From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-178.mta1.migadu.com (out-178.mta1.migadu.com [95.215.58.178]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C141C3BBFD9 for ; Mon, 29 Jun 2026 07:44:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.178 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782719095; cv=none; b=WZKWhbGz1vH2PleUOnRJCZ08is5wR4AElDS2J9pi9r9g1M8Of+K6M1cCZBxA6RncnHeaDCnqVUS7Y5k3CpAUIGKPic0Etp/JrEmVRPCBywsdirbZWl7tduIR65tQEUSkFR67Lp82NEvdVUTC+S6fHtp8B0BXNl1hXMV7BC2adMc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782719095; c=relaxed/simple; bh=QSVwLsSs4FEqC00GALi3iveivUqlb6NjyRWWlRoHsMI=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=OEb6lqIyqEOL4MKJt+YItEdJN9cnIVPbXEe0PlkQZvKKFNdCQrWHIe38k8CrTK3lD/rXvdiFI6zm5ho2CcTWEk6jxHWPpKQLFn3LuTKiaMf9rR0er8ALPEoDut1+v4S9Fy+zTRKhNh/o+F7xs/aN15AAMn6UY7lNuePsCAPeoiM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=VMQmRKU8; arc=none smtp.client-ip=95.215.58.178 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="VMQmRKU8" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1782719075; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=enUi8s33YMtcNMu0cUPvylJsFKbIfnnmtLi/VTHPnEE=; b=VMQmRKU8Wcpx1pIYXLRejhjJoC7WTv6ZPkm49qmUqyO90XAqFen+QEDmSUeSB0MaVf44gW akLRGw6k6puiD41gHB2D0OY6khJz+BZ3fGptpdMbkAZwIVlMXDAxYOBrXffalM9ePyma9p 6vYxmMH/EQSkytBVr8eG/esCrhrBHfk= From: haoran.jiang@linux.dev To: chenhuacai@kernel.org Cc: loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, kernel@xen0n.name, yangtiezhu@loongson.cn, Haoran Jiang , Xiujie Jiang Subject: [PATCH] LoongArch: Add support to dump the kernel page tables Date: Mon, 29 Jun 2026 15:43:35 +0800 Message-Id: <20260629074335.448256-1-haoran.jiang@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Haoran Jiang In a similar manner to riscv,arm64,x86 etc.,this patch allows dumping the page tables of the LoongArch page-mapped virtual memory region via a debugfs file, which is useful for kernel developers to inspect page table layouts and verify permissions and type settings. Co-developed-by: Xiujie Jiang Signed-off-by: Xiujie Jiang Signed-off-by: Haoran Jiang --- arch/loongarch/Kconfig | 1 + arch/loongarch/include/asm/ptdump.h | 61 ++++ arch/loongarch/mm/Makefile | 2 + arch/loongarch/mm/ptdump.c | 417 ++++++++++++++++++++++++++++ arch/loongarch/mm/ptdump_debugfs.c | 22 ++ 5 files changed, 503 insertions(+) create mode 100644 arch/loongarch/include/asm/ptdump.h create mode 100644 arch/loongarch/mm/ptdump.c create mode 100644 arch/loongarch/mm/ptdump_debugfs.c diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index bec7cc1d72ee..e97fe97e1955 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -25,6 +25,7 @@ config LOONGARCH select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE select ARCH_HAS_PREEMPT_LAZY select ARCH_HAS_PTE_SPECIAL if 64BIT + select ARCH_HAS_PTDUMP select ARCH_HAS_SET_MEMORY select ARCH_HAS_SET_DIRECT_MAP select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST diff --git a/arch/loongarch/include/asm/ptdump.h b/arch/loongarch/include/asm/ptdump.h new file mode 100644 index 000000000000..4590ea56abe6 --- /dev/null +++ b/arch/loongarch/include/asm/ptdump.h @@ -0,0 +1,61 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#ifndef __ASM_PTDUMP_H +#define __ASM_PTDUMP_H + +#include +#include +#include + +/* + * 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; +}; + +/* Private information for debugfs */ +struct ptd_mm_info { + struct mm_struct *mm; + const struct addr_marker *markers; + unsigned long base_addr; + unsigned long end; +}; + +/* Page Table Entry */ +struct prot_bits { + u64 mask; + u64 val; + const char *set; + const char *clear; +}; + +/* Page Level */ +struct pg_level { + const char *name; + u64 mask; +}; + +void ptdump_walk(struct seq_file *s, struct ptd_mm_info *pinfo); +void __init ptdump_debugfs_register(struct ptd_mm_info *info, const char *name); + +#endif /* __ASM_PTDUMP_H */ + diff --git a/arch/loongarch/mm/Makefile