REMOVE_slb.o = $(CC_FLAGS_FTRACE)
>> KASAN_SANITIZE_ppc_mmu_32.o := n
>> +KASAN_SANITIZE_fsl_booke_mmu.o := n
>> ifdef CONFIG_KASAN
>> CFLAGS_ppc_mmu_32.o += -DDISABLE_BRANCH_PROFILING
>> +CFLAGS_fsl_booke_mmu.o += -DDISABLE_BRANCH_PROFILING
>> endif
>> obj-y := fault.o mem.o pgtable.o mmap.o \
>> diff --git a/arch/powerpc/mm/kasan/Makefile
>> b/arch/powerpc/mm/kasan/Makefile
>> index 6577897673dd..f8f164ad8ade 100644
>> --- a/arch/powerpc/mm/kasan/Makefile
>> +++ b/arch/powerpc/mm/kasan/Makefile
>> @@ -3,3 +3,4 @@
>> KASAN_SANITIZE := n
>> obj-$(CONFIG_PPC32) += kasan_init_32.o
>> +obj-$(CONFIG_PPC_BOOK3E_64) += kasan_init_book3e_64.o
>> diff --git a/arch/powerpc/mm/kasan/kasan_init_book3e_64.c
>> b/arch/powerpc/mm/kasan/kasan_init_book3e_64.c
>> new file mode 100644
>> index 000000000000..f116c211d83c
>> --- /dev/null
>> +++ b/arch/powerpc/mm/kasan/kasan_init_book3e_64.c
>> @@ -0,0 +1,50 @@
>> +// 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>
>> +
>> +DEFINE_STATIC_KEY_FALSE(powerpc_kasan_enabled_key);
>> +
>> +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);
>> +
>> + map_kernel_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);
>> +
>> + /* map the zero page RO */
>> + map_kernel_page((unsigned long)kasan_early_shadow_page,
>> + __pa(kasan_early_shadow_page), PAGE_KERNEL_RO);
>> +
>> + /* Turn on checking */
>> + static_branch_inc(&powerpc_kasan_enabled_key);
>> +
>> + /* Enable error messages */
>> + init_task.kasan_depth = 0;
>> + pr_info("KASAN init done (64-bit Book3E)\n");
>> +}
>>
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