Message ID | 1458597885-19804-1-git-send-email-rashmicy@gmail.com (mailing list archive) |
---|---|
State | Not Applicable |
Headers | show |
Hi Rashmica, [auto build test ERROR on powerpc/next] [also build test ERROR on v4.5 next-20160322] [if your patch is applied to the wrong git tree, please drop us a note to help improving the system] url: https://github.com/0day-ci/linux/commits/Rashmica-Gupta/powerpc-pagetable-Add-option-to-dump-the-linux-pagetables/20160322-060934 base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next config: powerpc-allyesconfig (attached as .config) reproduce: wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # save the attached .config to linux build tree make.cross ARCH=powerpc All errors (new ones prefixed by >>): >> arch/powerpc/mm/dump_linuxpagetables.c:148:11: error: '_PAGE_COMBO' undeclared here (not in a function) .mask = _PAGE_COMBO, ^ vim +/_PAGE_COMBO +148 arch/powerpc/mm/dump_linuxpagetables.c 142 .clear = " ", 143 }, { 144 .mask = _PAGE_BUSY, 145 .val = _PAGE_BUSY, 146 .set = "busy", 147 }, { > 148 .mask = _PAGE_COMBO, 149 .val = _PAGE_COMBO, 150 .set = "combo", 151 }, { --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation
On 22/03/16 09:04, Rashmica Gupta wrote: > Useful to be able to dump the kernels page tables to check permissions > and memory types - derived from arm64's implementation. > > Add a debugfs file to check the page tables. To use this the PPC_PTDUMP > config option must be selected. > > Signed-off-by: Rashmica Gupta <rashmicy@gmail.com> > --- > arch/powerpc/Kconfig.debug | 12 ++ > arch/powerpc/mm/Makefile | 1 + > arch/powerpc/mm/dump_linuxpagetables.c | 377 +++++++++++++++++++++++++++++++++ > 3 files changed, 390 insertions(+) > create mode 100644 arch/powerpc/mm/dump_linuxpagetables.c > > diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug > index 638f9ce740f5..26a60effea1a 100644 > --- a/arch/powerpc/Kconfig.debug > +++ b/arch/powerpc/Kconfig.debug > @@ -344,4 +344,16 @@ config FAIL_IOMMU > > If you are unsure, say N. > > +config PPC_PTDUMP > + bool "Export kernel pagetable layout to userspace via debugfs" > + depends on DEBUG_KERNEL > + select DEBUG_FS > + help > + This option exports the state of the kernel pagetables to a > + debugfs file. This is only useful for kernel developers who are > + working in architecture specific areas of the kernel - probably > + not a good idea to enable this feature in a production kernel. > + > + If you are unsure, say N. > + Some minor comments below, but otherwise Acked-by: Balbir Singh <bsingharora@gmail.com> > endmenu > diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile > index adfee3f1aeb9..6935c6204fbc 100644 > --- a/arch/powerpc/mm/Makefile > +++ b/arch/powerpc/mm/Makefile > @@ -41,3 +41,4 @@ obj-$(CONFIG_NOT_COHERENT_CACHE) += dma-noncoherent.o > obj-$(CONFIG_HIGHMEM) += highmem.o > obj-$(CONFIG_PPC_COPRO_BASE) += copro_fault.o > obj-$(CONFIG_SPAPR_TCE_IOMMU) += mmu_context_iommu.o > +obj-$(CONFIG_PPC_PTDUMP) += dump_linuxpagetables.o > diff --git a/arch/powerpc/mm/dump_linuxpagetables.c b/arch/powerpc/mm/dump_linuxpagetables.c > new file mode 100644 > index 000000000000..f97fbfdac4b9 > --- /dev/null > +++ b/arch/powerpc/mm/dump_linuxpagetables.c > @@ -0,0 +1,377 @@ > +/* > + * Copyright 2016, Rashmica Gupta, IBM Corp. > + * > + * This traverses