b/arch/loongarch/mm/Makefile index 2aae3773de77..da9e6fee0439 100644 --- a/arch/loongarch/mm/Makefile +++ b/arch/loongarch/mm/Makefile @@ -10,5 +10,7 @@ obj-y += init.o cache.o tlb.o tlbex.o extable.o \ obj-$(CONFIG_HIGHMEM) += highmem.o obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o obj-$(CONFIG_KASAN) += kasan_init.o +obj-$(CONFIG_PTDUMP) += ptdump.o +obj-$(CONFIG_PTDUMP_DEBUGFS) += ptdump_debugfs.o KASAN_SANITIZE_kasan_init.o := n diff --git a/arch/loongarch/mm/ptdump.c b/arch/loongarch/mm/ptdump.c new file mode 100644 index 000000000000..cab6dad18150 --- /dev/null +++ b/arch/loongarch/mm/ptdump.c @@ -0,0 +1,417 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Derived from riscv implementation + */ + +#include +#include +#include +#include +#include +#include +#include + +#define _PAGE_PLV_VAL 0x0 + +#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_puts(m, fmt); \ +}) + +enum address_markers_idx { + PCI_IO_START_NR, + PCI_IO_END_NR, + MODULES_START_NR, + MODULES_END_NR, + VMALLOC_START_NR, + VMALLOC_END_NR, +#ifdef CONFIG_SPARSEMEM_VMEMMAP + VMEMMAP_START_NR, + VMEMMAP_END_NR, +#endif +#ifdef CONFIG_KFENCE + KFENCE_AREA_START_NR, + KFENCE_AREA_END_NR, +#endif +#ifdef CONFIG_KASAN + KASAN_SHADOW_START_NR, + KASAN_SHADOW_END_NR, +#endif + FIXMAP_START_NR, + FIXMAP_END_NR, + END_OF_SPACE_NR +}; + + + +static struct addr_marker address_markers[] = { + {0, "PCI I/O start"}, + {0, "PCI I/O end"}, + {0, "modules start"}, + {0, "modules end"}, + {0, "vmalloc() area"}, + {0, "vmalloc() end"}, +#ifdef CONFIG_SPARSEMEM_VMEMMAP + {0, "vmemmap start"}, + {0, "vmemmap end"}, +#endif +#ifdef CONFIG_KFENCE + {0, "kfence area start"}, + {0, "kfence area end"}, +#endif +#ifdef CONFIG_KASAN + {0, "Kasan shadow start"}, + {0, "Kasan shadow end"}, +#endif + {0, "Fixmap start"}, + {0, "Fixmap end"}, + {-1, NULL}, +}; + + +static struct ptd_mm_info kernel_ptd_info = { + .mm = &init_mm, + .markers = address_markers, + .base_addr = 0, + .end = ULONG_MAX, +}; + +static const struct prot_bits pte_bits[] = { + { + .mask = _PAGE_VALID, + .val = _PAGE_VALID, + .set = "V", + .clear = " ", + }, { + .mask = _PAGE_DIRTY, + .val = _PAGE_DIRTY, + .set = "D", + .clear = " ", + }, { + .mask = _PAGE_PLV, + .val = _PAGE_PLV_VAL, + .set = "KERN", + .clear = "USR ", + }, { + .mask = _CACHE_MASK, + .val = _CACHE_MASK, + .set = " ", + .clear = "SUC", + }, { + .mask = _PAGE_GLOBAL, + .val = _PAGE_GLOBAL, + .set = "G", + .clear = " ", + }, { + .mask = _PAGE_PRESENT, + .val = _PAGE_PRESENT, + .set = "P", + .clear = " ", + }, { + .mask = _PAGE_WRITE, + .val = _PAGE_WRITE, + .set = "W", + .clear = " ", + }, { + .mask = _PAGE_HGLOBAL, + .val = _PAGE_HGLOBAL, + .set = "HG", + .clear = " ", + }, { + .mask = _PAGE_NO_READ, + .val = _PAGE_NO_READ, + .set = "NR", + .clear = " ", + }, { + .mask = _PAGE_NO_EXEC, + .val = _PAGE_NO_EXEC, + .set = "NX", + .clear = " ", + }, { + .mask = _PAGE_RPLV, + .val = _PAGE_RPLV, + .set = "RPLV", + .clear = " ", + } +}; + +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 (pte_bits[i].mask == _CACHE_MASK) { + if ((st->current_prot & pte_bits[i].mask) == _CACHE_CC) + s = "CC "; + else if ((st->current_prot & pte_bits[i].mask) == _CACHE_WUC) + s = "WUC"; + else + s = pte_bits[i].clear; + } else if (pte_bits[i].mask == _PAGE_GLOBAL) { + if ((st->current_prot & pte_bits[i].mask) == pte_bits[i].val) { + if (st->level != 4) + s = "PSE"; + else + s = pte_bits[i].set; + } else { + s = pte_bits[i].clear; + } + + } else { + 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) == 0) + return; + if ((st->current_prot & _PAGE_NO_EXEC) == _PAGE_NO_EXEC) + return; + + st->wx_pages += (addr - st->start_address) / PAGE_SIZE; + +} + +static void note_page(struct ptdump_state *pt_st, unsigned long addr, + int level, u64 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 == -1) { + 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 note_page_pte(struct ptdump_state *pt_st, unsigned long addr, pte_t pte) +{ + note_page(pt_st, addr, 