diff options
author | Dave Martin <dave.martin@linaro.org> | 2011-01-26 12:34:26 -0500 |
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committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2011-01-27 06:48:58 -0500 |
commit | 5756e9dd0de6d5c307773f8f734c0684b3098fdd (patch) | |
tree | 4a92eded1b93fd91d2c40bc5bb5cb0405daeed79 /arch/x86/Makefile | |
parent | 6fb1b304255efc5c4c93874ac8c066272e257e28 (diff) |
ARM: 6640/1: Thumb-2: Symbol manipulation macros for function body copying
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@linaro.org>
Tested-by: Jean Pihet <j-pihet@ti.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/x86/Makefile')
0 files changed, 0 insertions, 0 deletions