the kernel pagetables and dumps the > + * information about the used sections of memory to > + * /sys/kernel/debug/kernel_pagetables. > + * > + * Derived from the arm64 implementation: > + * Copyright (c) 2014, The Linux Foundation, Laura Abbott. > + * (C) Copyright 2008 Intel Corporation, Arjan van de Ven. > + * > + * This program is free software; you can redistribute it and/or > + * modify it under the terms of the GNU General Public License > + * as published by the Free Software Foundation; version 2 > + * of the License. > + */ > +#include <linux/debugfs.h> > +#include <linux/fs.h> > +#include <linux/io.h> > +#include <linux/mm.h> > +#include <linux/sched.h> > +#include <linux/seq_file.h> > +#include <asm/fixmap.h> > +#include <asm/pgtable.h> > +#include <linux/const.h> > +#include <asm/page.h> > +#include <asm/pgalloc.h> > + > +struct addr_marker { > + unsigned long start_address; > + const char *name; > +}; > + > +static struct addr_marker address_markers[] = { > + { VMALLOC_START, "vmalloc() Area" }, > + { VMALLOC_END, "vmalloc() End" }, > + { ISA_IO_BASE, "isa I/O start" }, > + { ISA_IO_END, "isa I/O end" }, > + { PHB_IO_BASE, "phb I/O start" }, > + { PHB_IO_END, "phb I/O end" }, > + { IOREMAP_BASE, "I/O remap start" }, > + { IOREMAP_END, "I/O remap end" }, > + { -1, NULL }, > +}; > + > +/* > + * To visualise what is happening, > + * > + * - PTRS_PER_P** = how many entries there are in the corresponding P** > + * - P**_SHIFT = how many bits of the address we use to index into the > + * corresponding P** > + * - P**_SIZE is how much memory we can access through the table - not the > + * size of the table itself. > + * P**={PGD, PUD, PMD, PTE} > + * > + * > + * Each entry of the PGD points to a PUD. Each entry of a PUD points to a > + * PMD. Each entry of a PMD points to a PTE. And every PTE entry points to > + * a page. > + * > + * In the case where there are only 3 levels, the PUD is folded into the > + * PGD: every PUD has only one entry which points to the PMD. > + * > + * 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 - ie PTEs that are virtually contiguous > + * with the same PTE flags are chunked together. This is to make it clear how > + * different areas of the kernel virtual memory are used. > + * > + */ > +struct pg_state { > + struct seq_file *seq; > + const struct addr_marker *marker; > + unsigned long start_address; > + unsigned level; > + u64 current_flags; > +}; > + > +struct flag_info { > + u64 mask; > + u64 val; > + const char *set; > + const char *clear; > +}; > + > +static const struct flag_info flag_array[] = { > + { > + .mask = _PAGE_USER, > + .val = _PAGE_USER, > + .set = "user", > + .clear = " ", > + }, { > + .mask = _PAGE_RW, > + .val = _PAGE_RW, > + .set = "rw", > + .clear = "ro", > + }, { > + .mask = _PAGE_EXEC, > + .val = _PAGE_EXEC, > + .set = " X ", Can we make this small "x" to sort of go in line with "rw"/"ro" > + .clear = " ", > + }, { > + .mask = _PAGE_PTE, > + .val = _PAGE_PTE, > + .set = "pte", > + .clear = " ", > + }, { > + .mask = _PAGE_PRESENT, > + .val = _PAGE_PRESENT, > + .set = "present", > + .clear = " ", > + }, { > + .mask = _PAGE_HASHPTE, > + .val = _PAGE_HASHPTE, > + .set = "hpte", > + .clear = " ", > + }, { > + .mask = _PAGE_GUARDED, > + .val = _PAGE_GUARDED, > + .set = "guarded", > + .clear = " ", > + }, { > + .mask = _PAGE_DIRTY, > + .val = _PAGE_DIRTY, > + .set = "dirty", > + .clear = " ", > + }, { > + .mask = _PAGE_ACCESSED, > + .val = _PAGE_ACCESSED, > + .set = "accessed", > + .clear = " ", > + }, { > + .mask = _PAGE_WRITETHRU, > + .val = _PAGE_WRITETHRU, > + .set = "write through", > + .clear = " ", > + }, { > + .mask = _PAGE_NO_CACHE, > + .val = _PAGE_NO_CACHE, > + .set = "no cache", > + .clear = " ", > + }, { > + .mask = _PAGE_BUSY, > + .val = _PAGE_BUSY, > + .set = "busy", > + }, { > + .mask = _PAGE_COMBO, > + .val = _PAGE_COMBO, > + .set = "combo", > + }, { > + .mask = _PAGE_F_GIX, > + .val = _PAGE_F_GIX, > + .set = "f_gix", Can we use "primary"? > + }, { > + .mask = _PAGE_F_SECOND, > + .val = _PAGE_F_SECOND, > + .set = "f_second", "secondary idx" > + }, { > + .mask = _PAGE_SPECIAL, > + .val = _PAGE_SPECIAL, > + .set = "special", > + }, { > + .mask = _PAGE_4K_PFN, > + .val = _PAGE_4K_PFN, > + .set = "4K_pfn" > + } > +}; > + > +struct pgtable_level { > + const struct flag_info *flag; > + size_t num; > + u64 mask; > +}; > + > +static struct pgtable_level pg_level[] = { > + { > + }, { /* pgd */ > + .flag = flag_array, > + .num = ARRAY_SIZE(flag_array), > + }, { /* pud */ > + .flag = flag_array, > + .num = ARRAY_SIZE(flag_array), > + }, { /* pmd */ > + .flag = flag_array, > + .num = ARRAY_SIZE(flag_array), > + }, { /* pte */ > + .flag = flag_array, > + .num = ARRAY_SIZE(flag_array), > + }, > +}; > + > +static void dump_flag(struct pg_state *st, const struct flag_info *flag, > + size_t num) > +{ > + unsigned i; > + > + for (i = 0; i < num; i++, flag++) { > + const char *s; > + > + if ((st->current_flags & flag->mask) == flag->val) > + s = flag->set; > + else > + s = flag->clear; > + > + if (s) > + seq_printf(st->seq, " %s", s); > + } > +} > + > +static void dump_addr(struct pg_state *st, unsigned long addr) > +{ > + static const char units[] = "KMGTPE"; > + const char *unit = units; > + unsigned long delta; > + > + seq_printf(st->seq, "0x%016lx-0x%016lx ", st->start_address, addr-1); > + delta = (addr - st->start_address) >> 10; > + /* Work out what appropriate unit to use */ > + while (!(delta & 1023) && unit[1]) { 1023, I think ((1 << 10) - 1) is easier to understand but again you may find a better way of encapsulating this > + delta >>= 10; > + unit++; > + } > + seq_printf(st->seq, "%9lu%c", delta, *unit); > + > +} > + > +static void note_page(struct pg_state *st, unsigned long addr, unsigned level, > + u64 val) > +{ > + u64 flag = val & pg_level[level].mask; > + > + /* At first no level is set */ > + if (!st->level) { > + st->level = level; > + st->current_flags = flag; > + st->start_address = addr; > + seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); > + /* > + * Dump the section of virtual memory when: > + * - the PTE flags from one entry to the next differs. > + * - we change levels in the tree. > + * - the address is in a different section of memory and is thus > + * used for a different purpose, regardless of the flags. > + */ > + } else if (flag != st->current_flags || level != st->level || > + addr >= st->marker[1].start_address) { > + > + /* Check the PTE flags */ > + if (st->current_flags) { > + dump_addr(st, addr); > + > + /* Dump all the flags */ > + if (pg_level[st->level].flag) > + dump_flag(st, pg_level[st->level].flag, > + pg_level[st->level].num); > + seq_puts(st->seq, "\n"); > + } > + > + /* Address indicates we have passed the end of the > + * current section of virtual memory > + */ > + while (addr >= st->marker[1].start_address) { > + st->marker++; > + seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); > + } > + st->start_address = addr; > + st->current_flags = flag; > + st->level = level; > + } > +} > + > +static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start) > +{ > + pte_t *pte = pte_offset_kernel(pmd, 0); > + unsigned long addr; > + unsigned i; > + > + for (i = 0; i < PTRS_PER_PTE; i++, pte++) { > + addr = start + i * PAGE_SIZE; > + note_page(st, addr, 4, pte_val(*pte)); > + } > +} > + > +static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start) > +{ > + pmd_t *pmd = pmd_offset(pud, 0); > + unsigned long addr; > + unsigned i; > + > + for (i = 0; i < PTRS_PER_PMD; i++, pmd++) { > + addr = start + i * PMD_SIZE; > + if (!pmd_none(*pmd)) > + /* pmd exists */ > + walk_pte(st, pmd, addr); > + else > + note_page(st, addr, 3, pmd_val(*pmd)); > + } > +} > + > +static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start) > +{ > + pud_t *pud = pud_offset(pgd, 0); > + unsigned long addr; > + unsigned i; > + > + for (i = 0; i < PTRS_PER_PUD; i++, pud++) { > + addr = start + i * PUD_SIZE; > + if (!pud_none(*pud)) > + /* pud exists */ > + walk_pmd(st, pud, addr); > + else > + note_page(st, addr, 2, pud_val(*pud)); > + } > +} > + > +static void walk_pgd(struct pg_state *st, unsigned long start) > +{ > + pgd_t *pgd = pgd_offset_k(0UL); > + unsigned i; > + unsigned long addr; > + > + for (i = 0; i < PTRS_PER_PGD; i++, pgd++) { > + addr = start + i * PGDIR_SIZE; > + if (!pgd_none(*pgd)) > + /* pgd exists */ > + walk_pud(st, pgd, addr); > + else > + note_page(st, addr, 1, pgd_val(*pgd)); > + } > +} > + > +static int ptdump_show(struct seq_file *m, void *v) > +{ > + struct pg_state st = { > + .seq = m, > + .start_address = KERN_VIRT_START, > + .marker = address_markers, > + }; > + /* Traverse kernel page tables */ > + walk_pgd(&st, KERN_VIRT_START); > + note_page(&st, 0, 0, 0); > + return 0; > +} > + > +static int ptdump_open(struct inode *inode, struct file *file) > +{ > + return single_open(file, ptdump_show, NULL); > +} > + > +static const struct file_operations ptdump_fops = { > + .open = ptdump_open, > + .read = seq_read, > + .llseek = seq_lseek, > + .release = single_release, > +}; > + > +static void build_pgtable_complete_mask(void) > +{ > + unsigned i, j; > + > + for (i = 0; i < ARRAY_SIZE(pg_level); i++) > + if (pg_level[i].flag) > + for (j = 0; j < pg_level[i].num; j++) > + pg_level[i].mask |= pg_level[i].flag[j].mask; > +} > + > +static int ptdump_init(void) > +{ > + struct dentry *debugfs_file; > + > + build_pgtable_complete_mask(); > + debugfs_file = debugfs_create_file("kernel_pagetables", 0400, NULL, > + NULL, &ptdump_fops); > + return debugfs_file ? 0 : -ENOMEM; > +} > +device_initcall(ptdump_init);
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug index 638f9ce740f5..26a60effea1a 100644 --- a/arch/powerpc/Kconfig.debug +++ b/arch/powerpc/Kconfig.debug @@ -344,4 +344,16 @@ config FAIL_IOMMU If you are unsure, say N. +config PPC_PTDUMP + bool "Export kernel pagetable layout to userspace via debugfs" + depends on DEBUG_KERNEL + select DEBUG_FS + help + This option exports the state of the kernel pagetables to a + debugfs file. This is only useful for kernel developers who are + working in architecture specific areas of the kernel - probably + not a good idea to enable this feature in a production kernel. + + If you are unsure, say N. + endmenu diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile index adfee3f1aeb9..6935c6204fbc 100644 --- a/arch/powerpc/mm/Makefile +++ b/arch/powerpc/mm/Makefile @@ -41,3 +41,4 @@ obj-$(CONFIG_NOT_COHERENT_CACHE) += dma-noncoherent.o obj-$(CONFIG_HIGHMEM) += highmem.o obj-$(CONFIG_PPC_COPRO_BASE) += copro_fault.o obj-$(CONFIG_SPAPR_TCE_IOMMU) += mmu_context_iommu.o +obj-$(CONFIG_PPC_PTDUMP) += dump_linuxpagetables.o diff --git a/arch/powerpc/mm/dump_linuxpagetables.c b/arch/powerpc/mm/dump_linuxpagetables.c new file mode 100644 index 000000000000..f97fbfdac4b9 --- /dev/null +++ b/arch/powerpc/mm/dump_linuxpagetables.c @@ -0,0 +1,377 @@ +/* + * Copyright 2016, Rashmica Gupta, IBM Corp. + * + * This traverses the kernel pagetables and dumps the + * information about the used sections of memory to + * /sys/kernel/debug/kernel_pagetables. + * + * Derived from the arm64 implementation: + * Copyright (c) 2014, The Linux Foundation, Laura Abbott. + * (C) Copyright 2008 Intel Corporation, Arjan van de Ven. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; version 2 + * of the License. + */ +#include <linux/debugfs.h> +#include <linux/fs.h> +#include <linux/io.h> +#include <linux/mm.h> +#include <linux/sched.h> +#include <linux/seq_file.h> +#include <asm/fixmap.h> +#include <asm/pgtable.h> +#include <linux/const.h> +#include <asm/page.h> +#include <asm/pgalloc.h> + +struct addr_marker { + unsigned long start_address; + const char *name; +}; + +static struct addr_marker address_markers[] = { + { VMALLOC_START, "vmalloc() Area" }, + { VMALLOC_END, "vmalloc() End" }, + { ISA_IO_BASE, "isa I/O start" }, + { ISA_IO_END, "isa I/O end" }, + { PHB_IO_BASE, "phb I/O start" }, + { PHB_IO_END, "phb I/O end" }, + { IOREMAP_BASE, "I/O remap start" }, + { IOREMAP_END, "I/O remap end" }, + { -1, NULL }, +}; + +/* + * To visualise what is happening, + * + * - PTRS_PER_P** = how many entries there are in the corresponding P** + * - P**_SHIFT = how many bits of the address we use to index into the + * corresponding P** + * - P**_SIZE is how much memory we can access through the table - not the + * size of the table itself. + * P**={PGD, PUD, PMD, PTE} + * + * + * Each entry of the PGD points to a PUD. Each entry of a PUD points to a + * PMD. Each entry of a PMD points to a PTE. And every PTE entry points to + * a page. + * + * In the case where there are only 3 levels, the PUD is folded into the + * PGD: every PUD has only one entry which points to the PMD. + * + * 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 - ie PTEs that are virtually contiguous + * with the same PTE flags are chunked together. This is to make it clear how + * different areas of the kernel virtual memory are used. + * + */ +struct pg_state { + struct seq_file *seq; + const struct addr_marker *marker; + unsigned long start_address; + unsigned level; + u64 current_flags; +}; + +struct flag_info { + u64 mask; + u64 val; + const char *set; + const char *clear; +}; + +static const struct flag_info flag_array[] = { + { + .mask = _PAGE_USER, + .val = _PAGE_USER, + .set = "user", + .clear = " ", + }, { + .mask = _PAGE_RW, + .val = _PAGE_RW, + .set = "rw", + .clear = "ro", + }, { + .mask = _PAGE_EXEC, + .val = _PAGE_EXEC, + .set = " X ", + .clear = " ", + }, { + .mask = _PAGE_PTE, + .val = _PAGE_PTE, + .set = "pte", + .clear = " ", + }, { + .mask = _PAGE_PRESENT, + .val = _PAGE_PRESENT, + .set = "present", + .clear = " ", + }, { + .mask = _PAGE_HASHPTE, + .val = _PAGE_HASHPTE, + .set = "hpte", + .clear = " ", + }, { + .mask = _PAGE_GUARDED, + .val = _PAGE_GUARDED, + .set = "guarded", + .clear = " ", + }, { + .mask = _PAGE_DIRTY, + .val = _PAGE_DIRTY, + .set = "dirty", + .clear = " ", + }, { + .mask = _PAGE_ACCESSED, + .val = _PAGE_ACCESSED, + .set = "accessed", + .clear = " ", + }, { + .mask = _PAGE_WRITETHRU, + .val = _PAGE_WRITETHRU, + .set = "write through", + .clear = " ", + }, { + .mask = _PAGE_NO_CACHE, + .val = _PAGE_NO_CACHE, + .set = "no cache", + .clear = " ", + }, { + .mask = _PAGE_BUSY, + .val = _PAGE_BUSY, + .set = "busy", + }, { + .mask = _PAGE_COMBO, + .val = _PAGE_COMBO, + .set = "combo", + }, { + .mask = _PAGE_F_GIX, + .val = _PAGE_F_GIX, + .set = "f_gix", + }, { + .mask = _PAGE_F_SECOND, + .val = _PAGE_F_SECOND, + .set = "f_second", + }, { + .mask = _PAGE_SPECIAL, + .val = _PAGE_SPECIAL, + .set = "special", + }, { + .mask = _PAGE_4K_PFN, + .val = _PAGE_4K_PFN, + .set = "4K_pfn" + } +}; + +struct pgtable_level { + const struct flag_info *flag; + size_t num; + u64 mask; +}; + +static struct pgtable_level pg_level[] = { + { + }, { /* pgd */ + .flag = flag_array, + .num = ARRAY_SIZE(flag_array), + }, { /* pud */ + .flag = flag_array, + .num = ARRAY_SIZE(flag_array), + }, { /* pmd */ + .flag = flag_array, + .num = ARRAY_SIZE(flag_array), + }, { /* pte */ + .flag = flag_array, + .num = ARRAY_SIZE(flag_array), + }, +}; + +static void dump_flag(struct pg_state *st, const struct flag_info *flag, + size_t num) +{ + unsigned i; + + for (i = 0; i < num; i++, flag++) { + const char *s; + + if ((st->current_flags & flag->mask) == flag->val) + s = flag->set; + else + s = flag->clear; + + if (s) + seq_printf(st->seq, " %s", s); + } +} + +static void dump_addr(struct pg_state *st, unsigned long addr) +{ + static const char units[] = "KMGTPE"; + const char *unit = units; + unsigned long delta; + + seq_printf(st->seq, "0x%016lx-0x%016lx ", st->start_address, addr-1); + delta = (addr - st->start_address) >> 10; + /* Work out what appropriate unit to use */ + while (!(delta & 1023) && unit[1]) { + delta >>= 10; + unit++; + } + seq_printf(st->seq, "%9lu%c", delta, *unit); + +} + +static void note_page(struct pg_state *st, unsigned long addr, unsigned level, + u64 val) +{ + u64 flag = val & pg_level[level].mask; + + /* At first no level is set */ + if (!st->level) { + st->level = level; + st->current_flags = flag; + st->start_address = addr; + seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); + /* + * Dump the section of virtual memory when: + * - the PTE flags from one entry to the next differs. + * - we change levels in the tree. + * - the address is in a different section of memory and is thus + * used for a different purpose, regardless of the flags. + */ + } else if (flag != st->current_flags || level != st->level || + addr >= st->marker[1].start_address) { + + /* Check the PTE flags */ + if (st->current_flags) { + dump_addr(st, addr); + + /* Dump all the flags */ + if (pg_level[st->level].flag) + dump_flag(st, pg_level[st->level].flag, + pg_level[st->level].num); + seq_puts(st->seq, "\n"); + } + + /* Address indicates we have passed the end of the + * current section of virtual memory + */ + while (addr >= st->marker[1].start_address) { + st->marker++; + seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); + } + st->start_address = addr; + st->current_flags = flag; + st->level = level; + } +} + +static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start) +{ + pte_t *pte = pte_offset_kernel(pmd, 0); + unsigned long addr; + unsigned i; + + for (i = 0; i < PTRS_PER_PTE; i++, pte++) { + addr = start + i * PAGE_SIZE; + note_page(st, addr, 4, pte_val(*pte)); + } +} + +static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start) +{ + pmd_t *pmd = pmd_offset(pud, 0); + unsigned long addr; + unsigned i; + + for (i = 0; i < PTRS_PER_PMD; i++, pmd++) { + addr = start + i * PMD_SIZE; + if (!pmd_none(*pmd)) + /* pmd exists */ + walk_pte(st, pmd, addr); + else + note_page(st, addr, 3, pmd_val(*pmd)); + } +} + +static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start) +{ + pud_t *pud = pud_offset(pgd, 0); + unsigned long addr; + unsigned i; + + for (i = 0; i < PTRS_PER_PUD; i++, pud++) { + addr = start + i * PUD_SIZE; + if (!pud_none(*pud)) + /* pud exists */ + walk_pmd(st, pud, addr); + else + note_page(st, addr, 2, pud_val(*pud)); + } +} + +static void walk_pgd(struct pg_state *st, unsigned long start) +{ + pgd_t *pgd = pgd_offset_k(0UL); + unsigned i; + unsigned long addr; + + for (i = 0; i < PTRS_PER_PGD; i++, pgd++) { + addr = start + i * PGDIR_SIZE; + if (!pgd_none(*pgd)) + /* pgd exists */ + walk_pud(st, pgd, addr); + else + note_page(st, addr, 1, pgd_val(*pgd)); + } +} + +static int ptdump_show(struct seq_file *m, void *v) +{ + struct pg_state st = { + .seq = m, + .start_address = KERN_VIRT_START, + .marker = address_markers, + }; + /* Traverse kernel page tables */ + walk_pgd(&st, KERN_VIRT_START); + note_page(&st, 0, 0, 0); + return 0; +} + +static int ptdump_open(struct inode *inode, struct file *file) +{ + return single_open(file, ptdump_show, NULL); +} + +static const struct file_operations ptdump_fops = { + .open = ptdump_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +static void build_pgtable_complete_mask(void) +{ + unsigned i, j; + + for (i = 0; i < ARRAY_SIZE(pg_level); i++) + if (pg_level[i].flag) + for (j = 0; j < pg_level[i].num; j++) + pg_level[i].mask |= pg_level[i].flag[j].mask; +} + +static int ptdump_init(void) +{ + struct dentry *debugfs_file; + + build_pgtable_complete_mask(); + debugfs_file = debugfs_create_file("kernel_pagetables", 0400, NULL, + NULL, &ptdump_fops); + return debugfs_file ? 0 : -ENOMEM; +} +device_initcall(ptdump_init);
Useful to be able to dump the kernels page tables to check permissions and memory types - derived from arm64's implementation. Add a debugfs file to check the page tables. To use this the PPC_PTDUMP config option must be selected. Signed-off-by: Rashmica Gupta <rashmicy@gmail.com> --- arch/powerpc/Kconfig.debug | 12 ++ arch/powerpc/mm/Makefile | 1 + arch/powerpc/mm/dump_linuxpagetables.c | 377 +++++++++++++++++++++++++++++++++ 3 files changed, 390 insertions(+) create mode 100644 arch/powerpc/mm/dump_linuxpagetables.c