4, pte_val(pte)); +} + +static void note_page_pmd(struct ptdump_state *pt_st, unsigned long addr, pmd_t pmd) +{ + note_page(pt_st, addr, 3, pmd_val(pmd)); +} + +static void note_page_pud(struct ptdump_state *pt_st, unsigned long addr, pud_t pud) +{ + note_page(pt_st, addr, 2, pud_val(pud)); +} + +static void note_page_p4d(struct ptdump_state *pt_st, unsigned long addr, p4d_t p4d) +{ + note_page(pt_st, addr, 1, p4d_val(p4d)); +} + +static void note_page_pgd(struct ptdump_state *pt_st, unsigned long addr, pgd_t pgd) +{ + note_page(pt_st, addr, 0, pgd_val(pgd)); +} + +static void note_page_flush(struct ptdump_state *pt_st) +{ + pte_t pte_zero = {0}; + + note_page(pt_st, 0, -1, pte_val(pte_zero)); +} + +void ptdump_walk(struct seq_file *s, struct ptd_mm_info *pinfo) +{ + struct pg_state st = { + .seq = s, + .marker = pinfo->markers, + .level = -1, + .ptdump = { + .note_page_pte = note_page_pte, + .note_page_pmd = note_page_pmd, + .note_page_pud = note_page_pud, + .note_page_p4d = note_page_p4d, + .note_page_pgd = note_page_pgd, + .note_page_flush = note_page_flush, + .range = (struct ptdump_range[]) { + {pinfo->base_addr, pinfo->end}, + {0, 0} + } + } + }; + + ptdump_walk_pgd(&st.ptdump, pinfo->mm, NULL); +} + +bool ptdump_check_wx(void) +{ + struct pg_state st = { + .seq = NULL, + .marker = (struct addr_marker[]) { + {0, NULL}, + {-1, NULL}, + }, + .level = -1, + .check_wx = true, + .ptdump = { + .note_page_pte = note_page_pte, + .note_page_pmd = note_page_pmd, + .note_page_pud = note_page_pud, + .note_page_p4d = note_page_p4d, + .note_page_pgd = note_page_pgd, + .note_page_flush = note_page_flush, + .range = (struct ptdump_range[]) { + {vm_map_base, ULONG_MAX}, + {0, 0} + } + } + }; + + ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); + + if (st.wx_pages) { + pr_warn("Checked W+X mappings: failed, %lu W+X pages found\n", + st.wx_pages); + + return false; + } + + pr_info("Checked W+X mappings: passed, no W+X pages found\n"); + + return true; +} + + +static int __init ptdump_init(void) +{ + unsigned int i, j; + + address_markers[PCI_IO_START_NR].start_address = (unsigned long)PCI_IOBASE; + address_markers[PCI_IO_END_NR].start_address = (unsigned long)PCI_IOBASE + IO_SPACE_LIMIT; + + address_markers[MODULES_START_NR].start_address = MODULES_VADDR; + address_markers[MODULES_END_NR].start_address = MODULES_END; + + address_markers[VMALLOC_START_NR].start_address = VMALLOC_START; + address_markers[VMALLOC_END_NR].start_address = VMALLOC_END; + +#ifdef CONFIG_SPARSEMEM_VMEMMAP + address_markers[VMEMMAP_START_NR].start_address = (unsigned long)vmemmap; + address_markers[VMEMMAP_END_NR].start_address = VMEMMAP_END; +#endif + +#ifdef CONFIG_KFENCE + address_markers[KFENCE_AREA_START_NR].start_address = KFENCE_AREA_START; + address_markers[KFENCE_AREA_END_NR].start_address = KFENCE_AREA_END; +#endif + +#ifdef CONFIG_KASAN + address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START; + address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END; +#endif + + address_markers[FIXMAP_START_NR].start_address = FIXADDR_START; + address_markers[FIXMAP_END_NR].start_address = FIXADDR_TOP; + + kernel_ptd_info.base_addr = vm_map_base; + + 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; + } + + ptdump_debugfs_register(&kernel_ptd_info, "kernel_page_tables"); + + return 0; +} + +device_initcall(ptdump_init); diff --git a/arch/loongarch/mm/ptdump_debugfs.c b/arch/loongarch/mm/ptdump_debugfs.c new file mode 100644 index 000000000000..aa6169f6aa3a --- /dev/null +++ b/arch/loongarch/mm/ptdump_debugfs.c @@ -0,0 +1,22 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +#include +#include +#include + +static int ptdump_show(struct seq_file *m, void *v) +{ + struct ptd_mm_info *info = m->private; + + ptdump_walk(m, info); + return 0; +} +DEFINE_SHOW_ATTRIBUTE(ptdump); + +void __init ptdump_debugfs_register(struct ptd_mm_info *info, const char *name) +{ + debugfs_create_file(name, 0400, NULL, info, &ptdump_fops); +} + -- 2.43.0