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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 B1F61C47E49 for ; Thu, 24 Oct 2019 14:34:32 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 83EA821872 for ; Thu, 24 Oct 2019 14:34:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="usmtkjZd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 83EA821872 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Cc:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=n1zaA8K+zP2/ywEfEpN3CjkMBkLgGNwXTcrgL4XmtqM=; b=usmtkjZdvFajFXYFiUI5Zjdr0U vUaonfy6Kv9ouXwsYmqpORX4czn/McnGmWGbDbnU9z9UvtJbPzD4cMqL/tGsdmuvc8Kdoe75XTK+h dmkGH2vrDrTObFHGi4VoBitn8H4kxBEbkL1VuySZiey7E9kl67cpuCplmX73GnGakUjTPYg9GEbC6 RWRUCN8OigYvOrsfqqE2i4U/0Pm+qofMigul3NKkZyPI578WhQY7UjeWnfGvXuqyWgDruM+0Ol9tX 8uP32rT8YL33fRz5WrXPlONMeLlxyPIkb5Hx1GDC+ajrvMIidCK+2e9TbP/poWMSvjLc+n2IKU9ud gt4BhcLg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iNeC6-0001CA-Gh; Thu, 24 Oct 2019 14:34:30 +0000 Received: from [217.140.110.172] (helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iNeC3-0001Aj-BF for linux-riscv@lists.infradead.org; Thu, 24 Oct 2019 14:34:29 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3129128; Thu, 24 Oct 2019 07:34:14 -0700 (PDT) Received: from [10.1.194.43] (e112269-lin.cambridge.arm.com [10.1.194.43]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7B29F3F6C4; Thu, 24 Oct 2019 07:34:13 -0700 (PDT) Subject: Re: [PATCH 1/1] riscv: Add support to dump the kernel page tables To: Zong Li , linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, paul.walmsley@sifive.com, palmer@sifive.com References: <87a7b40428c94b57b9037108715bca60d72c1b94.1571920862.git.zong.li@sifive.com> From: Steven Price Message-ID: Date: Thu, 24 Oct 2019 15:34:12 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <87a7b40428c94b57b9037108715bca60d72c1b94.1571920862.git.zong.li@sifive.com> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191024_073427_477170_B26F3C01 X-CRM114-Status: GOOD ( 29.74 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+infradead-linux-riscv=archiver.kernel.org@lists.infradead.org On 24/10/2019 14:02, Zong Li wrote: > In a similar manner to arm64, x86, powerpc, etc., it can traverse all > page tables, and dump the page table layout with the memory types and > permissions. > > Add a debugfs file at /sys/kernel/debug/kernel_page_tables to export > the page table layout to userspace. > > Signed-off-by: Zong Li Great to see someone pick this up for another architecture. I'm not very familiar with riscv, so I can't review the arch aspects, but one minor comment below. > --- > arch/riscv/Kconfig | 1 + > arch/riscv/include/asm/pgtable.h | 10 ++ > arch/riscv/include/asm/ptdump.h | 19 +++ > arch/riscv/mm/Makefile | 1 + > arch/riscv/mm/ptdump.c | 309 +++++++++++++++++++++++++++++++++++++++ > 5 files changed, 340 insertions(+) > create mode 100644 arch/riscv/include/asm/ptdump.h > create mode 100644 arch/riscv/mm/ptdump.c > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index bc7598f..053cb7a 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -25,6 +25,7 @@ config RISCV > select GENERIC_CPU_DEVICES > select GENERIC_IRQ_SHOW > select GENERIC_PCI_IOMAP > + select GENERIC_PTDUMP > select GENERIC_SCHED_CLOCK > select GENERIC_STRNCPY_FROM_USER > select GENERIC_STRNLEN_USER > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h > index df6522d..be93e59 100644 > --- a/arch/riscv/include/asm/pgtable.h > +++ b/arch/riscv/include/asm/pgtable.h > @@ -444,6 +444,16 @@ extern void setup_bootmem(void); > extern void paging_init(void); > > /* > + * In the RV64 Linux scheme, we give the user half of the virtual-address space > + * and give the kernel the other (upper) half. > + */ > +#ifdef CONFIG_64BIT > +#define KERN_VIRT_START (-(BIT(CONFIG_VA_BITS)) + TASK_SIZE) > +#else > +#define KERN_VIRT_START FIXADDR_START > +#endif > + > +/* > * Task size is 0x4000000000 for RV64 or 0x9fc00000 for RV32. > * Note that PGDIR_SIZE must evenly divide TASK_SIZE. > */ > diff --git a/arch/riscv/include/asm/ptdump.h b/arch/riscv/include/asm/ptdump.h > new file mode 100644 > index 0000000..26d9221 > --- /dev/null > +++ b/arch/riscv/include/asm/ptdump.h > @@ -0,0 +1,19 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* > + * Copyright (C) 2019 SiFive > + */ > + > +#ifndef _ASM_RISCV_PTDUMP_H > +#define _ASM_RISCV_PTDUMP_H > + > +#ifdef CONFIG_PTDUMP_CORE > +void ptdump_check_wx(void); > +#endif /* CONFIG_PTDUMP_CORE */ I believe this file is only included from ptdump.c which is only build when CONFIG_PTDUMP_CORE is set. So the #ifdeffery isn't necessary. Thanks, Steve > + > +#ifdef CONFIG_DEBUG_WX > +#define debug_checkwx() ptdump_check_wx() > +#else > +#define debug_checkwx() do { } while (0) > +#endif > + > +#endif /* _ASM_RISCV_PTDUMP_H */ > diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile > index 9d9a173..d6132f8 100644 > --- a/arch/riscv/mm/Makefile > +++ b/arch/riscv/mm/Makefile > @@ -17,3 +17,4 @@ ifeq ($(CONFIG_MMU),y) > obj-$(CONFIG_SMP) += tlbflush.o > endif > obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o > +obj-$(CONFIG_PTDUMP_CORE) += ptdump.o > diff --git a/arch/riscv/mm/ptdump.c b/arch/riscv/mm/ptdump.c > new file mode 100644 > index 0000000..60c8af1 > --- /dev/null > +++ b/arch/riscv/mm/ptdump.c > @@ -0,0 +1,309 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Copyright (C) 2019 SiFive > + */ > + > +#include > +#include > +#include > +#include > + > +#include > +#include > + > +#define pt_dump_seq_printf(m, fmt, args...) \ > +({ \ > + if (m) \ > + seq_printf(m, fmt, ##args); \ > +}) > + > +#define pt_dump_seq_puts(m, fmt) \ > +({ \ > + if (m) \ > + seq_printf(m, fmt); \ > +}) > + > +/* > + * The page dumper groups page table entries of the same type into a single > + * description. It uses pg_state to track the range information while > + * iterating over the pte entries. When the continuity is broken it then > + * dumps out a description of the range. > + */ > +struct pg_state { > + struct ptdump_state ptdump; > + struct seq_file *seq; > + const struct addr_marker *marker; > + unsigned long start_address; > + unsigned long start_pa; > + unsigned long last_pa; > + int level; > + u64 current_prot; > + bool check_wx; > + unsigned long wx_pages; > +}; > + > +/* Address marker */ > +struct addr_marker { > + unsigned long start_address; > + const char *name; > +}; > + > +static struct addr_marker address_markers[] = { > + {FIXADDR_START, "Fixmap start"}, > + {FIXADDR_TOP, "Fixmap end"}, > +#ifdef CONFIG_SPARSEMEM_VMEMMAP > + {VMEMMAP_START, "vmemmap start"}, > + {VMEMMAP_END, "vmemmap end"}, > +#endif > + {VMALLOC_START, "vmalloc() area"}, > + {VMALLOC_END, "vmalloc() end"}, > + {PAGE_OFFSET, "Linear mapping"}, > + {-1, NULL}, > +}; > + > +/* Page Table Entry */ > +struct prot_bits { > + u64 mask; > + u64 val; > + const char *set; > + const char *clear; > +}; > + > +static const struct prot_bits pte_bits[] = { > + { > + .mask = _PAGE_SOFT, > + .val = _PAGE_SOFT, > + .set = "RSW", > + .clear = " ", > + }, { > + .mask = _PAGE_DIRTY, > + .val = _PAGE_DIRTY, > + .set = "D", > + .clear = ".", > + }, { > + .mask = _PAGE_ACCESSED, > + .val = _PAGE_ACCESSED, > + .set = "A", > + .clear = ".", > + }, { > + .mask = _PAGE_GLOBAL, > + .val = _PAGE_GLOBAL, > + .set = "G", > + .clear = ".", > + }, { > + .mask = _PAGE_USER, > + .val = _PAGE_USER, > + .set = "U", > + .clear = ".", > + }, { > + .mask = _PAGE_EXEC, > + .val = _PAGE_EXEC, > + .set = "X", > + .clear = ".", > + }, { > + .mask = _PAGE_WRITE, > + .val = _PAGE_WRITE, > + .set = "W", > + .clear = ".", > + }, { > + .mask = _PAGE_READ, > + .val = _PAGE_READ, > + .set = "R", > + .clear = ".", > + }, { > + .mask = _PAGE_PRESENT, > + .val = _PAGE_PRESENT, > + .set = "V", > + .clear = ".", > + } > +}; > + > +/* Page Level */ > +struct pg_level { > + const char *name; > + u64 mask; > +}; > + > +static struct pg_level pg_level[] = { > + { > + }, { /* pgd */ > + .name = "PGD", > + }, { /* p4d */ > + .name = (CONFIG_PGTABLE_LEVELS > 4) ? "P4D" : "PGD", > + }, { /* pud */ > + .name = (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD", > + }, { /* pmd */ > + .name = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD", > + }, { /* pte */ > + .name = "PTE", > + }, > +}; > + > +static void dump_prot(struct pg_state *st) > +{ > + unsigned int i; > + > + for (i = 0; i < ARRAY_SIZE(pte_bits); i++) { > + const char *s; > + > + if ((st->current_prot & pte_bits[i].mask) == pte_bits[i].val) > + s = pte_bits[i].set; > + else > + s = pte_bits[i].clear; > + > + if (s) > + pt_dump_seq_printf(st->seq, " %s", s); > + } > +} > + > +#ifdef CONFIG_64BIT > +#define ADDR_FORMAT "0x%016lx" > +#else > +#define ADDR_FORMAT "0x%08lx" > +#endif > +static void dump_addr(struct pg_state *st, unsigned long addr) > +{ > + static const char units[] = "KMGTPE"; > + const char *unit = units; > + unsigned long delta; > + > + pt_dump_seq_printf(st->seq, ADDR_FORMAT "-" ADDR_FORMAT " ", > + st->start_address, addr); > + > + pt_dump_seq_printf(st->seq, " " ADDR_FORMAT " ", st->start_pa); > + delta = (addr - st->start_address) >> 10; > + > + while (!(delta & 1023) && unit[1]) { > + delta >>= 10; > + unit++; > + } > + > + pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit, > + pg_level[st->level].name); > +} > + > +static void note_prot_wx(struct pg_state *st, unsigned long addr) > +{ > + if (!st->check_wx) > + return; > + > + if ((st->current_prot & (_PAGE_WRITE | _PAGE_EXEC)) != > + (_PAGE_WRITE | _PAGE_EXEC)) > + return; > + > + WARN_ONCE(1, "riscv/mm: Found insecure W+X mapping at address %p/%pS\n", > + (void *)st->start_address, (void *)st->start_address); > + > + st->wx_pages += (addr - st->start_address) / PAGE_SIZE; > +} > + > +static void note_page(struct ptdump_state *pt_st, unsigned long addr, > + int level, unsigned long val) > +{ > + struct pg_state *st = container_of(pt_st, struct pg_state, ptdump); > + u64 pa = PFN_PHYS(pte_pfn(__pte(val))); > + u64 prot = 0; > + > + if (level >= 0) > + prot = val & pg_level[level].mask; > + > + if (!st->level) { > + st->level = level; > + st->current_prot = prot; > + st->start_address = addr; > + st->start_pa = pa; > + st->last_pa = pa; > + pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); > + } else if (prot != st->current_prot || > + level != st->level || addr >= st->marker[1].start_address) { > + if (st->current_prot) { > + note_prot_wx(st, addr); > + dump_addr(st, addr); > + dump_prot(st); > + pt_dump_seq_puts(st->seq, "\n"); > + } > + > + while (addr >= st->marker[1].start_address) { > + st->marker++; > + pt_dump_seq_printf(st->seq, "---[ %s ]---\n", > + st->marker->name); > + } > + > + st->start_address = addr; > + st->start_pa = pa; > + st->last_pa = pa; > + st->current_prot = prot; > + st->level = level; > + } else { > + st->last_pa = pa; > + } > +} > + > +static void ptdump_walk(struct seq_file *s) > +{ > + struct pg_state st = { > + .seq = s, > + .marker = address_markers, > + .ptdump = { > + .note_page = note_page, > + .range = (struct ptdump_range[]) { > + {KERN_VIRT_START, ULONG_MAX}, > + {0, 0} > + } > + } > + }; > + > + ptdump_walk_pgd(&st.ptdump, &init_mm); > +} > + > +void ptdump_check_wx(void) > +{ > + struct pg_state st = { > + .seq = NULL, > + .marker = (struct addr_marker[]) { > + {0, NULL}, > + {-1, NULL}, > + }, > + .check_wx = true, > + .ptdump = { > + .note_page = note_page, > + .range = (struct ptdump_range[]) { > + {KERN_VIRT_START, ULONG_MAX}, > + {0, 0} > + } > + } > + }; > + > + ptdump_walk_pgd(&st.ptdump, &init_mm); > + > + if (st.wx_pages) > + pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", > + st.wx_pages); > + else > + pr_info("Checked W+X mappings: passed, no W+X pages found\n"); > +} > + > +static int ptdump_show(struct seq_file *m, void *v) > +{ > + ptdump_walk(m); > + > + return 0; > +} > + > +DEFINE_SHOW_ATTRIBUTE(ptdump); > + > +static int ptdump_init(void) > +{ > + unsigned int i, j; > + > + for (i = 0; i < ARRAY_SIZE(pg_level); i++) > + for (j = 0; j < ARRAY_SIZE(pte_bits); j++) > + pg_level[i].mask |= pte_bits[j].mask; > + > + debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, > + &ptdump_fops); > + > + return 0; > +} > + > +device_initcall(ptdump_init); > _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv