lkml.org 
[lkml]   [2014]   [Sep]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC/PATCH v2 02/10] x86_64: add KASan support
    Overall, the approach here looks pretty sane.  As you noted, it would be
    nice to keep PAGE_OFFSET in one place, but it's not a deal breaker for
    me. The use of the vmemmap code looks to be a nice fit.

    Few nits below.

    On 09/10/2014 07:31 AM, Andrey Ryabinin wrote:
    > 16TB of virtual addressed used for shadow memory.
    > It's located in range [0xffff800000000000 - 0xffff900000000000]
    > Therefore PAGE_OFFSET has to be changed from 0xffff880000000000
    > to 0xffff900000000000.
    ...
    > It would be nice to not have different PAGE_OFFSET with and without CONFIG_KASAN.
    > We have big enough hole between vmemmap and esp fixup stacks.
    > So how about moving all direct mapping, vmalloc and vmemmap 8TB up without
    > hiding it under CONFIG_KASAN?

    Is there a reason this has to be _below_ the linear map? Couldn't we
    just carve some space out of the vmalloc() area for the kasan area?


    > arch/x86/Kconfig | 1 +
    > arch/x86/boot/Makefile | 2 ++
    > arch/x86/boot/compressed/Makefile | 2 ++
    > arch/x86/include/asm/kasan.h | 20 ++++++++++++
    > arch/x86/include/asm/page_64_types.h | 4 +++
    > arch/x86/include/asm/pgtable.h | 7 ++++-
    > arch/x86/kernel/Makefile | 2 ++
    > arch/x86/kernel/dumpstack.c | 5 ++-
    > arch/x86/kernel/head64.c | 6 ++++
    > arch/x86/kernel/head_64.S | 16 ++++++++++
    > arch/x86/mm/Makefile | 3 ++
    > arch/x86/mm/init.c | 3 ++
    > arch/x86/mm/kasan_init_64.c | 59 ++++++++++++++++++++++++++++++++++++
    > arch/x86/realmode/Makefile | 2 +-
    > arch/x86/realmode/rm/Makefile | 1 +
    > arch/x86/vdso/Makefile | 1 +
    > include/linux/kasan.h | 3 ++
    > lib/Kconfig.kasan | 1 +
    > 18 files changed, 135 insertions(+), 3 deletions(-)
    > create mode 100644 arch/x86/include/asm/kasan.h
    > create mode 100644 arch/x86/mm/kasan_init_64.c

    This probably deserves an update of Documentation/x86/x86_64/mm.txt, too.

    > +void __init kasan_map_shadow(void)
    > +{
    > + int i;
    > +
    > + memcpy(early_level4_pgt, init_level4_pgt, 4096);
    > + load_cr3(early_level4_pgt);
    > +
    > + clear_zero_shadow_mapping(kasan_mem_to_shadow(PAGE_OFFSET),
    > + kasan_mem_to_shadow(0xffffc80000000000UL));

    This 0xffffc80000000000UL could be PAGE_OFFSET+MAXMEM.




    \
     
     \ /
      Last update: 2014-09-10 18:21    [W:3.166 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site