From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29EE4C433DB for ; Mon, 8 Feb 2021 06:29:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFCA664E61 for ; Mon, 8 Feb 2021 06:29:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229681AbhBHG3D (ORCPT ); Mon, 8 Feb 2021 01:29:03 -0500 Received: from relay4-d.mail.gandi.net ([217.70.183.196]:44203 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229581AbhBHG3A (ORCPT ); Mon, 8 Feb 2021 01:29:00 -0500 X-Originating-IP: 82.65.183.113 Received: from [172.16.5.113] (82-65-183-113.subs.proxad.net [82.65.183.113]) (Authenticated sender: alex@ghiti.fr) by relay4-d.mail.gandi.net (Postfix) with ESMTPSA id CCB10E0007; Mon, 8 Feb 2021 06:28:13 +0000 (UTC) From: Alex Ghiti Subject: Re: [PATCH v2 1/1] riscv/kasan: add KASAN_VMALLOC support To: Palmer Dabbelt , nylon7@andestech.com Cc: aou@eecs.berkeley.edu, nickhu@andestech.com, alankao@andestech.com, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, nylon7717@gmail.com, glider@google.com, Paul Walmsley , aryabinin@virtuozzo.com, linux-riscv@lists.infradead.org, dvyukov@google.com References: Message-ID: <2b2f3038-3e27-8763-cf78-3fbbfd2100a0@ghiti.fr> Date: Mon, 8 Feb 2021 01:28:13 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Nylon, Le 1/22/21 ŕ 10:56 PM, Palmer Dabbelt a écrit : > On Fri, 15 Jan 2021 21:58:35 PST (-0800), nylon7@andestech.com wrote: >> It references to x86/s390 architecture. >> >> So, it doesn't map the early shadow page to cover VMALLOC space. >> >> Prepopulate top level page table for the range that would otherwise be >> empty. >> >> lower levels are filled dynamically upon memory allocation while >> booting. I think we can improve the changelog a bit here with something like that: "KASAN vmalloc space used to be mapped using kasan early shadow page. KASAN_VMALLOC requires the top-level of the kernel page table to be properly populated, lower levels being filled dynamically upon memory allocation at runtime." >> >> Signed-off-by: Nylon Chen >> Signed-off-by: Nick Hu >> --- >>  arch/riscv/Kconfig         |  1 + >>  arch/riscv/mm/kasan_init.c | 57 +++++++++++++++++++++++++++++++++++++- >>  2 files changed, 57 insertions(+), 1 deletion(-) >> >> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig >> index 81b76d44725d..15a2c8088bbe 100644 >> --- a/arch/riscv/Kconfig >> +++ b/arch/riscv/Kconfig >> @@ -57,6 +57,7 @@ config RISCV >>      select HAVE_ARCH_JUMP_LABEL >>      select HAVE_ARCH_JUMP_LABEL_RELATIVE >>      select HAVE_ARCH_KASAN if MMU && 64BIT >> +    select HAVE_ARCH_KASAN_VMALLOC if MMU && 64BIT >>      select HAVE_ARCH_KGDB >>      select HAVE_ARCH_KGDB_QXFER_PKT >>      select HAVE_ARCH_MMAP_RND_BITS if MMU >> diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c >> index 12ddd1f6bf70..4b9149f963d3 100644 >> --- a/arch/riscv/mm/kasan_init.c >> +++ b/arch/riscv/mm/kasan_init.c >> @@ -9,6 +9,19 @@ >>  #include >>  #include >>  #include >> +#include >> + >> +static __init void *early_alloc(size_t size, int node) >> +{ >> +    void *ptr = memblock_alloc_try_nid(size, size, >> +        __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, node); >> + >> +    if (!ptr) >> +        panic("%pS: Failed to allocate %zu bytes align=%zx nid=%d >> from=%llx\n", >> +            __func__, size, size, node, (u64)__pa(MAX_DMA_ADDRESS)); >> + >> +    return ptr; >> +} >> >>  extern pgd_t early_pg_dir[PTRS_PER_PGD]; >>  asmlinkage void __init kasan_early_init(void) >> @@ -83,6 +96,40 @@ static void __init populate(void *start, void *end) >>      memset(start, 0, end - start); >>  } >> >> +void __init kasan_shallow_populate(void *start, void *end) >> +{ >> +    unsigned long vaddr = (unsigned long)start & PAGE_MASK; >> +    unsigned long vend = PAGE_ALIGN((unsigned long)end); >> +    unsigned long pfn; >> +    int index; >> +    void *p; >> +    pud_t *pud_dir, *pud_k; >> +    pgd_t *pgd_dir, *pgd_k; >> +    p4d_t *p4d_dir, *p4d_k; >> + >> +    while (vaddr < vend) { >> +        index = pgd_index(vaddr); >> +        pfn = csr_read(CSR_SATP) & SATP_PPN; At this point in the boot process, we know that we use swapper_pg_dir so no need to read SATP. >> +        pgd_dir = (pgd_t *)pfn_to_virt(pfn) + index; Here, this pgd_dir assignment is overwritten 2 lines below, so no need for it. >> +        pgd_k = init_mm.pgd + index; >> +        pgd_dir = pgd_offset_k(vaddr); pgd_offset_k(vaddr) = init_mm.pgd + pgd_index(vaddr) so pgd_k == pgd_dir. >> +        set_pgd(pgd_dir, *pgd_k); >> + >> +        p4d_dir = p4d_offset(pgd_dir, vaddr); >> +        p4d_k  = p4d_offset(pgd_k, vaddr); >> + >> +        vaddr = (vaddr + PUD_SIZE) & PUD_MASK; Why do you increase vaddr *before* populating the first one ? And pud_addr_end does that properly: it returns the next pud address if it does not go beyond end address to map. >> +        pud_dir = pud_offset(p4d_dir, vaddr); >> +        pud_k = pud_offset(p4d_k, vaddr); >> + >> +        if (pud_present(*pud_dir)) { >> +            p = early_alloc(PAGE_SIZE, NUMA_NO_NODE); >> +            pud_populate(&init_mm, pud_dir, p); init_mm is not needed here. >> +        } >> +        vaddr += PAGE_SIZE; Why do you need to add PAGE_SIZE ? vaddr already points to the next pud. It seems like this patch tries to populate userspace page table whereas at this point in the boot process, only swapper_pg_dir is used or am I missing something ? Thanks, Alex >> +    } >> +} >> + >>  void __init kasan_init(void) >>  { >>      phys_addr_t _start, _end; >> @@ -90,7 +137,15 @@ void __init kasan_init(void) >> >>      kasan_populate_early_shadow((void *)KASAN_SHADOW_START, >>                      (void *)kasan_mem_to_shadow((void *) >> -                                VMALLOC_END)); >> +                                VMEMMAP_END)); >> +    if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) >> +        kasan_shallow_populate( >> +            (void *)kasan_mem_to_shadow((void *)VMALLOC_START), >> +            (void *)kasan_mem_to_shadow((void *)VMALLOC_END)); >> +    else >> +        kasan_populate_early_shadow( >> +            (void *)kasan_mem_to_shadow((void *)VMALLOC_START), >> +            (void *)kasan_mem_to_shadow((void *)VMALLOC_END)); >> >>      for_each_mem_range(i, &_start, &_end) { >>          void *start = (void *)_start; > > Thanks, this is on for-next. > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv