On Mon, Jul 30, 2012 at 02:30:03PM -0700, Stephen Boyd wrote:
> Add the ARM machine identifier to sortextable and select the
> config option so that we can sort the exception table at compile
> time. sortextable relies on a section named __ex_table existing
> in the vmlinux, but ARM's linker script places the exception
> table in the data section. Give the exception table its own
> section so that sortextable can find it.
>
> This allows us to skip the runtime sorting step during boot.
>
> Signed-off-by: Stephen Boyd <sb...@codeaurora.org>
> Cc: David Daney <david.da...@cavium.com>
> ---
>
> I can't find any information on why the exception table lives in the data
> section. If there's a good reason for that, I'll look into changing
> sortextable to look for the __start___ex_table symbol.
>
> arch/arm/Kconfig | 1 +
> arch/arm/kernel/vmlinux.lds.S | 19 +++++++++----------
> scripts/sortextable.c | 1 +
> 3 files changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index b25c9d3..2af95e6 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1,6 +1,7 @@
> config ARM
> bool
> default y
> + select BUILDTIME_EXTABLE_SORT if MMU
> select ARCH_HAVE_CUSTOM_GPIO_H
> select HAVE_AOUT
> select HAVE_DMA_API_DEBUG
> diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
> index 36ff15b..0e3e8b4 100644
> --- a/arch/arm/kernel/vmlinux.lds.S
> +++ b/arch/arm/kernel/vmlinux.lds.S
> @@ -220,16 +220,6 @@ SECTIONS
> READ_MOSTLY_DATA(L1_CACHE_BYTES)
>
> /*
> - * The exception fixup table (might need resorting at runtime)
> - */
> - . = ALIGN(4);
> - __start___ex_table = .;
> -#ifdef CONFIG_MMU
> - *(__ex_table)
> -#endif
> - __stop___ex_table = .;
> -
> - /*
> * and the usual data section
> */
> DATA_DATA
> @@ -239,6 +229,15 @@ SECTIONS
> }
> _edata_loc = __data_loc + SIZEOF(.data);
>
> + . = ALIGN(4);
> + __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
> + __start___ex_table = .;
> +#ifdef CONFIG_MMU
> + *(__ex_table)
> +#endif
> + __stop___ex_table = .;
> + }
> +
Here you should be able to use the macro EXCEPTION_TABLE from
vmlinux.lds.h.
I cannot see why the ifdef for not NON-MMU case is needed,
but if it is needed the macro is not good...
Sam
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