Re: [PATCH 1/2] powerpc/pagetable: Add option to dump the linux pagetables

[Balbir Singh]

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 
> ---
>  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 

>  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 ..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 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +
> +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   

[v2 PATCH 1/2] powerpc/pagetable: Add option to dump the linux pagetables

[Rashmica Gupta]

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 
---
Do not check for COMBO pages if default page size is 4K.

 arch/powerpc/Kconfig.debug |  12 +
 arch/powerpc/mm/Makefile   |   1 +
 arch/powerpc/mm/dump_linuxpagetables.c | 398 +
 3 files changed, 411 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.
+
 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 ..566ae4487a19
--- /dev/null
+++ b/arch/powerpc/mm/dump_linuxpagetables.c
@@ -0,0 +1,398 @@
+/*
+ * 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 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+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;
+   boolis_val;
+   int shift;
+};
+
+static const struct flag_info flag_array[] = {
+   {
+   .mask   = _PAGE_USER,
+   .val= _PAGE_USER,
+   

Re: [PATCH 1/2] powerpc/pagetable: Add option to dump the linux pagetables

[kbuild test robot]

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 infrastructureOpen Source Technology Center
https://lists.01.org/pipermail/kbuild-all   Intel Corporation


.config.gz
Description: Binary data
___
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev

[PATCH 1/2] powerpc/pagetable: Add option to dump the linux pagetables

[Rashmica Gupta]

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 
---
 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.
+
 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 ..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 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+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,
+