linux-kernel - Re: [PATCH v3] vmlinux.lds: account for destructor sections

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Date:	Fri, 1 Jul 2016 17:19:47 +0200
From:	Dmitry Vyukov <dvyukov@...gle.com>
To:	Andrey Ryabinin <ryabinin.a.a@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"x86@...nel.org" <x86@...nel.org>, Arnd Bergmann <arnd@...db.de>,
	linux-arch@...r.kernel.org, kasan-dev <kasan-dev@...glegroups.com>,
	Alexander Potapenko <glider@...gle.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] vmlinux.lds: account for destructor sections

On Fri, Jul 1, 2016 at 4:58 PM, Andrey Ryabinin <ryabinin.a.a@...il.com> wrote:
> 2016-06-29 20:28 GMT+03:00 Dmitry Vyukov <dvyukov@...gle.com>:
>> On Fri, Jun 24, 2016 at 6:57 PM, Andrey Ryabinin <ryabinin.a.a@...il.com> wrote:
>>> 2016-06-24 18:39 GMT+03:00 Dmitry Vyukov <dvyukov@...gle.com>:
>>>> If CONFIG_KASAN is enabled and gcc is configured with
>>>> --disable-initfini-array and/or gold linker is used,
>>>> gcc emits .ctors/.dtors and .text.startup/.text.exit
>>>> sections instead of .init_array/.fini_array.
>>>> .dtors section is not explicitly accounted in the linker
>>>> script and messes vvar/percpu layout. Want:
>>>>
>>>> ffffffff822bfd80 D _edata
>>>> ffffffff822c0000 D __vvar_beginning_hack
>>>> ffffffff822c0000 A __vvar_page
>>>> ffffffff822c0080 0000000000000098 D vsyscall_gtod_data
>>>> ffffffff822c1000 A __init_begin
>>>> ffffffff822c1000 D init_per_cpu__irq_stack_union
>>>> ffffffff822c1000 A __per_cpu_load
>>>> ffffffff822d3000 D init_per_cpu__gdt_page
>>>>
>>>> Got:
>>>>
>>>> ffffffff8279a600 D _edata
>>>> ffffffff8279b000 A __vvar_page
>>>> ffffffff8279c000 A __init_begin
>>>> ffffffff8279c000 D init_per_cpu__irq_stack_union
>>>> ffffffff8279c000 A __per_cpu_load
>>>> ffffffff8279e000 D __vvar_beginning_hack
>>>> ffffffff8279e080 0000000000000098 D vsyscall_gtod_data
>>>> ffffffff827ae000 D init_per_cpu__gdt_page
>>>>
>>>> This happens because __vvar_page and .vvar get different
>>>> addresses in arch/x86/kernel/vmlinux.lds.S:
>>>>
>>>>         . = ALIGN(PAGE_SIZE);
>>>>         __vvar_page = .;
>>>>
>>>>         .vvar : AT(ADDR(.vvar) - LOAD_OFFSET) {
>>>>                 /* work around gold bug 13023 */
>>>>                 __vvar_beginning_hack = .;
>>>>
>>>> Discard .dtors/.fini_array/.text.exit, since we don't call dtors.
>>>> Merge .text.startup into init text.
>>>>
>>>> Signed-off-by: Dmitry Vyukov <dvyukov@...gle.com>
>>>
>>> Reviewed-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
>>
>>
>> Who can take it to some tree?
>
> akpm tends to be the maintainer of last resort.
> But you probably need to resend the patch, because LKML was not in CC list.
> Also, please add stable tag: Cc: <stable@...r.kernel.org> # v4.0+

Remailed. Thanks.