Re: [PATCHv3 1/4] arm64: dump: Make ptdump debugfs a separate option

[Ard Biesheuvel]

On 18 October 2016 at 23:01, Laura Abbott <labbott@xxxxxxxxxx> wrote:
>
> ptdump_register currently initializes a set of page table information and
> registers debugfs. There are uses for the ptdump option without wanting the
> debugfs options. Split this out to make it a separate option.
>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx>
> Tested-by: Mark Rutland <mark.rutland@xxxxxxx>
> Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
> ---
> v3: Minor header guard fixup.
>
> Mark Rutland pointed out that this needs to be reviewed by the EFI maintainers
> so I'm explicitly adding appropriate people/lists.

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>

> ---
>  arch/arm64/Kconfig.debug           |  6 +++++-
>  arch/arm64/include/asm/ptdump.h    | 15 +++++++++------
>  arch/arm64/mm/Makefile             |  3 ++-
>  arch/arm64/mm/dump.c               | 26 +++++---------------------
>  arch/arm64/mm/ptdump_debugfs.c     | 31 +++++++++++++++++++++++++++++++
>  drivers/firmware/efi/arm-runtime.c |  4 ++--
>  6 files changed, 54 insertions(+), 31 deletions(-)
>  create mode 100644 arch/arm64/mm/ptdump_debugfs.c
>
> diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
> index b661fe7..21a5b74 100644
> --- a/arch/arm64/Kconfig.debug
> +++ b/arch/arm64/Kconfig.debug
> @@ -2,9 +2,13 @@ menu "Kernel hacking"
>
>  source "lib/Kconfig.debug"
>
> -config ARM64_PTDUMP
> +config ARM64_PTDUMP_CORE
> +       def_bool n
> +
> +config ARM64_PTDUMP_DEBUGFS
>         bool "Export kernel pagetable layout to userspace via debugfs"
>         depends on DEBUG_KERNEL
> +       select ARM64_PTDUMP_CORE
>         select DEBUG_FS
>          help
>           Say Y here if you want to show the kernel pagetable layout in a
> diff --git a/arch/arm64/include/asm/ptdump.h b/arch/arm64/include/asm/ptdump.h
> index 07b8ed0..16335da 100644
> --- a/arch/arm64/include/asm/ptdump.h
> +++ b/arch/arm64/include/asm/ptdump.h
> @@ -16,9 +16,10 @@
>  #ifndef __ASM_PTDUMP_H
>  #define __ASM_PTDUMP_H
>
> -#ifdef CONFIG_ARM64_PTDUMP
> +#ifdef CONFIG_ARM64_PTDUMP_CORE
>
>  #include <linux/mm_types.h>
> +#include <linux/seq_file.h>
>
>  struct addr_marker {
>         unsigned long start_address;
> @@ -32,13 +33,15 @@ struct ptdump_info {
>         unsigned long                   max_addr;
>  };
>
> -int ptdump_register(struct ptdump_info *info, const char *name);
> -
> +void ptdump_walk_pgd(struct seq_file *s, struct ptdump_info *info);
> +#ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
> +int ptdump_debugfs_register(struct ptdump_info *info, const char *name);
>  #else
> -static inline int ptdump_register(struct ptdump_info *info, const char *name)
> +static inline int ptdump_debugfs_register(struct ptdump_info *info,
> +                                       const char *name)
>  {
>         return 0;
>  }
> -#endif /* CONFIG_ARM64_PTDUMP */
> -
> +#endif
> +#endif /* CONFIG_ARM64_PTDUMP_CORE */
>  #endif /* __ASM_PTDUMP_H */
> diff --git a/arch/arm64/mm/Makefile b/arch/arm64/mm/Makefile
> index 54bb209..e703fb9 100644
> --- a/arch/arm64/mm/Makefile
> +++ b/arch/arm64/mm/Makefile
> @@ -3,7 +3,8 @@ obj-y                           := dma-mapping.o extable.o fault.o init.o \
>                                    ioremap.o mmap.o pgd.o mmu.o \
>                                    context.o proc.o pageattr.o
>  obj-$(CONFIG_HUGETLB_PAGE)     += hugetlbpage.o
> -obj-$(CONFIG_ARM64_PTDUMP)     += dump.o
> +obj-$(CONFIG_ARM64_PTDUMP_CORE)        += dump.o
> +obj-$(CONFIG_ARM64_PTDUMP_DEBUGFS)     += ptdump_debugfs.o
>  obj-$(CONFIG_NUMA)             += numa.o
>
>  obj-$(CONFIG_KASAN)            += kasan_init.o
> diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
> index 9c3e75d..f0f0be7 100644
> --- a/arch/arm64/mm/dump.c
> +++ b/arch/arm64/mm/dump.c
> @@ -304,9 +304,8 @@ static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
>         }
>  }
>
> -static int ptdump_show(struct seq_file *m, void *v)
> +void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)
>  {
> -       struct ptdump_info *info = m->private;
>         struct pg_state st = {
>                 .seq = m,
>                 .marker = info->markers,
> @@ -315,33 +314,16 @@ static int ptdump_show(struct seq_file *m, void *v)
>         walk_pgd(&st, info->mm, info->base_addr);
>
>         note_page(&st, 0, 0, 0);
> -       return 0;
>  }
>
> -static int ptdump_open(struct inode *inode, struct file *file)
> +static void ptdump_initialize(void)
>  {
> -       return single_open(file, ptdump_show, inode->i_private);
> -}
> -
> -static const struct file_operations ptdump_fops = {
> -       .open           = ptdump_open,
> -       .read           = seq_read,
> -       .llseek         = seq_lseek,
> -       .release        = single_release,
> -};
> -
> -int ptdump_register(struct ptdump_info *info, const char *name)
> -{
> -       struct dentry *pe;
>         unsigned i, j;
>
>         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
>                 if (pg_level[i].bits)
>                         for (j = 0; j < pg_level[i].num; j++)
>                                 pg_level[i].mask |= pg_level[i].bits[j].mask;
> -
> -       pe = debugfs_create_file(name, 0400, NULL, info, &ptdump_fops);
> -       return pe ? 0 : -ENOMEM;
>  }
>
>  static struct ptdump_info kernel_ptdump_info = {
> @@ -352,6 +334,8 @@ static struct ptdump_info kernel_ptdump_info = {
>
>  static int ptdump_init(void)
>  {
> -       return ptdump_register(&kernel_ptdump_info, "kernel_page_tables");
> +       ptdump_initialize();
> +       return ptdump_debugfs_register(&kernel_ptdump_info,
> +                                       "kernel_page_tables");
>  }
>  device_initcall(ptdump_init);
> diff --git a/arch/arm64/mm/ptdump_debugfs.c b/arch/arm64/mm/ptdump_debugfs.c
> new file mode 100644
> index 0000000..eee4d86
> --- /dev/null
> +++ b/arch/arm64/mm/ptdump_debugfs.c
> @@ -0,0 +1,31 @@
> +#include <linux/debugfs.h>
> +#include <linux/seq_file.h>
> +
> +#include <asm/ptdump.h>
> +
> +static int ptdump_show(struct seq_file *m, void *v)
> +{
> +       struct ptdump_info *info = m->private;
> +       ptdump_walk_pgd(m, info);
> +       return 0;
> +}
> +
> +static int ptdump_open(struct inode *inode, struct file *file)
> +{
> +       return single_open(file, ptdump_show, inode->i_private);
> +}
> +
> +static const struct file_operations ptdump_fops = {
> +       .open           = ptdump_open,
> +       .read           = seq_read,
> +       .llseek         = seq_lseek,
> +       .release        = single_release,
> +};
> +
> +int ptdump_debugfs_register(struct ptdump_info *info, const char *name)
> +{
> +       struct dentry *pe;
> +       pe = debugfs_create_file(name, 0400, NULL, info, &ptdump_fops);
> +       return pe ? 0 : -ENOMEM;
> +
> +}
> diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
> index 7c75a8d..349dc3e 100644
> --- a/drivers/firmware/efi/arm-runtime.c
> +++ b/drivers/firmware/efi/arm-runtime.c
> @@ -39,7 +39,7 @@ static struct mm_struct efi_mm = {
>         .mmlist                 = LIST_HEAD_INIT(efi_mm.mmlist),
>  };
>
> -#ifdef CONFIG_ARM64_PTDUMP
> +#ifdef CONFIG_ARM64_PTDUMP_DEBUGFS
>  #include <asm/ptdump.h>
>
>  static struct ptdump_info efi_ptdump_info = {
> @@ -53,7 +53,7 @@ static struct ptdump_info efi_ptdump_info = {
>
>  static int __init ptdump_init(void)
>  {
> -       return ptdump_register(&efi_ptdump_info, "efi_page_tables");
> +       return ptdump_debugfs_register(&efi_ptdump_info, "efi_page_tables");
>  }
>  device_initcall(ptdump_init);
>
> --
> 2.7.4
>