Re: [PATCHv2 1/4] arm64: dump: Make ptdump debugfs a separate option
From: Kees Cook
Date: Wed Oct 12 2016 - 19:14:00 EST
On Wed, Oct 12, 2016 at 3:57 PM, Laura Abbott <labbott@xxxxxxxxxx> wrote:
> On 10/12/2016 03:45 PM, Kees Cook wrote:
>> On Wed, Oct 12, 2016 at 3:31 PM, 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
>>> debugfs options. Split this out to make it a separate option.
>>> Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
>>> v2: Minor style fixups per Mark Rutland, intialization is now separate
>>> register since it never needed to be combined in the first place, EFI
>>> page table registration.
>>> arch/arm64/Kconfig.debug | 6 +++++-
>>> arch/arm64/include/asm/ptdump.h | 13 ++++++++-----
>>> arch/arm64/mm/Makefile | 3 ++-
>>> arch/arm64/mm/dump.c | 26 +++++---------------------
>>> arch/arm64/mm/ptdump_debugfs.c | 31 +++++++++++++++++++++++++++++++
>>> drivers/firmware/efi/arm-runtime.c | 5 ++---
>>> 6 files changed, 53 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"
>> I think this can be a tristate now, yes? (I did this on x86 so I could
>> load ptdump as a module for Chrome OS image testing but then leave the
>> module off the read-only partition for release images...)
> I saw the module for x86. arm64 works slightly differently since there
> are multiple debugfs dumping sources, the init_mm and EFI page tables.
> These are built in and can call register but then have no way to
> actually register the debugfs entry when the module is inserted since
> the current config covers both/all of the exporters. I
> decided against trying to add the infrastructure to make modularity
> work because I was spending more time on that than the actual W^X checks.
Okay, sounds fine. I'll see if I can take a look at this in the future
if no one else beats me to it.
In the meantime, this whole series looks good to me. :)
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>