On 12/04/2014 10:10 PM, Dmitry Vyukov wrote:
> On Wed, Dec 3, 2014 at 9:19 AM, Andrey Ryabinin <a.ryabi...@samsung.com>
> wrote:
>> On 12/02/2014 08:56 PM, Dmitry Vyukov wrote:
>>> Hi,
>>>
>>> The following patch adds support for instrumentation of globals for
>>> Linux kernel (-fsanitize=kernel-address). Kernel only supports
>>> constructors with default priority, but the rest works fine.
>>>
>>> OK for trunk?
>>>
>>
>> I know this is too late already, but why we need this?
>> IMO it's much better to add support for constructors with priorities in
>> kernel.
>>
>> We need to do this in kernel anyway, because GCC 4.9.2 don't have this patch
>> and
>> I assume that we want to make instrumentation of globals work in kernel with
>> 4.9.2
>
>
> That would be an option too. I don't know whether it is much better or not.
> Kernel lives without constructors, they are used only by coverage. And
> coverage does not need priorities. So it is only kasan that needs
> priorities. That would be a plenty of code in lib/module.c only for
> kasan...
It will be a very little piece of code. I don't think that it will be a problem
Perhaps, I'll cook a patch today.
>
> Meanwhile here is backport to 4.9. Applied w/o conflicts (not counting
> ChangeLog).
>
> OK to commit to gcc.gnu.org/svn/gcc/branches/gcc-4_9-branch ?
>
>
>
> Index: gcc/ChangeLog
> ===================================================================
> --- gcc/ChangeLog (revision 218382)
> +++ gcc/ChangeLog (working copy)
> @@ -1,3 +1,8 @@
> +2014-12-04 Dmitry Vyukov <dvyu...@google.com>
> +
> + * asan.c: (asan_finish_file): Use default priority for constructors
> + in kernel mode.
> +
> 2014-12-04 Jakub Jelinek <ja...@redhat.com>
>
> PR c++/56493
> Index: gcc/asan.c
> ===================================================================
> --- gcc/asan.c (revision 218382)
> +++ gcc/asan.c (working copy)
> @@ -1295,7 +1295,9 @@
> the var that is selected by the linker will have
> padding or not. */
> || DECL_ONE_ONLY (decl)
> - /* Similarly for common vars. People can use -fno-common. */
> + /* Similarly for common vars. People can use -fno-common.
> + Note: Linux kernel is built with -fno-common, so we do instrument
> + globals there even if it is C. */
> || (DECL_COMMON (decl) && TREE_PUBLIC (decl))
> /* Don't protect if using user section, often vars placed
> into user section from multiple TUs are then assumed
> @@ -2383,6 +2385,13 @@
> nor after .LASAN* array. */
> flag_sanitize &= ~SANITIZE_ADDRESS;
>
> + /* For user-space we want asan constructors to run first.
> + Linux kernel does not support priorities other than default, and the
> only
> + other user of constructors is coverage. So we run with the default
> + priority. */
> + int priority = flag_sanitize & SANITIZE_USER_ADDRESS
> + ? MAX_RESERVED_INIT_PRIORITY - 1 : DEFAULT_INIT_PRIORITY;
> +
> if (flag_sanitize & SANITIZE_USER_ADDRESS)
> {
> tree fn = builtin_decl_implicit (BUILT_IN_ASAN_INIT);
> @@ -2436,12 +2445,10 @@
> build_fold_addr_expr (var),
> gcount_tree),
> &dtor_statements);
> - cgraph_build_static_cdtor ('D', dtor_statements,
> - MAX_RESERVED_INIT_PRIORITY - 1);
> + cgraph_build_static_cdtor ('D', dtor_statements, priority);
> }
> if (asan_ctor_statements)
> - cgraph_build_static_cdtor ('I', asan_ctor_statements,
> - MAX_RESERVED_INIT_PRIORITY - 1);
> + cgraph_build_static_cdtor ('I', asan_ctor_statements, priority);
> flag_sanitize |= SANITIZE_ADDRESS;
> }
>
