2016-06-23 19:06 GMT+03:00 Dmitry Vyukov <dvyukov@xxxxxxxxxx>:
Subsystem prefix in subject is wrong. Change it to vmlinux.lds
> If CONFIG_KASAN is enabled and gcc is configured with
> --disable-initfini-array, 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:
As far as I found out this happens if gold linker has been used.
Gcc configuration is irrelevant here.
> 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@xxxxxxxxxx>
>
> ---
>
> Changes since v1:
> - discard .dtors
> - don't define .mem sections
> ---
> include/asm-generic/vmlinux.lds.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index 6a67ab9..081d0f2 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -542,15 +542,19 @@
>
> #define INIT_TEXT \
> *(.init.text) \
> + *(.text.startup) \
> MEM_DISCARD(init.text)
>
> #define EXIT_DATA \
> *(.exit.data) \
> + *(.fini_array) \
> + *(.dtors) \
> MEM_DISCARD(exit.data) \
> MEM_DISCARD(exit.rodata)
>
> #define EXIT_TEXT \
> *(.exit.text) \
> + *(.text.exit) \
> MEM_DISCARD(exit.text)
>
> #define EXIT_CALL \
> --
> 2.8.0.rc3.226.g39d4020
>
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