From: liuwenliang@huawei.com (Liuwenliang (Abbott Liu))
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 01/11] Initialize the mapping of KASan shadow memory
Date: Sat, 24 Feb 2018 14:28:26 +0000 [thread overview]
Message-ID: <B8AC3E80E903784988AB3003E3E97330C0072EF7@dggemm510-mbs.china.huawei.com> (raw)
In-Reply-To: <20171019110921.GS20805@n2100.armlinux.org.uk>
On Oct 19, 2017 at 19:09, Russell King - ARM Linux [mailto:linux at armlinux.org.uk] wrote:
>On Wed, Oct 11, 2017 at 04:22:17PM +0800, Abbott Liu wrote:
>> +#else
>> +#define pud_populate(mm,pmd,pte) do { } while (0)
>> +#endif
>
>Please explain this change - we don't have a "pud" as far as the rest of
>the Linux MM layer is concerned, so why do we need it for kasan?
>
>I suspect it comes from the way we wrap up the page tables - where ARM
>does it one way (because it has to) vs the subsequently merged method
>which is completely upside down to what ARMs doing, and therefore is
>totally incompatible and impossible to fit in with our way.
We will use pud_polulate in kasan_populate_zero_shadow function.
....
>> obj-$(CONFIG_CACHE_TAUROS2) += cache-tauros2.o
>> +
>> +KASAN_SANITIZE_kasan_init.o := n
>> +obj-$(CONFIG_KASAN) += kasan_init.o
>
>Why is this placed in the middle of the cache object listing?
Sorry, I will place this at the end of the arch/arm/mm/Makefile.
>> +
>> +
>> obj-$(CONFIG_CACHE_UNIPHIER) += cache-uniphier.o
...
>> +pgd_t * __meminit kasan_pgd_populate(unsigned long addr, int node)
>> +{
>> + pgd_t *pgd = pgd_offset_k(addr);
>> + if (pgd_none(*pgd)) {
>> + void *p = kasan_alloc_block(PAGE_SIZE, node);
>> + if (!p)
>> + return NULL;
>> + pgd_populate(&init_mm, pgd, p);
>> + }
>> + return pgd;
>> +}
>This all looks wrong - you are aware that on non-LPAE platforms, there
>is only a _two_ level page table - the top level page table is 16K in
>size, and each _individual_ lower level page table is actually 1024
>bytes, but we do some special handling in the kernel to combine two
>together. It looks to me that you allocate memory for each Linux-
>abstracted page table level whether the hardware needs it or not.
You are right. If non-LPAE platform check if(pgd_none(*pgd)) true,
void *p = kasan_alloc_block(PAGE_SIZE, node) alloc space is not enough.
But the the function kasan_pgd_populate only used in :
Kasan_init-> create_mapping-> kasan_pgd_populate , so when non-LPAE platform
the if (pgd_none(*pgd)) always false.
But I also think change those code is much better :
if (IS_ENABLED(CONFIG_ARM_LPAE)) {
p = kasan_alloc_block(PAGE_SIZE, node);
} else {
/* non-LPAE need 16K for first level pagetabe*/
p = kasan_alloc_block(PAGE_SIZE*4, node);
}
>Is there any reason why the pre-existing "create_mapping()" function
>can't be used, and you've had to rewrite that code here?
Two reason:
1) Here create_mapping can dynamic alloc phys memory space for mapping to virtual space
Which from start to end, but the create_mapping in arch/arm/mm/mmu.c can't.
2) for LPAE, create_mapping need alloc pgd which we need use virtual space below 0xc0000000,
here create_mapping can alloc pgd, but create_mapping in arch/arm/mm/mmu.c can't.
>> +
>> +static int __init create_mapping(unsigned long start, unsigned long end, int node)
>> +{
>> + unsigned long addr = start;
>> + pgd_t *pgd;
>> + pud_t *pud;
>> + pmd_t *pmd;
>> + pte_t *pte;
>
>A blank line would help between the auto variables and the code of the
>function.
Ok, I will add blank line in new version.
