[PATCH v4] ARM: Thumb-2: Symbol manipulation macros for function body copying

[Jean Pihet]

Hi Dave,

On Mon, Jan 24, 2011 at 2:50 PM, Dave Martin <dave.martin at linaro.org> wrote:
> On Thu, Jan 20, 2011 at 9:42 AM, Dave Martin <dave.martin at linaro.org> wrote:
>> On Wed, Jan 19, 2011 at 10:29 PM, Kevin Hilman <khilman at ti.com> wrote:
>>> Dave Martin <dave.martin at linaro.org> writes:
>>>
>>>> In low-level board support code, there is sometimes a need to
>>>> copy a function body to another location at run-time.
>>>>
>>>> A straightforward call to memcpy doesn't work in Thumb-2,
>>>> because bit 0 of external Thumb function symbols is set to 1,
>>>> indicating that the function is Thumb.  Without corrective
>>>> measures, this will cause an off-by-one copy, and the copy
>>>> may be called using the wrong instruction set.
>>>>
>>>> This patch adds an fncpy() macro to help with such copies.
>>>>
>>>> Particular care is needed, because C doesn't guarantee any
>>>> defined behaviour when casting a function pointer to any other
>>>> type.  This has been observed to lead to strange optimisation
>>>> side-effects when doing the arithmetic which is required in
>>>> order to copy/move function bodies correctly in Thumb-2.
>>>>
>>>> Thanks to Russell King and Nicolas Pitre for their input
>>>> on this patch.
>>>>
>>>> Signed-off-by: Dave Martin <dave.martin at linaro.org>
>>>> Tested-by: Jean Pihet <j-pihet at ti.com>
>>>
>>> Tested-by: Kevin Hilman <khilman at ti.com>
>>>
>>> along with Jean's OMAP patch on:
>>>
>>> OMAP2420/n810: including basic suspend/resume test.
>>>
>>> OMAP16xx/OSK: boot test only.
>>>
>>> Kevin
>>>
>>
>> Thanks
>> ---Dave
>>
>
> Any more comments on this patch?
>
> I have no further changes so far.
Ok to me. The changes are now in the omap-testing branch of Tony's tree [1].

[1] http://git.kernel.org/?p=linux/kernel/git/tmlind/linux-omap-2.6.git;a=shortlog;h=refs/heads/omap-testing

Regards,
Jean

>
> Cheers
> ---Dave
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