| Message ID | 87a7b40428c94b57b9037108715bca60d72c1b94.1571920862.git.zong.li@sifive.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | RISC-V page table dumper | expand |
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 <zong.li@sifive.com> 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 <linux/init.h> > +#include <linux/debugfs.h> > +#include <linux/seq_file.h> > +#include <linux/ptdump.h> > + > +#include <asm/ptdump.h> > +#include <asm/pgtable.h> > + > +#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); >
On Thu, Oct 24, 2019 at 10:34 PM Steven Price <steven.price@arm.com> wrote: > > 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 <zong.li@sifive.com> > > 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. Yes, make sense, I will remove the condition there. Actually, I'm working on STRICT_KERNEL_RWX too, it will include the ptdump.h in another file for using debug_checkwx, but the condition is still unnecessary, because ptdump_check_wx() is only used when CONFIG_DEBUG_WX is enabled, and CONFIG_DEBUG_WX always selects the CONFIG_PTDUMP_CORE. Thanks to you for the suggestion. > 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 <linux/init.h> > > +#include <linux/debugfs.h> > > +#include <linux/seq_file.h> > > +#include <linux/ptdump.h> > > + > > +#include <asm/ptdump.h> > > +#include <asm/pgtable.h> > > + > > +#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); > > >
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 */ + +#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 <linux/init.h> +#include <linux/debugfs.h> +#include <linux/seq_file.h> +#include <linux/ptdump.h> + +#include <asm/ptdump.h> +#include <asm/pgtable.h> + +#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);
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 <zong.li@sifive.com> --- 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