Re: + vmlinuxldsh-gather-datashared_aligned-sections-in-data_data.patch added to -mm tree

[Greg Ungerer <gerg@snapgear.com>]

On 19/10/10 09:57, akpm@linux-foundation.org wrote:
> The patch titled
>       vmlinux.lds.h: gather .data..shared_aligned sections in DATA_DATA
> has been added to the -mm tree.  Its filename is
>       vmlinuxldsh-gather-datashared_aligned-sections-in-data_data.patch
>
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>
> *** Remember to use Documentation/SubmitChecklist when testing your code ***
>
> See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
> out what to do about this
>
> The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
>
> ------------------------------------------------------
> Subject: vmlinux.lds.h: gather .data..shared_aligned sections in DATA_DATA
> From: Mike Frysinger<vapier@gentoo.org>
>
> With the recent change "net: remove time limit in process_backlog()", the
> softnet_data variable changed from "DEFINE_PER_CPU()" to
> "DEFINE_PER_CPU_ALIGNED()" which moved it from the .data section to the
> .data.shared_align section.  I'm not saying this patch is wrong, just that
> is what caused me to notice this larger problem.  No one else in the
> kernel is using this aligned macro variant, so I imagine that's why no one
> has noticed yet.
>
> Since .data.shared_align isnt declared in any vmlinux files that I can

It is in arch/m68knommu/kernel/vmlinux.lds.S, merged on 2010-09-07.
(I take it you mean .data..shared_align here though?)

Obviously I can back that out once this hits Linus' tree.

Regards
Greg



> see, the linker just places it last.  This "just works" for most
> people, but when building a ROM kernel on Blackfin systems, it causes
> section overlap errors:
> bfin-uclinux-ld.real:
> 	section .init.data [00000000202e06b8 ->  00000000202e48b7] overlaps
> 	section .data.shared_aligned [00000000202e06b8 ->  00000000202e0723]
> I imagine other arches which support the ROM config option and thus do
> funky placement would see similar issues ...
>
> On x86, it is stuck in a dedicated section at the end:
>   [8] .data             PROGBITS ffffffff810ec000 2ec0000303a8 00 WA 0 0 4096
>   [9] .data.shared_alig PROGBITS ffffffff8111c3c0 31c3c00000c8 00 WA 0 0 64
>
> So make sure we include this section in the DATA_DATA macro so that it is
> placed in the right location.
>
> Signed-off-by: Mike Frysinger<vapier@gentoo.org>
> Cc: Sam Ravnborg<sam@ravnborg.org>
> Cc: Jeremy Fitzhardinge<jeremy@xensource.com>
> Cc: Rusty Russell<rusty@rustcorp.com.au>
> Cc: Alan Jenkins<alan-jenkins@tuffmail.co.uk>
> Cc:<linux-arch@vger.kernel.org>
> Signed-off-by: Andrew Morton<akpm@linux-foundation.org>
> ---
>
>   include/asm-generic/vmlinux.lds.h |    1 +
>   1 file changed, 1 insertion(+)
>
> diff -puN include/asm-generic/vmlinux.lds.h~vmlinuxldsh-gather-datashared_aligned-sections-in-data_data include/asm-generic/vmlinux.lds.h
> --- a/include/asm-generic/vmlinux.lds.h~vmlinuxldsh-gather-datashared_aligned-sections-in-data_data
> +++ a/include/asm-generic/vmlinux.lds.h
> @@ -150,6 +150,7 @@
>   #define DATA_DATA							\
>   	*(.data)							\
>   	*(.ref.data)							\
> +	*(.data..shared_aligned) /* percpu related */			\
>   	DEV_KEEP(init.data)						\
>   	DEV_KEEP(exit.data)						\
>   	CPU_KEEP(init.data)						\
> _
>
> Patches currently in -mm which might be from vapier@gentoo.org are
>
> drivers-misc-ad525x_dpot-fix-typo-in-spi-write16-and-write24-transfer-counts.patch
> linux-next.patch
> m68knommu-blackfin-remove-old-assembler-only-flags-bit-definitions.patch
> vmlinuxldsh-gather-datashared_aligned-sections-in-data_data.patch
> drivers-misc-ad525x_dpot-fix-part-name-typos-in-defines.patch
> drivers-misc-ad525x_dpot-new-features.patch
> misc-devices-do-not-enable-by-default.patch
> rtc-bfin-shrink-optimize-interrupt-handler-a-bit.patch
> rtc-bfin-add-debug-markers-to-suspend-resume-paths.patch
> gpio-adp5588-gpio-support-interrupt-controller.patch
> gpio-adp5588-gpio-gpio_start-must-be-signed.patch
> ptrace-cleanup-arch_ptrace-and-friends-on-blackfin.patch
>
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