>> + pr_info("populating shadow for %lx, %lx\n", start, end);
>
>Blank line here too please.
Ok, I will add blank line in new version.
>> + for (; addr < end; addr += PAGE_SIZE) {
>> + pgd = kasan_pgd_populate(addr, node);
>> + if (!pgd)
>> + return -ENOMEM;
...
>> +void __init kasan_init(void)
>> +{
>> + struct memblock_region *reg;
>> + u64 orig_ttbr0;
>> +
>> + orig_ttbr0 = cpu_get_ttbr(0);
>> +
>> +#ifdef CONFIG_ARM_LPAE
>> + memcpy(tmp_pmd_table, pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_START)), sizeof(tmp_pmd_table));
>> + memcpy(tmp_page_table, swapper_pg_dir, sizeof(tmp_page_table));
>> + set_pgd(&tmp_page_table[pgd_index(KASAN_SHADOW_START)], __pgd(__pa(tmp_pmd_table) | PMD_TYPE_TABLE | L_PGD_SWAPPER));
>> + cpu_set_ttbr0(__pa(tmp_page_table));
>> +#else
>> + memcpy(tmp_page_table, swapper_pg_dir, sizeof(tmp_page_table));
>> + cpu_set_ttbr0(__pa(tmp_page_table));
>> +#endif
>> + flush_cache_all();
>> + local_flush_bp_all();
>> + local_flush_tlb_all();
>What are you trying to achieve with all this complexity? Some comments
>might be useful, especially for those of us who don't know the internals
>of kasan.
OK, I will add some comments in kasan_init function in new version.
...
>> + for_each_memblock(memory, reg) {
>> + void *start = __va(reg->base);
>> + void *end = __va(reg->base + reg->size);
>
>Isn't this going to complain if the translation macro debugging is enabled?
Sorry, I don't what is the translation macro. Can you tell me.
next prev parent reply other threads:[~2018-02-24 14:28 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-11 8:22 [PATCH 00/11] KASan for arm Abbott Liu
2017-10-11 8:22 ` [PATCH 01/11] Initialize the mapping of KASan shadow memory Abbott Liu
2017-10-11 19:39 ` Florian Fainelli
2017-10-11 21:41 ` Russell King - ARM Linux
2017-10-17 13:28 ` Liuwenliang (Lamb)
2017-10-11 23:42 ` Dmitry Osipenko
2017-10-19 6:52 ` Liuwenliang (Lamb)
2017-10-19 12:01 ` Russell King - ARM Linux
2018-02-26 13:09 ` 答复: " Liuwenliang (Abbott Liu)
2017-10-12 7:58 ` Marc Zyngier
2017-11-09 7:46 ` Liuwenliang (Abbott Liu)
2017-11-09 10:10 ` Marc Zyngier
2017-11-15 10:20 ` Liuwenliang (Abbott Liu)
2017-11-15 10:35 ` Marc Zyngier
2017-11-15 13:16 ` Liuwenliang (Abbott Liu)
2017-11-15 13:54 ` Marc Zyngier
2017-11-16 3:07 ` Liuwenliang (Abbott Liu)
2017-11-16 9:54 ` Marc Zyngier
2017-11-16 14:24 ` Liuwenliang (Abbott Liu)
2017-11-16 14:40 ` Marc Zyngier
2017-11-17 1:39 ` 答复: " Liuwenliang (Abbott Liu)
2017-11-17 7:18 ` Liuwenliang (Abbott Liu)
2017-11-17 7:35 ` Christoffer Dall
2017-11-18 10:40 ` Liuwenliang (Abbott Liu)
2017-11-18 13:48 ` Marc Zyngier
2017-11-21 7:59 ` 答复: " Liuwenliang (Abbott Liu)
2017-11-21 9:40 ` Russell King - ARM Linux
2017-11-21 9:46 ` Marc Zyngier
2017-11-21 12:29 ` Mark Rutland
