* [PATCH] LoongArch: Add support to dump the kernel page tables @ 2026-06-29 7:43 haoran.jiang 2026-06-29 14:00 ` Huacai Chen 0 siblings, 1 reply; 3+ messages in thread From: haoran.jiang @ 2026-06-29 7:43 UTC (permalink / raw) To: chenhuacai Cc: loongarch, linux-kernel, kernel, yangtiezhu, Haoran Jiang, Xiujie Jiang From: Haoran Jiang <jianghaoran@kylinos.cn> 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 <jiangxiujie@kylinos.cn> Signed-off-by: Xiujie Jiang <jiangxiujie@kylinos.cn> Signed-off-by: Haoran Jiang <jianghaoran@kylinos.cn> --- 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 <linux/ptdump.h> +#include <linux/mm_types.h> +#include <linux/seq_file.h> + +/* + * 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 <linux/init.h> +#include <linux/debugfs.h> +#include <linux/seq_file.h> +#include <linux/ptdump.h> +#include <linux/pgtable.h> +#include <asm/kasan.h> +#include <asm/ptdump.h> + +#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 <linux/debugfs.h> +#include <linux/seq_file.h> + +#include <asm/ptdump.h> +#include <asm/pgtable.h> +#include <asm/kasan.h> + +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 ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] LoongArch: Add support to dump the kernel page tables 2026-06-29 7:43 [PATCH] LoongArch: Add support to dump the kernel page tables haoran.jiang @ 2026-06-29 14:00 ` Huacai Chen 2026-06-30 12:09 ` haoran.jiang 0 siblings, 1 reply; 3+ messages in thread From: Huacai Chen @ 2026-06-29 14:00 UTC (permalink / raw) To: haoran.jiang Cc: loongarch, linux-kernel, kernel, yangtiezhu, Haoran Jiang, Xiujie Jiang Hi, Haoran, On Mon, Jun 29, 2026 at 3:44 PM <haoran.jiang@linux.dev> wrote: > > From: Haoran Jiang <jianghaoran@kylinos.cn> > > 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. I like the RISC-V version that put everything in ptdump.c. Huacai > > Co-developed-by: Xiujie Jiang <jiangxiujie@kylinos.cn> > Signed-off-by: Xiujie Jiang <jiangxiujie@kylinos.cn> > Signed-off-by: Haoran Jiang <jianghaoran@kylinos.cn> > --- > 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 <linux/ptdump.h> > +#include <linux/mm_types.h> > +#include <linux/seq_file.h> > + > +/* > + * 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 <linux/init.h> > +#include <linux/debugfs.h> > +#include <linux/seq_file.h> > +#include <linux/ptdump.h> > +#include <linux/pgtable.h> > +#include <asm/kasan.h> > +#include <asm/ptdump.h> > + > +#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 <linux/debugfs.h> > +#include <linux/seq_file.h> > + > +#include <asm/ptdump.h> > +#include <asm/pgtable.h> > +#include <asm/kasan.h> > + > +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 > ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] LoongArch: Add support to dump the kernel page tables 2026-06-29 14:00 ` Huacai Chen @ 2026-06-30 12:09 ` haoran.jiang 0 siblings, 0 replies; 3+ messages in thread From: haoran.jiang @ 2026-06-30 12:09 UTC (permalink / raw) To: Huacai Chen Cc: loongarch, linux-kernel, kernel, yangtiezhu, Haoran Jiang, Xiujie Jiang 2026年6月29日 22:00, "Huacai Chen" <chenhuacai@kernel.org mailto:chenhuacai@kernel.org?to=%22Huacai%20Chen%22%20%3Cchenhuacai%40kernel.org%3E > 写到: > > Hi, Haoran, > > On Mon, Jun 29, 2026 at 3:44 PM <haoran.jiang@linux.dev> wrote: > > > > > From: Haoran Jiang <jianghaoran@kylinos.cn> > > > > 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. > > > I like the RISC-V version that put everything in ptdump.c. > > Huacai > 1，The ptdump functionality can be enabled via either CONFIG_PTDUMP_DEBUGFS or CONFIG_DEBUG_WX. For example, RISC-V enables it through DEBUG_WX, while other architectures support both options. CONFIG_DEBUG_WX performs a kernel page table permission check at boot time to enforce the W^X principle. It depends on CONFIG_STRICT_KERNEL_RWX; debug_checkwx() is only invoked when CONFIG_STRICT_KERNEL_RWX is enabled. However, on LoongArch, the kernel text segment resides in the direct mapping region, where permission control cannot be enforced via page tables. Therefore, CONFIG_STRICT_KERNEL_RWX is not necessary to implement, and enabling DEBUG_WX is also unnecessary. Instead, this patch adopts CONFIG_PTDUMP_DEBUGFS to enable the ptdump feature for LoongArch. 2，However, for page-mapped regions, the page table permissions should conform to the W^X principle. The MODULES region can meet this requirement via `CONFIG_STRICT_MODULE_RWX`.But other regions, such as vmalloc, currently still do not comply with the W^X principle (as can be verified by checking `cat /sys/kernel/debug/check_wx_pages`). I intend to add `PAGE_NO_EXEC` to the `PAGE_KERNEL` definition。 #define PAGE_KERNEL __pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \___ __ PAGE_GLOBAL | _PAGE_KERN | _CACHE_CC | _PAGE_NO_EXEC) #define PAGE_KERNEL_SUC __pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \ _PAGE_GLOBAL | _PAGE_KERN | _CACHE_SUC | _PAGE_NO_EXEC) #define PAGE_KERNEL_WUC __pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \ PAGE_GLOBAL | _PAGE_KERN | _CACHE_WUC | _PAGE_NO_EXEC) eBPF memory allocated from the MODULES region is not affected by this change, because it already gets executable permissions via `set_memory_rox`. The vmalloc, PCI I/O, vmemmap, KFENCE, KASAN, and Fixmap regions should all be non-executable by default. Would this modification have any other side effects? thanks! > > > > Co-developed-by: Xiujie Jiang <jiangxiujie@kylinos.cn> > > Signed-off-by: Xiujie Jiang <jiangxiujie@kylinos.cn> > > Signed-off-by: Haoran Jiang <jianghaoran@kylinos.cn> > > --- > > 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 <linux/ptdump.h> > > +#include <linux/mm_types.h> > > +#include <linux/seq_file.h> > > + > > +/* > > + * 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 <linux/init.h> > > +#include <linux/debugfs.h> > > +#include <linux/seq_file.h> > > +#include <linux/ptdump.h> > > +#include <linux/pgtable.h> > > +#include <asm/kasan.h> > > +#include <asm/ptdump.h> > > + > > +#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 <linux/debugfs.h> > > +#include <linux/seq_file.h> > > + > > +#include <asm/ptdump.h> > > +#include <asm/pgtable.h> > > +#include <asm/kasan.h> > > + > > +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 > > > ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-06-30 12:10 UTC | newest] Thread overview: 3+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2026-06-29 7:43 [PATCH] LoongArch: Add support to dump the kernel page tables haoran.jiang 2026-06-29 14:00 ` Huacai Chen 2026-06-30 12:09 ` haoran.jiang
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