2017-11-22 12:56 ` Liuwenliang (Abbott Liu)
2017-11-22 13:06 ` Marc Zyngier
2017-11-23 1:54 ` Liuwenliang (Abbott Liu)
2017-11-23 15:22 ` Russell King - ARM Linux
2017-11-27 1:23 ` Liuwenliang (Abbott Liu)
2017-11-23 15:31 ` Mark Rutland
2017-11-27 1:26 ` 答复: " Liuwenliang (Abbott Liu)
2017-10-19 11:09 ` Russell King - ARM Linux
2018-02-24 14:28 ` Liuwenliang (Abbott Liu) [this message]
2017-10-11 8:22 ` [PATCH 02/11] replace memory function Abbott Liu
2017-10-19 12:05 ` Russell King - ARM Linux
2017-10-22 12:42 ` 答复: " Liuwenliang (Lamb)
2017-10-11 8:22 ` [PATCH 03/11] arm: Kconfig: enable KASan Abbott Liu
2017-10-11 19:15 ` Florian Fainelli
2017-10-19 12:34 ` Russell King - ARM Linux
2017-10-22 12:27 ` Liuwenliang (Lamb)
2017-10-11 8:22 ` [PATCH 04/11] Define the virtual space of KASan's shadow region Abbott Liu
2017-10-14 11:41 ` kbuild test robot
2017-10-16 11:42 ` Liuwenliang (Lamb)
2017-10-16 12:14 ` Ard Biesheuvel
2017-10-17 11:27 ` Liuwenliang (Lamb)
2017-10-17 11:52 ` Ard Biesheuvel
2017-10-17 13:02 ` Liuwenliang (Lamb)
2017-10-19 12:43 ` Russell King - ARM Linux
2017-10-22 12:12 ` Liuwenliang (Lamb)
2017-10-19 12:41 ` Russell King - ARM Linux
2017-10-19 12:40 ` Russell King - ARM Linux
2017-10-11 8:22 ` [PATCH 05/11] Disable kasan's instrumentation Abbott Liu
2017-10-11 19:16 ` Florian Fainelli
2017-10-19 12:47 ` Russell King - ARM Linux
2017-11-15 10:19 ` Liuwenliang (Abbott Liu)
2017-10-11 8:22 ` [PATCH 06/11] change memory_is_poisoned_16 for aligned error Abbott Liu
2017-10-11 23:23 ` Andrew Morton
2017-10-12 7:16 ` Dmitry Vyukov
2017-10-12 11:27 ` Liuwenliang (Lamb)
2017-10-19 12:51 ` Russell King - ARM Linux
2017-12-05 14:19 ` Liuwenliang (Abbott Liu)
2017-12-05 17:08 ` Ard Biesheuvel
2017-10-11 8:22 ` [PATCH 07/11] Avoid cleaning the KASan shadow area's mapping table Abbott Liu
2017-10-11 8:22 ` [PATCH 08/11] Add support arm LPAE Abbott Liu
2017-10-11 8:22 ` [PATCH 09/11] Don't need to map the shadow of KASan's shadow memory Abbott Liu
2017-10-19 12:55 ` Russell King - ARM Linux
2017-10-22 12:31 ` Liuwenliang (Lamb)
2017-10-11 8:22 ` [PATCH 10/11] Change mapping of kasan_zero_page int readonly Abbott Liu
2017-10-11 19:19 ` Florian Fainelli
2017-10-11 8:22 ` [PATCH 11/11] Add KASan layout Abbott Liu
2017-10-11 19:13 ` [PATCH 00/11] KASan for arm Florian Fainelli
2017-10-11 19:50 ` Florian Fainelli
[not found] ` <44c86924-930b-3eff-55b8-b02c9060ebe3@gmail.com>
2017-10-11 22:10 ` Laura Abbott
2017-10-11 22:58 ` Russell King - ARM Linux
2017-10-17 12:41 ` Liuwenliang (Lamb)
2017-10-12 4:55 ` Liuwenliang (Lamb)
2017-10-12 7:38 ` Arnd Bergmann
2017-10-17 1:04 ` 答复: " Liuwenliang (Lamb)
2018-02-13 18:40 ` Florian Fainelli
2018-02-23 2:10 ` Liuwenliang (Abbott Liu)
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